{Collins} Re: 30S1 bias rectifiers



After you check proper operation of the negative bias
supply, check your screen voltage.  If your unit has a
modified screen voltage power supply, you'll need to
change the voltage divider network around the bias
voltage potentiometer.  With elevated screen voltage,
the stock bias circuit doesn't produce enough voltage
to properly set the plate current down where you want
it. Note, I don't recommend the higher screen voltage
modification. The original design didn't need
modification.
73,
Pete
K5PZ

--- Bob & Patricia <bobsw4@xxxxxxx> wrote:

> Regarding my 30S1 bias problem (can't get the
> idiling plate curent below 300 ma.) I think I have
> located the bias rectifiers I want to change...are
> they three on a shelf at the top right hand (as you
> face the amp) of the power supply cabinet and are
> they small, square black cubes? If so, which is the
> cathode side? Also I notice the transformer by these
> rectifiers is a Peter Dahl...is this normal or do I
> have a different xfmr with different voltages???I'm
> going to change the rectifiers and caps anyway. I
> hope to get it working soon. tnx in advance...Bob,
> K9ING
> Sponsored by the Collins Collectors Association
> http://www.collinsradio.org
> Nets: Tues: 3.805 Mc-2000 Central / Thur: 3.875
> Mc-2000 Central
> Fri: 3.895 Mc-2000 Pacific / Sun: 14.263 Mc-2000 UTC
> 1st Wed (of the month) AM Net 3.880 Mc-2000 local
> (ET, CT, MT, PT)
> Sun AM Net: 29.050 Mc-1200 Central
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> 

Sponsored by the Collins Collectors Association http://www.collinsradio.org
Nets: Tues: 3.805 Mc-2000 Central / Thur: 3.875 Mc-2000 Central
Fri: 3.895 Mc-2000 Pacific / Sun: 14.263 Mc-2000 UTC
1st Wed (of the month) AM Net 3.880 Mc-2000 local (ET, CT, MT, PT)
Sun AM Net: 29.050 Mc-1200 Central






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