Topband: Getting Started

[Jim Brown]

>KW twinlead, actually window line, is available from multiple sources 

You are talking about a VERY different product. I used Belden 8210, 
which is 75 ohm kW Twinlead. It's been discontinued for at least 30 
years, maybe longer. (It's still in my 1971 Belden catalog). I found a 
NOS 250 ft spool at a hamfest near Chicago about 30 years ago, and 
stashed it in the basement, knowing that I would someday find a use 
for it. It is NOT window line, but rather a close-spaced pair of #10 
stranded copperweld in a heavy moulded brown jacket. Amphenol also 
made a version of this cable, and I still have a short length. :) 

Why was it discontinued? Probably because while it had much lower loss 
than a good RG8 or RG11 on 160M and 80M, loss increased rapidly with 
increasing frequency (and much more rapidly than coax). Loss was equal 
to RG8/RG11 at 10 MHz, but about 70% greater than RG8/RG11 at 30 MHz, 
and more than double at 144 MHz. 

73,

Jim K9YC