From G3PLX:
On seeing the report of Droitwich being off frequency, I connected up my
Clicklock set-up, which enables me to measure off-air signal phase relative
to GPS.
I have to run the system with no antenna in order to get Droitwich low
enough in level, and that makes the measurement a little sensitive to
disturbances in the shack, but this is a disturbance in both amplitude and
phase, and it's quite easy to see that the few degrees wobble I am seeing in
the phase is the same as the wobble in amplitude, and is not due to a
systematic drift in phase. A random distrbance results in a blob on the
vectorscope. A frequency error shows as an arc around the origen.
If it had been 1Hz off, I would have expected to see a change of 360 degrees
PER SECOND, i.e. a full circle rotating once/sec. All I can see is a
circular blob about 2% amplitude, and that's over the last 20 minutes.
I would say Droitwich is spot-on. Has anyone who saw it off frequency
checked it again (since 20:00 utc) to see if it's back on frequency? Was it
off frequency and it's back again, or maybe it was never off.
73
Peter
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