[Elecraft] OT: Feedline Question

[Jim Brown]

On Tue,4/18/2017 10:10 AM, Guy Olinger K2AV wrote:
> Then there is the loss based on number of spacers and loss tangent of the spacer material modifying the lesser air loss.

Below UHF, loss in transmission line is virtually all due to copper 
losses unless the dielectric material is wet or is otherwise made 
conductive.

Quite a few years ago, N6WS did some excellent work showing that losses 
in window line are greatly increased when it is wet. His work was 
published in QST and later included in Antenna Compendium #6. It should 
be required reading for anyone considering window line. He measured four 
types of window line and some open wire line he built himself. Putting 
some numbers to it, Wes's measurements showed loss at 50 MHz increased 
from about 0.4 dB/100 ft to more almost 6 dB/100 ft when it was wet. The 
open wire line showed no increased loss when wet.

73, Jim K9YC