[aprssig] ARPS-HF Frequency Stability Question

Jon Adams jon at jonadams.com
Sun Oct 2 11:21:43 CDT 2005

Good morning all -

I've been running HF APRS for over 10 years and as an HF Gate for nearly
that long. When I listen to the traffic, I hear stations high and low of any
one frequency, and if they're more than a few dozen Hz off, they don't
decode very well. (running Kam+).

I don't know how every station sets its operating frequency, I'd heard some
time ago that some transceivers wouldn't let the station transmit if the
dial (no matter where the modulated signal really was) above 10,150.0 kHz,
so for a while it seemed that a block of stations were at that frequency.
Today, I'm hearing stations at 10,150.4. I go over and check WWV and it's
where it's always been.

I know it gets easy to get into a loop with tuning - station B tunes to Sta
A, C tunes to B, etc., until A discovers Z off-channel, and nudges the dial,
and the whole thing starts anew.

If there isn't a procedure already in place, then I'd suggest that a 24x7
station in the mid-country be the reference - K7PW, K5RAV, N5NGN, N0LRF,
KM5HG. I don't know which of those is more stable than the other, but maybe
they can decide among themselves and one be the "reference". Once they've
established that, then we can all tune to that one and lock the dial (unless
your own station drifts). No station would retune themselves because of some
other off-frequency station.

73 - Jon N7UV

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