[amsat-bb] Re: 2 Meter TV Interference

[John Geiger]

Rock Island, IL, where I used to live, still has a channel 4 on VHF channel 
4.

73s John AA5JG

----- Original Message ----- 
From: "Charles Suprin" <hamaa1vs at gmail.com>
To: "Bob Bruninga" <bruninga at usna.edu>
Cc: <amsat-bb at amsat.org>; "Gordon JC Pearce" <gordonjcp at gjcp.net>
Sent: Wednesday, December 07, 2011 9:48 PM
Subject: [amsat-bb] Re: 2 Meter TV Interference


>I didn't think there were any vhf stations left. All the numbers on the
> channels now are virtual. All the tv antenna plans are for uhf bands. A
> quick look in the Boston market and the lowest channel is 19, channel
> 2 at 500MHz. Are there places that still use vhf?
>
> Charles
> On Dec 7, 2011 1:38 PM, "Bob Bruninga" <bruninga at usna.edu> wrote:
>
>> HPF above 500 MHz?  Then the TV would not be able to see anything but a 
>> few
>> UHF channels.
>>
>> What is needed is a stub filter.  Just a piece of open ended coax 13" 
>> long
>> "T"ed into the antenna lead....
>>
>> The 13" is about 66% of a quarter wave at 2 meters.
>>
>> Done
>>
>> Bob, WB4APR
>>
>> -----Original Message-----
>> From: amsat-bb-bounces at amsat.org [mailto:amsat-bb-bounces at amsat.org] On
>> Behalf Of Gordon JC Pearce
>> Sent: Wednesday, December 07, 2011 3:02 AM
>> To: amsat-bb at amsat.org
>> Subject: [amsat-bb] Re: 2 Meter TV Interference
>>
>> On Tue, 6 Dec 2011 21:17:55 -0600
>> Wyatt Dirks <wyattdirks at msn.com> wrote:
>>
>>
>> > Just recently I have been having troubles with a neighbor while I am
>> working the FM satellites(SO-50 and AO-27). The setup I am currently 
>> using
>> is my mobile setup because I am unable to put a base station up for many
>> reasons. I am using a FT8900 with 50 watts out into a 1/4 wave or 1/2
>> Larson
>> mobile antenna.The 1/4 wave is mounted permanently via a hole in the roof
>> of
>> my truck an the 1/2 wave is mounted on a mount opposite the factory
>> installed FM/AM radio whip. It doesn't seem to matter what antenna I use
>> for
>> the problem to occur. Then I use either the arrow antenna or my cju for 
>> the
>> downlink.
>>
>> Use 5W into a hand-held Yagi.  You'll get far better results.
>>
>>
>> > Today I had another local ham over at the request of the neighbor and 
>> > his
>> mobile Kenwood radio did the same thing to the neighbors tv when he
>> transmitted on 2 meter with 50 watts out. He also recommended that they 
>> get
>> a filter. I did not see the specs on the filter nor do I know what
>> bandwidth
>> it was for.
>>
>> What you want is a highpass filter that will lop off everything below
>> 500MHz.  The chances are that your TX output is clean enough but the 
>> little
>> amplifier in the splitter for the TV is causing all sorts of intermod - 
>> and
>> probably covers from broadcast VHF radio to the top of the TV band.
>>
>> --
>> Gordon JC Pearce MM0YEQ <gordonjcp at gjcp.net>
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> _______________________________________________
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