I e-mailed Rob Sherwood regarding his test data of various receivers. I
thought his reply might interest you Topbanders.
73, de Earl, K6SE
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Hi, Rob,
I ran across the table of receiver test data you posted on your Web
site. Very interesting data, but I notice none of the more modern
receivers are included, i.e., FT-1000MP, TS-870, IC-775DSP, IC-756, and
others.
Q. I wonder if you plan to test any of the newer rigs and publish the
results?
A. Not too likely. I am too busy being a computer consultant. I cannot
keep up with the work.
Q I'm now using my old TS-830S (with 250/270Hz filters in both IFs),
which does a decent job during crowded CW contest condx. The 830 you
rate #4 on your list indicates that a YK88 filter was used -- I wonder
which one (500 or 250Hz)?
A. 500 Hz filter.
Q. I'm considering upgrading to one of the newer DSP rigs, which is why
I'm curious about their performance as a receiver.
A. I really don't know what to recommend. The problem with DSP is when
it get overloaded, it does not go down gracefully. When I tested the WJ
HF-1000, I felt it was harsh sounding, and if the DSP was pushed like it
would be in a CW pile up on 160 meters, then it put out nothing but
trash. You really need to have a filter earlier than the DSP that can
protect it from a swath 10 to 20 kHz wide full of S9 +40 signals. That
is a lot to ask. So while I like the infinite variable bandwidth a DSP
can offer, there is a trade off.
I own an Icom 781, and it does well, but is pre DSP days. JRC is
bringing out a new DSP 545 receiver, but have not seen it yet. All up
conversion rigs have some level of first IF "window" overload problems
when in a CW pile up. That is why the C-Line did so well with a 600 Hz
first IF filter and a 500, 250, or 125 second IF filter. The first got
rid of 90% of the crud, and the second just had a limited job to do.
First IF filter protected second mixer - not possible with up conversion
rigs, or DSPs. Big problem, but no good answers.
73, Rob, NC0B
--------- End forwarded message ----------
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