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K3: internal 2m transverter offset problem

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Jim Spears

K3: internal 2m transverter offset problem

I have K3 s/n 6866 with internal 2m transverter. I have not paid much
attention to the transverter for a while but I noticed something odd a
couple days ago and have not been able to do anything about it.

If I set the Elecraft XG3 to 144.100 and feed its output into the
transverter input connector, the signal shows up at 144.095, 5 KHz low.

If I tell this K3 to output 2m rf on 144.100, I hear the signal at 144.015
on K3 s/n 6425 which has an external 2m transverter.

I first noticed this when monitoring a local 2m FM repeater and could not
copy its output until I tuned 5 KHz low.

The K3 does have an external 10 MHz clock and CONFIG REF CAL has the
blinking asterisk. FWIW, the value shown is 49.379.962.

CONFIG XV OFS is 144 -0.08 and cannot be changed, when I go to adjust it
REFLOCK appears.

What's up Doc?

Jim/N1NK

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Grant Youngman

Re: K3: internal 2m transverter offset problem

Are you on the latest firmware rev level in the 2M module? I thought I was and missed an update somewhere along the way.

I recently pulled my 2M module and sent it to Elecraft because one of the two crystals was marginal, and it was dead from 146-148 MHz. I got back their evaluation and, along with the crystal replacement, I was (very sheepishly, I might add) informed that I did not have the latest firmware which is needed to enable REFLOCK in the 2M module … This sounds (sadly) familiar and might be the issue …

Grant NQ5T
K3 #2091, KX3 #8342

>
> If I set the Elecraft XG3 to 144.100 and feed its output into the
> transverter input connector, the signal shows up at 144.095, 5 KHz low.
>
>
>
> I
> CONFIG XV OFS is 144 -0.08 and cannot be changed, when I go to adjust it
> REFLOCK appears.
>
>
>

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W1GO (Joe)

Re: K3: internal 2m transverter offset problem

In reply to this post by Jim Spears

Jim

I have the same issue pre and post REFLOCK installation. My software is up to date.

I'm still trying to troubleshoot it.

Joe
W1GO

> On May 3, 2016, at 14:03, Jim Spears <[hidden email]> wrote:
>
> I have K3 s/n 6866 with internal 2m transverter. I have not paid much
> attention to the transverter for a while but I noticed something odd a
> couple days ago and have not been able to do anything about it.
>
>
>
> If I set the Elecraft XG3 to 144.100 and feed its output into the
> transverter input connector, the signal shows up at 144.095, 5 KHz low.
>
>
>
> If I tell this K3 to output 2m rf on 144.100, I hear the signal at 144.015
> on K3 s/n 6425 which has an external 2m transverter.
>
>
>
> I first noticed this when monitoring a local 2m FM repeater and could not
> copy its output until I tuned 5 KHz low.
>
>
>
> The K3 does have an external 10 MHz clock and CONFIG REF CAL has the
> blinking asterisk. FWIW, the value shown is 49.379.962.
>
>
>
> CONFIG XV OFS is 144 -0.08 and cannot be changed, when I go to adjust it
> REFLOCK appears.
>
>
>
> What's up Doc?
>
>
>
> Jim/N1NK
>
> ______________________________________________________________
> 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]

Edward R Cole

Re: K3: internal 2m transverter offset problem

In reply to this post by Jim Spears

Jim,

First the XG3 is not exact on frequency. I use a very good counter
which will read up to 26-GHz and has an internal TCXO. I've noted
the XG3 being off up to several tens of Hz, so to use as a frequency
std is not sufficient for measuring EXREF frequency accuracy. Its
pretty good for its intended use as signal source.

But 5-KHz is quite a lot for 2m. Frequency accuracy is the sum of
the K3 error and transverter LO. Most often I find the transverter
that uses a xtal LO can be quite far off frequency. You pretty much
need a frequency counter to read this (if IF is 28-MHz, then LO is
116-MHz). At present my 2m transverter LO is low by 50-Hz since I
have not adjusted it for some time. Originally, I had it within +5
Hz. I recently fixed my EXREF in the K3 and its within 1-Hz at 28-MHz.

But sometime during the time my EXREF was not working*, I entered a
fixed offset for the transverter in the k3 CONFIG: XV1 OFS. I was
wondering why my frequency was off 22-Hz after fixing the EXREF. I
had to disable EXREF to reset the offset to zero. Then after
reentering EXREF my 28-MHz frequency was within 1-Hz (after 15-min
warm up). Your REF CAL looks normal for running EXREF after warm
up. The TCXO will drift as it warms up resulting in the EXREF
correction. You should not see much change once the K3 is fully warmed up.

Using a transverter+K3 as frequency meter is not very conclusive if
you have not checked it with an accurate counter. Most VHF radios and
HF+VHF transverters will be off frequency at VHF unless one has
checked with an accurate frequency counter. Usually I see up to
100-Hz of error from other VHF stations. Makes it fun running the
RIT during a 2m SSB net. Have you measured the K3 frequency at
IF? I will guess the error is in the transverter LO.

You can check the K3 against 15-MHz WWV.

73, Ed - KL7UW
*EXREF quit because of a loose sma connector from the 10-MHz source.

Date: Tue, 3 May 2016 14:03:23 -0400
From: "Jim Spears" <[hidden email]>
To: <[hidden email]>
Cc: <[hidden email]>
Subject: [Elecraft] K3: internal 2m transverter offset problem
Message-ID: <000501d1a566$1580b9e0$40822da0$@net>
Content-Type: text/plain; charset="us-ascii"

I have K3 s/n 6866 with internal 2m transverter. I have not paid much
attention to the transverter for a while but I noticed something odd a
couple days ago and have not been able to do anything about it.

If I set the Elecraft XG3 to 144.100 and feed its output into the
transverter input connector, the signal shows up at 144.095, 5 KHz low.

If I tell this K3 to output 2m rf on 144.100, I hear the signal at 144.015
on K3 s/n 6425 which has an external 2m transverter.

I first noticed this when monitoring a local 2m FM repeater and could not
copy its output until I tuned 5 KHz low.

The K3 does have an external 10 MHz clock and CONFIG REF CAL has the
blinking asterisk. FWIW, the value shown is 49.379.962.

CONFIG XV OFS is 144 -0.08 and cannot be changed, when I go to adjust it
REFLOCK appears.

What's up Doc?

Jim/N1NK

73, Ed - KL7UW
http://www.kl7uw.com
"Kits made by KL7UW"
Dubus Mag business:
[hidden email]

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