This may not be the correct forum - please forgive me if it is not.
I have a 900 MHz link between my home and my remote station, and at present the
UHF antenna is at the 240' level on the tower which also carries my 1.8 MHz
antenna. The radio is in the hut at the base and there is a bi-directional
amplifier by the 900 MHz antenna. I have had no interference issues at all even
with a kW on 160m even though the (vertical) driven element is only a few feet
from the 900 MHz antenna.
I have recently however had interference problems from a local ISP also using
900 MHz on a tower quite close to mine, to the extent that I have had to change
the type of 900 MHz radio to a more modern one which lives better with the
interference. Unfortunately that would also mean that I need to change the type
of amplifier OR actually put the radio high up the tower. The latter would be
cheaper, but I am concerned about having roughly a half wave of CAT5 cable
running parallel and a few feet away from my 160m driven element.
I would intend to choke off common mode at both ends of the ethernet cable. I
know that the construction of CAT5 cable means that it has good common mode
rejection, but this is a pretty severe test, and of course the cable length is
getting rather close to the limit.
I have had no lightning problems with the amplifier/coax set-up even though the
tower is frequently struck and I guess the fact that the coax outer is very
well 'grounded' both at the antenna and the base of the tower may help. The
same might not be true for ethernet.
Would appreciate any thoughts.
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