Seems That 6 Meters is Some What Open

[Dave-3]

Alan

Does your k3 have the KTCXO3-1 upgraded reference oscillator or the original
KREF3 oscillator? The KTCXO3-1 is recommended by Elecraft when locking

I had a similar issue to you on my 1st K144XV installation locking it with
the KREF3, as it was outside the range of the software offset
calculator/corrector. When I did the upgrade the problem was solved

Dave
G4FRE


Message: 2
Date: Fri, 22 Jun 2018 20:22:46 +0100
From: "G4GNX" <[hidden email]>
To: "Elecraft Reflector" <[hidden email]>
Subject: Re: [Elecraft] Transverter calibration
Message-ID: <CCD010CE7B2341E2AF516C8BE18794D7@G4GNXLaptop>
Content-Type: text/plain; format=flowed; charset="utf-8";
        reply-type=response

Hi Don.
I just got back from 'experimenting'!

I turned the Reflock off and manually set the offsets according to the
figures on the Xverter top.

With the Reflock still turned off, the discrepancy is several KHz (I did not

note the exact figures).

With the Reflock turned back on, the discrepancy is back to around 200 Hz
and there's no way to manually adjust that in software.

I wonder if the K144XV itself is a tad off? I bought it from another amateur

so I don't know its 'tweak' history, other than I have never adjusted any of

it internally.

73,

Alan. G4GNX


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[W1GO (Joe)]

Alan,

I have the same issue; mine is off about 50Hz.  Not a huge deal but just enough to be annoying on VHF SSB and CW.  I do have the REFLOCK, EXTREF (10MHz GPSDO) and KTCXO-1; nothing left to add.  You are correct that you can’t adjust the offset once you’re in this configuration.  As I say, for me its “only” about 50Hz but its consistent.  I was gonna have to Elecraft team look at it in their lab the next time I send the rig in (if I send it in).  Aside from that I’m living with the 50Hz delta.

Joe
W1GO

> On Jun 21, 2018, at 6:35 PM, G4GNX <[hidden email]> wrote:
>
> I built a K3S a few months ago and I've installed the K144XV 2 metre transverter into it, along with the K144XV Ref lock option.
>
> Although all of the main K3S calibration is OK, I find that the K144XV is about 200Hz off nominal frequency, certainly in the 144-146 MHz segment.
>
> The manuals mention calibration being automatic, so I can't find any reference to adjustment where the frequency is incorrect.
>
> Anyone any ideas how I can get the transverter on frequency across the band?
>
>
> 73,
>
> Alan. G4GNX
>
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[Elecraft mailing list]

G'day,

Another data point to add. Apologies for it being a bit long.

My K3 is fitted with the line up REFLOCK, EXTREF (10MHz GPSDO) and
KTCXO-3 +/-1ppm. In the past I have done several warm up runs from cold
start to to T+4 hours where for all practical purposes KTCXO-3 drift as
measured by the EXTREF module stopped. The results are repeatable with
small variations, cold start temperature and room temperature were a
reasonably consistent, +23C. Front panel temperature change gives a
reasonable indication of the warm up environment of the KTCXO-3.

My KTCXO-3 at power up starts at 49.379.836 on average and after warm up
stops drifting at 49.379.890. It goes through two plateaux phases the
first at T+5 minutes (49.379.863) until T+26 minutes (49.379.865). It
then starts a slow rise to T+120 where after it enters the second
plateaux (49.379.884) where after there is little change. This is
repeatable. However, it must be noted that this is my KTCXO-3 other
units will have their own characteristic, even drifting in the opposite
direction.

I was unable to programme my GPSDO for both 10MHz and 145.5MHz outputs,
maybe a forbidden combination, must get to grips with this. So I decided
to do a run with a sniff of the 145.5MHz signal fed into the 2m input
and the K3 not locked to an external source.

The manual REFCAL setting was at the top end of the drift range
(49.379.886).

After cold start and a quick tune to the 145.500.000 signal the initial
dial reading had to be set 176Hz high. There after retune took place for
the first hour at one minute intervals and the dial error recorded.
Retune was accomplished by offsetting the dial slightly LF and netting
with TAP SPOT. There is a small 3Hz difference between netting from LF
or HF using this method so for consistency LF was always used.

The change in dial reading was consistent with the previously measured
warm up drift characteristic of my KTCXO-3:

T+1   +176Hz
T+5   +98Hz
T+28  +86Hz
T+60  +17Hz
T+80  +11Hz
T+100 +9Hz
T+120 +8Hz
T+180 +4Hz
T+240 +1Hz

At T+240 the manually set REFCAL frequency and the true drifting
frequency of the KTCXO-3 will have converged. The dial frequency and the
signal frequency has also essentially converged.

When I figure out how to programme two frequencies out of my GPSDO or
find a suitably stable 2m source it will be interesting to run the same
test with my K3 EXTREF locked.

There is great faith placed in digital displays to tell the truth,
however, there are factors at play which can render this truth to be a
little coloured. Any radio with a free running reference oscillator for
example will be in error at some point.

I standby to be shot down.

Regards,

Mike VP8NO

On 23/06/2018 19:41, W1GO (Joe) wrote:
> Alan,
>
> I have the same issue; mine is off about 50Hz.  Not a huge deal but just enough to be annoying on VHF SSB and CW.  I do have the REFLOCK, EXTREF (10MHz GPSDO) and KTCXO-1; nothing left to add.  You are correct that you can’t adjust the offset once you’re in this configuration.  As I say, for me its “only” about 50Hz but its consistent.  I was gonna have to Elecraft team look at it in their lab the next time I send the rig in (if I send it in).  Aside from that I’m living with the 50Hz delta.
>
> Joe
> W1GO
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