[Elecraft] OT - Astron RS-20A - Part IV (me bad)

[Don Wilhelm]

Lee,

The pass transistors *could* be to blame, but check all the connections 
both inside and outside the power supply before drawing a conclusion 
that the pass transistors are at fault.  At 15 amps it only takes 0.1 
ohm resistance  to drop 1.5 volts.  It is a good idea to re-tighten all 
the hardware in the PS.

73,
Don W3FPR

Lee Buller wrote:
> One of those AH-HA moments.  I noticed the battery indicator had appeared on my Digital Multi Meter....low battery.   Think that would make a different measuring voltages?  Even this Liberal Arts Major understands that.  Replaced the battery and the PS could be set at 13.80 volts.  Low batt in the DMM caused the false readings.
>
> But, now....under full load (about 15> Amps) it drops to 12.1 volts...a drop of 1.70 volts....which means the voltage regulation percent is 14 %.  I don't know if that is bad or good.  I might have a Pass Transistor gone...it has two.  Any one venture and opinion?  On my RS-12A at 10 amps, I am dropping just .05 volts for a percentage of less that 1%....
>
> I think I need some 3055 or something like that.
>
>