One problem with the basic combination of tape and PVC is that the tape gets slightly kinked as it passes
over the boom at the T and Cross. You can either shim it out using 2-3 layers of double-sided tape, or carve
the PVC like I do so that the tape passes straight through. You can probably avoid the need to carve or shim
the driven though if you cut some "V" notches at the feed point,
This shows the Cross piece on the driven element carved for use. The Cross at the reflector gets the same
treatment. This does weaken it slightly, but I'm using 600psi PVC (not 315psi) so there's plenty of material
and it's still plenty strong enough for this.
I use hose clamps for the driven elements, and I crank them down pretty tight so the elements don't move.
The pictures also show the 'v' cut on the feed ends of the driven element. (to make soldering easier, and also
to avoid the need for more carving on that side) Use a wire wheel or sandpaper to remove the paint, and tin
the elements before assembly and soldering of the coax. Don't forget the hairpin match. In my tests, the
length of the hairpin wasn't too critical. There's no reason to use heavy gauge wire for the hairpin. I've
seen people use #10 solid copper, but solid #18 or #20 works just fine too.
After sticking down the hook-side velcro on the other side, I give the corners a little cut to get the velcro
to fit a bit closer.
I installed a ferrite choke on the (RG-174) coax right at the element feed point. This is necessary to help
produce the good front-to-back ratio, don't omit it. These can be harvested from any USB cable etc that has
that characteristic choke bulge on it. Clamp-on chokes are also available for about a dollar.
1 reflector and driven carving
2 reflector and driven carving
3 driven bottom
4 driven side
5 driven side closeup
6 driven top
highest resolution images
last updated 12/08/2023 at 23:31:05 by make_www_index.command version 2023.12.08.B
