For many years I’ve been using #24 AWG stranded type E teflon wire. The mfr of my wire is Thermax, but there are others. The code on the tag on a spool is 24-TE-1936 WHT.
24 is #24 AWG
TE is teflon
1936 is 19 strands of #36 AWG
WHT is white
The stated OD of the silver-plated stranded copper conductor is 0.023 inches. The insulation OD is 0.043 inches. That means that the insulation thickness is about 0.01 inches. The military number M16878 is on the tag. I found a “make offer” deal on Ebay years ago. Maybe you will too.
I’ve seen tin-plated teflon wire for sale on Ebay, as well as other low-quality versions. Be careful to buy what you really want.
White is not good in the snow, but otherwise it’s better than black. Black is bad because people may walk into it. Colors are better. My favorite SOTA antenna is 65 feet of red #24 stranded teflon wire with the same specs as above. I’ve used the same wire for about 1000 activations over several years, and I’ve only had to repair it a few times, usually at the link, or at the mini-banana connector on the fed end.
I do alpine activations, and low weight is very important. RF and physical performance is important too. #24 stranded is ideal for use on lightweight graphite/carbon poles. #22 is too heavy for a longer wire, it sags down more, or pulls the pole over more than #24. I have used #26, but it’s more prone to break, kink, or tangle than #24. It would be good for a back-up antenna.
Thicker wires are much easier to splice in the field than thinner wires. I have “fixed” #24 teflon with just a knife.
In high winds, telescoping poles whip around, sometimes violently, and so do trees. A fair amount of tension is needed hold the wire up high enough, and #26 copper is too fragile for conditions on local alpine summits. In the snow wires are tricky to handle, they get caught on snowshoes, boots, bushes, rocks, and the snow itself, and they are subject to jerking in the course of setting up or taking down, as well as during a windy activation.
EZNEC models reveal how the losses increase with thinner wires. They also show how the silver plating slightly reduces wire loss at RF. Overall I think #24 is the best compromise. If you use a heavy pole, #22 might be better. #26 is ultralight, and you get more loss, so use it if you’re careful.
Teflon is a good choice for running the wire through or across tree branches, over rock outcrops, lying on the ground, in the snow, etc. There’s still coupling through capacitance, so RF can be lost, but teflon is a low-loss dielectric, so that helps. I’ve not seen any arcs at the 10W level, even at high-impedance points.
Teflon may flow or thin under pressure, but it rarely cracks. It holds up really well to UV radiation, which is strong in the alpine environment.
Teflon insulation has good characteristics in cold conditions. It will kink, but it recovers well. Silicone may also be an excellent choice.
Below 0 degrees C PVC wire tends to stiffen, but #24 stranded PVC wire should be OK for many operators. This is a a good low-cost choice.
Much of the PVC stranded hook-up wire available is tin plated. This is not good for RF, since RF flows mostly in the outer part or “skin” of the wire. Tin increases the RF resistive losses!
Many people are using #26 copperweld, “spider wire”, stealthy, and it certainly works. This is steel wire, copper plated, with insulation. I’ve never used it. Losses surely are greater than #24 teflon, and it’s probably hard to splice in the field. It’s light and strong, so good for the alpine zone. It’s hard to see - use it if you’re careful.
I’m sticking with the #24 stranded teflon wire. The military uses miles and miles of it for many good reasons!
73
George/Carey
KX0R
