For LF reception there's no great secret. A decent communications
receiver tuning down to 30kHz combined with a wire aerial broadly (or
sharply) tuned to 136kHz, a correct loading coil should do the same job,
this reduces broadcast signals to more acceptable levels.
The receiver should have no attenuation below (say) 550khz, most of them
have a bandpass filter on the front end, the older ones with a tuned
front end were good but not stable enough. If you can get a circuit of
the front end and re-draw it in a software program such as Tina it will
display the frequency response and allow modifications to be set. I
altered one inductor only. Beware of the remaining stations on Long
Wave, it may require a notch filter, this is where software helps again.
I think many transceivers for Amateur use have very poor, mediocre or
just average receiver response at LF so I'm not sure if a preamplifier
would help unless it's tuned.
A notch filter on the receiver is essential and a good USB filter as
well. It's worth buying extra filters according to the receiver as
supplied. There is some choice but an internet search may help.
Hugh, M0DSZ
Hello Hugh,
Sunday, April 17, 2016
Likewise, many thanks to Alex, it is a generous and useful service,
and I look forward to seeing who heard who. Thanks Alex!!
BTW Hugh, may I ask what you are using for LF reception please? I
want to get a better RX setup here, it isn't very good compared to what
you are achieving. Thanks.
Best regards,
Chris 2E0ILY mailto:[email protected]
I must thank Alex (R7NT) for his carefully collated, weekly reports, it
helps to coordinate everyone's LF tests. For some reason I haven't been
receiving him well or often though there are times when I'm not in Rx
mode by virtue of being on HF fro a while, especially on Sunday mornings.
Hugh, M0DSZ
|
