Topband: DXE 8 Verticals

Guy Olinger K2AV olinger at
Mon Feb 20 12:30:46 PST 2012

One thing I specifically recall is that setting RX amps for maximum gain
does NOT necessarily produce the best s/n. That depends on all kinds of
complex stuff. These days some amps are set to work with extremely reactive
input impedances.  If you can't set that up and measure that on a bench,
you can't set it yourself, and you may decidedly make it worse.  The best
IMD performance is OFTEN NOT at highest gain.  Need your manufacturer's
instructions on that, and follow them.  Really not a good place for
undirected diddling.

Further, from prior email in this thread, the MFR setting the gain maximum
BETWEEN 160 and 80 MIGHT be entirely deliberate, providing best s/n on both
bands.  Consult the manufacturer to get the true scoop.  They are the only
ones who know for sure.

You can do fine with whips and modern amps.

Driving noise up to AGC threshold is most often not a good thing.  The
biggest difference you will make is to have the RX amps at the antenna,
matched for best s/n in that situation, and get the feedline common mode
stuff isolated from the RX amp.  Seems to me that the DXE already comes
that way if you use their stuff??

73, Guy.

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