Bret, I can't fully agree with you on several points. The KWM and 75S
receivers are pretty good but so is the 51S1. The 75S-3B/C are arguable
better when tuned properly and in good electrical condition and in
consideration of the available filters. The problem with SWLing, so to
speak, is that although movable (read: re-tunable) throughout the HF
spectrum, both the KWM and the 75S receivers require an "internal"
retuning to maximize sensitivity when the excursion is made outside an
adjacent 200 kHz segment. You'll note in the manual a reference to a
"field alignment". This is required when shifting a noteworthy amount.
The KWM and 75S have limited re-tuning ability via the front panel
(preselector). The 51S1, on the other hand, has a fully tracked tuning
system throughout the HF spectrum. Price aside, and given a choice of
the two types of receivers, the 51S1 would wins hands down, in my mind,
as an SWL receiver. Frankly, though, I'd prefer and in fact use, among
others, R-390As or a Drake R4C (or "B") and an S&S DVFO-II. But, that's
why there are Fords, Chevys, and Toyotas.
de Jeep/K3HVG

Bret Ludwig wrote:
The Collins S-line is not exactly ham band only. If you have enough
crystals you can have any 200 kHz, I think, of Hf spectrum between 3.4
and 30 MHz except for 5 to 6.5 MHz.

Using a remote RF gen with programmed steps instead of the xtals is
possible with only minor modification, I think. But perhaps an internal
synth would be possible, and could be made quiet enough to not detract
from the superb performance, better than most synthesized icoms and so
forth.

I'm told that for specific 200 kHz swaths, a 75S or KWM is a much
better receiver than the 51S-1, which has a very promiscuous front end.


Any thoughts?