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Title: R-392 no receive below 2 MHz Post by: W4SSB on June 18, 2015, 08:22:44 PM R-392 seems to work fine on all bands but nothing below 2 MHz. Any ideas?
Title: Re: R-392 no receive below 2 MHz Post by: WBear2GCR on June 19, 2015, 10:15:52 AM I just got one myself. I *think* I read that at LF it is direct conversion... otoh someone may have transmitted into the front end. One thing to check is to compare between the whip and the coax ANT input, since the whip bypasses the first RF coils... Does it hear the calibrator signal? Assume you have downloaded the manuals from 'bama? The manuals have detailed circuit descriptions and troubleshooting procedures. Title: Re: R-392 no receive below 2 MHz Post by: WD8BIL on June 19, 2015, 11:48:05 AM Looking at pg. 129 of the TM it appears to be dual conversion from .5 to 8MHz. So if it is working from 2 to 8MHz it looks like the 1st mixer is good.
I'd look for a problem in the band switching. Bad or mis-aligned contacts???? Title: Re: R-392 no receive below 2 MHz Post by: W4SSB on June 19, 2015, 02:49:59 PM Thanks everyone for the suggestions. I removed the slug rack and cleaned all the band switches. Works fine now.
Title: Re: R-392 no receive below 2 MHz Post by: WD8BIL on June 19, 2015, 03:45:55 PM Good deal. Enjoy!
Title: Re: R-392 no receive below 2 MHz Post by: Opcom on June 19, 2015, 08:20:43 PM Those are more or less sealed and should have dessicant. There is a plug-like screw in them in the back/ that holds the cartridge. If the dessicant is already absorbed what it can or if the plug is missing then water vapor could be an issue.
If there is moisture and the set is not used for a long time the switches can oxidize causing all sorts of issues. You can know if you have moisture by turning on the set to standby and the dial lamp on dim or sometimes full. the air circulates and will condense water on the dial glass. btw if you are lucky you got one with the real radium meter. It is harmless but don't open it for cleaning etc. Title: Re: R-392 no receive below 2 MHz Post by: AJ1G on June 21, 2015, 04:24:29 PM One thing to check is to compare between the whip and the coax ANT input, since the whip bypasses the first RF coils... Hmm....didn't know that. I have been using the whip input on my 392 for a long time because the thing sounded kind of numb using the coax input...will have to check for fried input coils, there may have been a patching error at some point that caused it to have some transmit RF pumped into it via the coax input. I definitely have a quirky set of band switch contacts for the 3 to 4 meg band. Have to finesse it several times when changing bands to get it to full sensitivity. I have tried listening to stuff below 500 kHz on the first band switch position but sensitivity drops way off below 500 kHz. |