I'm troubleshooting the HT-41. The 3B28s rectifiers do not show any color=
when the HV switch is in the on position after several seconds the rectifi=
ers flash with color (normal) for a second or two and then back to no color=
I have tried two sets of 3B28 tubes and the results are the same. I've rep= >laced the HV electrolytics and bleed resistors. The unit has never caused i= >ts 15 amp circuit breaker to open. I don't have experience with the 3B28s = >or the HT41. I have had this station for several decades and have the Sx111=
and HT37 running good. Now trying to compete the station with the HT-41.
OOooMoment <wa3...@gmail.com> wrote:
I'm troubleshooting the HT-41. The 3B28s rectifiers do not show any color=
when the HV switch is in the on position after several seconds the rectifi=
ers flash with color (normal) for a second or two and then back to no color=
If no current is pulled by the finals, the rectifiers will not light.
Use an external meter with an HV probe to measure the voltage at one of the 7094 plates. You see anything?
I have tried two sets of 3B28 tubes and the results are the same. I've rep= >laced the HV electrolytics and bleed resistors. The unit has never caused i=You know those rectifiers are supposed to the 866As? I don't know if a 3B28 is a good sub or not. The pinout is the same, I know.
ts 15 amp circuit breaker to open. I don't have experience with the 3B28s = >or the HT41. I have had this station for several decades and have the Sx111=
and HT37 running good. Now trying to compete the station with the HT-41.
--scott
--Hi Scott,
"C'est un Nagra. C'est suisse, et tres, tres precis."
Thanks for the fast response. The 3B28s apparently do not show much if any=
color. I haven't had a chance to drive RF into the input just yet. Testin=
g today I discovered the 15 amp circuit breaker in the unit was defective. =
It was a very old bi-metal breaker and I'm guessing it sat for two many ye=
ars just corroding. The corrosion inserted resistance into the AC line feed= >ing the unit. That resistance caused significant current to be drawn when t= >he HV supply switch was turned on. That current has pitted the contacts on=
the breaker increasing the likelihood of more resistance in the AC circuit=
. I worked the breaker several times and that has reduced the resistance a= >cross the breaker to about half an ohm. That was low enough for the unit to=
operate normally.
s steady at 2.5 volts. I'm going to replace the two front panel switches, = >wire the HV switch to a 30amp 12vac relay that will handle the high current=
demanded from the HV power supply and removing the load from the front pan=
el HV ON/OFF switch.
Did you know the 7094 was developed to replace the 813 tube. I can't belie= >ve it as the 7094s appear to be a much less robust tube. =20
Sysop: | Keyop |
---|---|
Location: | Huddersfield, West Yorkshire, UK |
Users: | 297 |
Nodes: | 16 (2 / 14) |
Uptime: | 10:36:00 |
Calls: | 6,666 |
Files: | 12,213 |
Messages: | 5,336,335 |