My QTH is afflicted by very high QRM level radiated from my overhead mains
supply. It was very bad when I first started experimenting with LF and got
progressively worse over the years, so much so that I almost gave up on LF.
It occured to me early on that if could find a spot clear of QRN within a
reasonable distance I could park my car there with a small active receiving
antenna and re- transmit 136 KHz signals to my shack, much as many US
stations do on HF and VHF over their fixed relay installations. There was a
question of the legality of the relay, remotely operated, under UK licence
conditions, but it did not look absolutely impossible.
There is such a QRN free spot in Crawley, only 2k away from my QTH, namely
the Crawley Amateur Radio Club Shack.
It seemed reasonble to try the experiment and see if it worked.
Stewart G3YSX and Derek G3GRO had similar ideas and went to work on the
project. And so, the much maligned MB7LF relay (not repeater) was conceived.
It's effectivness was meant to be demonstrated at the RSGB Windsor
Convention QTH. In spite of the fact that the Loran cancelling system was
not operational it was demonstrated that the idea worked very well indeed.
The relay is experimental and is not intended for a permanent global
coverage, as I uderstand it.
Any amateur with local QRN problem could adapt similar approach. Find a
right spot, persuade the owner to allow a small whip antenna on his/her
field with a small UHF yagi for relay and there you are. There are already
in existence low power UHF systems that do not require a licence in some
countries. The regulatory authorities in UK appear to be receptive to
amateur needs and may in due course approve such operation on specified
conditions.
Well, it is all about experimentation and self education.
Nobody objected when in the early days of LF I made a short, low power,
SSB test transmission with limited audio bandwidth on 136KHz. To my
amazement the phone didn't stop ringing for hours but no stones were hurled
through my windows. Similarly just because I had a QSO with Windsor using my
50milliwats signal generator and two metres receiver does not mean that it
will be my future mode of operation. It was possible only because I live
near the relay and line of sight and I enjoy experimenting. I am not
claiming any QRP DX awards on that score.
73 to All LF Experimenters and users de Lech G3KAU
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