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K3 Front Panel Temps/freq drift

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alsopb

K3 Front Panel Temps/freq drift

Guys,

I'm curious what is the max front panel temp you're seeing after a
period of operating with significant transmit time? Also what is the
room temp at this value.

The reason I ask has to do with the K3 Master Oscillator calibration
procedure and later drift. A detailed set of measurements with a stock
K3 indicates a good correlation of drift with front panel temperature.
With the standard oscillator, measurements indicate that the K3 drifts
about -1.2 Hz/C (.12ppm/C) degree at 10 MHz. Here a Rb 10MHz secondary
frequency standard was used as well as a counter to measure how the
audio tone changes vs time. This allows sub Hz changes to be observed.

Normally one does the calibration receive only. In that case with an
ambient temp of 24C here, the front panel temp rises 34 C after 90
minutes. I normally calibrate after such a warmup.

If the front panel temp rises another 10C after periods of transmit, the
frequency could be off by about -12 Hz at 10 MHz (-60 Hz at 50 MHz).
Sure that's not a lot. But it says, perhaps one shouldn't knock
themselves off trying to be super accurate with the calibration. There
will be another couple or perhaps as much another 10 Hz (1ppm) error due
to transmiter heat buildup. The actual amount can probably never be
predicted.

It is clear to me if one "needs" more accuracy, the high precision
oscillator option and/or locking to an external reference would be needed.

I'd love to look at the high stability oscillator drift as well.
However, satisfying that curiosity for $100 isn't going to happen.
Perhaps someone out there with the high stability oscillator could
repeat the above measurements and report the results.

73 de Brian/K3KO

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Guy, K2AV

Re: K3 Front Panel Temps/freq drift

There has been talk off and on from Wayne of completing the firmware
that would interpret the TCXO cal figures. Given that, those who
really want this (for whatever reason - I won't comment on that)
could, with a separate precise frequency standard, actually develop
their own TCXO cal figures which pretty much nailed temp change for a
given K3. This would be better than figures for a stand-alone TCXO
calibrated in a lab.

My add to that would be that an individual K3 could be brought into
line on a curve that would be a fourth of the K3's spec. My take is
that without dissing someone for WHY they want it, it IS possible and
just another aspect of excellence that only lacks firmware to become
reality.

The TCXO cal interpret firmware would then become a tool which the
OWNERS could perfect, and in turn can move into future products,
including a utility that takes a precision calibration routine and
automatically maxes the frequency stability for a given unit.

It could also become a cottage industry for someone who got really
good at it to calibrate K3's for temperature stability.

Why not?

73, Guy.

On Wed, Jun 29, 2011 at 9:19 AM, Brian Alsop <[hidden email]> wrote:

> Guys,
>
> I'm curious what is the max front panel temp you're seeing after a
> period of operating with significant transmit time? Also what is the
> room temp at this value.
>
> The reason I ask has to do with the K3 Master Oscillator calibration
> procedure and later drift. A detailed set of measurements with a stock
> K3 indicates a good correlation of drift with front panel temperature.
> With the standard oscillator, measurements indicate that the K3 drifts
> about -1.2 Hz/C (.12ppm/C) degree at 10 MHz. Here a Rb 10MHz secondary
> frequency standard was used as well as a counter to measure how the
> audio tone changes vs time. This allows sub Hz changes to be observed.
>
> Normally one does the calibration receive only. In that case with an
> ambient temp of 24C here, the front panel temp rises 34 C after 90
> minutes. I normally calibrate after such a warmup.
>
> If the front panel temp rises another 10C after periods of transmit, the
> frequency could be off by about -12 Hz at 10 MHz (-60 Hz at 50 MHz).
> Sure that's not a lot. But it says, perhaps one shouldn't knock
> themselves off trying to be super accurate with the calibration. There
> will be another couple or perhaps as much another 10 Hz (1ppm) error due
> to transmiter heat buildup. The actual amount can probably never be
> predicted.
>
> It is clear to me if one "needs" more accuracy, the high precision
> oscillator option and/or locking to an external reference would be needed.
>
> I'd love to look at the high stability oscillator drift as well.
> However, satisfying that curiosity for $100 isn't going to happen.
> Perhaps someone out there with the high stability oscillator could
> repeat the above measurements and report the results.
>
> 73 de Brian/K3KO
>
>
>
>
>
> -----
> No virus found in this message.
> Checked by AVG - www.avg.com
> Version: 10.0.1388 / Virus Database: 1516/3733 - Release Date: 06/29/11
>
> ______________________________________________________________
> 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

Jack Chomley

Re: K3 Front Panel Temps/freq drift

Mmmm......given that there is now a Pactor 4 modem available, this could be
an advantage? JT65 too?

73,

Jack VK4JRC

On Thu, Jun 30, 2011 at 3:15 AM, Guy Olinger K2AV <[hidden email]>wrote:

> There has been talk off and on from Wayne of completing the firmware
> that would interpret the TCXO cal figures. Given that, those who
> really want this (for whatever reason - I won't comment on that)
> could, with a separate precise frequency standard, actually develop
> their own TCXO cal figures which pretty much nailed temp change for a
> given K3. This would be better than figures for a stand-alone TCXO
> calibrated in a lab.
>
> My add to that would be that an individual K3 could be brought into
> line on a curve that would be a fourth of the K3's spec. My take is
> that without dissing someone for WHY they want it, it IS possible and
> just another aspect of excellence that only lacks firmware to become
> reality.
>
> The TCXO cal interpret firmware would then become a tool which the
> OWNERS could perfect, and in turn can move into future products,
> including a utility that takes a precision calibration routine and
> automatically maxes the frequency stability for a given unit.
>
> It could also become a cottage industry for someone who got really
> good at it to calibrate K3's for temperature stability.
>
> Why not?
>
> 73, Guy.
>
>