[R-390] Wanted: 14mHz Crystal

Sun Jul 5 20:29:33 EDT 2026

Larry, 

That is some interesting work you have done on drift during warm-up.  It helps
explain why the original owner was interested in 'ovenizing' the crystals, by
greatly reducing the warm-up time.  

In that case, the Digikey approach to finding a replacement is going to be a
"last hope" approach. 

-Fred 

------ Original Message ------
Received: Sun, 05 Jul 2026 11:37:17 PM GMT
From: Mike Peace via R-390 <r-390 at mailman.qth.net>
To: Larry Haney <larry41gm2 at gmail.com>Cc: r-390 at mailman.qth.net
Subject: Re: [R-390] Wanted: 14mHz Crystal

Hi Everyone,
Here's the link to the document that Larry Haney mentioned:
https://r-390a.net/R390A%20Ovens%20and%20Freq%20Stability.pdf
Cheers,
Mike
VK6ADA

On Sun, Jul 5, 2026 at 6:30 PM Larry Haney via R-390
<r-390 at mailman.qth.net>
wrote:

> Hi all,  To get the best frequency stability out of your 390x read my
> short doc: 'R-390A Ovens and Frequency Stability' on our website.  The
> type of crystals do make a difference.  Here's a link:
> R390A Ovens and Freq Stability.pdf.
>
> Regards, Larry
>
> On Sun, Jul 5, 2026 at 6:55 AM Francesco Ledda via R-390
> <r-390 at mailman.qth.net> wrote:
> >
> > It probably doesn’t matter, as the turning point of the original
R-390’s
> crystal is at the operating point of the ovens, and most owners keep the
> ovens turned off.
> >
> > Best, Francesco K5URG
> >
> >
> > Sent from my iPad
> >
> > > On Jul 5, 2026, at 07:00, Bob kb8tq via R-390 <r-390 at mailman.qth.net>
> wrote:
> > >
> > > Hi
> > >
> > > A generic crystal from Digikey is not going to have the same
> temperature characteristic
> > > as the original. The radio may drift a bit as a result.
> > >
> > > it also may not have the ability to tune to the correct frequency.
> > >
> > > For < $1, try it and see is not that bad an idea. Just be willing to
> check things out a bit
> > > and possibly buy a couple candidates.
> > >
> > > Bob
> > >
> > >> On Jul 4, 2026, at 6:42 PM, Fred Moore via R-390 <
> r-390 at mailman.qth.net> wrote:
> > >>
> > >> Bill (and others needing crystals),
> > >>
> > >> 1.  I do have one from an R-390 (not A) oscillator unit.  Fair Radio
> was
> > >> selling these for $20 near their end, plus shipping.  Payment by
> check.
> > >>
> > >> 2.  But other crystals will fail from time to time.  So I went on
> > >> Digikey.com... They have a bunch of crystals, mostly SMD types.
> These could
> > >> be put inside the original holder.  Even MHz are pretty common
> there.  What
> > >> about drive levels?  Is a tube osc too much drive for this little
> thing?
> > >> There is a datasheet for it on this page.  So this approach might
> help others
> > >> in the future.
> > >>
> > >> Here is one by CTS for $0.72:
> > >>
>
https://www.digikey.com/en/products/detail/cts-frequency-controls/406C35B14M00000/604558
> > >>
> > >> So this approach might help others in the future.
> > >>
> > >> -Fred
> > >>
> > >> ------ Original Message ------
> > >> Received: Sat, 04 Jul 2026 05:22:44 PM GMT
> > >> From: Bill Cotter via R-390 <r-390 at mailman.qth.net>
> > >> To: r-390 at mailman.qth.net
> > >> Subject: [R-390] Wanted:  14mHz Crystal
> > >>
> > >> Happy July 4th!
> > >>
> > >> Does anyone have a donor crystal bank with a 14mHz crystal they
> > >> would be willing to part with? Please advise with price + shipping
> > >> to my QTH (below).
> > >>
> > >> Thanks es 73 Bill N4LG
> > >>
> > >>
> > >>
> > >>
> > >> ------------------------------------------------------------
> > >> Bill Cotter, N4LG              E-mail: n4lg at qx.net
> > >> 173 Carolyn Lane               Cell: (859) 552-7481
> > >> Nicholasville, KY 40356-9340 https://www.qrz.com/db/n4lg
> > >>
> > >> ARCI #9878, QRPl #1646, QCWA #29393, FISTS #4535, NAQCC 7470
> > >> ------------------------------------------------------------
> > >>
> > >> ______________________________________________________________
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