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turretslug · 1st Nov 2017, 3:03 pm

Excellent news- I wonder if the resistor lead-outs and connections had become brittle and granular with prolonged heat. Those ceramic body wirewounds are capable of pretending to be bar-fire elements, but the things surrounding them will suffer in the end!

An AR88 in good working order is a lively and rewarding set to use (without the fake liveliness of images and other spurios), there must have been many people over many years who enjoyed the smooth tuning, good tuning rate (at least for SWL AM-type use) and good stability as they dug across a busy band. Just a shame that HF broadcasting isn't the eclectic world-wide kaleidoscope that it was. The front-end alignment on the two top HF bands could well be worth going over- not that difficult but there are quite a few individual tweaks to get right. With band 6 in particular (22-32MHz) it may well be that it is genuinely a bit quiet out there currently. At least a signal generator won't deceive.

If anything, the 304V HT sounds a bit (not desperately) high- substitute or later type rectifier valves (often 5Z4s in metal or glass end up here) have a lower forward voltage than the original somewhat lossy 5Y3GT and may cause this. Also check the voltage selector setting- ISTR that some of the numbers on the voltage selector differ from the tag-plate on the transformer base! I just removed the selector and hard-wired to the 240V tapping, I don't like voltage selectors from the contact liability or disaster-in-waiting point of view and the AR88s isn't the best of the breed.

1st Nov 2017, 3:03 pm	#24
turretslug Dekatron Join Date: Nov 2011 Location: Surrey, UK. Posts: 4,395	Re: AR88 Low HT Excellent news- I wonder if the resistor lead-outs and connections had become brittle and granular with prolonged heat. Those ceramic body wirewounds are capable of pretending to be bar-fire elements, but the things surrounding them will suffer in the end! An AR88 in good working order is a lively and rewarding set to use (without the fake liveliness of images and other spurios), there must have been many people over many years who enjoyed the smooth tuning, good tuning rate (at least for SWL AM-type use) and good stability as they dug across a busy band. Just a shame that HF broadcasting isn't the eclectic world-wide kaleidoscope that it was. The front-end alignment on the two top HF bands could well be worth going over- not that difficult but there are quite a few individual tweaks to get right. With band 6 in particular (22-32MHz) it may well be that it is genuinely a bit quiet out there currently. At least a signal generator won't deceive. If anything, the 304V HT sounds a bit (not desperately) high- substitute or later type rectifier valves (often 5Z4s in metal or glass end up here) have a lower forward voltage than the original somewhat lossy 5Y3GT and may cause this. Also check the voltage selector setting- ISTR that some of the numbers on the voltage selector differ from the tag-plate on the transformer base! I just removed the selector and hard-wired to the 240V tapping, I don't like voltage selectors from the contact liability or disaster-in-waiting point of view and the AR88s isn't the best of the breed.