My homebrew receiver (see QRZ.COM, W0IYH) has a 1.0 MHz xtal osc and a
divide by 10 to 100 kHz. I can get the beats from WWV at 10 MHZ and set to
zero beat using a front panel (lower right hand corner) trimmer capacitor
and ON/OFF switch. The 100 kHz marker is then within several Hz on any ham
band, including a possible small doppler shift of the sky wave signal from
Colorado. The accuracy and short term stability are more than good enough
for 100 kHz harmonics in the ham bands. In CW mode the zero beat is offset
by 500 Hz and I can use an audio freq counter to get a 500 Hz count. The 1.0
MHz freq goes to a jack on the back of the rcvr and I use that to set the
reference freq on my Heath freq counter while I am at the same time
monitoring WWV at 10 MHz. A digital counter in the rcvr indicates signal
freq with a 100 Hz resolution. To avoid possible accumulated frequency
counting errors I stay 1 kHz away from band edges.

Bill W0IYH

"Dave Platt" wrote in message
...
In article ,
budgie wrote:

I'm told that 'zero beating' typically has accuracy not much better than
some
tens of Hz due to the limited lower frequency response of the human
ear... has
anyone tried zero beating a signal from above and below and taking the
average
to get what might be a more accurate frequency estimate?

When the frequencies are close, a CRO is a great zero beat detector.

Yup.

It's a bit easier if your crystal happens to be on a frequency which
lets you zero-beat against an AM-modulated carrier signal, such as WWV
(during the early part of each minute, when it's sending a tone
burst). You don't have to try to pick out the beat frequency
directly... instead, you listen for the tone to waver in and out, and
tweak for the slowest wavering.

It's not hard to get the zero-beating accurate to within 1 Hz or
better with a bit of patience.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
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