Re: K3EXREF issue? K3 - Resolved

[Gary Smith-2]

Folks,

FYI, there is a resolution to the issue.

A history in short: I started having
issues of localized frequency changes. I
discovered REF CAL would only lock on a
10MHz source if the source was cold and
then only after I rebooted the K3. I tried
two different sources with the same exact
results. Once it locked on, I could not
engage XREF OUT, when I left REF CAL and
returned to it, the asterisk was solid,
not flashing. Rebooting with a cold 10MHz
source was the only way to get a lock.

After exchanging emails with support it at
first appeared to be an issue with the
K3EXREF board or connections but with the
numerical value displayed in REF CAL, it
was lower than expected and Elecraft
support felt the TXCO in the K3 was
suspect.

With that, I had my old TXCO from when I
exchanged it with the .1 TXCO, I replaced
the failed .1 and WooHah, there is the
always reliable K3 operating exactly as it
should. Lock with REF CAL is working
perfectly, the frequency is stable and it
works fine with both 10MHz sources.

This revelation coming last night, it's
too soon to tell but I think I am seeing
less artifacts that looked like constant
vertical lines with regular horizontal
lines in the waterfall on the P3 SVGA.
This was only at certain times and worse
on specific frequencies. Perhaps some of
the stuff I've been trying to track down
and failing to do so is because of this
failing TXCO?

Maybe someone with this future issue will
find this thread and it'll help them, it's
been a real work maker for me.

73,

Gary
KA1J

> Ed,
>
> Thanks for the reply. I do need an
> oscilloscope. The only frequency counter
> at this QTH is this K3, my K3s is at the
> factory for an issue with SSB.
>
> That said, there does appear to be a 10MHz
> signal coming from the GPSDO. There's
> enough bleed-through that when I tune to
> 10MHz I can still pick up the ticks from
> WWV, however removing power from the GPSDO
> and the signal drops considerably. I
> connected 10' of wire to the center
> conductor of the SMA and the signal in the
> K3 increased considerably and it was dead
> on top of WWV. So I'm feeling it's putting
> out a signal at 10MHV but the strength or
> condition of the signal, I have no way to
> tell.
>
> Looking at the info on the K3EXREF, the
> Tech MD is on, REF CAL is displayed and I
> need to engage keypad #2 to switch between
> the EXREF being in or out, I have it
> switched in. No asterisk.
>
> I have not been inside the radio since I
> started using it a week ago and the
> asterisk was flashing at that time. I
> saved the current configuration and loaded
> the configuration that was good the last
> time I used the radio and that didn't
> help. I can't imagine the cable in the
> radio failed without any mechanical
> action. I'll have to take a look and see
> if anything has become somehow dislodged
> though it's been just sitting on the
> table.
>
> I was hoping it was something in a setting
> that might have been altered and it seems
> like that's not it. Thanks again for the
> assistance.
>
> 73,
>
> Gary
> KA1J
>
>
>
>
> > Gary,
> >
> > Well first thing I would check is whether 10-MHz is present at the
> > K3 EXREF sma jack.  If you have a freq counter check for correct
> > freq. No counter then use a radio that can tune 10-MHz for
> > presence of signal on correct freq.
> >
> > Check for adequate reference level (I run 10mw which is more than
> > adequate; probably will run with 3mw to 5mw).  If you have no
> > milliwatt meter then use an oscilloscope to measure RF voltage.
> > Pav = Vrms^2/R  or Vrms = 0.3535*Vp-p*probe multiplier.
> >
> > From: http://www.ab4oj.com/test/pwrmeas.html
> > Pav = 10*10^-3 = 0.01 w , Vrms = sqrt(Pav*R) = 0.707v, Vp-p =
> > 2,.828*Vrms = 2v
> >
> > If you are using a 10x probe Vp-p = 0.2v; Be sure to measure
> > voltage across 50-ohm load connected to the REF input.
> >
> > If this is low or nonexistent try a different cable from the
> > GPSDO.  Also check 10-MHz output at the GPSDO.
> >
> > My guess either you have no 10-MHz ref signal or its off
> > frequency.  If that is good then recheck configuration to enable
> > EXREF.  Still bad: then check internal coax from EXREF connector
> > to syn  board.
> >
> > 73, Ed - KL7UW
> >    http://www.kl7uw.com
> > Dubus-NA Business mail:
> >    [hidden email]
> >
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