K3S new synthesizer query

[briancom]

Please correct me if I am wrong.

I believe the heart of the new synthesizer is a SI-570.

Great phase noise but the output frequency is quite sensitive to
temperature changes.

It has been observed that the corrections to bring the synthesizer in
step with the master oscillator happen over longer and longer periods as
the K3 warms up.  It never seems to reach a point of stability even
after 24 hours of warmup.

Is there some kind of thermal material that one can put around the
SI-570 to lengthen these periods and/or reduce it's drift?

73 de Brian/K3KO

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[Don Wilhelm]

Brian,

The main frequency determining element in the K3/K3S is the TCXO and not
the SI-570.

Are you looking only at the native SI-570 thermal data, or are you
finding from our measurements that the SI-570 in the new synth boards is
not following the stability of the TCXO?  The SI-570 should slave off
the frequency of the TCXO.

I do not know the rate of synchronization between the SI-570 and the
TCXO, so I will have to leave that part of your question unanswered.  
Perhaps the engineer for the new synth boards will respond with
definitive information.

73,
Don W3FPR

On 6/28/2016 10:09 PM, brian wrote:

> Please correct me if I am wrong.
>
> I believe the heart of the new synthesizer is a SI-570.
>
> Great phase noise but the output frequency is quite sensitive to
> temperature changes.
>
> It has been observed that the corrections to bring the synthesizer in
> step with the master oscillator happen over longer and longer periods
> as the K3 warms up.  It never seems to reach a point of stability even
> after 24 hours of warmup.
>

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[Roger]

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[Robert .]

Brian,    tis a relative drift?

For Example: many use the K3 with Spectrum Lab audio software & soundcard
and perform very well in measurement tests in ARRL FMT
http://www.b4h.net/fmt/fmtresults201604.php

Typically turn K3 on before work on day of FMT
can get within 1 hz in FMT (not always but most)
The corrections (step) and wiggle can be seen on the Spectrum Lab screen but
after several hours of warm up it's typically less than 1 hz

If you are trying to more stability, the temperature controlled TCXO might
be for you

GL & 73 Robert W5AJ


-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of brian
Sent: Tuesday, June 28, 2016 9:09 PM
To: [hidden email]
Subject: [Elecraft] K3S new synthesizer query

Please correct me if I am wrong.

I believe the heart of the new synthesizer is a SI-570.

Great phase noise but the output frequency is quite sensitive to temperature
changes.

It has been observed that the corrections to bring the synthesizer in step
with the master oscillator happen over longer and longer periods as the K3
warms up.  It never seems to reach a point of stability even after 24 hours
of warmup.

Is there some kind of thermal material that one can put around the
SI-570 to lengthen these periods and/or reduce it's drift?

73 de Brian/K3KO

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delivered to [hidden email]

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[Roger]

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