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.
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
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