Last summer, I put in 2 x 190-foot runs of LDF4-50A from the base of my tower
to alongside the house. From there, I run RG-213 about 45 feet into the shack.
I decided to measure the loss in these feed-lines, so as to have a point of
reference, using the Coax Loss function of the 259B. Measuring at around 30
MHz, I was surprised to read large cyclical variations in the loss reported
with relatively small changes in frequency. For example, one of the feedlines
(they have slightly different-length "pigtails" on the tower end) shows as much
as 2.0 dB loss at ~30.3 MHz, but at 30.1 the reported loss is 1.2 dB, and at 32
MHz it is back up to 2 dB.
Naturally, I was expecting a gradual increase in loss with frequency, but this
change seems both abrupt and cyclical in nature. Anyone have any clues on what
is going on? Defective meter (it otherwise seems to work fine)? Defect in the
flexible coax causing an impedance mismatch?
73, Pete N4ZR
The World HF Contest Station Database
Full details on 3226 contest stations
recently updated at http://www.pvrc.org/WCSD/WCSDsearch.htm
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