On 14/09/2021 11:33, gareth evans wrote:

On 13/09/2021 23:47, SSDN via rec.radio.amateur.moderated Admin wrote:

SolderSmoke Daily News

///////////////////////////////////////////
So Where DID the LSB/USB Convention Come From?

Posted: 13 Sep 2021 12:39 PM PDT
http://soldersmoke.blogspot.com/2021/09/so-where-did-lsbusb-convention-come-from.html



-- Bottom line:   I still don't know why ham radio adopted as a
convention LSB below 10 MHz and USB above 10 MHz.  There are several
theories. but so far there is no convincing explanation in favor of any
one of them. And almost all of the people involved are probably Silent
Keys by now; this makes it more difficult to gather first-hand
information. -- I'm not even sure when the convention began

It is because of early SSB designs based on a 5MHz VFO with a 9MHz IF
to give operation on 20m and 80m, with the sideband inversions that
happens with that arrangement.

Sorry, just done a quick thumbnail sketch and I think that's bollocks
because to get the inversion, the VFO has to be above the IF.

It is bollocks, and that myth has been exploded many years ago, but
some people keep trotting it out.

Jeff

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In message <shsd2r$rnd$2@gioia.aioe.org>, Jeff <jeff@ukra.com> writes

On 14/09/2021 11:33, gareth evans wrote:

On 13/09/2021 23:47, SSDN via rec.radio.amateur.moderated Admin wrote:

SolderSmoke Daily News

///////////////////////////////////////////
So Where DID the LSB/USB Convention Come From?

Posted: 13 Sep 2021 12:39 PM PDT

http://soldersmoke.blogspot.com/2021/09/so-where-did-lsbusb-convention >>>-come-from.html


-- Bottom line:   I still don't know why ham radio adopted as a
convention LSB below 10 MHz and USB above 10 MHz.  There are several
theories. but so far there is no convincing explanation in favor of any
one of them. And almost all of the people involved are probably Silent
Keys by now; this makes it more difficult to gather first-hand
information. -- I'm not even sure when the convention began

It is because of early SSB designs based on a 5MHz VFO with a 9MHz
IF
to give operation on 20m and 80m, with the sideband inversions that
happens with that arrangement.
Sorry, just done a quick thumbnail sketch and I think that's
bollocks
because to get the inversion, the VFO has to be above the IF.

It is bollocks, and that myth has been exploded many years ago, but
some people keep trotting it out.

It possibly originated when it was more common to generate SSB by the
'phasing method'. Here, you can swap sideband simply by reversing phase
of (one of ??) the 90 degree audio signals - so it's no great thing.
--
Ian

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