On 5/9/2011 8:33 AM, Vic K2VCO wrote:
> Actually, I think 2 dB can make a difference on 160 meters. I don't
> know about 1.4!
It's when your signal is on the edge of the other guy's noise that small
increases matter. Several years ago, I went through the process of
squeezing a few extra dB out of my antenna system, raising dipoles from
80 ft to 110 ft, replacing RG8X and RG59 with low loss RG8/RG213 and
RG11. It was a dB here and another dB there, and the combined result
made me a bit louder. I went through the same exercise when I put up a
120 ft tower 250 ft from the shack -- it's fed with hard line, so the
loss is just under 1dB on 10M. The lowest loss RG8-size coax would have
burned another dB or two.
During 160M contests, I often operate in search and pounce mode, QSYing
from the bottom edge to well above 1900 kHz. That's nearly 6% change in
frequency, and both the amp and antenna need some retuning to get full
power. Sometimes I won't retune, and the power will drop by 3dB. I'll
get most of guys I call, but there are always some for whom I'll need to
retune and get those 3dB back to work. And sometimes it's only 2dB.
Remember -- all those little dB add, so 1.5 dB of amplifier power added
to a 1.5 dB reduction of feedline loss makes you 3 dB louder!
73, Jim K9YC
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