At 14:33 13/07/99 +0200, PA0SE wrote:
There are two factors to be considered, sensitivity and selectivity.
A dc-receiver can be made as sensitive as a superhet.
...
I think that a third factor has te be considered, especially on LF : the
intermodulation behavior of the RX.
From my experience with DC-receivers on 80m I know that strong signals near
the 'passband' can not only cause 'gost-signals' but also make the RX very
insensitive (DC breakthrough).
The most critical part (assuming you have a proper designed RF preamp with
good IM behavior) is the mixer, this should be a a high-quality DBM.
But on 136kHz an almost-perfect DBM is much easier to realise than on HF, I
have heard about good results using analog switches as replacement for the
diodes.
73, Rik
Rik Strobbe ON7YD
[email protected]
Villadreef 14 B-3128 Baal BELGIUM (JO20IX)
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