[R-390] R-390 (non-A) - Low RF Gain or bad Antenna relay?

[Barry Scott]

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 <Outposter30 at shaw.ca> 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" <72volkswagon at gmail.com>
> To: "Larry Haney" <larry41gm2 at gmail.com>
> Cc: <r-390 at mailman.qth.net>
> 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 <larry41gm2 at gmail.com> 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
>