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LF: Re: Receivers

To: [email protected]
Subject: LF: Re: Receivers
From: "James Moritz" <[email protected]>
Date: Mon, 12 Jul 2004 22:45:41 +0100
References: <[email protected]>
Reply-to: [email protected]
Sender: [email protected]
Dear Mike, LF group

I have an Icom IC718 transceiver - it tunes down to 30kHz, and has the
typical 20dB loss of sensitivity at 136kHz compared to HF. I have the
optional 250Hz filter, which is very good for LF, if a bit narrow for HF.
With the filter, it needs 1uV for 10dB SNR on 136k. This gives adequate RX
sensitivity with my TX  wire antenna resonated with a suitable coil - for
smaller antennas, a preamp is required. The sensitivity deteriorates as the
frequency decreases. The noise blanker doesn't seem to do very much at LF;
the preamp causes a loss of sensitivity. The AGC has the effect of turning
the LF band noise into a uniform mush, which does not help readability much,
and you can't switch it off, but backing off the RF gain improves things a
lot. I think it is quite usable for LF, allthough obviously not ideal.

Cheers, Jim Moritz
73 de M0BMU

----- Original Message -----
From: Mike Dennison <[email protected]>
To: <[email protected]>
Sent: Monday, July 12, 2004 5:49 PM
Subject: LF: Receivers

I am compiling a list of receivers and transceivers suitable
for 136kHz.

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