• Crystal oven theory

    From bitrex@21:1/5 to All on Sat May 21 20:50:12 2022
    Here's a paper on the theory of crystal ovens:

    <http://www.karlquist.com/oven.pdf>

    There's a lot more to it than just slapping a crystal & heater in a
    metal box and calling it a day! There are probably some pathologically
    bad geometries even a really fast control loop can never stabilize very
    well.

    The part about the outer can acting like a Faraday shield is
    interesting, shunting ambient gradients around the core. Does anyone
    know how they make the negative space look like a linear tehrmal
    resistance over a wide range? There's some kind of insulating foam in
    there, is main heat thermal transfer radiative or conduction?

    I picked up an otherwise really nice HP 5334b frequency counter with
    both the 1.3 GHz input and OCXO options for a song. Unfortunately
    there's a fault somewhere inside the OCXO module and it outputs about
    1.8 MHz instead of 10...seems to be maybe a bad cap somewhere around the Colpitts section and the crystal and heater sections are OK.

    The heater transistors screws to the internal mass have to be re-torqued
    to spec if you mess with them, I didn't mess with 'em.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to bitrex on Sat May 21 21:46:10 2022
    bitrex wrote:
    Here's a paper on the theory of crystal ovens:

    <http://www.karlquist.com/oven.pdf>

    There's a lot more to it than just slapping a crystal & heater in a
    metal box and calling it a day! There are probably some pathologically
    bad geometries even a really fast control loop can never stabilize very
    well.

    The part about the outer can acting like a Faraday shield is
    interesting, shunting ambient gradients around the core. Does anyone
    know how they make the negative space look like a linear tehrmal
    resistance over a wide range? There's some kind of insulating foam in
    there, is main heat thermal transfer radiative or conduction?

    I picked up an otherwise really nice HP 5334b frequency counter with
    both the 1.3 GHz input and OCXO options for a song. Unfortunately
    there's a fault somewhere inside the OCXO module and it outputs about
    1.8 MHz instead of 10...seems to be maybe a bad cap somewhere around the Colpitts section and the crystal and heater sections are OK.

    The heater transistors screws to the internal mass have to be re-torqued
    to spec if you mess with them, I didn't mess with 'em.


    Rick Karlquist used to post here from time to time--a very smart guy.
    (I know him slightly from a side gig some years back, before he retired.)

    He also did some interesting ham radio work on direct frequency
    synthesizers based on cheap 455 kHz ceramic IF filters, and got pretty impressive results.

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Gerhard Hoffmann@21:1/5 to All on Sun May 22 04:27:16 2022
    Am 22.05.22 um 03:46 schrieb Phil Hobbs:

    Rick Karlquist used to post here from time to time--a very smart guy. (I
    know him slightly from a side gig some years back, before he retired.)

    He also did some interesting ham radio work on direct frequency
    synthesizers based on cheap 455 kHz ceramic IF filters, and got pretty impressive results.

    10.7 MHz filters IIRC.
    He is a regular in the Time Nuts email group on febo.com.


    Cheers

    Gerhard

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to bitrex on Sat May 21 20:14:57 2022
    On Sat, 21 May 2022 20:50:12 -0400, bitrex <user@example.net> wrote:

    Here's a paper on the theory of crystal ovens:

    <http://www.karlquist.com/oven.pdf>

    There's a lot more to it than just slapping a crystal & heater in a
    metal box and calling it a day! There are probably some pathologically
    bad geometries even a really fast control loop can never stabilize very
    well.

    The part about the outer can acting like a Faraday shield is
    interesting, shunting ambient gradients around the core. Does anyone
    know how they make the negative space look like a linear tehrmal
    resistance over a wide range? There's some kind of insulating foam in
    there, is main heat thermal transfer radiative or conduction?

    I picked up an otherwise really nice HP 5334b frequency counter with
    both the 1.3 GHz input and OCXO options for a song. Unfortunately
    there's a fault somewhere inside the OCXO module and it outputs about
    1.8 MHz instead of 10...seems to be maybe a bad cap somewhere around the >Colpitts section and the crystal and heater sections are OK.

    The heater transistors screws to the internal mass have to be re-torqued
    to spec if you mess with them, I didn't mess with 'em.

    Here's my EO modulator oven, with the big top cover removed.

    https://www.dropbox.com/s/f6h8tfyq0xkqx1q/Oven_Cables_pub.jpg?raw=1

    There are six mosfets on the big blue board on the bottom of the box
    as heaters.

    The temp sensors are thermistor wheatstone bridges on the small blue
    board on the bottom of the modulator, with a 24-bit ADC. The modulator
    is mounted on spacers inside the main oven block, not very thermally conductive, so thermally it's a second-order system. It's stable to
    way better than a millikelvin.

    Note the SMA feedthrus and long squiggly cables, which reduce cold
    sneaking into the EOM over the coaxes.



    --

    Anybody can count to one.

    - Robert Widlar

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Anthony William Sloman@21:1/5 to jla...@highlandsniptechnology.com on Sun May 22 01:31:04 2022
    On Sunday, May 22, 2022 at 1:15:05 PM UTC+10, jla...@highlandsniptechnology.com wrote:
    On Sat, 21 May 2022 20:50:12 -0400, bitrex <us...@example.net> wrote:

    Here's a paper on the theory of crystal ovens:

    <http://www.karlquist.com/oven.pdf>

    He didn't survey the literature all that well.

    There's a lot more to it than just slapping a crystal & heater in a
    metal box and calling it a day! There are probably some pathologically
    bad geometries even a really fast control loop can never stabilize very >well.

    The part about the outer can acting like a Faraday shield is
    interesting, shunting ambient gradients around the core. Does anyone
    know how they make the negative space look like a linear tehrmal
    resistance over a wide range? There's some kind of insulating foam in >there, is main heat thermal transfer radiative or conduction?

    Conduction. Foam pretty much stops convection.

    The heater transistors screws to the internal mass have to be re-torqued
    to spec if you mess with them, I didn't mess with 'em.

    Here's my EO modulator oven, with the big top cover removed.

    https://www.dropbox.com/s/f6h8tfyq0xkqx1q/Oven_Cables_pub.jpg?raw=1

    There are six mosfets on the big blue board on the bottom of the box
    as heaters.

    The temp sensors are thermistor wheatstone bridges on the small blue
    board on the bottom of the modulator, with a 24-bit ADC. The modulator
    is mounted on spacers inside the main oven block, not very thermally conductive, so thermally it's a second-order system. It's stable to
    way better than a millikelvin.

    People have been managing that since the 1960's. It's not easy, though good inter-changeable thermistors and 20-bit A/D converter chips have made it easier.

    Note the SMA feedthrus and long squiggly cables, which reduce cold sneaking into the EOM over the coaxes.

    Probably more helpful to say that they increase the thermal time constant of modulator whose temperature is being controlled.

    --
    Bill Sloman, Sydney

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to Gerhard Hoffmann on Sun May 22 12:53:22 2022
    Gerhard Hoffmann wrote:
    Am 22.05.22 um 03:46 schrieb Phil Hobbs:

    Rick Karlquist used to post here from time to time--a very smart guy.
    (I know him slightly from a side gig some years back, before he retired.)

    He also did some interesting ham radio work on direct frequency
    synthesizers based on cheap 455 kHz ceramic IF filters, and got pretty
    impressive results.

    10.7 MHz filters IIRC.

    Right, thanks. Cool gizmo, anyway.


    He is a regular in the Time Nuts email group on febo.com.

    Cheers

    Phil Hobbsn

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From bitrex@21:1/5 to bitrex on Sun May 22 13:24:30 2022
    On 5/22/2022 1:24 PM, bitrex wrote:
    On 5/22/2022 4:31 AM, Anthony William Sloman wrote:
    On Sunday, May 22, 2022 at 1:15:05 PM UTC+10,
    jla...@highlandsniptechnology.com wrote:
    On Sat, 21 May 2022 20:50:12 -0400, bitrex <us...@example.net> wrote:

    Here's a paper on the theory of crystal ovens:

    <http://www.karlquist.com/oven.pdf>

    He didn't survey the literature all that well.

    There's a lot more to it than just slapping a crystal & heater in a
    metal box and calling it a day! There are probably some pathologically >>>> bad geometries even a really fast control loop can never stabilize very >>>> well.

    The part about the outer can acting like a Faraday shield is
    interesting, shunting ambient gradients around the core. Does anyone
    know how they make the negative space look like a linear tehrmal
    resistance over a wide range? There's some kind of insulating foam in
    there, is main heat thermal transfer radiative or conduction?

    Conduction. Foam pretty much stops convection.

    It was mentioned on another thread that the thermal resistance of
    radiation between two concentric blackbodies at 300K is about 6mm

    Equivalent to 6mm of air, rather.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From bitrex@21:1/5 to Anthony William Sloman on Sun May 22 13:24:02 2022
    On 5/22/2022 4:31 AM, Anthony William Sloman wrote:
    On Sunday, May 22, 2022 at 1:15:05 PM UTC+10, jla...@highlandsniptechnology.com wrote:
    On Sat, 21 May 2022 20:50:12 -0400, bitrex <us...@example.net> wrote:

    Here's a paper on the theory of crystal ovens:

    <http://www.karlquist.com/oven.pdf>

    He didn't survey the literature all that well.

    There's a lot more to it than just slapping a crystal & heater in a
    metal box and calling it a day! There are probably some pathologically
    bad geometries even a really fast control loop can never stabilize very
    well.

    The part about the outer can acting like a Faraday shield is
    interesting, shunting ambient gradients around the core. Does anyone
    know how they make the negative space look like a linear tehrmal
    resistance over a wide range? There's some kind of insulating foam in
    there, is main heat thermal transfer radiative or conduction?

    Conduction. Foam pretty much stops convection.

    It was mentioned on another thread that the thermal resistance of
    radiation between two concentric blackbodies at 300K is about 6mm, interestingly that's very close to the same thickness of foam-filled
    negative space between the outer and inner shells of the OCXO module on
    my 5334B.

    Don't know if that's a coincidence or not, obviously the two aren't at
    exactly 300K. The interior I think runs about 355K, while the exterior
    (I haven't measured it) seems cool enough to keep your hand on a while.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to bitrex on Sun May 22 11:21:21 2022
    On Sun, 22 May 2022 13:24:02 -0400, bitrex <user@example.net> wrote:

    On 5/22/2022 4:31 AM, Anthony William Sloman wrote:
    On Sunday, May 22, 2022 at 1:15:05 PM UTC+10, jla...@highlandsniptechnology.com wrote:
    On Sat, 21 May 2022 20:50:12 -0400, bitrex <us...@example.net> wrote:

    Here's a paper on the theory of crystal ovens:

    <http://www.karlquist.com/oven.pdf>

    He didn't survey the literature all that well.

    There's a lot more to it than just slapping a crystal & heater in a
    metal box and calling it a day! There are probably some pathologically >>>> bad geometries even a really fast control loop can never stabilize very >>>> well.

    The part about the outer can acting like a Faraday shield is
    interesting, shunting ambient gradients around the core. Does anyone
    know how they make the negative space look like a linear tehrmal
    resistance over a wide range? There's some kind of insulating foam in
    there, is main heat thermal transfer radiative or conduction?

    Conduction. Foam pretty much stops convection.

    It was mentioned on another thread that the thermal resistance of
    radiation between two concentric blackbodies at 300K is about 6mm, >interestingly that's very close to the same thickness of foam-filled
    negative space between the outer and inner shells of the OCXO module on
    my 5334B.

    Don't know if that's a coincidence or not, obviously the two aren't at >exactly 300K. The interior I think runs about 355K, while the exterior
    (I haven't measured it) seems cool enough to keep your hand on a while.


    In a reasonably close-fitting box, without a lot of space for
    convection, air is a better thermal insulator than foam or fiberglass.



    --

    Anybody can count to one.

    - Robert Widlar

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to jlarkin@highlandsniptechnology.com on Sun May 22 15:14:12 2022
    jlarkin@highlandsniptechnology.com wrote:
    On Sun, 22 May 2022 13:24:02 -0400, bitrex <user@example.net> wrote:

    On 5/22/2022 4:31 AM, Anthony William Sloman wrote:
    On Sunday, May 22, 2022 at 1:15:05 PM UTC+10, jla...@highlandsniptechnology.com wrote:
    On Sat, 21 May 2022 20:50:12 -0400, bitrex <us...@example.net> wrote:

    Here's a paper on the theory of crystal ovens:

    <http://www.karlquist.com/oven.pdf>

    He didn't survey the literature all that well.

    There's a lot more to it than just slapping a crystal & heater in a
    metal box and calling it a day! There are probably some pathologically >>>>> bad geometries even a really fast control loop can never stabilize very >>>>> well.

    The part about the outer can acting like a Faraday shield is
    interesting, shunting ambient gradients around the core. Does anyone >>>>> know how they make the negative space look like a linear tehrmal
    resistance over a wide range? There's some kind of insulating foam in >>>>> there, is main heat thermal transfer radiative or conduction?

    Conduction. Foam pretty much stops convection.

    It was mentioned on another thread that the thermal resistance of
    radiation between two concentric blackbodies at 300K is about 6mm,
    interestingly that's very close to the same thickness of foam-filled
    negative space between the outer and inner shells of the OCXO module on
    my 5334B.

    Don't know if that's a coincidence or not, obviously the two aren't at
    exactly 300K. The interior I think runs about 355K, while the exterior
    (I haven't measured it) seems cool enough to keep your hand on a while.


    In a reasonably close-fitting box, without a lot of space for
    convection, air is a better thermal insulator than foam or fiberglass.

    That depends very much on the thermal emissivity of the surfaces and on
    the thickness of the gap. The JWST doesn't have to deal with a lot of convection, but its sun shield has many layers on account of the
    radiation issue.

    Cheers

    Phil Hobbs


    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Anthony William Sloman@21:1/5 to Phil Hobbs on Sun May 22 13:30:51 2022
    On Monday, May 23, 2022 at 5:14:27 AM UTC+10, Phil Hobbs wrote:
    jla...@highlandsniptechnology.com wrote:
    On Sun, 22 May 2022 13:24:02 -0400, bitrex <us...@example.net> wrote:

    On 5/22/2022 4:31 AM, Anthony William Sloman wrote:
    On Sunday, May 22, 2022 at 1:15:05 PM UTC+10, jla...@highlandsniptechnology.com wrote:
    On Sat, 21 May 2022 20:50:12 -0400, bitrex <us...@example.net> wrote: >>>>
    Here's a paper on the theory of crystal ovens:

    <http://www.karlquist.com/oven.pdf>

    He didn't survey the literature all that well.

    There's a lot more to it than just slapping a crystal & heater in a >>>>> metal box and calling it a day! There are probably some pathologically >>>>> bad geometries even a really fast control loop can never stabilize very >>>>> well.

    The part about the outer can acting like a Faraday shield is
    interesting, shunting ambient gradients around the core. Does anyone >>>>> know how they make the negative space look like a linear tehrmal
    resistance over a wide range? There's some kind of insulating foam in >>>>> there, is main heat thermal transfer radiative or conduction?

    Conduction. Foam pretty much stops convection.

    It was mentioned on another thread that the thermal resistance of
    radiation between two concentric blackbodies at 300K is about 6mm,
    interestingly that's very close to the same thickness of foam-filled
    negative space between the outer and inner shells of the OCXO module on
    my 5334B.

    Don't know if that's a coincidence or not, obviously the two aren't at
    exactly 300K. The interior I think runs about 355K, while the exterior
    (I haven't measured it) seems cool enough to keep your hand on a while.

    In a reasonably close-fitting box, without a lot of space for
    convection, air is a better thermal insulator than foam or fiberglass.

    You add foam or fibre-glass to stop air convecting.Both the walls of the foam cells and the glass in the glass-fibre have much higher thermal conductivities than air, but you don't put in enough to short-circuit the air.

    Convection does depend on the space available. 6mm isn't much.

    https://en.wikipedia.org/wiki/Rayleigh_number

    If it is less than 500 you don't get significant heat transfer by convection. If it's more than 100,000 you get turbulent convection

    That depends very much on the thermal emissivity of the surfaces and on
    the thickness of the gap. The JWST doesn't have to deal with a lot of convection, but its sun shield has many layers on account of the
    radiation issue.

    Radiation goes as the fourth power of temperature, and the sun is at 6000K. It's not really a relevant example.

    --
    Bill Sloman. Sydney

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From bitrex@21:1/5 to jlarkin@highlandsniptechnology.com on Sun May 22 16:46:44 2022
    On 5/22/2022 2:21 PM, jlarkin@highlandsniptechnology.com wrote:
    On Sun, 22 May 2022 13:24:02 -0400, bitrex <user@example.net> wrote:

    On 5/22/2022 4:31 AM, Anthony William Sloman wrote:
    On Sunday, May 22, 2022 at 1:15:05 PM UTC+10, jla...@highlandsniptechnology.com wrote:
    On Sat, 21 May 2022 20:50:12 -0400, bitrex <us...@example.net> wrote:

    Here's a paper on the theory of crystal ovens:

    <http://www.karlquist.com/oven.pdf>

    He didn't survey the literature all that well.

    There's a lot more to it than just slapping a crystal & heater in a
    metal box and calling it a day! There are probably some pathologically >>>>> bad geometries even a really fast control loop can never stabilize very >>>>> well.

    The part about the outer can acting like a Faraday shield is
    interesting, shunting ambient gradients around the core. Does anyone >>>>> know how they make the negative space look like a linear tehrmal
    resistance over a wide range? There's some kind of insulating foam in >>>>> there, is main heat thermal transfer radiative or conduction?

    Conduction. Foam pretty much stops convection.

    It was mentioned on another thread that the thermal resistance of
    radiation between two concentric blackbodies at 300K is about 6mm,
    interestingly that's very close to the same thickness of foam-filled
    negative space between the outer and inner shells of the OCXO module on
    my 5334B.

    Don't know if that's a coincidence or not, obviously the two aren't at
    exactly 300K. The interior I think runs about 355K, while the exterior
    (I haven't measured it) seems cool enough to keep your hand on a while.


    In a reasonably close-fitting box, without a lot of space for
    convection, air is a better thermal insulator than foam or fiberglass.


    Here's a glamour shot of the internals:

    <https://imgur.com/a/W4hmKt4>

    Don't know what the foam is. It doesn't seem to conduct heat too good.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Mike Coon@21:1/5 to All on Sun May 22 22:51:09 2022
    In article <bt9j8h5plkg05fmbgr8ra4fj9rqktuup2v@4ax.com>, jlarkin@highlandsniptechnology.com says...

    On Sat, 21 May 2022 20:50:12 -0400, bitrex <user@example.net> wrote:

    Here's a paper on the theory of crystal ovens:

    <http://www.karlquist.com/oven.pdf>

    There's a lot more to it than just slapping a crystal & heater in a
    metal box and calling it a day! There are probably some pathologically
    bad geometries even a really fast control loop can never stabilize very >well.

    The part about the outer can acting like a Faraday shield is
    interesting, shunting ambient gradients around the core. Does anyone
    know how they make the negative space look like a linear tehrmal
    resistance over a wide range? There's some kind of insulating foam in >there, is main heat thermal transfer radiative or conduction?

    I picked up an otherwise really nice HP 5334b frequency counter with
    both the 1.3 GHz input and OCXO options for a song. Unfortunately
    there's a fault somewhere inside the OCXO module and it outputs about
    1.8 MHz instead of 10...seems to be maybe a bad cap somewhere around the >Colpitts section and the crystal and heater sections are OK.

    The heater transistors screws to the internal mass have to be re-torqued
    to spec if you mess with them, I didn't mess with 'em.

    Here's my EO modulator oven, with the big top cover removed.

    https://www.dropbox.com/s/f6h8tfyq0xkqx1q/Oven_Cables_pub.jpg?raw=1

    There are six mosfets on the big blue board on the bottom of the box
    as heaters.

    The temp sensors are thermistor wheatstone bridges on the small blue
    board on the bottom of the modulator, with a 24-bit ADC. The modulator
    is mounted on spacers inside the main oven block, not very thermally conductive, so thermally it's a second-order system. It's stable to
    way better than a millikelvin.

    Note the SMA feedthrus and long squiggly cables, which reduce cold
    sneaking into the EOM over the coaxes.

    My design for a foyer quartz clock back in the early 1960s included a
    crystal in a thermostatic oven made from Perspex. I have a sketch and
    isometric of the oven and a note that there were five thermistors in a
    bridge, but no schematic. I do remember that on first testing the
    control circuit initially ran at full power heating, then cut off, then gradually settled on steady warmth!

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to pcdhSpamMeSenseless@electrooptical. on Sun May 22 16:57:14 2022
    On Sun, 22 May 2022 15:14:12 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Sun, 22 May 2022 13:24:02 -0400, bitrex <user@example.net> wrote:

    On 5/22/2022 4:31 AM, Anthony William Sloman wrote:
    On Sunday, May 22, 2022 at 1:15:05 PM UTC+10, jla...@highlandsniptechnology.com wrote:
    On Sat, 21 May 2022 20:50:12 -0400, bitrex <us...@example.net> wrote: >>>>>
    Here's a paper on the theory of crystal ovens:

    <http://www.karlquist.com/oven.pdf>

    He didn't survey the literature all that well.

    There's a lot more to it than just slapping a crystal & heater in a >>>>>> metal box and calling it a day! There are probably some pathologically >>>>>> bad geometries even a really fast control loop can never stabilize very >>>>>> well.

    The part about the outer can acting like a Faraday shield is
    interesting, shunting ambient gradients around the core. Does anyone >>>>>> know how they make the negative space look like a linear tehrmal
    resistance over a wide range? There's some kind of insulating foam in >>>>>> there, is main heat thermal transfer radiative or conduction?

    Conduction. Foam pretty much stops convection.

    It was mentioned on another thread that the thermal resistance of
    radiation between two concentric blackbodies at 300K is about 6mm,
    interestingly that's very close to the same thickness of foam-filled
    negative space between the outer and inner shells of the OCXO module on
    my 5334B.

    Don't know if that's a coincidence or not, obviously the two aren't at
    exactly 300K. The interior I think runs about 355K, while the exterior
    (I haven't measured it) seems cool enough to keep your hand on a while.


    In a reasonably close-fitting box, without a lot of space for
    convection, air is a better thermal insulator than foam or fiberglass.

    That depends very much on the thermal emissivity of the surfaces and on
    the thickness of the gap. The JWST doesn't have to deal with a lot of >convection, but its sun shield has many layers on account of the
    radiation issue.

    JSTW is dealing with a huge delta-t, and vacuum is a poor thermal
    conductor. I've experimented with heated gadgets inside a deep-drawn
    aluminum box, which has a low emissivity. My testing usually showed
    that I got less heater power dissipation with air, as opposed to
    styrafoam or fiberglas.

    It's not a difficult experiment. I think most people just assume that insulation always helps.



    --

    Anybody can count to one.

    - Robert Widlar

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to bitrex on Sun May 22 16:59:17 2022
    On Sun, 22 May 2022 16:46:44 -0400, bitrex <user@example.net> wrote:

    On 5/22/2022 2:21 PM, jlarkin@highlandsniptechnology.com wrote:
    On Sun, 22 May 2022 13:24:02 -0400, bitrex <user@example.net> wrote:

    On 5/22/2022 4:31 AM, Anthony William Sloman wrote:
    On Sunday, May 22, 2022 at 1:15:05 PM UTC+10, jla...@highlandsniptechnology.com wrote:
    On Sat, 21 May 2022 20:50:12 -0400, bitrex <us...@example.net> wrote: >>>>>
    Here's a paper on the theory of crystal ovens:

    <http://www.karlquist.com/oven.pdf>

    He didn't survey the literature all that well.

    There's a lot more to it than just slapping a crystal & heater in a >>>>>> metal box and calling it a day! There are probably some pathologically >>>>>> bad geometries even a really fast control loop can never stabilize very >>>>>> well.

    The part about the outer can acting like a Faraday shield is
    interesting, shunting ambient gradients around the core. Does anyone >>>>>> know how they make the negative space look like a linear tehrmal
    resistance over a wide range? There's some kind of insulating foam in >>>>>> there, is main heat thermal transfer radiative or conduction?

    Conduction. Foam pretty much stops convection.

    It was mentioned on another thread that the thermal resistance of
    radiation between two concentric blackbodies at 300K is about 6mm,
    interestingly that's very close to the same thickness of foam-filled
    negative space between the outer and inner shells of the OCXO module on
    my 5334B.

    Don't know if that's a coincidence or not, obviously the two aren't at
    exactly 300K. The interior I think runs about 355K, while the exterior
    (I haven't measured it) seems cool enough to keep your hand on a while.


    In a reasonably close-fitting box, without a lot of space for
    convection, air is a better thermal insulator than foam or fiberglass.


    Here's a glamour shot of the internals:

    <https://imgur.com/a/W4hmKt4>

    Don't know what the foam is. It doesn't seem to conduct heat too good.



    The interesting test would be to measure heater power with and without
    the foam.



    --

    Anybody can count to one.

    - Robert Widlar

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to jlarkin@highlandsniptechnology.com on Sun May 22 21:49:49 2022
    jlarkin@highlandsniptechnology.com wrote:
    On Sun, 22 May 2022 15:14:12 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Sun, 22 May 2022 13:24:02 -0400, bitrex <user@example.net> wrote:

    On 5/22/2022 4:31 AM, Anthony William Sloman wrote:
    On Sunday, May 22, 2022 at 1:15:05 PM UTC+10, jla...@highlandsniptechnology.com wrote:
    On Sat, 21 May 2022 20:50:12 -0400, bitrex <us...@example.net> wrote: >>>>>>
    Here's a paper on the theory of crystal ovens:

    <http://www.karlquist.com/oven.pdf>

    He didn't survey the literature all that well.

    There's a lot more to it than just slapping a crystal & heater in a >>>>>>> metal box and calling it a day! There are probably some pathologically >>>>>>> bad geometries even a really fast control loop can never stabilize very >>>>>>> well.

    The part about the outer can acting like a Faraday shield is
    interesting, shunting ambient gradients around the core. Does anyone >>>>>>> know how they make the negative space look like a linear tehrmal >>>>>>> resistance over a wide range? There's some kind of insulating foam in >>>>>>> there, is main heat thermal transfer radiative or conduction?

    Conduction. Foam pretty much stops convection.

    It was mentioned on another thread that the thermal resistance of
    radiation between two concentric blackbodies at 300K is about 6mm,
    interestingly that's very close to the same thickness of foam-filled
    negative space between the outer and inner shells of the OCXO module on >>>> my 5334B.

    Don't know if that's a coincidence or not, obviously the two aren't at >>>> exactly 300K. The interior I think runs about 355K, while the exterior >>>> (I haven't measured it) seems cool enough to keep your hand on a while. >>>>

    In a reasonably close-fitting box, without a lot of space for
    convection, air is a better thermal insulator than foam or fiberglass.

    That depends very much on the thermal emissivity of the surfaces and on
    the thickness of the gap. The JWST doesn't have to deal with a lot of
    convection, but its sun shield has many layers on account of the
    radiation issue.

    JSTW is dealing with a huge delta-t, and vacuum is a poor thermal
    conductor.

    The delta-T is only huge in the first gap. After that it's much much
    smaller. The temperature of the first shield is near the subsolar
    temperature, but the amount it radiates into the first gap is much lower
    than a black body's, on account of the very low emissivity (i. e. high reflectivity) of its surfaces.

    The subsolar temperature of a flat plate at a radial distance r from a
    star of radius a is

    T_ss = T_star * sqrt(a/( r sqrt(2) ) ),

    i.e. the temperature at which the thermal emission of the star (sigma
    T_star**4 * a**2) balances that of a notional sphere of unit emissivity
    (sigma T_ss**4 * r**2). (The factor of sqrt(2) is there because the
    plate radiates from both sides--for a spherical planet, whose area is 4
    pi R**2, it's a full factor of 2.)

    The temperature of the solar photosphere is around 6000K, and its radius
    is 7e5 km. The mean radius of the Earth's orbit is 1.5e8 km. Thus the subsolar temperature for a flat plate is

    T_ss = 6000 K * sqrt(7e5 km / 1.5e8 km / sqrt(2)) = 334 K.

    (For a spherical object such as the Earth and Moon, it would be
    sqrt(sqrt(2)) less than that, i.e. 281 K.)

    There are two main contributors to the effective thermal resistance of a multilayer stack of spaced reflectors. One is just breaking up the gap
    into N subgaps, which does what you'd expect--M layers gets you about M
    times the thermal resistance. (The effect is bigger at larger deltaT,
    where the emission from inner layers is much less.)

    The other contributor is that, since the layers of JWST's heat shield
    are spaced wide apart, the great majority of the thermal emission of
    each surface bounces around until it escapes into space. Of course the
    ambient radiation comes in as well, but since its temperature is very
    low, that's not a big worry.

    I've experimented with heated gadgets inside a deep-drawn
    aluminum box, which has a low emissivity. My testing usually showed
    that I got less heater power dissipation with air, as opposed to
    styrafoam or fiberglas.

    It's not a difficult experiment. I think most people just assume that insulation always helps.

    Plain air is better than insulation for narrow spaces and small delta-T,
    and insulation is better otherwise. Just where the break-even point
    happens depends a lot on the situation.

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From whit3rd@21:1/5 to jla...@highlandsniptechnology.com on Mon May 23 01:18:34 2022
    On Sunday, May 22, 2022 at 4:57:25 PM UTC-7, jla...@highlandsniptechnology.com wrote:


    ... I've experimented with heated gadgets inside a deep-drawn
    aluminum box, which has a low emissivity. My testing usually showed
    that I got less heater power dissipation with air, as opposed to
    styrafoam or fiberglas.

    It's not a difficult experiment. I think most people just assume that insulation always helps.

    Insulation in the sense of low-conductivity material is NOT the intended function of
    fiberglass; it is used to reduce air convection, which (thermal convection is delta-T squared heat transfer) is a tiny effect in a low-temperature-gradient system.
    In a house-on-fire, fiberglass in the walls is not tiny, but a big help in getting out alive.

    In a very real sense, fiberglass filled cavities are air-insulated.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jan Panteltje@21:1/5 to gravity@mjcoon.plus.com on Mon May 23 08:23:05 2022
    On a sunny day (Sun, 22 May 2022 22:51:09 +0100) it happened Mike Coon <gravity@mjcoon.plus.com> wrote in <MPG.3cf4c0956a87c90d9896be@usenet.plus.net>:

    My design for a foyer quartz clock back in the early 1960s included a
    crystal in a thermostatic oven made from Perspex. I have a sketch and >isometric of the oven and a note that there were five thermistors in a >bridge, but no schematic. I do remember that on first testing the
    control circuit initially ran at full power heating, then cut off, then >gradually settled on steady warmth!

    Yes that is overshot, maybe over-compensated

    This was pretty good too:
    http://panteltje.com/panteltje/tri_pic/

    Little box inside big box...

    temperature within a few ADC steps over many years..
    Took about half an hour to get the PID working correctly in PIC asm ..

    For the rest the 1 ppm TCXOs as in my RTL-SDR sticks are very good and very small.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to jlarkin@highlandsniptechnology.com on Mon May 23 09:48:57 2022
    jlarkin@highlandsniptechnology.com wrote:
    On Sun, 22 May 2022 16:46:44 -0400, bitrex <user@example.net> wrote:

    On 5/22/2022 2:21 PM, jlarkin@highlandsniptechnology.com wrote:
    On Sun, 22 May 2022 13:24:02 -0400, bitrex <user@example.net> wrote:

    On 5/22/2022 4:31 AM, Anthony William Sloman wrote:
    On Sunday, May 22, 2022 at 1:15:05 PM UTC+10, jla...@highlandsniptechnology.com wrote:
    On Sat, 21 May 2022 20:50:12 -0400, bitrex <us...@example.net> wrote: >>>>>>
    Here's a paper on the theory of crystal ovens:

    <http://www.karlquist.com/oven.pdf>

    He didn't survey the literature all that well.

    There's a lot more to it than just slapping a crystal & heater in a >>>>>>> metal box and calling it a day! There are probably some pathologically >>>>>>> bad geometries even a really fast control loop can never stabilize very >>>>>>> well.

    The part about the outer can acting like a Faraday shield is
    interesting, shunting ambient gradients around the core. Does anyone >>>>>>> know how they make the negative space look like a linear tehrmal >>>>>>> resistance over a wide range? There's some kind of insulating foam in >>>>>>> there, is main heat thermal transfer radiative or conduction?

    Conduction. Foam pretty much stops convection.

    It was mentioned on another thread that the thermal resistance of
    radiation between two concentric blackbodies at 300K is about 6mm,
    interestingly that's very close to the same thickness of foam-filled
    negative space between the outer and inner shells of the OCXO module on >>>> my 5334B.

    Don't know if that's a coincidence or not, obviously the two aren't at >>>> exactly 300K. The interior I think runs about 355K, while the exterior >>>> (I haven't measured it) seems cool enough to keep your hand on a while. >>>>

    In a reasonably close-fitting box, without a lot of space for
    convection, air is a better thermal insulator than foam or fiberglass.


    Here's a glamour shot of the internals:

    <https://imgur.com/a/W4hmKt4>

    Don't know what the foam is. It doesn't seem to conduct heat too good.



    The interesting test would be to measure heater power with and without
    the foam.

    Air at room temperature has an alpha of about 0.026 W/m/K. High-density styrofoam (the kind that crunches when you poke it with your finger) is
    about 0.040, and low-density styrofoam (the kind that squeaks) is around
    0.030.

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to Jan Panteltje on Mon May 23 09:50:20 2022
    Jan Panteltje wrote:
    On a sunny day (Sun, 22 May 2022 22:51:09 +0100) it happened Mike Coon <gravity@mjcoon.plus.com> wrote in <MPG.3cf4c0956a87c90d9896be@usenet.plus.net>:

    My design for a foyer quartz clock back in the early 1960s included a
    crystal in a thermostatic oven made from Perspex. I have a sketch and
    isometric of the oven and a note that there were five thermistors in a
    bridge, but no schematic. I do remember that on first testing the
    control circuit initially ran at full power heating, then cut off, then
    gradually settled on steady warmth!

    Yes that is overshot, maybe over-compensated

    Or else windup, which is pretty likely if the sensors and heaters aren't
    well coupled.

    This was pretty good too:
    http://panteltje.com/panteltje/tri_pic/

    Little box inside big box...

    temperature within a few ADC steps over many years..
    Took about half an hour to get the PID working correctly in PIC asm ..

    For the rest the 1 ppm TCXOs as in my RTL-SDR sticks are very good and very small.


    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to All on Mon May 23 06:50:33 2022
    On Mon, 23 May 2022 01:18:34 -0700 (PDT), whit3rd <whit3rd@gmail.com>
    wrote:

    On Sunday, May 22, 2022 at 4:57:25 PM UTC-7, jla...@highlandsniptechnology.com wrote:


    ... I've experimented with heated gadgets inside a deep-drawn
    aluminum box, which has a low emissivity. My testing usually showed
    that I got less heater power dissipation with air, as opposed to
    styrafoam or fiberglas.

    It's not a difficult experiment. I think most people just assume that
    insulation always helps.

    Insulation in the sense of low-conductivity material is NOT the intended function of
    fiberglass; it is used to reduce air convection, which (thermal convection is >delta-T squared heat transfer) is a tiny effect in a low-temperature-gradient system.
    In a house-on-fire, fiberglass in the walls is not tiny, but a big help in getting out alive.

    In a very real sense, fiberglass filled cavities are air-insulated.

    Try it.



    --

    Anybody can count to one.

    - Robert Widlar

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to pNaonStpealmtje@yahoo.com on Mon May 23 06:55:52 2022
    On Mon, 23 May 2022 08:23:05 GMT, Jan Panteltje
    <pNaonStpealmtje@yahoo.com> wrote:

    On a sunny day (Sun, 22 May 2022 22:51:09 +0100) it happened Mike Coon ><gravity@mjcoon.plus.com> wrote in ><MPG.3cf4c0956a87c90d9896be@usenet.plus.net>:

    My design for a foyer quartz clock back in the early 1960s included a >>crystal in a thermostatic oven made from Perspex. I have a sketch and >>isometric of the oven and a note that there were five thermistors in a >>bridge, but no schematic. I do remember that on first testing the
    control circuit initially ran at full power heating, then cut off, then >>gradually settled on steady warmth!

    Yes that is overshot, maybe over-compensated

    Heaters usually run at some limited full power after cold-start, so
    the initial temperature curve is linear, slew-limited. If you have a
    well-tuned PID loop, the integrator rails and it will usually
    overshoot at the end of the slew. That can be fixed but it's usually
    not worth the trouble.



    --

    Anybody can count to one.

    - Robert Widlar

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From DecadentLinuxUserNumeroUno@decadenc@21:1/5 to jlarkin@highlandsniptechnology.com on Mon May 23 14:11:54 2022
    jlarkin@highlandsniptechnology.com wrote in news:4hjl8hd5d42lhge1c7lu0kt7m29led31kd@4ax.com:

    On Sun, 22 May 2022 16:46:44 -0400, bitrex <user@example.net>
    wrote:

    On 5/22/2022 2:21 PM, jlarkin@highlandsniptechnology.com wrote:
    On Sun, 22 May 2022 13:24:02 -0400, bitrex <user@example.net>
    wrote:

    On 5/22/2022 4:31 AM, Anthony William Sloman wrote:
    On Sunday, May 22, 2022 at 1:15:05 PM UTC+10,
    jla...@highlandsniptechnology.com wrote:
    On Sat, 21 May 2022 20:50:12 -0400, bitrex
    <us...@example.net> wrote:

    Here's a paper on the theory of crystal ovens:

    <http://www.karlquist.com/oven.pdf>

    He didn't survey the literature all that well.

    There's a lot more to it than just slapping a crystal &
    heater in a metal box and calling it a day! There are
    probably some pathologically bad geometries even a really
    fast control loop can never stabilize very well.

    The part about the outer can acting like a Faraday shield is
    interesting, shunting ambient gradients around the core.
    Does anyone know how they make the negative space look like
    a linear tehrmal resistance over a wide range? There's some
    kind of insulating foam in there, is main heat thermal
    transfer radiative or conduction?

    Conduction. Foam pretty much stops convection.

    It was mentioned on another thread that the thermal resistance
    of radiation between two concentric blackbodies at 300K is
    about 6mm, interestingly that's very close to the same
    thickness of foam-filled negative space between the outer and
    inner shells of the OCXO module on my 5334B.

    Don't know if that's a coincidence or not, obviously the two
    aren't at exactly 300K. The interior I think runs about 355K,
    while the exterior (I haven't measured it) seems cool enough to
    keep your hand on a while.


    In a reasonably close-fitting box, without a lot of space for
    convection, air is a better thermal insulator than foam or
    fiberglass.


    Here's a glamour shot of the internals:

    <https://imgur.com/a/W4hmKt4>

    Don't know what the foam is. It doesn't seem to conduct heat too
    good.



    The interesting test would be to measure heater power with and
    without the foam.




    The foam is for physical shock absorption, silly.

    Hard to protect against that "floating in air". They should try
    some nice aerogel inserts. I think it has pretty good thermals
    compared to foam.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to pcdhSpamMeSenseless@electrooptical. on Mon May 23 08:35:53 2022
    On Mon, 23 May 2022 09:48:57 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Sun, 22 May 2022 16:46:44 -0400, bitrex <user@example.net> wrote:

    On 5/22/2022 2:21 PM, jlarkin@highlandsniptechnology.com wrote:
    On Sun, 22 May 2022 13:24:02 -0400, bitrex <user@example.net> wrote:

    On 5/22/2022 4:31 AM, Anthony William Sloman wrote:
    On Sunday, May 22, 2022 at 1:15:05 PM UTC+10, jla...@highlandsniptechnology.com wrote:
    On Sat, 21 May 2022 20:50:12 -0400, bitrex <us...@example.net> wrote: >>>>>>>
    Here's a paper on the theory of crystal ovens:

    <http://www.karlquist.com/oven.pdf>

    He didn't survey the literature all that well.

    There's a lot more to it than just slapping a crystal & heater in a >>>>>>>> metal box and calling it a day! There are probably some pathologically >>>>>>>> bad geometries even a really fast control loop can never stabilize very
    well.

    The part about the outer can acting like a Faraday shield is
    interesting, shunting ambient gradients around the core. Does anyone >>>>>>>> know how they make the negative space look like a linear tehrmal >>>>>>>> resistance over a wide range? There's some kind of insulating foam in >>>>>>>> there, is main heat thermal transfer radiative or conduction?

    Conduction. Foam pretty much stops convection.

    It was mentioned on another thread that the thermal resistance of
    radiation between two concentric blackbodies at 300K is about 6mm,
    interestingly that's very close to the same thickness of foam-filled >>>>> negative space between the outer and inner shells of the OCXO module on >>>>> my 5334B.

    Don't know if that's a coincidence or not, obviously the two aren't at >>>>> exactly 300K. The interior I think runs about 355K, while the exterior >>>>> (I haven't measured it) seems cool enough to keep your hand on a while. >>>>>

    In a reasonably close-fitting box, without a lot of space for
    convection, air is a better thermal insulator than foam or fiberglass. >>>>

    Here's a glamour shot of the internals:

    <https://imgur.com/a/W4hmKt4>

    Don't know what the foam is. It doesn't seem to conduct heat too good.



    The interesting test would be to measure heater power with and without
    the foam.

    Air at room temperature has an alpha of about 0.026 W/m/K. High-density >styrofoam (the kind that crunches when you poke it with your finger) is
    about 0.040, and low-density styrofoam (the kind that squeaks) is around >0.030.

    Cheers

    Phil Hobbs

    I just did some tests and noted the heater power.



    --

    Anybody can count to one.

    - Robert Widlar

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to DecadentLinuxUserNumeroUno@decadenc on Mon May 23 08:46:19 2022
    On Mon, 23 May 2022 14:11:54 -0000 (UTC), DecadentLinuxUserNumeroUno@decadence.org wrote:

    jlarkin@highlandsniptechnology.com wrote in >news:4hjl8hd5d42lhge1c7lu0kt7m29led31kd@4ax.com:

    On Sun, 22 May 2022 16:46:44 -0400, bitrex <user@example.net>
    wrote:

    On 5/22/2022 2:21 PM, jlarkin@highlandsniptechnology.com wrote:
    On Sun, 22 May 2022 13:24:02 -0400, bitrex <user@example.net>
    wrote:

    On 5/22/2022 4:31 AM, Anthony William Sloman wrote:
    On Sunday, May 22, 2022 at 1:15:05 PM UTC+10,
    jla...@highlandsniptechnology.com wrote:
    On Sat, 21 May 2022 20:50:12 -0400, bitrex
    <us...@example.net> wrote:

    Here's a paper on the theory of crystal ovens:

    <http://www.karlquist.com/oven.pdf>

    He didn't survey the literature all that well.

    There's a lot more to it than just slapping a crystal &
    heater in a metal box and calling it a day! There are
    probably some pathologically bad geometries even a really
    fast control loop can never stabilize very well.

    The part about the outer can acting like a Faraday shield is
    interesting, shunting ambient gradients around the core.
    Does anyone know how they make the negative space look like
    a linear tehrmal resistance over a wide range? There's some
    kind of insulating foam in there, is main heat thermal
    transfer radiative or conduction?

    Conduction. Foam pretty much stops convection.

    It was mentioned on another thread that the thermal resistance
    of radiation between two concentric blackbodies at 300K is
    about 6mm, interestingly that's very close to the same
    thickness of foam-filled negative space between the outer and
    inner shells of the OCXO module on my 5334B.

    Don't know if that's a coincidence or not, obviously the two
    aren't at exactly 300K. The interior I think runs about 355K,
    while the exterior (I haven't measured it) seems cool enough to
    keep your hand on a while.


    In a reasonably close-fitting box, without a lot of space for
    convection, air is a better thermal insulator than foam or
    fiberglass.


    Here's a glamour shot of the internals:

    <https://imgur.com/a/W4hmKt4>

    Don't know what the foam is. It doesn't seem to conduct heat too
    good.



    The interesting test would be to measure heater power with and
    without the foam.




    The foam is for physical shock absorption, silly.

    None of my ovens depended on foam for mechanical support. Sometimes
    long lead wires are bad news too.

    I did mount one OCXO on some custom springs. Mating and unmating an
    nearby SMB test connector made my PLL lose lock.

    https://www.dropbox.com/s/0k8agdfyiqlwn84/Spring_2.JPG?raw=1

    https://www.dropbox.com/s/l2gr4fxas2k05fz/Sprung_Osc_2.JPG?raw=1



    Hard to protect against that "floating in air". They should try
    some nice aerogel inserts. I think it has pretty good thermals
    compared to foam.

    Have you done that? Is aerogel rigid enough to support a subassembly?
    Would mechanical shocks scrunch it down?





    --

    Anybody can count to one.

    - Robert Widlar

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Mike Coon@21:1/5 to All on Mon May 23 17:34:33 2022
    In article <t6fga4$f2p$1@dont-email.me>, pNaonStpealmtje@yahoo.com
    says...

    On a sunny day (Sun, 22 May 2022 22:51:09 +0100) it happened Mike Coon <gravity@mjcoon.plus.com> wrote in <MPG.3cf4c0956a87c90d9896be@usenet.plus.net>:

    My design for a foyer quartz clock back in the early 1960s included a >crystal in a thermostatic oven made from Perspex. I have a sketch and >isometric of the oven and a note that there were five thermistors in a >bridge, but no schematic. I do remember that on first testing the
    control circuit initially ran at full power heating, then cut off, then >gradually settled on steady warmth!

    Yes that is overshot, maybe over-compensated

    My definition of over-compensated would be indefinite oscillation, which
    is what I was concerned about when I was monitoring the behaviour... No
    theory involved!

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Lasse Langwadt Christensen@21:1/5 to All on Mon May 23 09:59:02 2022
    mandag den 23. maj 2022 kl. 17.46.31 UTC+2 skrev jla...@highlandsniptechnology.com:
    On Mon, 23 May 2022 14:11:54 -0000 (UTC),
    DecadentLinux...@decadence.org wrote:

    jla...@highlandsniptechnology.com wrote in >news:4hjl8hd5d42lhge1c...@4ax.com:

    On Sun, 22 May 2022 16:46:44 -0400, bitrex <us...@example.net>
    wrote:

    On 5/22/2022 2:21 PM, jla...@highlandsniptechnology.com wrote:
    On Sun, 22 May 2022 13:24:02 -0400, bitrex <us...@example.net>
    wrote:

    On 5/22/2022 4:31 AM, Anthony William Sloman wrote:
    On Sunday, May 22, 2022 at 1:15:05 PM UTC+10,
    jla...@highlandsniptechnology.com wrote:
    On Sat, 21 May 2022 20:50:12 -0400, bitrex
    <us...@example.net> wrote:

    Here's a paper on the theory of crystal ovens:

    <http://www.karlquist.com/oven.pdf>

    He didn't survey the literature all that well.

    There's a lot more to it than just slapping a crystal &
    heater in a metal box and calling it a day! There are
    probably some pathologically bad geometries even a really
    fast control loop can never stabilize very well.

    The part about the outer can acting like a Faraday shield is >>>>>>>> interesting, shunting ambient gradients around the core.
    Does anyone know how they make the negative space look like
    a linear tehrmal resistance over a wide range? There's some
    kind of insulating foam in there, is main heat thermal
    transfer radiative or conduction?

    Conduction. Foam pretty much stops convection.

    It was mentioned on another thread that the thermal resistance
    of radiation between two concentric blackbodies at 300K is
    about 6mm, interestingly that's very close to the same
    thickness of foam-filled negative space between the outer and
    inner shells of the OCXO module on my 5334B.

    Don't know if that's a coincidence or not, obviously the two
    aren't at exactly 300K. The interior I think runs about 355K,
    while the exterior (I haven't measured it) seems cool enough to
    keep your hand on a while.


    In a reasonably close-fitting box, without a lot of space for
    convection, air is a better thermal insulator than foam or
    fiberglass.


    Here's a glamour shot of the internals:

    <https://imgur.com/a/W4hmKt4>

    Don't know what the foam is. It doesn't seem to conduct heat too
    good.



    The interesting test would be to measure heater power with and
    without the foam.




    The foam is for physical shock absorption, silly.
    None of my ovens depended on foam for mechanical support. Sometimes
    long lead wires are bad news too.

    I did mount one OCXO on some custom springs. Mating and unmating an
    nearby SMB test connector made my PLL lose lock.

    https://www.dropbox.com/s/0k8agdfyiqlwn84/Spring_2.JPG?raw=1

    https://www.dropbox.com/s/l2gr4fxas2k05fz/Sprung_Osc_2.JPG?raw=1

    Hard to protect against that "floating in air". They should try
    some nice aerogel inserts. I think it has pretty good thermals
    compared to foam.
    Have you done that? Is aerogel rigid enough to support a subassembly?
    Would mechanical shocks scrunch it down?

    https://youtu.be/o5nzYpRdY4g

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From DecadentLinuxUserNumeroUno@decadenc@21:1/5 to jlarkin@highlandsniptechnology.com on Mon May 23 17:08:08 2022
    jlarkin@highlandsniptechnology.com wrote in news:2gan8hdp7v3lhp44joaa278gmtktgva985@4ax.com:

    On Mon, 23 May 2022 14:11:54 -0000 (UTC), DecadentLinuxUserNumeroUno@decadence.org wrote:

    jlarkin@highlandsniptechnology.com wrote in >>news:4hjl8hd5d42lhge1c7lu0kt7m29led31kd@4ax.com:

    On Sun, 22 May 2022 16:46:44 -0400, bitrex <user@example.net>
    wrote:

    On 5/22/2022 2:21 PM, jlarkin@highlandsniptechnology.com wrote:
    On Sun, 22 May 2022 13:24:02 -0400, bitrex <user@example.net>
    wrote:

    On 5/22/2022 4:31 AM, Anthony William Sloman wrote:
    On Sunday, May 22, 2022 at 1:15:05 PM UTC+10,
    jla...@highlandsniptechnology.com wrote:
    On Sat, 21 May 2022 20:50:12 -0400, bitrex
    <us...@example.net> wrote:

    Here's a paper on the theory of crystal ovens:

    <http://www.karlquist.com/oven.pdf>

    He didn't survey the literature all that well.

    There's a lot more to it than just slapping a crystal &
    heater in a metal box and calling it a day! There are
    probably some pathologically bad geometries even a really
    fast control loop can never stabilize very well.

    The part about the outer can acting like a Faraday shield
    is
    interesting, shunting ambient gradients around the core.
    Does anyone know how they make the negative space look like
    a linear tehrmal resistance over a wide range? There's some
    kind of insulating foam in there, is main heat thermal
    transfer radiative or conduction?

    Conduction. Foam pretty much stops convection.

    It was mentioned on another thread that the thermal resistance
    of radiation between two concentric blackbodies at 300K is
    about 6mm, interestingly that's very close to the same
    thickness of foam-filled negative space between the outer and
    inner shells of the OCXO module on my 5334B.

    Don't know if that's a coincidence or not, obviously the two
    aren't at exactly 300K. The interior I think runs about 355K,
    while the exterior (I haven't measured it) seems cool enough
    to
    keep your hand on a while.


    In a reasonably close-fitting box, without a lot of space for
    convection, air is a better thermal insulator than foam or
    fiberglass.


    Here's a glamour shot of the internals:

    <https://imgur.com/a/W4hmKt4>

    Don't know what the foam is. It doesn't seem to conduct heat too
    good.



    The interesting test would be to measure heater power with and
    without the foam.




    The foam is for physical shock absorption, silly.

    None of my ovens depended on foam for mechanical support. Sometimes
    long lead wires are bad news too.

    I did mount one OCXO on some custom springs. Mating and unmating an
    nearby SMB test connector made my PLL lose lock.

    https://www.dropbox.com/s/0k8agdfyiqlwn84/Spring_2.JPG?raw=1

    https://www.dropbox.com/s/l2gr4fxas2k05fz/Sprung_Osc_2.JPG?raw=1



    Hard to protect against that "floating in air". They should try
    some nice aerogel inserts. I think it has pretty good thermals
    compared to foam.

    Have you done that? Is aerogel rigid enough to support a
    subassembly?
    Would mechanical shocks scrunch it down?

    The word for today is scrunch.

    I don't know. it isn't a foam. so scrunching of any kind would be a
    different animal with it. One has to wonder how it reacts to
    thermals though.

    There were/are several ISS exterior exposure tests taking place.
    For micro-meteor impact data and I think there were some thermal
    tests.

    Someone will make some carbon nanotube matrix thing that beats it
    all because we will be able to shape it. Oh wait. that's conduction.
    even electrical. They could come up with an idealized resistance
    medium and make big high wattage "carbon comp" resistors again for
    certain applications. Less noisy than what we used for so many
    decades. Or, a nice 'clean' noise... the sound of things going bump
    in the night (day too).

    Insulation... right. Aerogel. Maybe they make a Hydrogel or
    Nitrogel. Or Xenon... apply juice and get a glow gel.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From whit3rd@21:1/5 to jla...@highlandsniptechnology.com on Mon May 23 10:09:23 2022
    On Monday, May 23, 2022 at 8:46:31 AM UTC-7, jla...@highlandsniptechnology.com wrote:
    On Mon, 23 May 2022 14:11:54 -0000 (UTC),
    DecadentLinux...@decadence.org wrote:

    The foam is for physical shock absorption, silly.

    None of my ovens depended on foam for mechanical support. Sometimes
    long lead wires are bad news too.

    I did mount one OCXO on some custom springs...

    Hard to protect against that "floating in air". They should try
    some nice aerogel inserts. I think it has pretty good thermals
    compared to foam.

    Have you done that? Is aerogel rigid enough to support a subassembly?
    Would mechanical shocks scrunch it down?

    Some aerogels are foam-like quartz, quite strong enough for most uses, and relatively tough. You could use 'em to support, and they're good in vacuum (if you want a good insulator, ditch the air). On the other hand, a perforated section of fiberglass PCB should likewise be a thermal break. How
    stingy on heater power do you want to be?

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Doe@21:1/5 to jlarkin@highlandsniptechnology.com on Mon May 23 16:45:12 2022
    jlarkin@highlandsniptechnology.com wrote:

    Anybody can count to one.

    - Robert Widlar

    I don't get it.

    allintext:"Anybody can count to one" "Robert Widlar"

    Produces four results, all of them from John Larkin.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to Mike Coon on Mon May 23 13:38:47 2022
    Mike Coon wrote:
    In article <t6fga4$f2p$1@dont-email.me>, pNaonStpealmtje@yahoo.com
    says...

    On a sunny day (Sun, 22 May 2022 22:51:09 +0100) it happened Mike Coon
    <gravity@mjcoon.plus.com> wrote in
    <MPG.3cf4c0956a87c90d9896be@usenet.plus.net>:

    My design for a foyer quartz clock back in the early 1960s included a
    crystal in a thermostatic oven made from Perspex. I have a sketch and
    isometric of the oven and a note that there were five thermistors in a
    bridge, but no schematic. I do remember that on first testing the
    control circuit initially ran at full power heating, then cut off, then
    gradually settled on steady warmth!

    Yes that is overshot, maybe over-compensated

    My definition of over-compensated would be indefinite oscillation, which
    is what I was concerned about when I was monitoring the behaviour... No theory involved!


    The usual terminology would be "underdamped" if it's linear, or "windup"
    if it isn't.

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From DecadentLinuxUserNumeroUno@decadenc@21:1/5 to John Dope on Mon May 23 17:16:26 2022
    John Dope <always.look@message.header> wrote in news:t6gdmo$or8$6@dont- email.me:

    jlarkin@highlandsniptechnology.com wrote:

    Anybody can count to one.

    - Robert Widlar

    I don't get it.

    allintext:"Anybody can count to one" "Robert Widlar"

    Produces four results, all of them from John Larkin.


    Widlar was an engineer, idiot. Consider yourself 'flipped off'.

    You have to be a complete idiot to search and not find Widlar info.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From bitrex@21:1/5 to bitrex on Mon May 23 17:41:12 2022
    On 5/23/2022 5:40 PM, bitrex wrote:

      Hard to protect against that "floating in air".  They should try
    some nice aerogel inserts.  I think it has pretty good thermals
    compared to foam.

    Have you done that? Is aerogel rigid enough to support a subassembly?
    Would mechanical shocks scrunch it down?

    The foam inside the HP oven is stiff & brittle.

    Basically the consistency of dehydrated "astronaut" ice cream if you've
    had that stuff..

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From bitrex@21:1/5 to Phil Hobbs on Mon May 23 17:44:32 2022
    On 5/23/2022 9:48 AM, Phil Hobbs wrote:

    The interesting test would be to measure heater power with and without
    the foam.

    Air at room temperature has an alpha of about 0.026 W/m/K.  High-density styrofoam (the kind that crunches when you poke it with your finger) is
    about 0.040, and low-density styrofoam (the kind that squeaks) is around 0.030.

    Cheers

    Phil Hobbs


    The way I would describe the "insulating" (or whatever it does) foam in
    the HP oven is sort of the consistency of freeze-dried ice cream.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From bitrex@21:1/5 to jlarkin@highlandsniptechnology.com on Mon May 23 17:40:00 2022
    On 5/23/2022 11:46 AM, jlarkin@highlandsniptechnology.com wrote:
    On Mon, 23 May 2022 14:11:54 -0000 (UTC), DecadentLinuxUserNumeroUno@decadence.org wrote:

    jlarkin@highlandsniptechnology.com wrote in
    news:4hjl8hd5d42lhge1c7lu0kt7m29led31kd@4ax.com:

    On Sun, 22 May 2022 16:46:44 -0400, bitrex <user@example.net>
    wrote:

    On 5/22/2022 2:21 PM, jlarkin@highlandsniptechnology.com wrote:
    On Sun, 22 May 2022 13:24:02 -0400, bitrex <user@example.net>
    wrote:

    On 5/22/2022 4:31 AM, Anthony William Sloman wrote:
    On Sunday, May 22, 2022 at 1:15:05 PM UTC+10,
    jla...@highlandsniptechnology.com wrote:
    On Sat, 21 May 2022 20:50:12 -0400, bitrex
    <us...@example.net> wrote:

    Here's a paper on the theory of crystal ovens:

    <http://www.karlquist.com/oven.pdf>

    He didn't survey the literature all that well.

    There's a lot more to it than just slapping a crystal &
    heater in a metal box and calling it a day! There are
    probably some pathologically bad geometries even a really
    fast control loop can never stabilize very well.

    The part about the outer can acting like a Faraday shield is >>>>>>>>> interesting, shunting ambient gradients around the core.
    Does anyone know how they make the negative space look like
    a linear tehrmal resistance over a wide range? There's some
    kind of insulating foam in there, is main heat thermal
    transfer radiative or conduction?

    Conduction. Foam pretty much stops convection.

    It was mentioned on another thread that the thermal resistance
    of radiation between two concentric blackbodies at 300K is
    about 6mm, interestingly that's very close to the same
    thickness of foam-filled negative space between the outer and
    inner shells of the OCXO module on my 5334B.

    Don't know if that's a coincidence or not, obviously the two
    aren't at exactly 300K. The interior I think runs about 355K,
    while the exterior (I haven't measured it) seems cool enough to
    keep your hand on a while.


    In a reasonably close-fitting box, without a lot of space for
    convection, air is a better thermal insulator than foam or
    fiberglass.


    Here's a glamour shot of the internals:

    <https://imgur.com/a/W4hmKt4>

    Don't know what the foam is. It doesn't seem to conduct heat too
    good.



    The interesting test would be to measure heater power with and
    without the foam.




    The foam is for physical shock absorption, silly.

    None of my ovens depended on foam for mechanical support. Sometimes
    long lead wires are bad news too.

    I did mount one OCXO on some custom springs. Mating and unmating an
    nearby SMB test connector made my PLL lose lock.

    https://www.dropbox.com/s/0k8agdfyiqlwn84/Spring_2.JPG?raw=1

    https://www.dropbox.com/s/l2gr4fxas2k05fz/Sprung_Osc_2.JPG?raw=1



    Hard to protect against that "floating in air". They should try
    some nice aerogel inserts. I think it has pretty good thermals
    compared to foam.

    Have you done that? Is aerogel rigid enough to support a subassembly?
    Would mechanical shocks scrunch it down?

    The foam inside the HP oven is stiff & brittle. I think it may just be
    to separate the bits from each other and provide mechanical support, but
    I don't think I'd want to rely on it to absorb much shock.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From DecadentLinuxUserNumeroUno@decadenc@21:1/5 to bitrex on Mon May 23 22:05:22 2022
    bitrex <user@example.net> wrote in news:QaTiK.4601$8T.2667@fx40.iad:

    On 5/23/2022 11:46 AM, jlarkin@highlandsniptechnology.com wrote:
    On Mon, 23 May 2022 14:11:54 -0000 (UTC),
    DecadentLinuxUserNumeroUno@decadence.org wrote:

    jlarkin@highlandsniptechnology.com wrote in
    news:4hjl8hd5d42lhge1c7lu0kt7m29led31kd@4ax.com:

    On Sun, 22 May 2022 16:46:44 -0400, bitrex <user@example.net>
    wrote:

    On 5/22/2022 2:21 PM, jlarkin@highlandsniptechnology.com
    wrote:
    On Sun, 22 May 2022 13:24:02 -0400, bitrex <user@example.net>
    wrote:

    On 5/22/2022 4:31 AM, Anthony William Sloman wrote:
    On Sunday, May 22, 2022 at 1:15:05 PM UTC+10,
    jla...@highlandsniptechnology.com wrote:
    On Sat, 21 May 2022 20:50:12 -0400, bitrex
    <us...@example.net> wrote:

    Here's a paper on the theory of crystal ovens:

    <http://www.karlquist.com/oven.pdf>

    He didn't survey the literature all that well.

    There's a lot more to it than just slapping a crystal &
    heater in a metal box and calling it a day! There are
    probably some pathologically bad geometries even a really
    fast control loop can never stabilize very well.

    The part about the outer can acting like a Faraday shield
    is interesting, shunting ambient gradients around the
    core. Does anyone know how they make the negative space
    look like a linear tehrmal resistance over a wide range?
    There's some kind of insulating foam in there, is main
    heat thermal transfer radiative or conduction?

    Conduction. Foam pretty much stops convection.

    It was mentioned on another thread that the thermal
    resistance of radiation between two concentric blackbodies
    at 300K is about 6mm, interestingly that's very close to the
    same thickness of foam-filled negative space between the
    outer and inner shells of the OCXO module on my 5334B.

    Don't know if that's a coincidence or not, obviously the two
    aren't at exactly 300K. The interior I think runs about
    355K, while the exterior (I haven't measured it) seems cool
    enough to keep your hand on a while.


    In a reasonably close-fitting box, without a lot of space for
    convection, air is a better thermal insulator than foam or
    fiberglass.


    Here's a glamour shot of the internals:

    <https://imgur.com/a/W4hmKt4>

    Don't know what the foam is. It doesn't seem to conduct heat
    too good.



    The interesting test would be to measure heater power with and
    without the foam.




    The foam is for physical shock absorption, silly.

    None of my ovens depended on foam for mechanical support.
    Sometimes long lead wires are bad news too.

    I did mount one OCXO on some custom springs. Mating and unmating
    an nearby SMB test connector made my PLL lose lock.

    https://www.dropbox.com/s/0k8agdfyiqlwn84/Spring_2.JPG?raw=1

    https://www.dropbox.com/s/l2gr4fxas2k05fz/Sprung_Osc_2.JPG?raw=1



    Hard to protect against that "floating in air". They should
    try
    some nice aerogel inserts. I think it has pretty good thermals
    compared to foam.

    Have you done that? Is aerogel rigid enough to support a
    subassembly? Would mechanical shocks scrunch it down?

    The foam inside the HP oven is stiff & brittle. I think it may
    just be to separate the bits from each other and provide
    mechanical support, but I don't think I'd want to rely on it to
    absorb much shock.



    Compared to being suspended in air, I am sure it wil absorb more.
    Just what do you think "mechanical support" is?

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Larkin@21:1/5 to bitrex on Mon May 23 15:54:29 2022
    On Mon, 23 May 2022 17:41:12 -0400, bitrex <user@example.net> wrote:

    On 5/23/2022 5:40 PM, bitrex wrote:

    Hard to protect against that "floating in air". They should try
    some nice aerogel inserts. I think it has pretty good thermals
    compared to foam.

    Have you done that? Is aerogel rigid enough to support a subassembly?
    Would mechanical shocks scrunch it down?

    The foam inside the HP oven is stiff & brittle.

    Basically the consistency of dehydrated "astronaut" ice cream if you've
    had that stuff..

    Dehydrated ice cream? I'm glad I didn't become an astronaut.

    --

    If a man will begin with certainties, he shall end with doubts,
    but if he will be content to begin with doubts he shall end in certainties. Francis Bacon

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From bitrex@21:1/5 to DecadentLinuxUserNumeroUno@decadenc on Mon May 23 18:44:16 2022
    On 5/23/2022 6:05 PM, DecadentLinuxUserNumeroUno@decadence.org wrote:
    bitrex <user@example.net> wrote in news:QaTiK.4601$8T.2667@fx40.iad:

    On 5/23/2022 11:46 AM, jlarkin@highlandsniptechnology.com wrote:
    On Mon, 23 May 2022 14:11:54 -0000 (UTC),
    DecadentLinuxUserNumeroUno@decadence.org wrote:

    jlarkin@highlandsniptechnology.com wrote in
    news:4hjl8hd5d42lhge1c7lu0kt7m29led31kd@4ax.com:

    On Sun, 22 May 2022 16:46:44 -0400, bitrex <user@example.net>
    wrote:

    On 5/22/2022 2:21 PM, jlarkin@highlandsniptechnology.com
    wrote:
    On Sun, 22 May 2022 13:24:02 -0400, bitrex <user@example.net>
    wrote:

    On 5/22/2022 4:31 AM, Anthony William Sloman wrote:
    On Sunday, May 22, 2022 at 1:15:05 PM UTC+10,
    jla...@highlandsniptechnology.com wrote:
    On Sat, 21 May 2022 20:50:12 -0400, bitrex
    <us...@example.net> wrote:

    Here's a paper on the theory of crystal ovens:

    <http://www.karlquist.com/oven.pdf>

    He didn't survey the literature all that well.

    There's a lot more to it than just slapping a crystal &
    heater in a metal box and calling it a day! There are
    probably some pathologically bad geometries even a really >>>>>>>>>>> fast control loop can never stabilize very well.

    The part about the outer can acting like a Faraday shield >>>>>>>>>>> is interesting, shunting ambient gradients around the
    core. Does anyone know how they make the negative space
    look like a linear tehrmal resistance over a wide range? >>>>>>>>>>> There's some kind of insulating foam in there, is main
    heat thermal transfer radiative or conduction?

    Conduction. Foam pretty much stops convection.

    It was mentioned on another thread that the thermal
    resistance of radiation between two concentric blackbodies
    at 300K is about 6mm, interestingly that's very close to the
    same thickness of foam-filled negative space between the
    outer and inner shells of the OCXO module on my 5334B.

    Don't know if that's a coincidence or not, obviously the two
    aren't at exactly 300K. The interior I think runs about
    355K, while the exterior (I haven't measured it) seems cool
    enough to keep your hand on a while.


    In a reasonably close-fitting box, without a lot of space for
    convection, air is a better thermal insulator than foam or
    fiberglass.


    Here's a glamour shot of the internals:

    <https://imgur.com/a/W4hmKt4>

    Don't know what the foam is. It doesn't seem to conduct heat
    too good.



    The interesting test would be to measure heater power with and
    without the foam.




    The foam is for physical shock absorption, silly.

    None of my ovens depended on foam for mechanical support.
    Sometimes long lead wires are bad news too.

    I did mount one OCXO on some custom springs. Mating and unmating
    an nearby SMB test connector made my PLL lose lock.

    https://www.dropbox.com/s/0k8agdfyiqlwn84/Spring_2.JPG?raw=1

    https://www.dropbox.com/s/l2gr4fxas2k05fz/Sprung_Osc_2.JPG?raw=1



    Hard to protect against that "floating in air". They should
    try
    some nice aerogel inserts. I think it has pretty good thermals
    compared to foam.

    Have you done that? Is aerogel rigid enough to support a
    subassembly? Would mechanical shocks scrunch it down?

    The foam inside the HP oven is stiff & brittle. I think it may
    just be to separate the bits from each other and provide
    mechanical support, but I don't think I'd want to rely on it to
    absorb much shock.



    Compared to being suspended in air, I am sure it wil absorb more.
    Just what do you think "mechanical support" is?

    Do u require mechanical support:

    <https://www.mayoclinic.org/tests-procedures/penis-pump/about/pac-20385225>

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From bitrex@21:1/5 to John Larkin on Mon May 23 22:02:28 2022
    On 5/23/2022 6:54 PM, John Larkin wrote:
    On Mon, 23 May 2022 17:41:12 -0400, bitrex <user@example.net> wrote:

    On 5/23/2022 5:40 PM, bitrex wrote:

      Hard to protect against that "floating in air".  They should try >>>>> some nice aerogel inserts.  I think it has pretty good thermals
    compared to foam.

    Have you done that? Is aerogel rigid enough to support a subassembly?
    Would mechanical shocks scrunch it down?

    The foam inside the HP oven is stiff & brittle.

    Basically the consistency of dehydrated "astronaut" ice cream if you've
    had that stuff..

    Dehydrated ice cream? I'm glad I didn't become an astronaut.


    Yeah, freeze-dried. No idea if this stuff was actually used on space
    flights or when. My mother used to buy it for me at science museum gift
    shops when I was a kid, we didn't have much money but she didn't like to
    turn me down for a few souvenirs so long as they were "educational"!

    It was sweet at least and most sweet stuff tastes good to an 8 y/o:

    <https://youtu.be/gmGDBmeyBIs>

    The pull-back racer Space Shuttle toy was another classic gift shop crowd-pleaser.

    <https://www.amazon.com/5-Diecast-Pullback-Space-Shuttle/dp/B003PATHLU/>

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to All on Mon May 23 19:24:14 2022
    On Mon, 23 May 2022 10:09:23 -0700 (PDT), whit3rd <whit3rd@gmail.com>
    wrote:

    On Monday, May 23, 2022 at 8:46:31 AM UTC-7, jla...@highlandsniptechnology.com wrote:
    On Mon, 23 May 2022 14:11:54 -0000 (UTC),
    DecadentLinux...@decadence.org wrote:

    The foam is for physical shock absorption, silly.

    None of my ovens depended on foam for mechanical support. Sometimes
    long lead wires are bad news too.

    I did mount one OCXO on some custom springs...

    Hard to protect against that "floating in air". They should try
    some nice aerogel inserts. I think it has pretty good thermals
    compared to foam.

    Have you done that? Is aerogel rigid enough to support a subassembly?
    Would mechanical shocks scrunch it down?

    Some aerogels are foam-like quartz, quite strong enough for most uses, and >relatively tough. You could use 'em to support, and they're good in vacuum (if
    you want a good insulator, ditch the air). On the other hand, a perforated
    section of fiberglass PCB should likewise be a thermal break. How
    stingy on heater power do you want to be?

    Heater power is seldom an issue. Heat loss is bad because it makes an
    assembly non-isothermal, so that some bits are not at the same
    temperature as the feedback sensor. And the difference will vary with
    heater power, namely ambient temp.



    --

    Anybody can count to one.

    - Robert Widlar

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jan Panteltje@21:1/5 to gravity@mjcoon.plus.com on Tue May 24 05:50:14 2022
    On a sunny day (Mon, 23 May 2022 17:34:33 +0100) it happened Mike Coon <gravity@mjcoon.plus.com> wrote in <MPG.3cf5c7f82510056d9896bf@usenet.plus.net>:

    In article <t6fga4$f2p$1@dont-email.me>, pNaonStpealmtje@yahoo.com
    says...

    On a sunny day (Sun, 22 May 2022 22:51:09 +0100) it happened Mike Coon
    <gravity@mjcoon.plus.com> wrote in
    <MPG.3cf4c0956a87c90d9896be@usenet.plus.net>:

    My design for a foyer quartz clock back in the early 1960s included a
    crystal in a thermostatic oven made from Perspex. I have a sketch and
    isometric of the oven and a note that there were five thermistors in a
    bridge, but no schematic. I do remember that on first testing the
    control circuit initially ran at full power heating, then cut off, then
    gradually settled on steady warmth!

    Yes that is overshot, maybe over-compensated

    My definition of over-compensated would be indefinite oscillation, which
    is what I was concerned about when I was monitoring the behaviour... No >theory involved!

    http://panteltje.com/pub/under_and_over_compensated_IXIMG_0818.JPG

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Doe@21:1/5 to All on Tue May 24 07:01:07 2022
    Bob Widlar was a big engineer.

    Now, what is the significance of "Anybody can count to one"?

    Seems not to be a famous quote.

    --

    John Dope <always.look@message.header> wrote in news:t6gdmo$or8$6@dont- email.me:

    jlarkin@highlandsniptechnology.com wrote:

    Anybody can count to one.

    - Robert Widlar

    I don't get it.

    allintext:"Anybody can count to one" "Robert Widlar"

    Produces four results, all of them from John Larkin.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Mike Coon@21:1/5 to All on Tue May 24 08:41:01 2022
    In article <t6hrnr$2ac$1@dont-email.me>, pNaonStpealmtje@yahoo.com
    says...

    On a sunny day (Mon, 23 May 2022 17:34:33 +0100) it happened Mike Coon <gravity@mjcoon.plus.com> wrote in <MPG.3cf5c7f82510056d9896bf@usenet.plus.net>:

    In article <t6fga4$f2p$1@dont-email.me>, pNaonStpealmtje@yahoo.com
    says...

    On a sunny day (Sun, 22 May 2022 22:51:09 +0100) it happened Mike Coon
    <gravity@mjcoon.plus.com> wrote in
    <MPG.3cf4c0956a87c90d9896be@usenet.plus.net>:

    My design for a foyer quartz clock back in the early 1960s included a
    crystal in a thermostatic oven made from Perspex. I have a sketch and
    isometric of the oven and a note that there were five thermistors in a
    bridge, but no schematic. I do remember that on first testing the
    control circuit initially ran at full power heating, then cut off, then >> >gradually settled on steady warmth!

    Yes that is overshot, maybe over-compensated

    My definition of over-compensated would be indefinite oscillation, which
    is what I was concerned about when I was monitoring the behaviour... No >theory involved!

    http://panteltje.com/pub/under_and_over_compensated_IXIMG_0818.JPG

    Thanks for that idiosyncratic illustration! You could also have reminded
    me of the calculus of feedback theory which I studied for my degree back
    in the early 1960s. It was merely the modern (?) terminology I was
    querying. "Windup" indeed; that's a gramophone!

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Anthony William Sloman@21:1/5 to Mike Coon on Tue May 24 02:05:05 2022
    On Tuesday, May 24, 2022 at 2:34:46 AM UTC+10, Mike Coon wrote:
    In article <t6fga4$f2p$1...@dont-email.me>, pNaonSt...@yahoo.com
    says...

    On a sunny day (Sun, 22 May 2022 22:51:09 +0100) it happened Mike Coon <gra...@mjcoon.plus.com> wrote in
    <MPG.3cf4c0956...@usenet.plus.net>:

    My design for a foyer quartz clock back in the early 1960s included a >crystal in a thermostatic oven made from Perspex. I have a sketch and >isometric of the oven and a note that there were five thermistors in a >bridge, but no schematic. I do remember that on first testing the
    control circuit initially ran at full power heating, then cut off, then >gradually settled on steady warmth!

    Yes that is overshot, maybe over-compensated
    My definition of over-compensated would be indefinite oscillation, which
    is what I was concerned about when I was monitoring the behaviour... No theory involved!

    Clearly not. Most people understand over-compensated to mean very long settling times, and under-compensated to mean ringing. If it is second or or higher order system, a sufficiently undercompensates unit can oscillate.

    --
    Bill Sloman, Sydney

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to gravity@mjcoon.plus.com on Tue May 24 07:28:27 2022
    On Tue, 24 May 2022 08:41:01 +0100, Mike Coon
    <gravity@mjcoon.plus.com> wrote:

    In article <t6hrnr$2ac$1@dont-email.me>, pNaonStpealmtje@yahoo.com
    says...

    On a sunny day (Mon, 23 May 2022 17:34:33 +0100) it happened Mike Coon
    <gravity@mjcoon.plus.com> wrote in
    <MPG.3cf5c7f82510056d9896bf@usenet.plus.net>:

    In article <t6fga4$f2p$1@dont-email.me>, pNaonStpealmtje@yahoo.com
    says...

    On a sunny day (Sun, 22 May 2022 22:51:09 +0100) it happened Mike Coon
    <gravity@mjcoon.plus.com> wrote in
    <MPG.3cf4c0956a87c90d9896be@usenet.plus.net>:

    My design for a foyer quartz clock back in the early 1960s included a
    crystal in a thermostatic oven made from Perspex. I have a sketch and
    isometric of the oven and a note that there were five thermistors in a >> >> >bridge, but no schematic. I do remember that on first testing the
    control circuit initially ran at full power heating, then cut off, then >> >> >gradually settled on steady warmth!

    Yes that is overshot, maybe over-compensated

    My definition of over-compensated would be indefinite oscillation, which
    is what I was concerned about when I was monitoring the behaviour... No
    theory involved!

    http://panteltje.com/pub/under_and_over_compensated_IXIMG_0818.JPG

    Thanks for that idiosyncratic illustration! You could also have reminded
    me of the calculus of feedback theory which I studied for my degree back
    in the early 1960s. It was merely the modern (?) terminology I was
    querying. "Windup" indeed; that's a gramophone!

    We usually tune thermal loops in the classic linear style, for critically-damped small signal disturbance. They will typically
    overshoot at cold-start powerup because the integrator winds up and
    rails. Rob did a lot of fancy math to define the software control
    loop; I just Spice things like that.

    The oven that I pictured has a 2nd order plant response, about 75
    minutes tau for the huge aluminum block and about another 17 for the
    platform and e/o modulator inside. Spacers set the second time
    constant; aluminum, stainless, or plastic.

    One goal was to force minimal thermal gradients along the length of
    the Mach-Zender electro-optical modulator.

    https://www.dropbox.com/sh/knkoywpv6563mj5/AACy1sLNcyqIO8Eik4NRCC9Da?dl=0

    We have lots of heater power available so we can stabilize to
    millikelvins in about a half hour.





    --

    Anybody can count to one.

    - Robert Widlar

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to jlarkin@highlandsniptechnology.com on Tue May 24 11:06:16 2022
    jlarkin@highlandsniptechnology.com wrote:
    On Tue, 24 May 2022 08:41:01 +0100, Mike Coon
    <gravity@mjcoon.plus.com> wrote:

    In article <t6hrnr$2ac$1@dont-email.me>, pNaonStpealmtje@yahoo.com
    says...

    On a sunny day (Mon, 23 May 2022 17:34:33 +0100) it happened Mike Coon
    <gravity@mjcoon.plus.com> wrote in
    <MPG.3cf5c7f82510056d9896bf@usenet.plus.net>:

    In article <t6fga4$f2p$1@dont-email.me>, pNaonStpealmtje@yahoo.com
    says...

    On a sunny day (Sun, 22 May 2022 22:51:09 +0100) it happened Mike Coon >>>>> <gravity@mjcoon.plus.com> wrote in
    <MPG.3cf4c0956a87c90d9896be@usenet.plus.net>:

    My design for a foyer quartz clock back in the early 1960s included a >>>>>> crystal in a thermostatic oven made from Perspex. I have a sketch and >>>>>> isometric of the oven and a note that there were five thermistors in a >>>>>> bridge, but no schematic. I do remember that on first testing the
    control circuit initially ran at full power heating, then cut off, then >>>>>> gradually settled on steady warmth!

    Yes that is overshot, maybe over-compensated

    My definition of over-compensated would be indefinite oscillation, which >>>> is what I was concerned about when I was monitoring the behaviour... No >>>> theory involved!

    http://panteltje.com/pub/under_and_over_compensated_IXIMG_0818.JPG

    Thanks for that idiosyncratic illustration! You could also have reminded
    me of the calculus of feedback theory which I studied for my degree back
    in the early 1960s. It was merely the modern (?) terminology I was
    querying. "Windup" indeed; that's a gramophone!

    We usually tune thermal loops in the classic linear style, for critically-damped small signal disturbance. They will typically
    overshoot at cold-start powerup because the integrator winds up and
    rails. Rob did a lot of fancy math to define the software control
    loop; I just Spice things like that.

    The oven that I pictured has a 2nd order plant response, about 75
    minutes tau for the huge aluminum block and about another 17 for the
    platform and e/o modulator inside. Spacers set the second time
    constant; aluminum, stainless, or plastic.

    One goal was to force minimal thermal gradients along the length of
    the Mach-Zender electro-optical modulator.

    https://www.dropbox.com/sh/knkoywpv6563mj5/AACy1sLNcyqIO8Eik4NRCC9Da?dl=0

    We have lots of heater power available so we can stabilize to
    millikelvins in about a half hour.

    One of the less-frequently remarked advantages of thermoelectrics is
    that anywhere near room temperature they can have considerably better
    forcing resistance than heater-only loops with a given bandwidth.

    A heater-only loop gets its negative slewing exclusively from the heat
    leak, which of course leaks in both directions, whereas a TEC can pull
    as well as push, so a TEC-based loop can be better insulated for the
    same control bandwidth and slew rate.

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From DecadentLinuxUserNumeroUno@decadenc@21:1/5 to bitrex on Tue May 24 16:12:57 2022
    bitrex <user@example.net> wrote in
    news:47UiK.3545$vAW9.2843@fx10.iad:

    On 5/23/2022 6:05 PM, DecadentLinuxUserNumeroUno@decadence.org
    wrote:
    bitrex <user@example.net> wrote in
    news:QaTiK.4601$8T.2667@fx40.iad:

    On 5/23/2022 11:46 AM, jlarkin@highlandsniptechnology.com wrote:
    On Mon, 23 May 2022 14:11:54 -0000 (UTC),
    DecadentLinuxUserNumeroUno@decadence.org wrote:

    jlarkin@highlandsniptechnology.com wrote in
    news:4hjl8hd5d42lhge1c7lu0kt7m29led31kd@4ax.com:

    On Sun, 22 May 2022 16:46:44 -0400, bitrex <user@example.net>
    wrote:

    On 5/22/2022 2:21 PM, jlarkin@highlandsniptechnology.com
    wrote:
    On Sun, 22 May 2022 13:24:02 -0400, bitrex
    <user@example.net> wrote:

    On 5/22/2022 4:31 AM, Anthony William Sloman wrote:
    On Sunday, May 22, 2022 at 1:15:05 PM UTC+10,
    jla...@highlandsniptechnology.com wrote:
    On Sat, 21 May 2022 20:50:12 -0400, bitrex
    <us...@example.net> wrote:

    Here's a paper on the theory of crystal ovens:

    <http://www.karlquist.com/oven.pdf>

    He didn't survey the literature all that well.

    There's a lot more to it than just slapping a crystal & >>>>>>>>>>>> heater in a metal box and calling it a day! There are
    probably some pathologically bad geometries even a
    really fast control loop can never stabilize very well. >>>>>>>>>>>>
    The part about the outer can acting like a Faraday
    shield is interesting, shunting ambient gradients
    around the core. Does anyone know how they make the
    negative space look like a linear tehrmal resistance
    over a wide range? There's some kind of insulating foam >>>>>>>>>>>> in there, is main heat thermal transfer radiative or
    conduction?

    Conduction. Foam pretty much stops convection.

    It was mentioned on another thread that the thermal
    resistance of radiation between two concentric blackbodies
    at 300K is about 6mm, interestingly that's very close to
    the same thickness of foam-filled negative space between
    the outer and inner shells of the OCXO module on my 5334B.

    Don't know if that's a coincidence or not, obviously the
    two aren't at exactly 300K. The interior I think runs
    about 355K, while the exterior (I haven't measured it)
    seems cool enough to keep your hand on a while.


    In a reasonably close-fitting box, without a lot of space
    for convection, air is a better thermal insulator than foam
    or fiberglass.


    Here's a glamour shot of the internals:

    <https://imgur.com/a/W4hmKt4>

    Don't know what the foam is. It doesn't seem to conduct heat
    too good.



    The interesting test would be to measure heater power with
    and without the foam.




    The foam is for physical shock absorption, silly.

    None of my ovens depended on foam for mechanical support.
    Sometimes long lead wires are bad news too.

    I did mount one OCXO on some custom springs. Mating and
    unmating an nearby SMB test connector made my PLL lose lock.

    https://www.dropbox.com/s/0k8agdfyiqlwn84/Spring_2.JPG?raw=1

    https://www.dropbox.com/s/l2gr4fxas2k05fz/Sprung_Osc_2.JPG?raw=1



    Hard to protect against that "floating in air". They
    should try
    some nice aerogel inserts. I think it has pretty good
    thermals compared to foam.

    Have you done that? Is aerogel rigid enough to support a
    subassembly? Would mechanical shocks scrunch it down?

    The foam inside the HP oven is stiff & brittle. I think it may
    just be to separate the bits from each other and provide
    mechanical support, but I don't think I'd want to rely on it to
    absorb much shock.



    Compared to being suspended in air, I am sure it wil absorb more.
    Just what do you think "mechanical support" is?

    Do u require mechanical support:

    Look at it. It is smaller than the can it is in. So yes, it
    requires mechanical support.

    snipped retarded link post.

    Real mature, twerp.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Larkin@21:1/5 to pcdhSpamMeSenseless@electrooptical. on Tue May 24 10:00:56 2022
    On Tue, 24 May 2022 11:06:16 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Tue, 24 May 2022 08:41:01 +0100, Mike Coon
    <gravity@mjcoon.plus.com> wrote:

    In article <t6hrnr$2ac$1@dont-email.me>, pNaonStpealmtje@yahoo.com
    says...

    On a sunny day (Mon, 23 May 2022 17:34:33 +0100) it happened Mike Coon >>>> <gravity@mjcoon.plus.com> wrote in
    <MPG.3cf5c7f82510056d9896bf@usenet.plus.net>:

    In article <t6fga4$f2p$1@dont-email.me>, pNaonStpealmtje@yahoo.com
    says...

    On a sunny day (Sun, 22 May 2022 22:51:09 +0100) it happened Mike Coon >>>>>> <gravity@mjcoon.plus.com> wrote in
    <MPG.3cf4c0956a87c90d9896be@usenet.plus.net>:

    My design for a foyer quartz clock back in the early 1960s included a >>>>>>> crystal in a thermostatic oven made from Perspex. I have a sketch and >>>>>>> isometric of the oven and a note that there were five thermistors in a >>>>>>> bridge, but no schematic. I do remember that on first testing the >>>>>>> control circuit initially ran at full power heating, then cut off, then >>>>>>> gradually settled on steady warmth!

    Yes that is overshot, maybe over-compensated

    My definition of over-compensated would be indefinite oscillation, which >>>>> is what I was concerned about when I was monitoring the behaviour... No >>>>> theory involved!

    http://panteltje.com/pub/under_and_over_compensated_IXIMG_0818.JPG

    Thanks for that idiosyncratic illustration! You could also have reminded >>> me of the calculus of feedback theory which I studied for my degree back >>> in the early 1960s. It was merely the modern (?) terminology I was
    querying. "Windup" indeed; that's a gramophone!

    We usually tune thermal loops in the classic linear style, for
    critically-damped small signal disturbance. They will typically
    overshoot at cold-start powerup because the integrator winds up and
    rails. Rob did a lot of fancy math to define the software control
    loop; I just Spice things like that.

    The oven that I pictured has a 2nd order plant response, about 75
    minutes tau for the huge aluminum block and about another 17 for the
    platform and e/o modulator inside. Spacers set the second time
    constant; aluminum, stainless, or plastic.

    One goal was to force minimal thermal gradients along the length of
    the Mach-Zender electro-optical modulator.

    https://www.dropbox.com/sh/knkoywpv6563mj5/AACy1sLNcyqIO8Eik4NRCC9Da?dl=0

    We have lots of heater power available so we can stabilize to
    millikelvins in about a half hour.

    One of the less-frequently remarked advantages of thermoelectrics is
    that anywhere near room temperature they can have considerably better
    forcing resistance than heater-only loops with a given bandwidth.

    A heater-only loop gets its negative slewing exclusively from the heat
    leak, which of course leaks in both directions, whereas a TEC can pull
    as well as push, so a TEC-based loop can be better insulated for the
    same control bandwidth and slew rate.

    Cheers

    Phil Hobbs

    We only run at 30c, and ambient is very reliably 22. We considered
    TECs but that was too complex and expensive. We sure don't want a fan
    anywhere close to our optics.

    The dpak mosfet heaters are cheap!

    --

    If a man will begin with certainties, he shall end with doubts,
    but if he will be content to begin with doubts he shall end in certainties. Francis Bacon

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From DecadentLinuxUserNumeroUno@decadenc@21:1/5 to John Dope on Tue May 24 16:36:39 2022
    John Dope <always.look@message.header> wrote in news:t6hvrj$kq3$3@dont- email.me:

    Bob Widlar was a big engineer.

    Now, what is the significance of "Anybody can count to one"?

    Seems not to be a famous quote.


    John Dope is still in the dark. You never knew electronics and have
    been a mere interloper all these years, at best.

    The actual quote is "Every idiot can count to one."

    So even your google skill sucks. John Dope lives up to his name
    every time he posts into SED.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Gerhard Hoffmann@21:1/5 to All on Tue May 24 20:35:43 2022
    Am 24.05.22 um 17:06 schrieb Phil Hobbs:
    jlarkin@highlandsniptechnology.com wrote:
    he Mach-Zender electro-optical modulator.

    https://www.dropbox.com/sh/knkoywpv6563mj5/AACy1sLNcyqIO8Eik4NRCC9Da?dl=0

    We have lots of heater power available so we can stabilize to
    millikelvins in about a half hour.

    One of the less-frequently remarked advantages of thermoelectrics is
    that anywhere near room temperature they can have considerably better
    forcing resistance than heater-only loops with a given bandwidth.

    A heater-only loop gets its negative slewing exclusively from the heat
    leak, which of course leaks in both directions, whereas a TEC can pull
    as well as push, so a TEC-based loop can be better insulated for the
    same control bandwidth and slew rate.

    But a TEC has a thermal low-impedance-path from inside to the
    outside. That is unwanted and one of the reasons for their bad efficiency.
    That means that heat transients on the outside get in
    immediately and must be activly regulated away, AFTER they have happened.

    Yes, one could insulate the outside of the TEC, but that is somewhat ill?

    Cheers, Gerhard

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Doe@21:1/5 to DecadentLinuxUserNumeroUno@decadenc on Tue May 24 18:41:31 2022
    The proper quote helped.

    Thanks for doing that work for me, Always Insulting.


    DecadentLinuxUserNumeroUno@decadence.org wrote:

    John Dope <always.look@message.header> wrote in news:t6hvrj$kq3$3@dont- email.me:

    Bob Widlar was a big engineer.

    Now, what is the significance of "Anybody can count to one"?

    Seems not to be a famous quote.


    John Dope is still in the dark. You never knew electronics and have
    been a mere interloper all these years, at best.

    The actual quote is "Every idiot can count to one."

    So even your google skill sucks. John Dope lives up to his name
    every time he posts into SED.


    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Lasse Langwadt Christensen@21:1/5 to All on Tue May 24 11:50:25 2022
    tirsdag den 24. maj 2022 kl. 20.35.50 UTC+2 skrev Gerhard Hoffmann:
    Am 24.05.22 um 17:06 schrieb Phil Hobbs:
    jla...@highlandsniptechnology.com wrote:
    he Mach-Zender electro-optical modulator.

    https://www.dropbox.com/sh/knkoywpv6563mj5/AACy1sLNcyqIO8Eik4NRCC9Da?dl=0 >>
    We have lots of heater power available so we can stabilize to
    millikelvins in about a half hour.

    One of the less-frequently remarked advantages of thermoelectrics is
    that anywhere near room temperature they can have considerably better forcing resistance than heater-only loops with a given bandwidth.

    A heater-only loop gets its negative slewing exclusively from the heat leak, which of course leaks in both directions, whereas a TEC can pull
    as well as push, so a TEC-based loop can be better insulated for the
    same control bandwidth and slew rate.
    But a TEC has a thermal low-impedance-path from inside to the
    outside. That is unwanted and one of the reasons for their bad efficiency. That means that heat transients on the outside get in
    immediately and must be activly regulated away, AFTER they have happened.

    and every time you stop cooling the heat you just moved come right back at you

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Doe@21:1/5 to DecadentLinuxUserNumeroUno@decadenc on Tue May 24 20:43:13 2022
    Our reactionary foulmouthed troll, a.k.a. Always Wrong...


    DecadentLinuxUserNumeroUno@decadence.org wrote:

    John Dope <always.look@message.header> wrote in news:t6j8sq$61v$3@dont- email.me:

    The proper quote helped.


    You are a fucking total retard. ALL that was EVER needed was the
    guy's name. So you are dumber than a 5 year old. It does not get
    dumber than you John Dope.

    Kids know how to use the hardware better than you do and they get
    better results too.

    Aren't you the total retard trying to power a bicycle with a drill
    motor?


    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to John Larkin on Tue May 24 16:49:29 2022
    John Larkin wrote:
    On Tue, 24 May 2022 11:06:16 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Tue, 24 May 2022 08:41:01 +0100, Mike Coon
    <gravity@mjcoon.plus.com> wrote:

    In article <t6hrnr$2ac$1@dont-email.me>, pNaonStpealmtje@yahoo.com
    says...

    On a sunny day (Mon, 23 May 2022 17:34:33 +0100) it happened Mike Coon >>>>> <gravity@mjcoon.plus.com> wrote in
    <MPG.3cf5c7f82510056d9896bf@usenet.plus.net>:

    In article <t6fga4$f2p$1@dont-email.me>, pNaonStpealmtje@yahoo.com >>>>>> says...

    On a sunny day (Sun, 22 May 2022 22:51:09 +0100) it happened Mike Coon >>>>>>> <gravity@mjcoon.plus.com> wrote in
    <MPG.3cf4c0956a87c90d9896be@usenet.plus.net>:

    My design for a foyer quartz clock back in the early 1960s included a >>>>>>>> crystal in a thermostatic oven made from Perspex. I have a sketch and >>>>>>>> isometric of the oven and a note that there were five thermistors in a >>>>>>>> bridge, but no schematic. I do remember that on first testing the >>>>>>>> control circuit initially ran at full power heating, then cut off, then
    gradually settled on steady warmth!

    Yes that is overshot, maybe over-compensated

    My definition of over-compensated would be indefinite oscillation, which >>>>>> is what I was concerned about when I was monitoring the behaviour... No >>>>>> theory involved!

    http://panteltje.com/pub/under_and_over_compensated_IXIMG_0818.JPG >>>>
    Thanks for that idiosyncratic illustration! You could also have reminded >>>> me of the calculus of feedback theory which I studied for my degree back >>>> in the early 1960s. It was merely the modern (?) terminology I was
    querying. "Windup" indeed; that's a gramophone!

    We usually tune thermal loops in the classic linear style, for
    critically-damped small signal disturbance. They will typically
    overshoot at cold-start powerup because the integrator winds up and
    rails. Rob did a lot of fancy math to define the software control
    loop; I just Spice things like that.

    The oven that I pictured has a 2nd order plant response, about 75
    minutes tau for the huge aluminum block and about another 17 for the
    platform and e/o modulator inside. Spacers set the second time
    constant; aluminum, stainless, or plastic.

    One goal was to force minimal thermal gradients along the length of
    the Mach-Zender electro-optical modulator.

    https://www.dropbox.com/sh/knkoywpv6563mj5/AACy1sLNcyqIO8Eik4NRCC9Da?dl=0 >>>
    We have lots of heater power available so we can stabilize to
    millikelvins in about a half hour.

    One of the less-frequently remarked advantages of thermoelectrics is
    that anywhere near room temperature they can have considerably better
    forcing resistance than heater-only loops with a given bandwidth.

    A heater-only loop gets its negative slewing exclusively from the heat
    leak, which of course leaks in both directions, whereas a TEC can pull
    as well as push, so a TEC-based loop can be better insulated for the
    same control bandwidth and slew rate.


    We only run at 30c, and ambient is very reliably 22. We considered
    TECs but that was too complex and expensive. We sure don't want a fan anywhere close to our optics.

    The dpak mosfet heaters are cheap!


    Sure, I'm all in favour of what works. The lower heat leak thing is a
    big help if there's forcing above a few percent of the loop bandwidth.

    Cheers

    Phil Hobbs



    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From DecadentLinuxUserNumeroUno@decadenc@21:1/5 to John Dope on Tue May 24 20:34:53 2022
    John Dope <always.look@message.header> wrote in news:t6j8sq$61v$3@dont- email.me:

    The proper quote helped.


    You are a fucking total retard. ALL that was EVER needed was the
    guy's name. So you are dumber than a 5 year old. It does not get
    dumber than you John Dope.

    Kids know how to use the hardware better than you do and they get
    better results too.

    Aren't you the total retard trying to power a bicycle with a drill
    motor?

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to Gerhard Hoffmann on Tue May 24 20:43:45 2022
    Gerhard Hoffmann wrote:
    Am 24.05.22 um 17:06 schrieb Phil Hobbs:
    jlarkin@highlandsniptechnology.com wrote:
    he Mach-Zender electro-optical modulator.

    https://www.dropbox.com/sh/knkoywpv6563mj5/AACy1sLNcyqIO8Eik4NRCC9Da?dl=0 >>>

    We have lots of heater power available so we can stabilize to
    millikelvins in about a half hour.

    One of the less-frequently remarked advantages of thermoelectrics is
    that anywhere near room temperature they can have considerably better
    forcing resistance than heater-only loops with a given bandwidth.

    A heater-only loop gets its negative slewing exclusively from the heat
    leak, which of course leaks in both directions, whereas a TEC can pull
    as well as push, so a TEC-based loop can be better insulated for the
    same control bandwidth and slew rate.

    But a TEC has a thermal low-impedance-path from inside to the
    outside. That is unwanted and one of the reasons for their bad efficiency. That means that heat transients on the outside get in
    immediately and must be activly regulated away, AFTER they have happened.

    I invite you to compute the ratio of the bandwidth available to a TEC
    loop vs a heater loop as the delta-T goes to zero. ;)

    Yes, one could insulate the outside of the TEC, but that is somewhat ill?

    You can get TECs in all sorts of sizes.

    Heater loops work fine at larger delta-T.

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to Chris Jones on Wed May 25 09:34:24 2022
    Chris Jones wrote:
    On 25/05/2022 04:35, Gerhard Hoffmann wrote:
    Am 24.05.22 um 17:06 schrieb Phil Hobbs:
    jlarkin@highlandsniptechnology.com wrote:
    he Mach-Zender electro-optical modulator.

    https://www.dropbox.com/sh/knkoywpv6563mj5/AACy1sLNcyqIO8Eik4NRCC9Da?dl=0 >>>>

    We have lots of heater power available so we can stabilize to
    millikelvins in about a half hour.

    One of the less-frequently remarked advantages of thermoelectrics is
    that anywhere near room temperature they can have considerably better
    forcing resistance than heater-only loops with a given bandwidth.

    A heater-only loop gets its negative slewing exclusively from the
    heat leak, which of course leaks in both directions, whereas a TEC
    can pull as well as push, so a TEC-based loop can be better insulated
    for the same control bandwidth and slew rate.

    But a TEC has a thermal low-impedance-path from inside to the
    outside. That is unwanted and one of the reasons for their bad
    efficiency.
    That means that heat transients on the outside get in
    immediately and must be activly regulated away, AFTER they have happened.

    You could put another temperature sensor on the outside end of the TEC,
    and do some sort of feed-forward as well, to remove most of the effect
    before it gets in.

    A really important tool in high-stability temperature control is a local feedback loop around each actuator. Proportional-only is fine, but what
    you really want is super high speed. These days we do a lot of
    TEC-based controllers. Our favourite method is to put a bare ENIG pour
    on the bottom side of the cold plate board (which usually has a laser or
    one or more photodetectors). This contacts the cold side of the TEC via (usually) silver grease.(*) One end of an 0603 thermistor is soldered
    to the pour, and the other goes via a longish skinny trace to the loop amp.

    Doing that costs next to nothing, and allows us to make a much faster
    simulated actuator with much much lower effective thermal conductance.

    Feedforward to the outer loop can also be done, but requires much more
    tuning because the speed of the outer loop changes dramatically with
    delta-T and Qdot.

    Cheers

    Phil Hobbs


    (*) Thermal silver grease has much much more silver than electrically-conductive silver paste.

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Chris Jones@21:1/5 to Gerhard Hoffmann on Wed May 25 23:17:29 2022
    On 25/05/2022 04:35, Gerhard Hoffmann wrote:
    Am 24.05.22 um 17:06 schrieb Phil Hobbs:
    jlarkin@highlandsniptechnology.com wrote:
    he Mach-Zender electro-optical modulator.

    https://www.dropbox.com/sh/knkoywpv6563mj5/AACy1sLNcyqIO8Eik4NRCC9Da?dl=0 >>>

    We have lots of heater power available so we can stabilize to
    millikelvins in about a half hour.

    One of the less-frequently remarked advantages of thermoelectrics is
    that anywhere near room temperature they can have considerably better
    forcing resistance than heater-only loops with a given bandwidth.

    A heater-only loop gets its negative slewing exclusively from the heat
    leak, which of course leaks in both directions, whereas a TEC can pull
    as well as push, so a TEC-based loop can be better insulated for the
    same control bandwidth and slew rate.

    But a TEC has a thermal low-impedance-path from inside to the
    outside. That is unwanted and one of the reasons for their bad efficiency. That means that heat transients on the outside get in
    immediately and must be activly regulated away, AFTER they have happened.

    You could put another temperature sensor on the outside end of the TEC,
    and do some sort of feed-forward as well, to remove most of the effect
    before it gets in.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to lugnut808@spam.yahoo.com on Wed May 25 07:13:47 2022
    On Wed, 25 May 2022 23:17:29 +1000, Chris Jones
    <lugnut808@spam.yahoo.com> wrote:

    On 25/05/2022 04:35, Gerhard Hoffmann wrote:
    Am 24.05.22 um 17:06 schrieb Phil Hobbs:
    jlarkin@highlandsniptechnology.com wrote:
    he Mach-Zender electro-optical modulator.

    https://www.dropbox.com/sh/knkoywpv6563mj5/AACy1sLNcyqIO8Eik4NRCC9Da?dl=0 >>>>

    We have lots of heater power available so we can stabilize to
    millikelvins in about a half hour.

    One of the less-frequently remarked advantages of thermoelectrics is
    that anywhere near room temperature they can have considerably better
    forcing resistance than heater-only loops with a given bandwidth.

    A heater-only loop gets its negative slewing exclusively from the heat
    leak, which of course leaks in both directions, whereas a TEC can pull
    as well as push, so a TEC-based loop can be better insulated for the
    same control bandwidth and slew rate.

    But a TEC has a thermal low-impedance-path from inside to the
    outside. That is unwanted and one of the reasons for their bad efficiency. >> That means that heat transients on the outside get in
    immediately and must be activly regulated away, AFTER they have happened.

    You could put another temperature sensor on the outside end of the TEC,
    and do some sort of feed-forward as well, to remove most of the effect
    before it gets in.

    Bad ovens sometimes sense ambient temp and feed-forward into the
    setpoint, to shotgun compensate the badness.

    The SRS SC10 is a good example of an oven done wrong. The manual of
    rev L is available online.



    --

    Anybody can count to one.

    - Robert Widlar

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Chris Jones@21:1/5 to Phil Hobbs on Thu May 26 23:36:03 2022
    On 25/05/2022 23:34, Phil Hobbs wrote:
    Chris Jones wrote:
    On 25/05/2022 04:35, Gerhard Hoffmann wrote:
    Am 24.05.22 um 17:06 schrieb Phil Hobbs:
    jlarkin@highlandsniptechnology.com wrote:
    he Mach-Zender electro-optical modulator.

    https://www.dropbox.com/sh/knkoywpv6563mj5/AACy1sLNcyqIO8Eik4NRCC9Da?dl=0 >>>>>

    We have lots of heater power available so we can stabilize to
    millikelvins in about a half hour.

    One of the less-frequently remarked advantages of thermoelectrics is
    that anywhere near room temperature they can have considerably
    better forcing resistance than heater-only loops with a given
    bandwidth.

    A heater-only loop gets its negative slewing exclusively from the
    heat leak, which of course leaks in both directions, whereas a TEC
    can pull as well as push, so a TEC-based loop can be better
    insulated for the same control bandwidth and slew rate.

    But a TEC has a thermal low-impedance-path from inside to the
    outside. That is unwanted and one of the reasons for their bad
    efficiency.
    That means that heat transients on the outside get in
    immediately and must be activly regulated away, AFTER they have
    happened.

    You could put another temperature sensor on the outside end of the
    TEC, and do some sort of feed-forward as well, to remove most of the
    effect before it gets in.

    A really important tool in high-stability temperature control is a local feedback loop around each actuator.  Proportional-only is fine, but what
    you really want is super high speed.  These days we do a lot of
    TEC-based controllers.  Our favourite method is to put a bare ENIG pour
    on the bottom side of the cold plate board (which usually has a laser or
    one or more photodetectors).  This contacts the cold side of the TEC via (usually) silver grease.(*)  One end of an 0603 thermistor is soldered
    to the pour, and the other goes via a longish skinny trace to the loop amp.

    Doing that costs next to nothing, and allows us to make a much faster simulated actuator with much much lower effective thermal conductance.

    That scheme makes a lot of sense.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to Chris Jones on Thu May 26 10:08:51 2022
    Chris Jones wrote:
    On 25/05/2022 23:34, Phil Hobbs wrote:
    Chris Jones wrote:
    On 25/05/2022 04:35, Gerhard Hoffmann wrote:
    Am 24.05.22 um 17:06 schrieb Phil Hobbs:
    jlarkin@highlandsniptechnology.com wrote:
    he Mach-Zender electro-optical modulator.

    https://www.dropbox.com/sh/knkoywpv6563mj5/AACy1sLNcyqIO8Eik4NRCC9Da?dl=0


    We have lots of heater power available so we can stabilize to
    millikelvins in about a half hour.

    One of the less-frequently remarked advantages of thermoelectrics
    is that anywhere near room temperature they can have considerably
    better forcing resistance than heater-only loops with a given
    bandwidth.

    A heater-only loop gets its negative slewing exclusively from the
    heat leak, which of course leaks in both directions, whereas a TEC
    can pull as well as push, so a TEC-based loop can be better
    insulated for the same control bandwidth and slew rate.

    But a TEC has a thermal low-impedance-path from inside to the
    outside. That is unwanted and one of the reasons for their bad
    efficiency.
    That means that heat transients on the outside get in
    immediately and must be activly regulated away, AFTER they have
    happened.

    You could put another temperature sensor on the outside end of the
    TEC, and do some sort of feed-forward as well, to remove most of the
    effect before it gets in.

    A really important tool in high-stability temperature control is a
    local feedback loop around each actuator.  Proportional-only is fine,
    but what you really want is super high speed.  These days we do a lot
    of TEC-based controllers.  Our favourite method is to put a bare ENIG
    pour on the bottom side of the cold plate board (which usually has a
    laser or one or more photodetectors).  This contacts the cold side of
    the TEC via (usually) silver grease.(*)  One end of an 0603 thermistor
    is soldered to the pour, and the other goes via a longish skinny trace
    to the loop amp.

    Doing that costs next to nothing, and allows us to make a much faster
    simulated actuator with much much lower effective thermal conductance.

    That scheme makes a lot of sense.

    With the thermistor hanging five right at the edge of the pour (right
    next to the edge of the cold side of the TEC) the response is faster
    than 100 ms.

    Thermal diffusion is quadratically slow at large distances, so of course
    it's quadratically fast at small ones!

    Cheers

    Phil Hobbs


    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Anthony William Sloman@21:1/5 to Phil Hobbs on Fri May 27 04:58:17 2022
    On Friday, May 27, 2022 at 12:09:00 AM UTC+10, Phil Hobbs wrote:
    Chris Jones wrote:
    On 25/05/2022 23:34, Phil Hobbs wrote:
    Chris Jones wrote:
    On 25/05/2022 04:35, Gerhard Hoffmann wrote:
    Am 24.05.22 um 17:06 schrieb Phil Hobbs:
    jla...@highlandsniptechnology.com wrote:
    he Mach-Zender electro-optical modulator.

    https://www.dropbox.com/sh/knkoywpv6563mj5/AACy1sLNcyqIO8Eik4NRCC9Da?dl=0


    We have lots of heater power available so we can stabilize to
    millikelvins in about a half hour.

    One of the less-frequently remarked advantages of thermoelectrics
    is that anywhere near room temperature they can have considerably
    better forcing resistance than heater-only loops with a given
    bandwidth.

    A heater-only loop gets its negative slewing exclusively from the
    heat leak, which of course leaks in both directions, whereas a TEC >>>>> can pull as well as push, so a TEC-based loop can be better
    insulated for the same control bandwidth and slew rate.

    But a TEC has a thermal low-impedance-path from inside to the
    outside. That is unwanted and one of the reasons for their bad
    efficiency.
    That means that heat transients on the outside get in
    immediately and must be activly regulated away, AFTER they have
    happened.

    You could put another temperature sensor on the outside end of the
    TEC, and do some sort of feed-forward as well, to remove most of the
    effect before it gets in.

    A really important tool in high-stability temperature control is a
    local feedback loop around each actuator. Proportional-only is fine,
    but what you really want is super high speed. These days we do a lot
    of TEC-based controllers. Our favourite method is to put a bare ENIG
    pour on the bottom side of the cold plate board (which usually has a
    laser or one or more photodetectors). This contacts the cold side of
    the TEC via (usually) silver grease.(*) One end of an 0603 thermistor
    is soldered to the pour, and the other goes via a longish skinny trace
    to the loop amp.

    Doing that costs next to nothing, and allows us to make a much faster
    simulated actuator with much much lower effective thermal conductance.

    That scheme makes a lot of sense.
    With the thermistor hanging five right at the edge of the pour (right
    next to the edge of the cold side of the TEC) the response is faster
    than 100 ms.

    Thermal diffusion is quadratically slow at large distances, so of course
    it's quadratically fast at small ones!

    There's a lower limit set by the structure of the thermistor. It's finite lump of metal oxides,and it takes a finite time for heat to diffuse from the edges to the middle.

    --
    Bill Sloman, Sydney

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)