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K3EXREF issue? K3

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Gary Smith-2

K3EXREF issue? K3

I noticed CW stations were a bit off from
the P3 and thought I needed to
re-calibrate the P3 again. I did so and
still encountered issues. I have the
K3EXREF installed and it has been working
fine for some time now with the GPSDO 10
MHz source.

On a hunch I looked at the K3 REF CAL
results and the asterisk is not flashing.
I rebooted the GPSDO and the K3 but no
asterisk. I checked the cables and all are
intact. I pressed the #2 button for XREF
IN & no change, same if I tap it again for
XREFOUT.

It's either the GPSDO failed, the K3EXREF
board has failed or something else.

Any suggestions?

73,

Gary
KA1J
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Edward R Cole

Re: K3EXREF issue? K3

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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Gary Smith-2

Re: K3EXREF issue? K3

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]
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

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Help: http://mailman.qth.net/mmfaq.htm
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Gary Smith-2

Re: K3EXREF issue? K3

The issue seems to be within the K3,
likely the K3EXREF board? I just tried a
different GPSDO for the 10MHz reference, a
Trimble Thunderbolt. When I first
connected the Thunderbolt I did get a
rapid flashing asterisk.

Satisfied I went on to use the K3. On a
hunch I went back to REF CAL and
discovered the asterisk was now solid and
not flashing. I restarted the radio and no
asterisk in REF CAL. Neither GPSDO elicits
a flashing asterisk but both are putting
out a 10MHZ signal & the Thunderbolt for a
short time, worked.

Seeing as two different oscillators are
not being recognized by the K3, I have to
assume it is the K3EXREF board that is of
issue. Can't be the .1 TXCO or the radio
would fail.

I'll have to contact Elecraft to see if
it's worth sending the board in for
repair.

Back to the contest.

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]
> >
> > ______________________________________________________________
> > Elecraft mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:[hidden email]
> >
> > This list hosted by: http://www.qsl.net
> > Please help support this email list: http://www.qsl.net/donate.html
> > Message delivered to [hidden email]
> >
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>