To set a starting reference in case of future problems, I have just
measured the cable losses on a new tower installation. The cable lengths
are all 360 feet from shack to tower and have no switches or anything else
in line. Just UHF connectors on each end.
A Bird wattmeter and a Bird dummy load were connected to a radio and the
power was set to 50 watts (full scale) at 28 MHz. The dummy was moved to
the tower end and the power was rechecked at the sending end. The
wattmeter was moved to the tower end and a reading was taken. This was
done on one cable first. Then the other cables were measured in a loop
from the shack to the tower and back to the shack. All the combinations of
cables were looped and tested.
The losses were determined and normalized to dB/100'
Cable Measured From ARRL Chart
LMR600DB 0.52 dB 0.4 dB (from spec.)
RG-213 1.0 1.2
RG8X 1.9 2.0
Note the 213 is quite a bit better than the chart shows.
George
w2vjn@rosenet.net
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