It has been an interesting weekend.
I powered up the 52-Set Friday evening to see what propagation was like and make sure my retuning of WWV from 10.0 MHz for the winter to 5.0 MHz for the summer was still tuned and stable. After the usual 10 to 12 second warmup, I was surprised to hear the merry hum of the vibrator coming from the speaker and no signals of any kind.
The meter was showing the usual LT reading of 11.0 Volts DC (still missing 1.70 Volts) but a quick check of the HT status showed a drop from the usual 130 Volts to just 70 Volts, well under the operating minimum mentioned in the manual. That discovery was followed by a quick shutdown.
Something has been stealing 1.7 Volts of Low Tension and 20 Volts of High Tension from the Receiver from the very start. I know the Vibrator is in great shape and the OZ4A was brand new prior to first starting the Supply Unit up.
Looking at the schematics, the first suspect I will have to look at is the 20 mF “Twins in a Tin” electrolytic filter caps, following a retest of the OZ4A on the Tube Tester. If that cap set checks out OK, the next on the list are two PIO electrolytic caps on the secondary side of the transformer. These are described as ‘Secondary Timing Capacitors’ in the manual. This is something new to me to wrap my head around. No references to such an animal at all in my 1960 and 1970 ARRL Handbooks, though all sorts of information seems to be on the internet with reference to these caps in modern solid state electronics.
Funny how Life always seems to send you a Learning Curve when you least expect it.
David
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