Larry, W6FUB says:
>What would you recommend for spreaders, not on ladder line but for
>parallel dipole spreaders? Delrin is readily available in both natural
>and black. The black has good UV resistance.
My preference is for PTFE (Teflon) or ceramic. Over here, of course, we
don't get Californian sunshine, but even so, I've been disappointed in
delrin, Nylon, polycarbonate and perspex (trade name - the stuff is
methyl methacrylate - if I've got that wrong, G3SEK will put me right)
under our daylight conditions, Black delrin might be all right, but
quite often, the black is produced by carbon loading, making it even
more lossy and liable to catch fire. There still something to be said
for the old fashioned wood, boiled in paraffin wax, or better,
polyurethane yacht varnish coated! If you were in the central
Californian valley, or Arizona or some where like that, you probably
wouldn't need to varnish it. Currently, for open wire line, I'm using
the centre polyethylene out of scrap UR67 (RG213) coax. Ask me in 5 to 8
years how it's doing. The nylon spacers I put on the o/w line in '86 are
breaking up and very brittle now. Suitable ceramic spreaders are running
about $1.50 each over here - that's expensive for a 60 foot run, and
I'm mean about spending money!
73
Peter G3RZP
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