[Elecraft] coaxial dipole (was: What do you have in your portable/travel kit?)

[Brian Lloyd]

To make a coaxial dipole strip the external insulation from the end of  
your coax to a length about 10% longer than 1/4 wave. This leaves just  
shield (braid), center dielectric, and center conductor.

push back a bit of the braid so it increases in diameter. Fold it back  
over itself and carefully stretch it backward until it covers the  
remaining external insulation leaving just the center conductor and  
center dielectric exposed. The folded-back braid should now form a  
cylinder over the coax. Trim this braid until it is 1/4 wave long.  
Trim the center conductor until it is also 1/4 wave long.

You now have a dipole that is end-fed. The folded-back braid functions  
as both radiator and 1/4-wave stub to cancel the currents on the  
shield of the coax. For 2M I put this whole thing in a piece of PVC  
pipe and shoot in some foam insulation to keep things in place. It  
works just peachy.

Caveat: you may find that turning the braid inside-out to make the  
outer element to be a real challenge. You can cheat by cutting the  
braid off, compressing it so it slips over the outside of the coax,  
and then reattaching it to the shield of the coax with solder. To be  
honest, that is what I usually do. ;-)

Brian Lloyd
Granite Bay Montessori School          9330 Sierra College Bl
brian AT gbmontessori DOT com          Roseville, CA 95661
+1.916.367.2131 (voice)                +1.791.912.8170 (fax)

PGP key ID:          12095C52A32A1B6C
PGP key fingerprint: 3B1D BA11 4913 3254 B6E0  CC09 1209 5C52 A32A 1B6C