I recently replaced all the mixer tubes with ones that checked at the 1000 um level. Some of mine were well under that. I realize that the tube checker is but one data point and it _could_ be tubes but I need to do more checking.
I'm using an HP410C so it should be sufficiently decoupled. Thanks for the reply, Barry - N4BUQ On Sat, Nov 9, 2024 at 4:20 PM Jordan Arndt <[email protected]> wrote: > > My first instinct would be to try some different tubes and make sure you're > making the measurement with sufficient decoupling... > > 73...Jordan VE6ZT > > ----- Original Message ----- > From: "Barry Scott" <[email protected]> > To: "Larry Haney" <[email protected]> > Cc: <[email protected]> > Sent: Saturday, November 09, 2024 3:13 PM > Subject: Re: [R-390] R-390 (non-A) - Low RF Gain or bad Antenna relay? > > > > Larry, > > > > Your document prompted me to check the three oscillators in my R390/URR. > > > > On page 46 of TM 11-5820-357-35, the expected voltages of the three > > oscillators is defined as being -3v to -11v. I just checked those and > > the 1st oscillator is probably good enough (~ -4.8v) but the 2nd > > oscillator and the PTO are both quite under spec. > > > > I had scoped the outputs several months ago and I thought they were > > stronger than that (or, at least, good enough) but checking just now > > while in STANDBY with the VTVM tells a different story. Looks like I > > have work to do. > > > > Thanks, > > Barry - N4BUQ > > > > On Thu, Nov 7, 2024 at 2:21 AM Larry Haney <[email protected]> wrote: > >> > >> Jerry, Because I found many different 'specs' for the oscillator > >> voltages > >> in the A, I wrote a doc about it. The 390 voltages should be very > >> similar to the 390As in my doc: R390A Oscillator Output Level Affects > >> <https://www.r-390a.net/R390A%20Oscillator%20Output%20Level%20Affects.pdf> > >> . > >> > >> Regards, Larry > ______________________________________________________________ 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
