Over the past month, I had become aware that a certain G-station - new
to LF, but with a very commanding signal on 136.53 kHz - was often heard
to 'clobber' QSOs, and CQ calls from other stations. This puzzled me
greatly, because I knew that the station concerned could usually hear
the other stations involved.
It appeared to me - and to others - as if the station was deliberately
causing QRM to his fellow LFers.
Having recently telephoned the operator concerned, I can report that the
reason for the unintentional QRM amounted to a lack of understanding
concerning typical IF bandwidths employed by amateurs on 136 kHz. The
operator concerned is using a receiver with an effective IF bandwidth of
50 Hz (!), and he was quite happy to operate to within 100Hz of other
stations!
I advised the operator that we tend to assume a receive IF bandwidth of
250 Hz and generally aim to maintain a 300 Hz separation from other
stations. (I believe that 300 Hz has been the figure quoted during LF
Group discussions and at the LF Forum.) I hope I did the right thing.
But with the fancy new receivers now available (which I'll probably
never be able to afford!), does the Group still feel 300 Hz to be a
reasonable separation for normal CW operation?
Regards to all,
Steve GW4ALG
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