Hi Ward,
Depends on the reason for the pigtail, but in many cases you can avoid the
pigtail by using a commercial current balun. That works well for most wire
antennas, as well as most yagis that have screw terminals at the driven
element or matching network. Besides, the current balun will suppress common
mode current in cases where the match isn't perfect (which is almost always
the case.) I have current baluns on all antennas that don't have one
built-in. For yagis, my preference is the EB series from Cal-Av. They have
built-in pigtails that are well sealed against moisture, and a well-sealed
SO-239 at the other end (comes with a rubber gasket to help keep moisture
out of that connection, though I always seal it the K7LXC way -- tape, vapor
wrap, tape.)
73, Dick WC1M
> -----Original Message-----
> From: Ward Silver [mailto:hwardsil@gmail.com]
> Sent: Wednesday, February 06, 2008 5:54 PM
> To: Towertalk Reflector
> Subject: [TowerTalk] Sealing Pigtails - Opinions?
>
> As long as we're discussing sealing, I have a question about sealing
> coax
> pigtails. Waterproofing the end of a coax pigtail can be difficult
> because
> of the exposed braid and the stranded center conductor of most coax.
> Both
> wick water back into the cable. I've attempted waterproofing a couple
> of
> ways - I'm sure the group can suggest some improvements.
>
> Both methods assume that the jacket has been peeled back and that I
> have a
> flat braid pigtail and some center insulator and exposed center
> conductor
> forming the other pigtail. Furthermore, the center insulator is solid
> and
> the center conductor is stranded. Ring or spade terminals are the
> preferred
> termination.
>
> Method #1 - Crimp on the terminals and solder, flooding the end of the
> wire
> and braid with solder, attempting to fill the interstrand volumes.
> From the
> braid terminal, flood with solder back at least 1 cm. From the center
> conductor terminal, flood with solder down into the center conductor.
> Paint
> entire cable end liberally, but apolitically, with liquid electrical
> tape up
> to the terminal. Work the goo into the strands as much as possible.
>
> Method #2 - Crimp terminal on center conductor and flood with solder
> as in
> Method #1. Trim braid to about 1 cm long and solder to a solid jumper
> wire
> with terminal soldered on. Now paint with the liquid electrical tape
> as in
> Method #1.
>
> The goal of both methods is to form a relatively solid barrier to
> water
> being wicked into the cable. The pigtails formed by either method can
> be
> wrapped with electrical tape, if desired, but the water barrier should
> not
> depend on the tape.
>
> 73, Ward N0AX
>
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