Coax as an inductor

[bob]

I am trying to determine how a length of RG-8 coax that is shorted on each end and wound into a coil would compare to using 1/4 copper tubing instead. I built a link coupled tuner for 75 meters using tubing for the main coil and coax for the link. All values came from W4RNL, and used my 4170 to determine actual values. It works just fine, but I'm trying to decide if using tubing for the link would be any more efficient. I had a tough time trying to wind that link with tubing - the fixed coax link made that part of the project easy. Now, I want to build another one for 160, and will use tubing for both coils if there would be any real advantage, but would like to use coax for the link if there is no reason not to. Anyone ever used coax as an inductor before? I haven't been able to find anything about this on the net.

Thanks in advance for any and all opinions,

bob WA5JOT

[Bob]

Hi Bob,

I haven't tried that but it sounds like an interesting idea. You could use the AIM to compare the Q's of the 80 meter coils with tubing and coax to see how their loss compares. If there is loss, the power dissipated is a consideration. The coax won't dissipate the heat as well as the bare tubing, but if the lost power is very low, it won't matter.

-- 73/Bob

[bob]

Thanks Bob, I'll give that another try. I did run a little test with a piece of RG-58 and an equal length of #10 wire and the wire won as far as resistance goes. I am new to the AIM, and not sure I did the test properly, but I seem to remember the wire showing higher efficiency. I don't run very much power - just looking for minimum loss, and the coax was easier to wind around the coil. I'll experiment some more, paying more attention to Q as well as resistance. Thanks again, Bob...

73,
bob WA5JOT