[AMRadio] BC1004B


W2EMN via AMRadio amradio at mailman.qth.net
Fri May 1 13:21:12 EDT 2015


Two reasons I can think of:  First, both the National and Hammarlund had separate supplies to keep the heat down in the radio.  The Hammarlund drifts quite a bit even with the off-board power supply.  
Second, the power supply is bulletproof.  I have a BC-779 that had a bypass cap short- right on the B+ line from the power supply.  I had left the radio to warm up, and it sat with the short for about 2 hours.  I was sure the power supply would be toast, but after it cooled off it worked fine.  I think the resistance of the chokes limited the current to a safe level.  Needless to say, I replaced all of the paper caps in the radio.  The only original cap left is the oil-filled filter cap in the power supply.
Ed  W2EMN

 

 

 

-----Original Message-----
From: CL in NC via AMRadio <amradio at mailman.qth.net>
To: amradio <amradio at mailman.qth.net>
Sent: Thu, Apr 30, 2015 9:17 pm
Subject: [AMRadio] BC1004B


I have a Hammarlund Super Pro/BC1004B, second one I've owned in 45 years.  Never
knew the answer to this, maybe someone can shed some light.  Why was it designed
with such a massive external power supply?

Charlie, W4MEC in
NC
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