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Re: Astron Power Supply



Greeting all

I utilize a Astron VS 50 M power supply for my station.       The supply
after 10 years decided to give me some grief.      This problem was first
noted when placing a 100 watt 70cm rig in CW ( key down).       I noted
that the voltage was no longer regulated at 13.6 VDC and that there was
not sufficient current to drive the amplifier to 100 watts.    In fact
the display on the exciter dimmed way down.       As long as I was
running only the exciter ( 30 watts ) there was no problem with the
voltage regulation or the available current 

Going over the unit visually found nothing apparent .    I thought of the
possibility that some of the pass transistors had gone south on me.   
That was not the case.    Then I thought the current limiting circuit had
devised a mind of it's own.    Also Not the case.       
Building a load to test the supply provided an interesting search thru
the junk boxes.
A load to handle 37 amps continouously at 12.6 VDc is hefty .     I
managed a 28 amp load to test with. 

The problem was found to be the LM-723-CN,  Voltage regulator IC was not
seated in the socket firmly.     The printed circuit board ( socket )
hangs upside down and this may have helped cause the problem since there
is the normal 60 hertz transformer vibration occurring while it is in
operation.

I hope this will save somebody a little time if the same thing occurs to
them.


Joe Murray K0VTY
Amsat # 0860

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