Charles, Our Channels 8 & 10 moved the digital channel from UHF to VHF at the end of the conversion period. Since they had to give up one channel and the operating costs for the same coverage are considerably less on VHF it was a easy decision to make. I doubt this is what FCC had in mind, but that is how it worked out.
UHF has less noise (Very little galactic noise) and significantly smaller antennas,(shorter wavelength) making the UHF segment more desirable for portable operations. Best policy is to use the VHF band for TV and save UHF for other uses.
Interesting enough a 5 Watt "S" Band link transmitter carries the video signal to the local cable TV companies that serve 90% of the viewers. Only 10% receive their TV signals over the air!
That is how it is done in Southern California.
73, Art KC6UQH
-----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Charles Suprin Sent: Wednesday, December 07, 2011 1:49 PM To: Bob Bruninga Cc: amsat-bb@amsat.org; Gordon JC Pearce 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@500MHz. Are there places that still use vhf?
Charles On Dec 7, 2011 1:38 PM, "Bob Bruninga" bruninga@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@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Gordon JC Pearce Sent: Wednesday, December 07, 2011 3:02 AM To: amsat-bb@amsat.org Subject: [amsat-bb] Re: 2 Meter TV Interference
On Tue, 6 Dec 2011 21:17:55 -0600 Wyatt Dirks wyattdirks@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@gjcp.net _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
_______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
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