[R-390] Capehart made R-390A Serial #312

[Larry Haney]

Thank you, Karsten.  The reason I asked is in reference to what Jacques
said about not loading the T401 secondary (or the primary) with additional
capacitance.  As you can see, any additional capacitance is a bad thing,
especially for the top 3 bands that use a 3-12 pf trimmer.  Since you said
that the 31 mc band oscillator peaks ok, your problem might be the 30 mc
trimmer, 11 mc crystal or adjustment of T401.  If all your
trimmers adjust OK except the one, then T401 is probably OK.

The tech ref says to adjust the 2nd xtal osc using the Carrier Level meter
as an indicator.  That does work, but is not very sensitive and can be hard
to see any change some times.  I like using the Diode Load in mgc mode to
make most adjustments. Because the trimmer is hard to get at to repair, I'd
try a different crystal (even if it's way off frequency), just to see if
that is it.

Regards, Larry

On Thu, Apr 10, 2025 at 1:37 PM Karsten Simon <karstenpg.simon at web.de>
wrote:

> Hi Larry,
>
> > Does the 31 mc band adjust OK?
>
> Yes
>
> 73, Karsten
>
>
>
> *Von:* Larry Haney [mailto:larry41gm2 at gmail.com]
> *Gesendet:* Donnerstag, 10. April 2025 19:11
> *An:* Karsten Simon
> *Cc:* r-390 at mailman.qth.net
> *Betreff:* Re: [R-390] Capehart made R-390A Serial #312
>
>
>
> Hi Karsten, Does the 31 mc band adjust OK?
>
>
>
> Regards, Larry
>
>
>
> On Thu, Apr 10, 2025 at 4:53 AM Karsten Simon via R-390 <
> r-390 at mailman.qth.net> wrote:
>
> I am currently working on realignment: checking and tuning Crystal
> Oscillator subchassis. Frequencies measured with an accurate  8-digit
> digital counter. Everything appears to be ok. One exception: oscillator
> output on band 30 is 22 MHz (2nd harmonic), should be 33 MHz (3rd
> harmonic).
> Active crystal is Y403 (11 MHz). Trimmer capacitor C431H appears to be ok.
> Output (pin 3 of T401) is in the range of 3 to 5 volts and can be adjusted
> by turning C431H. Band 8 (11 MHz osc. output) is ok. Band 19 (22 MHz osc.
> output = 2nd harmonic) is ok. Any ideas why band 30 output is 2nd harmonic
> and not 3rd?
>
> Regards
>
> Karsten
>
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