I disagree with Tadek on several points, but most important
are:
1.) I work much more than 160. I find I need 80dB or more of
close-spaced IM3 and blocking on 80 meters and higher.
2.) In a noisy location like the city, he needs less IM3 DR
and blocking than I do at ANY spacing. The exception would
be if he has very strong local neighbors on the same band in
the same pileup.
3.) I mostly work DX, and absolutely never have a problem
with wide spaced signals due to receiver problems with any
of my conventional receivers. Contests are MUCH worse than
DX pileups because you have all the close-frequency stations
plus MANY more strong wide-frequency spaced stations. I
cannot imagine anyone needing better than 90 or 95dB DR at
wide spacing in a very quiet location, let alone a noisy
location like a urban environment!
4.) Most DX stations only use a few kHz spacing on CW. All
of this is generally within the roofing filters. If you look
only at wide spacing, it is a SERIOUS mistake. For example
say you consider the IC-7800 good. This means your decision
is based on never using a receiver at spacings under 5kHz in
pileups.
I am very puzzled why anyone would ever pick a radio knowing
it was no good at close spacing, when 99% of the troubles we
have are all at close spacing! I have never experienced
wide-spacing overload except for my own transmitters.
I would like to know how many others experience and have
identified wide spacing (say over 5-10kHz) overload.
73, Tom W8JI
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