[TowerTalk] 135 foot dipole, 300 ohm twinlead

[Joe Giacobello]

Buck, something isn't right.  A properly constructed and tuned balanced 
feed line antenna should be less likely to generate TVI than a coax fed 
antenna because there should be little or no radiation from the feed 
line.  If you're tuner uses a ferrite balun, it could be saturating and 
generating all sorts of spurious radiation.  If you're confident that 
the antenna is constructed properly, try changing the feed line length 
in 10 foot increments or so.  You may have a high impedance at the tuner 
output with consequent high voltage and core saturation.  Another 
solution would be to replace your current tuner with an old Viking 
Matchbox or homebrew balanced, balun-less tuner.

73, Joe

Buck - N4PGW wrote:

>I had a 129 foot dipole fed with CATV coax.  It did ok, but where the
>aluminum met the copper, it oxidized and I have been suffering with AM
>broadcast band bleedover on all frequencies below 14 MHz.  I recently
>replaced it with a 135 foot dipole fed by 300 ohm TV twinlead to my tuner on
>which my IC-706 sits.  The problem I have now is TVI.  When I get the
>antenna tuned and run more than 30 watts, the TV pictures turn red, green,
>or blue.  We are on Cable TV and I cannot recall the last time I had TVI
>other than when I operated 6 meters and the rig is sitting less than two
>feet from my TV.  (the TVI now is all over the house.)  I don't know if it
>is getting into neighbors homes at this time.
>
>I figure I am getting less loss tuning that antenna with twinlead as opposed
>to coax, but I have a piece of RG-8 foam I am thinking about feeding the
>antenna with instead.  
>
>Any suggestions or ideas?
>
>thanks,
>Buck
>N4PGW
>
>
>
>_______________________________________________
>
>See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any questions and ask for Sherman, W2FLA.
>
>_______________________________________________
>TowerTalk mailing list
>TowerTalk at contesting.com
>http://lists.contesting.com/mailman/listinfo/towertalk
>
>
>  
>