The topic of blown resistors has come up again... for those who may have this
problem, keeping the coax end of the beverage grounded when not in use seems
to be effective... I have 5 beverages, and each has a SPDT relay at the coax
end... the beverage is grounded when the relay is not energized to connect
the antenna to the coax/balun... I have the typical 2 watt resistor on the
terminated end of each... These beverages were installed two years ago... and
many thunderstorms, and many days of blowing dry snow later and I have not
lost a single resistor... I suspect that grounding also protects the
resistors from induced current when transmitting...
Also on this topic... you can check the resistor on a beverage from the
antenna feedpoint... simply disconnect the coax end of the wire, and use your
VOM to measure the resistance from the end of the wire to ground... saves a
lot of walking and pinpoints those wires the deer have managed to break,
again ....(my only problem with beverages)...
Another topic... In the process of doing some tuning on the transmit array, I
found that one of the elevated radials on the North vertical had sagged down
and was almost touching a radial on the East vertical, which crossed
underneath at right angles... When the wind would swing the wires they would
touch... at this point both wires showed burned and blackened insulation for
a foot from the contact point (thhn), and the exposed copper at the contact
point showed evidence of pitting and arc damage... the crossover point was
about 2/3 of the way to the free end of the radial, for both.. I was duly
impressed... my findings show that parasitically coupled, elevated radials
have considerable induced current and voltage... all parasitic elements are
isolated from their respective coax, and are not connected to ground...
Denny
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