Over the last week or so, I have managed to track down a potential source for a replacement tube, and should have it in the next few days. New tube is a 25VCZP22, which appears to be a tension banded successor to the bonded faceplate VAB/VAD types. Hoping it fits the mask on my set OK. Datasheet comparison looks promising.
Spent an hour or so setting up the UHF tuning presets. To use all 12 presets, I selected all the now defunct local UHF stations I can remember, and added a handful of others. 14 and 83 just to cover the entire band for testing purposes, 37 just in case I want to listen for aliens, and channel 62 to tune in the occasional Blonder/Tongue modulator broadcast of "UHF".
Dialed all channels in using a VA62. All the channel number stickers were in great shape, and applied to the UHF channel display wheel.
Varactor UHF tuner works VERY nicely, good stable reception on all channels. Did any commercial sets have varactor UHF tuning in 1969?
Am pondering how best to add a composite AV input to this set. Video amplitude out of the detector measures about 2Vpp, but proper polarity. Applying a proper level video signal from the VA62 right into the video cable to the IF module gives a GREAT picture. I need to design a video amplifier with a gain of ~2, preferably to operate from the single ended 30V power supply available in the set. Shouldn't be too big a deal using a modern video opamp. Line level audio input will probably be done by just rewiring the provided "HiFi out" line level audio output jack to be a line level input to the top end of the volume pot.
The set has an unused position between 2 and 13 on the VHF tuning dial (where UHF would be on a non varactor setup) which displays "H" (for Heathkit I guess
) on both UHF and VHF tuning dials. I am contemplating rigging up a switch/relay to automatically select the AV input in this tuner position, so as not to have to add a separate line/RF switch.
Dynamic convergence has drifted a tiny bit in the last week or so (maybe 8 hours run time). Nudged it back, but obviously going to be redone again at CRT swap.
Contemplating a cabinet design to be a winter project. Thinking wooden front and bottom, with transparent top, sides, and back.