Re: RCA AR88D Comms Receiver.
A couple of comments.
I use a variable HT supply to check old receivers for the first time (with no valve heater supply). Often you get a pretty high initial current at say 50 volts which drops steadily, then you can increase the voltage keeping an eye on HT current. Bad wax condensers will get warm and sometimes one might suddenly fail with a sudden increase in current followed by a puff of smoke.
There appears to be two types of degradation. One where the leakage increases with voltage ending with an avalanche effect, and the second where leakage drops and then remains low.
I'm now at the stage of aligning my old Moreton Cheyney receiver and meeting much the same issues as John. Some RF coils do not seem to peak or will peak intermittently. Also, I found the local oscillator on two HF ranges stopped working at the same point on the dial. That was a bent plate on the tuning condenser. One TC is used for LF and MF bands and a smaller TC for the two HF bands. Once I started hearing broadcasts they were intermittent. I found corrosion at every point on the tuning condensers that relied on metal-to-metal contact. I also found the (8) mounting screws were all loose as well as rusty and no earthing braid provided. The slow motion drive is too complicated to allow removal of the two tuning condensers but a new can of switch cleaner is working its magic.
Allan
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