[NLRS] VHF low pass filters?

[w0zq at aol.com]

Tough one Kirk.  Here are my thoughts.

If you can arrange it, have him watch his TV while your transmit.  

Questions to ask are:

Does the interference happen on all channels or just some?   
If its some, which ones and are these channels still the over-the-air VHF channels .... UHF channels are OK?   This means figuring out where each channel is actually transmitting (freq wise that is)
If all channels are affected then check to see if his over-the-air UHF antenna has a preamp .... it may be built into the antenna or perhaps he is using an (additional?) external preamp downstream.  You are most likely swamping (blocking) the preamp.  Some of these preamps have adjustable gain .... try turning the gain down if its adjustable.  I have not done this myself, but it may be possible to put a high pass filter between the antenna and the preamp, or the UHF antenna manufacturer may have such an option.  Again, I don't recall where all the over-the-air TV stations are transmitting (in terms of freq) these days.  

I doubt the problem is on your end so there is not much that you can do other than to try dropping your transmit power to see if there is a threshold that is reasonable ..... for example maybe 400 watts doesn't cause a problem, etc.   

If the problem is that his antenna preamp is being overloaded, you can point this out to him and suggest that he switches to cable .... more of a sales job here than a technical one.  Again, it most likely not your fault that his powered UHF antenna preamp is of such a design that its easiely overloaded (if that is what it is).

73, Jon
W0ZQ