Glenn,
The qualities of a frequency counter capable of setting the K2 reference
accurately is that it be capable of counting down to 1 Hz and have adequate
accuracy - which means that it must be properly calibrated. The calibration
is more important than having any particular counter. Most any counter
capable of input frequencies 15 MHz and above will do a good job if properly
calibrated. For general ham use at HF, I would look for one that will go to
at least 50 MHz or preferrably 100 MHz - calibration to off the air WWV is
just not accurate enough for most purposes, calibration to a GPS based
standard or a WWVB based standard should be adequate. Be aware of the long
term and short term stability specs of the reference oscillator in any
frequency counter that you invest in - that will tell you how accurate your
counter should be and how much drift you may experience after it is
calibrated. Usually, the calibration standard must be about 10 times more
accurate than the instrument being calibrated, so if you need to calibrate
an instrument to 1 part in 10^6, you will need a standard that is guaranteed
to 1 part in 10^-7 to do a proper calibration. The major point I am trying
to make here is that you should know your instrument's accuracy so that you
know just how 'far to trust it' - that fact pertains to all measurement
instruments not just frequency counters, if you don't know the accuracy, the
lower order digits shown on a multi-digit instrument may be pure garbage.
If setting the K2 reference oscillator is your major goal, I strongly
suggest that you use the internal K2 counter and the 'N6KR' method - which
is the one detailed on the Elecraft website
http://www.elecraft.com/Apps/K2%20C22%20Adjust%20App%20Note.pdf. That
method does require that you be able to tune WWV in precisely - listening to
the voice announcements will get you close, I highly recommend that you use
Spectrogram to view the tones transmitted by WWV - they alternate between
500 and 600 Hz on alternate minutes, and if you set Spectrogram markers at
both 500 and 600 Hz, after a few minutes you can tune the K2 so that the
Spectrogram peaks from the tones line up with the markers. This method for
setting the K2 reference is more accurate than using an external counter
unless you know that your counter is calibrated properly and accurately
(calibration to 1 part in 10^-7 or better is my recommedation).
73,
Don W3FPR
> -----Original Message-----
>
> Can someone recommend a general purpose frequency counter
> suitable for setting C22 in a K2 and for other ham shack uses?
>
> Glenn
> K5ZE
>
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