I my case I had insulation on both wires, so I was mainly interested in
the VF difference between solid copper and copperweld at 3.5 MHZ.
I had sworn off copperweld many years ago after noting that the copper
plating did not last forever. But I recently discovered that there is an
insulated version which is marketed to directional borers to pull in
outside of the conduit as a tracer wire.
The PVC should protect the plating...at least until it falls off.
-Steve K8LX
On 9/20/2022 1:10 PM, Grant Saviers wrote:
The dielectric loading of insulation makes the wire electrically longer
for RF. EZNEC can model it, if you know the dielectric constant
(usually around 3 for PVC, nylon) and thickness.
The height of the dipole has a larger effect. Plus for 160 & 80 quality
copperweld is needed with thick copper, so the internal field (skin
depth) is in the copper, not in the steel which will cause high losses.
Grant KZ1W
On 9/19/2022 14:56, Steve Maki wrote:
Wondering whether there is any substantial difference between #12
solid THHN and #12 PVC jacketed copperweld (steel) in terms of cutting
a dipole to length.
I'm in the process of installing a K8UR style 80M four square. I
trimmed the first element to length using THHN. Then I decided that I
should use steel wire for at least the top half of the elements
because of the high wire tension I ended up with after pulling the
feed-point out far enough from the array center. It's an issue with
not enough acreage around the tower.
Even so I ended up with a 50 ohm antenna rather than the desired 30-40
ohm antenna per the DXE instruction manual. But that's an entirely
difference issue (though I'd appreciate any comments on that as well).
Should I expect the steel wire lengths to be pretty close to the THHN
lengths, or should I re-do the initial step of carefully cutting the
first element in isolation?
TIA!
-Steve K8LX
_______________________________________________
_______________________________________________
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
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|