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XG50 - Frequency Instability

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kj7rt

XG50 - Frequency Instability

I am trying to use my XG50 to run the Extended Temperature Compensation
Procedure on my KX3. This is the first time I have attempted to use the
XG50 since building it. I have completed the 8 hour burn-in.

When I first connect the XG-50 to my HP frequency counter, I get a
reading of something like 49.379990. Then after running for several
minutes it starts dropping in frequency to something more like
49.32xxxx. It is still wildly fluctuating. If I connect the 10MHz output
of my Trimble Thunderbolt GPSDO to the counter it stays quite stable
just below 10 MHz.

I re-soldered all the XG50 components and tried with both a metered
home-brew power supply and a 12v SLA battery with the same result
although re-soldering made a significant but not permanent improvement.

My lab is in my photographic darkroom which has an ambient temperature
of about 68 degrees F and the AC does blow across the work area.

Thanks,

Gary Marklund
KJ7RT
Sun City, AZ
USA

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Elecraft mailing list

Re: XG50 - Frequency Instability

I would try putting something around the oscillator (Styrofoamm etc)

________________________________
From: "[hidden email]" <[hidden email]>
To: [hidden email]
Sent: Thursday, May 22, 2014 10:31 AM
Subject: [Elecraft] XG50 - Frequency Instability

I am trying to use my XG50 to run the Extended Temperature Compensation
Procedure on my KX3. This is the first time I have attempted to use the
XG50 since building it. I have completed the 8 hour burn-in.

When I first connect the XG-50 to my HP frequency counter, I get a
reading of something like 49.379990. Then after running for several
minutes it starts dropping in frequency to something more like
49.32xxxx. It is still wildly fluctuating. If I connect the 10MHz output
of my Trimble Thunderbolt GPSDO to the counter it stays quite stable
just below 10 MHz.

I re-soldered all the XG50 components and tried with both a metered
home-brew power supply and a 12v SLA battery with the same result
although re-soldering made a significant but not permanent improvement.

My lab is in my photographic darkroom which has an ambient temperature
of about 68 degrees F and the AC does blow across the work area.

Thanks,

Gary Marklund
KJ7RT
Sun City, AZ
USA

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Phil Genera

Re: XG50 - Frequency Instability

In reply to this post by kj7rt

This doesn't answer your question, but I was able to use the 5th harmonic
of my thunderbolt without trouble.

--
Phil

On Thu, May 22, 2014 at 10:31 AM, <[hidden email]> wrote:

> I am trying to use my XG50 to run the Extended Temperature Compensation
> Procedure on my KX3. This is the first time I have attempted to use the
> XG50 since building it. I have completed the 8 hour burn-in.
>
> When I first connect the XG-50 to my HP frequency counter, I get a
> reading of something like 49.379990. Then after running for several
> minutes it starts dropping in frequency to something more like
> 49.32xxxx. It is still wildly fluctuating. If I connect the 10MHz output
> of my Trimble Thunderbolt GPSDO to the counter it stays quite stable
> just below 10 MHz.
>
> I re-soldered all the XG50 components and tried with both a metered
> home-brew power supply and a 12v SLA battery with the same result
> although re-soldering made a significant but not permanent improvement.
>
> My lab is in my photographic darkroom which has an ambient temperature
> of about 68 degrees F and the AC does blow across the work area.
>
>
> Thanks,
>
> Gary Marklund
> KJ7RT
> Sun City, AZ
> USA
>
> ______________________________________________________________
> 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]
>

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Alan Bloom

Re: XG50 - Frequency Instability

In reply to this post by kj7rt

50-60 kHz instability of a 49 MHz source is over 1000 ppm, two or three
orders of magnitude greater than would be expected, even with air
conditioning blowing across the oscillator. There must be something
wrong with the XG50, or perhaps some problem with the frequency measurement.

Alan N1AL

On 05/22/2014 07:31 AM, [hidden email] wrote:

GM4JJJ

Re: XG50 - Frequency Instability

In reply to this post by kj7rt

It could be the low level of the XG50 is not enough to trigger the counter properly. I think I found a similar problem and had to use a scope probe on the counter and put it before the output attenuator on the XG50.

73

David Anderson GM4JJJ

> On 22 May 2014, at 15:31, <[hidden email]> wrote:
>
> I am trying to use my XG50 to run the Extended Temperature Compensation
> Procedure on my KX3. This is the first time I have attempted to use the
> XG50 since building it. I have completed the 8 hour burn-in.
>
> When I first connect the XG-50 to my HP frequency counter, I get a
> reading of something like 49.379990. Then after running for several
> minutes it starts dropping in frequency to something more like
> 49.32xxxx. It is still wildly fluctuating. If I connect the 10MHz output
> of my Trimble Thunderbolt GPSDO to the counter it stays quite stable
> just below 10 MHz.
>
> I re-soldered all the XG50 components and tried with both a metered
> home-brew power supply and a 12v SLA battery with the same result
> although re-soldering made a significant but not permanent improvement.
>
> My lab is in my photographic darkroom which has an ambient temperature
> of about 68 degrees F and the AC does blow across the work area.
>
>
> Thanks,
>
> Gary Marklund
> KJ7RT
> Sun City, AZ
> USA
>
> ______________________________________________________________
> 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]

Chip Stratton

Re: XG50 - Frequency Instability

Though I'm sure you want to be sure the XG-50 is working well, I second
Phil's recommendation to use your Trimble Thunderbolt as your frequency
source. Worked fine for me, there was a very strong 5th harmonic at 50 mHz,
even after inserting an inline attenuator.

Chip
AE5KA

On Thu, May 22, 2014 at 12:56 PM, David Anderson <[hidden email]> wrote:

> It could be the low level of the XG50 is not enough to trigger the counter
> properly. I think I found a similar problem and had to use a scope probe on
> the counter and put it before the output attenuator on the XG50.
>
> 73
>
> David Anderson GM4JJJ
>
> > On 22 May 2014, at 15:31, <[hidden email]> wrote:
> >
> > I am trying to use my XG50 to run the Extended Temperature Compensation
> > Procedure on my KX3. This is the first time I have attempted to use the
> > XG50 since building it. I have completed the 8 hour burn-in.
> >
> > When I first connect the XG-50 to my HP frequency counter, I get a
> > reading of something like 49.379990. Then after running for several
> > minutes it starts dropping in frequency to something more like
> > 49.32xxxx. It is still wildly fluctuating. If I connect the 10MHz output
> > of my Trimble Thunderbolt GPSDO to the counter it stays quite stable
> > just below 10 MHz.
> >
> > I re-soldered all the XG50 components and tried with both a metered
> > home-brew power supply and a 12v SLA battery with the same result
> > although re-soldering made a significant but not permanent improvement.
> >
> > My lab is in my photographic darkroom which has an ambient temperature
> > of about 68 degrees F and the AC does blow across the work area.
> >
> >
> > Thanks,
> >
> > Gary Marklund
> > KJ7RT
> > Sun City, AZ
> > USA
> >
> > ______________________________________________________________
> > 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]
> ______________________________________________________________
> 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]
>

Elecraft mailing list

Re: XG50 - Frequency Instability

In reply to this post by GM4JJJ

David Anderson GM4JJJ wrote: It could be the low level of the XG50 is not enough to trigger the counter properly.

I suspect you are correct, David. The XG50 output is spec’d at 10mv p-p and, as an example, an HP 5315 counter requires 25mv rms between 10Mhz and 100Mhz. Not sure which HP counter kj7rt was using, though.

Mark
ars: KE6BB
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