[Elecraft] Coiled Coax Choke

[david Moes]

You say a 1:1 balun.    What type is it and  should it not be preventing 
common mode currents?   If not Id consider one that will rather than 
adding a choke.  I bought a commercial 1:1 Balun  opened it up and found 
it to be just a length of RG8X looped once inside the casing with half a 
dozen ferrites around it.  What I have done is have ground rods at the 
base of the pole.   I am using a 10-80 +warc fan dipole that looks a 
little like a flattened spider web supported with guyed camouflage tent 
poles to about 40 ft   I have 6 ferrites on the coax at the feed  the 
ones I got out of the commercial balun. Then at the base I have several 
5 ft copper pipes driven into the ground  around the pole about 5 ft 
apart  all bonded together with 6 gauge bare copper that is also burred 
a few inched below the surface  safe from the lawn mower.  I have a 
barrel connector at the base that lets me connect the shield  to this 
ground    I have no common mode issues. at least I have not experienced 
any.


David VE3SD

On 10/20/2014 22:28, Dauer, Edward wrote:
> I am thinking of adding a coiled coax common-mode choke to my system.
> Presently it goes K3-KPA500-KAT500 then 100 ft coax to the base of an
> inverted Vee¹s center support pole (collapsible fiberglass), then 30 feet
> up the pole to a 1:1 balun feeding a fanned 10-15-20 Vee.  The idea, for a
> couple of reasons, is to put the choke at the base of the pole, something
> I haven¹t seen discussed in the literature.  Two questions I am wondering
> about:  1. The choke would be 100 feet from the tuner and about 25 feet
> from the antenna/balun.  Probably not as good as having it right at the
> Vee, but is that compromise worth while?  2.  For appearance sake I am
> thinking about winding the coax around the base of the support pole.  It
> is 2 inches in diameter but I could slip a 3 inch PVC over that section to
> increase the diameter.  Anyone know an algorithm for determining the
> number of turns in the winding if I do that?  I would be much obliged for
> any thoughts and suggestions . . .   Tnx!
>
> Ted, KN1CBR
>
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