EMRFD Message Archive 6696

Message Date From Subject
6696 2011-09-20 06:29:47 Alan Melia using WWV 10MHz
Hi all, I have filed this interesting thread away for a good read later but
did notice a comment about someone trying to "beat" in a local 10MHz souce
with Spectran. If you try this, dont do it at zero beat.

In the days before digital counters and PC ( standby by for Old Timer bore
;-)) ) we used a method called the three oscillator method. Put the BFO on
on the RX and tune for an audio beat (600Hz to 1000Hz) against the WWV
carrier. Then adjust the coupling of your local 10MHz source to the aerial
input to make the note sound rough, then tweak the source so the rough tone
goes down in frequency by ear. As you get into the 1Hz beat region (between
local source and WWV) the BFO note will "swell" at the difference fequency.
It is possible to adjust the local source until the peaks of swell are 10
seconds or more apart ....depending on how stable your source is. Now this
repesents 1 part in 10^8 which is probably as good as you ever can reliably
get with an HF signal off air, and is probably good enough for most amateur
applications. Ah the days of the BC-221 :-)) Note it doesnt matter how
unstable, within reason, you rx is is just changes the frequency of the beat
note, not the swell rate.

Bore over. It easier to do than describe. We no longer have a 10MHz ( or any
HF) standard frequency transmission in UK :-((