On Sat,8/6/2016 11:38 AM, TexasRF--- via TowerTalk wrote:
This sounds like more fly excrement in the pepper. 52R +j2 equates to a
vswr of 1.06 or a reflection of -30.7 dB.
But it introduces errors into loss measurements -- if you measure at a
lot of frequencies, you see the loss oscillate above and below a trend
line because of the mismatch. Remember, Gerald, we're trying to measure
the loss of coax on 160M and 80M. Look at data sheets -- the loss in
these cables is about 0.2dB/100 ft, so you have to measure a VERY long
piece of cable (I measured 1200 ft) for the loss to be great enough to
get even 10% accuracy!
WHICH is a point I've made several times. I don't waste my hard line on
long runs to 160M and 80M antennas, because the loss in RG8 and RG11 is
so low at these frequencies. My longest runs to 160M TX antennas are
about 220 ft. They are Commscope 3227, which is #10 solid copper center
with a shield that's tinned copper braid plus heavy bonded foil. Loss is
about 0.22dB/100 ft, so less than 0.5 dB for those 220 ft runs. The runs
to my high dipoles are less than 200 ft of Belden 8213, also less than
0.5 dB.
73, Jim K9YC
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