Well that's interesting, I guess I'll need to find an original BFO switch. No wonder the thing didn't work, there are no substituted tubes in it. Now I get to figure out how to undo all of this.
:( On Wed, Oct 8, 2025, 10:18 Jacques Fortin <[email protected]> wrote: > Hi Adam, > > I think I recognise this mod., the clue being the 56k resistor in the > picture. > > See attached doc. > > If it is really the original W3JHR mod. that was implemented there, the > BFO on/off switch has been also changed for a DPDT version (switching the > audio input between the AM and product detectors and powering the BFO > oscillator at the same time). > > If it is that, the BFO tube (V508) have to be a 6BE6/5750 instead of a > 6BA6/5749… > > This is basically the same product detector that I use in my own R-390 and > R-390As, by using a changeover relay inside the IF deck instead of using a > substitute BFO switch. > > See also the W7DI type of implementation attached. > > Larry Haney also worked around this theme and used a 6BY6 tube for the > product detector because it works better than a 6BE6 in the same > configuration. > > I also worked with Larry to find a way to still use the noise limiter in > the SSB mode, but the result of our experiments are not final, and the AGC > modifications we devised to “improve” the R-390 / 390A are still not fully > tested. > > Stay tuned, I should have time to re-visit that during the next winter. > > > > 73, Jacques, VE2JFE in Montreal > > > > -----Message d'origine----- > De : [email protected] <[email protected]> De la > part de Adam Morehouse > Envoyé : 8 octobre 2025 03:44 > À : R-390 Mailing List <[email protected]> > Objet : Re: [R-390] R-390 Woes > > > > I might have found the issue. > > > > Can anyone tell me if the white coax in the follow pictures is supposed to > be there? > > > > https://photos.app.goo.gl/M6Qcr9mXFrZ6sgiRA > > > > It doesn't look original to me, nor does the the resistors and caps in > front of the BFO. They seem to be hooked to V508 and RT512. > > > > > > > > > > On Tue, Oct 7, 2025, 16:55 Adam Morehouse <[email protected]> wrote: > > > > > Hey guys, > > > > > > I appreciate the pointers on my R-392, and now that it's buttoned up, > > > it's time to work on my R-390. I only tested this briefly when I first > > > got it, today I threw it up on the bench. Supposedly this was restored > > > by Rick Mish, it is very clean (except the gear train, which has a lot > > > of fresh grease...), and the front panel is pristine. > > > > > > It does pull stations, but the volume is extremely low in AGC mode, > > > and gets slightly louder when placed into MGC. > > > > > > In MGC, with the BFO switched on, it plays at a normal (not super > > > loud, but loud) volume. > > > In AGC, with the BFO switched on, it hums, low volume audio. > > > > > > The limiter seems to have no effect, and varying the BFO doesn't do > > > anything at all no matter AGC/MGC. > > > > > > I have Tom's solid state kit installed, and B+ at the AF deck test > > > point is a steady 180.5vdc. > > > > > > I am going to dig out the TM's later on, I have them somewhere...but > > > maybe somebody here can help point me in the right direction. > > > > > > Thanks! > > > > > > Adam K2AAM > > > > > > > > > > > ______________________________________________________________ > > R-390 mailing list > > Home: http://mailman.qth.net/mailman/listinfo/r-390 > > Help: http://mailman.qth.net/mmfaq.htm > > Post: mailto:[email protected] <[email protected]> > > > > This list hosted by: http://www.qsl.net > > Please help support this email list: http://www.qsl.net/donate.html > ______________________________________________________________ R-390 mailing list Home: http://mailman.qth.net/mailman/listinfo/r-390 Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
