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

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.

Lee - K0WA



In our day and age it seems that Common Sense is in short supply.  If you don't have any Common Sense - get some Common Sense and use it.  If you can't find any Common Sense, ask for help from somebody who has some Common Sense.  Is Common Sense divine?
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[Don Wilhelm-4]

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.
>
>  
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