Frequency Counter

[Dennis Vavra]

Don,

Thanks for the info regarding the XG2/Freq Ctr. Could you recommend a make/model freq ctr for kit building? Iv'e looked on the MFJ web site, but if you have better ideas it would be of great help. Preferably one that is not too expensive!!
Dennis Vavra,  AD5LY
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[Don Wilhelm-3]

Dennis,

I would not recommend ANY kit frequency counter if one will be using it
for calibration purposes - unless you have some means of calibrating it.

I can recommend a recently calibrated HP or Fluke frequency counter -
you can sometimes find them used at auction sites, but they may not have
recent (and tracable) calibration.  Good calibration does cost dearly at
a calibration lab.

To be properly used as a calibration device the instrument should have a
tracable calibration accuracy of 10 times the accuracy that you seek
when using it.  That means if you wish to achieve 1 Hz accuracy at 10
MHz, that instrument must be calibrated to an accuracy of 10^-7 or
better.  That kind of accuracy just cannot be achieved with an
over-the-air signal from WWV - syncing to WWVB might be possible, but
that is not easy for most ham/experimenter situations.  If you can find
a GPS synced standard, you may be able to achieve 10^-8 or with care
even 10^-9 in some cases.

You alone must decide what kind of accuracy you wish to achieve and make
your decisions based on the specifications for the counter and the
accuracy of your calibration techniques.

73,
Don W3FPR

Dennis Vavra wrote:

> Don,
>
> Thanks for the info regarding the XG2/Freq Ctr. Could you recommend a make/model freq ctr for kit building? Iv'e looked on the MFJ web site, but if you have better ideas it would be of great help. Preferably one that is not too expensive!!
> Dennis Vavra,  AD5LY
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[Ron D'Eau Claire-2]

I have a little portable counter (ancient - late 70's technology) that uses
a 4 MHz crystal. It was nothing fancy. It didn't even have a way to adjust
the crystal frequency.  I had to add a small piston trimmer cap to the
design. I used it commercially to confirm that shipboard transmitters were
in spec before the FCC checked them during the annual inspection. I noted
that my counter was always very, very close to the FCC examiner's much more
sophisticated instrument.

Mine used the common 4 MHz crystal. Before going out to a ship the check the
transmitters I'd set it using the 5th harmonic of the xtal to beat against
WWV. I could easily set it to with 1/2 Hz at 20 MHz. That is the S-meter on
the receiver monitoring WWV would wander every so slowly, completing a cycle
in no less than 1 second. That meant the time base error was 1/5 that for a
total error of 1/10 Hz or less.

If I ever have to retire my little counter I'll look for a similar
capability in any design I use to replace it. As long as I can check the
calibration regularly I'll know how much a counter tends to drift and I can
quickly set it very accurately whenever I need to make an especially precise
adjustment. It's pretty rare when WWV isn't booming in here on 20 MHz on the
west coast.

I set my K2's calibration using the procedure Wayne provided on the web
site, primarily because I wanted to see how easily it worked. It was simple,
quick and yielded results well within the 20 Hz or so possible error of the
DAC's used in the K2. So I never tried using WWV at 20 MHz to zero beat the
K2 control board oscillator, but I'd expect it to work just as well.

After all, the K2 has a built in frequency counter. It's that built-in
counter's time base that C22 adjusts! Why not set it as accurately as
possible and use it as it was intended.

Ron AC7AC

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[Matt Osborn]

I can recommend the M3 FPM1 Frequency Counter and Power Meter..

<http://www.m3electronix.com/fpm1.html>

It's a great kit but the calibration problem still remains.  For
calibration, M3 sells the RF Calibrator which is NOT a kit, but does
come calibrated by M3.

<http://www.m3electronix.com/rfcal.html>

Both are remarkably accurate and I've found them to be very useful
additions to my bench.

Disclaimer:  I do not work for M3 Electronix, I'm just a satisfied
customer.


On Mon, 23 Apr 2007 14:30:33 -0500, "Dennis Vavra" <[hidden email]>
wrote:

>Don,
>
>Thanks for the info regarding the XG2/Freq Ctr. Could you recommend a make/model freq ctr for kit building? Iv'e looked on the MFJ web site, but if you have better ideas it would be of great help. Preferably one that is not too expensive!!
>Dennis Vavra,  AD5LY
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>Elecraft mailing list
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-- kc0ukk at msosborn dot com
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