What wire can I use to make an OCF dipole for amateur radio?
SamToucan41 said:
Hi,
Making an off-center fed dipole for 20, 40 & 80m amateur radio (yes, I do have appropriate licensing for Australia). I have the right balun made up, but I am not sure what types of wire I can use. The dipole will be 40m long - I have a nice big yard.
Can it be something simple like gal fencing wire?
Yes, you could use that. You can in fact use any wire.
Phosphor-bronze would be the favourite but it’s not the easiest to get hold of. You could ask A.W.A. if they still use it.
neither iron or zinc is especially good conductor of RF. copper conducts good, but is not strong enough to be suspended in air.
the best antenna wire is copperweld. this is steel wire which has an outside cladding of copper. the copper is thick enough to carry the RF and even allows soldering connections. it should be available from communications suppliers.
Yes, copperweld is GREAT. Nobody carries it locally to me, but you can often find it at hamfests. Mail order is a good bet – that’s where I got mine from for a T2FD that I built.
For most of my other stuff, I use #12 Solid copper wire. I just get black THHN (or just whatever single conductor black you can get ahold of.) The black seems to not stand out too bad. I’ve never tried white, but it probably blends into the sky a lot better and isn’t as noticeable.
Try not to use Stranded wire. It will “stretch.” It doesn’t really stretch so much as untwist, lengthening in the process. Both solid and stranded copper WILL stretch, as stated above, but I’ve had good luck even with 100 foot lengths. There will be a bit of sag, but if you wanted to put that much tension that you would need copperweld, then you probably have some strong dedicated supports to begin with.
You can leave the black insulation on without a significant change in the radiation efficiency. You will need to add about 3% length to compensate for the change in velocity factor.