"Larry Gagnon" wrote in message
newsp.uj37o6zpaiss39@localhost...
Hello. I have a homebrew linear 13.8V 20A power supply I have been using
for some years to power an IC-735, a 2M rig and some accessories. The PS
has these characteristics:

- well filtered (35000uF)22AMP, 21 volt DC output from diode bridge
circuit
- LM-317 regulator circuit (as per LM-317 datasheets)
- MJ2955 NPN feeder transistor from regulator driving 4 - 2N3055 PNP power
transistors in parallel
- large heat sinks (I don't think heat is a problem)
- good air circulation with fan

I have the regulator set to 13.7 VDC out. Lately however, I have had some
problems with voltage drops: while drawing 20 amps the voltage drops to
about 11.3 volts and I have had reports of a rough CW signal as a result.

I have tested the reg circuit and even replaced the LM-317 to no avail. I
cannot see where the problem lies, unless perhaps the MJ2955 feeder
transistor is not working as it should? (I don't yet have a replacement
transistor to test that idea, hence this post).

Any ideas greatly appreciated.


In addition to Tim's suggestion, If a rectifer diode opened, you might also
experience a similar problem. With a scope, it'll have 60 Hz ripple instead
of 120 Hz ripple when loaded.

-NM