[TenTec] Openwire feedlines

[Dr. Gerald N. Johnson, P.E.]

While open wire line just won't work in this situation because pipe
underground isn't going to stay dry or hold the open wire line a decent
distance from the conductive (e.g. very lossy) earth there has been a
balanced line that will work fine along side coax and in under ground
conduits. It used to be called 8290 Color line by Belden. Its a shielded
twin lead rated at 300 ohms. I've tested it as a shorted line with a
series tuner (huge coil and capacitors) running 200 watts RF without
damage and with the same tuner and final parallel tuned. Had lots of
corona off the cut end so had to neaten it up and put some corona balls,
but it still took all I could give either voltage or current.

At my suggestion N0AN acquired a supply of this line and has been using
it underground in a plastic conduit for several years without any
troubles.

Belden seems to have dropped it but other makers make it. I think I've
seen something like it at Radio Shack. Any way the shield around the
oval dielectric allows it to be in conduit or close to metal and it
works fine.

73, Jerry, K0CQ

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