[ForSale-Swap] VHF interference on digital TV signals

[DALE PARFITT]

  ----- Original Message ----- 
  From: Larry Brown 
  To: forsale-swap at mailman.qth.net 
  Sent: Sunday, October 26, 2008 11:52 PM
  Subject: [ForSale-Swap] VHF interference on digital TV signals


  Not a sale/swap topic but something many of us out in the rural areas might be dealing with soon.  

  Since we do not have cable in our area and I refuse to shell out the $$$$$ for DirectTV  I purchased two digital converters. After several weeks of installing the boxes changing splitters to 1.2gig gold plate splitters,buying and installing signal boosters and other fussing,cussing and fine tuning I've finally got TV most of the time(with analog I get 10-12 stations,with digital setup I get 3-4 and only part of the time but that's a story for another time.)

  Now that winters heading this way I've set up the shack in the house and !&?#?? my 2 meter kills the TV signal whenever I key up!  Kenwood TS-711a running 25watts or less(mostly 2-10w)going to a Cushcraft 11 element beam.  All TV connections have been checked and weather-sealed. Same for radio transmission line. SWR checks 1.2-1.5 across the 2meter band @ 25w. A MFJ analyzer shows no RF leakage between the radio and antenna.

  Any thoughts on the next steps? By the time Feb. 19th rolls around I'll have experienced almost every problem possible with the DTV conversion I'm thinking!

  Thanks for any input and if anyone has not started setting up their converter box yet start soon. No matter what the ads say,it's not "just hooking up a box" if you live 30+ miles from  town.

  Larry
  KG4ZAR

  Hi Larry,
  Although you don't mention the frequencies of the TV channels- the likely culprits are the in-line amps. Unless you bought some hi end amplifiers with excellent IP3 characteristics (Winegard, Channel Master etc)- these amps are likely being driven into Xmod or IM dostortion.  Eliminate the amps and connect one TV directly to the antenna (w/o splitters and their loss). If signals are now OK, build a 2M trap and insert it on the input side of the amps.

  Dale W4OP
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