Gerald Youngblood wrote:
For virtually all HF use, the Medium setting of the preamp is best.
The High would typically only be used for weak signal work on 6 and 10
meters. Use of the Low and Off positions should be extremely rare to
prevent overload of the sound card A/D converter if you neighbor is on
the air. In the Off position, the system gain is very low and you
will see a rise in the noise floor on a dummy load. By definition,
the sensitivity will be lower than the High or Medium setting.
Gerald
Interestingly enough, my actual experience mildly contradicts this. Or,
maybe just a change of emphasis. This is probably a theory versus
practice discussion, because I'm disagreeing with the owner/designer and
one of his principal DSP programmer/architects here. So, I do this with
a little foreboding.
None the less, while most of the time, medium is indeed the ideal
setting for HF, there are exceptions (at least for my rig, currently
using the Turtle Beach card -- we'll see if this changes with the Delta 44).
1. 17 meters. This is a wonderful band, actually. It has a lower
noise floor than 20 and so it can stand the High setting. Maybe I
should be jacking up the sound card gain instead, but I routinely put it
in "high" on this band with good results. Unlike on 40 and 20, I don't
get the extra cross-talk that I get when I try "high" there.
2. While there haven't been many openings, I've had similar experiences
on 15, but I'm not as sure of my ground here.
3. Desperation weak signal work. Mostly, this doesn't work (my ears
are bigger than my mouth) but I've worked a few by jacking it up to the
max and getting the job done. This is probably not the best idea, but
it doesn't seem a lot different on 20 and 40 than jacking up the sound
card to higher values than recommended (the recommendation is minimum
gain to allowit to work, which is, I assume, connected to the "medium"
recommendation, too). Doing this also requires things like using
narrower skirts because of whatever noise gets let in by the too-high
setting.
I've also jacked it down when strong stateside stations come on (you
know, the ones that just beat me out for the DX). If the AF control was
a slider, I probably wouldn't do this, however.
My advise is to start out with medium (except on 17) and adjust when
needed. Mostly, you won't, but there are times. . .
Larry WO0Z
