Elecraft › [K3]

K3 Frequency Shift

Classic

List

Threaded

5 messages Options

w0ih

K3 Frequency Shift

A couple weeks ago, I was on 40 meters with a group of friends, and one of the guys (likes everyone on frequency ;-) suggested that I was off.

I finally got around to checking the K3 last week and found that it was off by about 260 Hz from what it should have been. I rechecked the calibration (against WWV, per the manual instructions) and the reference oscillator had not changed from the original setting (I had it marked down in the manual from when I first calibrated it). I had to move it by 260 Hz to get it to zero beat WWV.

Anyone have any idea why it should shift frequency? I can't say that I'm terribly concerned, more curious about it.

Mike

Oliver Dröse

Re: K3 Frequency Shift

Aging of components?

Vy 73, Olli - DH8BQA
http://www.dh8bqa.de/

----- Original Message -----
From: "w0ih" <[hidden email]>
To: <[hidden email]>
Sent: Sunday, April 29, 2012 4:52 AM
Subject: [Elecraft] K3 Frequency Shift

>A couple weeks ago, I was on 40 meters with a group of friends, and one of
> the guys (likes everyone on frequency ;-) suggested that I was off.
>
> I finally got around to checking the K3 last week and found that it was
> off
> by about 260 Hz from what it should have been. I rechecked the
> calibration
> (against WWV, per the manual instructions) and the reference oscillator
> had
> not changed from the original setting (I had it marked down in the manual
> from when I first calibrated it). I had to move it by 260 Hz to get it to
> zero beat WWV.
>
> Anyone have any idea why it should shift frequency? I can't say that I'm
> terribly concerned, more curious about it.
>
> Mike
>

______________________________________________________________
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

Mike Harris

Re: K3 Frequency Shift

Quite so. The calibration against WWV is not a one time event, I do it
at least a couple of times a year. Actually it can vary a few counts in
a day, mainly dependent upon heat soak of the front panel. Mine
regularly runs at 37C.

If my understanding is correct the REF CAL number is a stored number not
a direct measurement of the TCXO frequency, though it might look like
that. Therefore it will not change, ever, unless manually done so or
the EXTREF board is installed and running.

It would be interesting if someone with an EXTREF board installed would
post the change in REF CAL number from cold to hot and extended run.

I used to drive the local Intelsat Std. B earth station and our uplinks
at 6GHz were locked to an approximately 4MHz precision TCXO which locked
a 100MHz osc, which locked the final SHF osc. It was not unusual to see
a couple of Hz/month wander (at 4MHz).

Not done like that in the new station. Neither does it have two stage
parametric RX preamps that need de-icing twice a year at the feed
assembly, but that is another story.

Regards,

Mike VP8NO

On 29/04/2012 06:06, Oliver Dröse wrote:

> Aging of components?
>
> Vy 73, Olli - DH8BQA
> http://www.dh8bqa.de/
>
>
>
> ----- Original Message -----
> From: "w0ih"<[hidden email]>
> To:<[hidden email]>
> Sent: Sunday, April 29, 2012 4:52 AM
> Subject: [Elecraft] K3 Frequency Shift
>
>
>> A couple weeks ago, I was on 40 meters with a group of friends, and one of
>> the guys (likes everyone on frequency ;-) suggested that I was off.
>>
>> I finally got around to checking the K3 last week and found that it was
>> off
>> by about 260 Hz from what it should have been. I rechecked the
>> calibration
>> (against WWV, per the manual instructions) and the reference oscillator
>> had
>> not changed from the original setting (I had it marked down in the manual
>> from when I first calibrated it). I had to move it by 260 Hz to get it to
>> zero beat WWV.
>>
>> Anyone have any idea why it should shift frequency? I can't say that I'm
>> terribly concerned, more curious about it.
>>
>> Mike
>>
>
> ______________________________________________________________
> 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
>

Matt Zilmer

Re: K3 Frequency Shift

>It would be interesting if someone with an EXTREF board installed would
>post the change in REF CAL number from cold to hot and extended run.

For K3 #24, w/EXTREF:
Cold start: 49.379.774 is typical;
After ~2 hours warmiing up: 49.379.693 is typical.
The EXTREF here is driven by a Trimble Thunderbolt-based GPSDO.

73,
matt W6NIA

==

>
>I used to drive the local Intelsat Std. B earth station and our uplinks
>at 6GHz were locked to an approximately 4MHz precision TCXO which locked
>a 100MHz osc, which locked the final SHF osc. It was not unusual to see
>a couple of Hz/month wander (at 4MHz).
>
>Not done like that in the new station. Neither does it have two stage
>parametric RX preamps that need de-icing twice a year at the feed
>assembly, but that is another story.
>
>Regards,
>
>Mike VP8NO
>
>On 29/04/2012 06:06, Oliver Dröse wrote:
>> Aging of components?
>>
>> Vy 73, Olli - DH8BQA
>> http://www.dh8bqa.de/
>>
>>
>>
>> ----- Original Message -----
>> From: "w0ih"<[hidden email]>
>> To:<[hidden email]>
>> Sent: Sunday, April 29, 2012 4:52 AM
>> Subject: [Elecraft] K3 Frequency Shift
>>
>>
>>> A couple weeks ago, I was on 40 meters with a group of friends, and one of
>>> the guys (likes everyone on frequency ;-) suggested that I was off.
>>>
>>> I finally got around to checking the K3 last week and found that it was
>>> off
>>> by about 260 Hz from what it should have been. I rechecked the
>>> calibration
>>> (against WWV, per the manual instructions) and the reference oscillator
>>> had
>>> not changed from the original setting (I had it marked down in the manual
>>> from when I first calibrated it). I had to move it by 260 Hz to get it to
>>> zero beat WWV.
>>>
>>> Anyone have any idea why it should shift frequency? I can't say that I'm
>>> terribly concerned, more curious about it.
>>>
>>> Mike
>>>
>>
>> ______________________________________________________________
>> 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
>>
>______________________________________________________________
>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

Edward R Cole

Re: K3 Frequency Shift

In reply to this post by w0ih

Mike,

I was one of the beta-testers of the K3EXREF and see about a move
from 49.380 to 49.380.080 over about an hour from cold start. Then
is settles down to moving only in single digit amounts. MY 10-MHz
reference is a surplus OCXO (oven controlled xtal osc) rated at +/- 5
E-12 which holds the K3 to within +/- 2 Hz at 28-MHz. The error is
proportional to frequency so error is < 1Hz at 20m and below. On 6m
it runs between 2-Hz and 3-Hz error measured on my mw frequency
counter locked to a Rubidium standard. You can view my complete
beta-test report on the EXREF at:
http://www.kl7uw.com/K3EXREF.htm
----------------
Date: Sun, 29 Apr 2012 06:58:42 -0700
From: Matt Zilmer <[hidden email]>
Subject: Re: [Elecraft] K3 Frequency Shift
To: Mike Harris <[hidden email]>
Cc: [hidden email]
Message-ID: <[hidden email]>
Content-Type: text/plain; charset=ISO-8859-1

>It would be interesting if someone with an EXTREF board installed would
>post the change in REF CAL number from cold to hot and extended run.

For K3 #24, w/EXTREF:
Cold start: 49.379.774 is typical;
After ~2 hours warmiing up: 49.379.693 is typical.
The EXTREF here is driven by a Trimble Thunderbolt-based GPSDO.

73, Ed - KL7UW, WD2XSH/45
======================================
BP40IQ 500 KHz - 10-GHz www.kl7uw.com
EME: 50-1.1kw?, 144-1.4kw, 432-QRT, 1296-?, 3400-?
DUBUS Magazine USA Rep [hidden email]
"Kits made by KL7UW" http://www.kl7uw.com/kits.htm
======================================
______________________________________________________________
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