[NLRS] VHF low pass filters?

[Matt Arthur]

Hi all,
Make sure the tv owner understands that what your doing is with in f.c.c 
regulations.
Do not back down to the nabor.
I have seen people give up there ham radio because of some nabor.
that's out right wrong.
The nabor isn't giving up anything so why should you.
Thanks 73 Matt ka0pqw
----- Original Message ----- 
From: "Chris Elmquist" <chrise at pobox.com>
To: <nlrs at mailman.qth.net>
Sent: Wednesday, January 02, 2013 9:14 AM
Subject: Re: [NLRS] VHF low pass filters?


>
>
>
> Another consideration is whether your own TV equipment has any issues.
> If you can demonstrate that your own TV is unaffected, then this helps
> focus where the problem lies.
>
> The suggestions about preamps are very good.  Many people are using
> "digital antennas" which have embedded preamps in the enclosure and
> they may not even know it (or know what a preamp is).  The clue is if
> there is a power injector on the coax leading to the antenna--  as this
> supplies the DC to run the preamp which may be inside the antenna housing.
> Often these antennas are flat panel-like assemblies or round radomes--
> not traditional yagi style designs.  And they are made pretty cheap and
> very likely to suffer saturation from strong, out-of-band RF nearby.
>
> How far out from Shoreview is the problem TV located?  If the TV is
> already getting marginal signal, it will be pretty easy for your RF to
> swamp it even if your signal is out-of-band.  The TV owner may need to
> move up to a higher gain, narrower beam-width antenna (ie, a real yagi)
> or at the very least, ensure he is pointing optimally at Shoreview in
> order to get stronger signal in the TV band and reject your stuff.
>
> Good luck.  Keep us posted.
>
> Chris N0JCF
>
> On Wednesday (01/02/2013 at 08:40AM -0600), Ed WB0VHF wrote:
>>
>>
>> Kirk,
>>
>> Another thought would be to check with the League (either or both the web 
>> and call) to see what tvi resources they have.
>>
>> GL & 73,
>> Ed
>> WB0VHF
>>
>>
>> Sent from my HTC
>>
>> ----- Reply message -----
>> From: w0zq at aol.com
>> Date: Wed, Jan 2, 2013 08:29
>> Subject: [NLRS] VHF low pass filters?
>> To: <nlrs at mailman.qth.net>
>>
>>
>>
>>
>> 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
>>
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>
> -- 
> Chris Elmquist
>
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