Brian;
Last spring I replaced the coax on my A3S-JK with a new (and longer) length of
Bury-Flex. I did a great job of soldering on the PL-259s. It wasn’t until I
had it connected to the choke and fully wx sealed that I realized I forgot to
install the Kellum Grip. I have spent quite a while trying to figure out how to
slide one over the PL-259 to no avail. I will shortly go out to the tower base,
cut off the bottom PL-259, slide on the Kellum Grip, then re-install a new
PL-259. But not in 95+ degree heat we are still having.
I have found that the one antenna type that absolutely must have a choke is a
vertical. Without it the coax will provide a return for the current (no matter
how many radials) and give all sorts of problems. If I were to put one of those
up (K9YC-style with tall trees holding up the antenna at over 100 feet), and
forgot to add the choke, I guarantee that I would be out winding the coax (with
installed PL-259) through the toroid to get the results I need. Jim’s method of
installing verticals is to use a single piece of coax, remove the jacket and
shield for 1/4-wave to form the top portion of a dipole, then add a choke
1/4-wave down from the “feed” point. No connectors needed until it gets down to
the shack entry. Large toroids are very useful here. Having said that, I am
pretty sure Jim placed connectors at the lower end of the dipole.
But, I wonder, how important is it to have a choke at every current node?
Having one at the antenna feed is important, and perhaps at the shack entry
point. But does the modeling really show that we need them in-between?
73,
Jack, W6FB
> On Sep 26, 2025, at 4:08 PM, Brian Beezley <k6sti@att.net> wrote:
>
> "Why sever the connector? If we are talking about RG-213 size coax, that is
> .405 inches in diameter."
>
>
> Sever the coax. I assumed the desired spot was far from the shack and it
> would be too much trouble to fetch the end of the coax and then wind the
> whole length several times through a large core. But maybe not! And maybe
> installing connectors isn't that much trouble for someone good at it (I'm
> not). I'd just want to be sure I had the right spot first.
>
> A quick model of the two-wire current shunt didn't look that promising, at
> least for the initial geometry I picked. I'm not sure the idea is worth
> pursuing.
>
> Brian
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|