The AM Forum

  I need to build a 24-28 volt supply to power a GRC-19.
  I have two 800 VA transformers that have taps for ouput at 12 or 16 volts. These two transformers in series should supply plenty of current. ;D Now, how to hook them up. Do I series them at 12 volts each, rectify and filter the output to get 24 to 28 volts? Or, do I series them at 32 volts and build up a series of pass transistors and a regulator?
 Of course the other option is to use a couple of deep cycle batteries in series and charge them up when they run down. Don't much care for this unless I can find a 24 volt charger to keep on them. The "real" power supply sounds better.
  What are you other military types using or what can you suggest?

 

Bill:

I have a 24 VDC 50 Amp continuous duty power supply/float charger that came out of a microwave installation.  This thing had enough surge capacity to spin my ART-13 dyno back when.  I've tried unsuccessfully to unload it, but noobody seems to be interested around here.  Too bad you're in OH and I'm in NJ; your problem could have been solved (UPS stock prices would surge if you paid them to ship it).  Anyway, you might look for one of those.  Downside is that most microwave intalls are 48 V, so the 24 Volt versions are a bit harder to come by.

73,
Jim
w2bvm

You should go for the 32v and go from there.I have both a military supply and battery backup.I found a 24v charger from a diesel generator at a ham fest.Several great articles about the GRC-19 are in past issues of Electric Radio written by W7QHO.Best of luck...Lee,N2UDF.

mil 704 power of that vintage allowed voltage to swing fairly wide. I would go with the higher voltage and check the sag during transmit. I would only worry if the heater voltages get too high. 28 VDC is the nominal voltage
and 24 is on the low side.  22 v is low line for 704A if I remember.