Hi All,
I take the point that if one local TV is not being interfered with on any of
the channels that the transmitter is not at fault. At the moment I am
suffering from TVI on the 160 Meter band only. Though there is no trace of
interference on any signal or on any TV in our QTH there is a problem with
a neighbour. The problem at the neighbours happens only with terrestrial
signals from a transmitter north of Belfast seventy miles distant. I have
to tread carefully as my neighbour is a friend and his good wife has
advanced MS so TV is one of her few pleasures. Some of the HPF seem to be
of little help as for some reason some indicate a lower rejection limit of 5
MHz. Why I can not imagine. I have ordered some HPFs from Industrial
Communications Engineers (ICE) of Indianapolis and these may help with the
neighbour. Sadly ICE build to order and are slow in filling orders.
There are no HPFs used in our QTH but I hope this is the solution for our
good neighbour. Ferrites and braid breakers have not helped.
As to the LPF I use an ICE filter but it does not seem to make any
difference in my case. Still I keep it as additional insurance. However
there is a point from the ICE LPF manual which I would like to share.
"Because the filter's job is to eliminate these higher frequencies it should
be kept in mind that the wavelengths of signals the filter is designed to
attenuate are very short. Thus, long ground leads from the filter body to
earth ground lessen the filter performance somewhat.
In order to get the best performance from your filter try to keep the
connecting lead length from the filter body to the *** point at which the
ground rod actually touches the ground as short as possible." ICE
recommend mounting the filter just above the ground rod. My shack is on
the second floor so perhaps I will mount my filter outside in a plastic box
in immediate contact with the ground rod. The main coax will then drop to
this filter and the ground rod before proceeding from the filter to the
external antenna selector. There are problems for hams operating above
ground level. Again I accept that my problem is likely one of overloading
my neighbour's TV. This problem still manifests itself while running 100 W
output though 400 W output does not upset my own sets on the most marginal
of signals.
This reflector has been a great help and interest to me and I thank all of
you for this. I love my O2 and look forward to improvements from the
mother ship. In time I will purchase the O3 but I hope this is a few years
off and that TenTec provides additional improvements. Greed is not always a
bad thing. 73 Doug EI2CN
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