Quote:
Originally Posted by Skywave
Just a quick one for now, since here in the U.K. it's early morning and I should be in bed!
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Al, if ever there was someone who deserved a good night's sleep it is you because you've been holding my hand on this HQ-180A-thing all day. It's now 3 AM in Chard so I hope you're deep in REM sleep and enjoying a wonderful dream.
There are some things about this receiver that have bugged me since I bought it and I am coming to the conclusion that someone has worked on it before. But what I don't understand is that it worked "OK"---not like you'd expect it to...but, just "OK." Like USradcoll1 intimated, its sensitivity was poor and its passband filtering was awful. I tried to do a sweep alignment and could not get anywhere near a decent flattening of the sweep. The alignment was flaky even after doing the factory manual's stock-in-trade peaking voltage to a VTVM. I suspected the IF coils had something going on so I dug in to find a couple of the mica resonant capacitors were bad. I drew the diagrams of the underside before I did any IF can work so I am perplexed as to how the receiver even worked at all prior to my project with the 1 K ohm resistor feeding T4. But Al, your suspicion coincides with my suspicion that there should be a 1 K ohm resistor that is missing in that B+ line to V3 and V17's plate. I also wonder if (in the frenzied heat of the "battle") early-on in my work if I might have removed the second 1 K ohm resistor, set it aside, forgot about it or it dropped into an abyss in my work area never to be seen again. Anyway, I am toying with the idea of rerouting the B+ feed and see what it does. I'll report back here to Mission Control afterwards.
And Dave...neighbor...nice to hear from you. I've owned several HQ-180As over the years, all splendid performers but this one has been a disappointment. However I also am a firm believer that HQ-180As are good receivers so maybe this one just needs some corrective measures or perhaps a house-cleaning of work others have done on it.