[TowerTalk] TH7 SWR trouble ... Coax balun question

[GALE STEWARD]

On my TH6, I used the same length for the "pigtails"
as what is shown in the TH6 manual for the amount to
strip back the coax when using a coax coil "choke"
balun.  As I recall, the length was 6 3/4 inches.  The
temptation is to make them as short as possible which
then tunes the antenna higher in frequency.  Mine
antenna is set to the CW dimensions and shorter
pigtails tune the antenna farther up in the band. 
BTW, I'm using a teflon coax/ferrite bead balun.

73, Stew  K3ND

--- markku.a.oksanen@nokia.com wrote:
> 
> Hi,
> 
> I think I may have left something out:  You may
> remember that the TH6
> instructions call for a 12-turn balun located at the
> junction of the boom
> and the mast, couple of feet from the feedpoint with
> the coax to the
> feedpoint taped to the boom.  OK, I did not do this
> for the TH7, however I
> do have about 8 inches of taped RG213 on the boom
> between the 6-turn, single
> layer coil. I am beginning to think that this may be
> the reason, the taped
> part may contribute a small capacitance to one side
> of the feedpoint.  Any
> other opinions?  
> 
> How did others use the coax balun with a TH7?  How
> is it attached?  Length
> of pigtail wires to the antenna feedpoint?  Length
> of coax between pigtails
> and balun coil?
> 
> 
> 
> Markku
> OH2RA
> 
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