> If the coax feeds are brought up through the tower body and tied to
> one of the legs is there any or enough choking effect to preclude a
> coax choke at the top at the center insulator. Life would be a lot
> simpler if we didn't need the choke at the top.
You may not need a choke at each dipole, it all depends on many
things. I use them just to be safe, because I like my antenna to do
all the radiating!
> I seem to recall folks running coax through the boom to the DE and
> claiming a choke effect of the metal boom got them out of using a
> balun at the DE, urban myth??
Yep, that's mostly an urban myth!
The only way a sleeve works is if it is 1/4 wl long and open at the
dipole feedpoint and grounded to the coax shield 1/4 wl from the
feedpoint.
You also have to include the velocity factor change caused by the
outside insulation of the coax and the spacers used. The coax has
to be centered in the sleeve, and preferably the diameter ratio of
coax OD to sleeve ID should be large.
73, Tom W8JI
W8JI@contesting.com
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