[Amps] wires through center of coax

[John Lyles]

Bill - WA4LAV
I hope that running wires through coax center conductor like this won't 
cause problems because I am doing it with the 9 3/16 inch diameter 
output feeder of a new amplifier I have been working on. I have a 
mechanical linkage going through the middler of the center conductor to 
the tuning paddle in the cavity amplifier. Also, have a RTD applied to 
the back of the paddle (inside) to measure temperature when it is 
running. The linkage and wires run through a 1/4 wave stub into the 3 
megawatt PA.

73
John
K5PRO


>      I give up. I think most everyone else gets it. It is like a conversation I had with some old hams, not much older than I am aboiut some large coax.
> They were convinced that since the center conductor was hollow you could run wires up thru it to carry current to lights and rotators without affecting the
> impedance of the coax. Their argument was that current only  flows on the outside of the conductors. But that is not always true.
> Current flows on the surfaces and in the case of a hollow conductor it is true it will flow on the outside as long there is nothing to electric
> create fields on the inside. There are electric/magnetic fields between the outside of the inner conductor and the inside of the outer conductor. But once you put a conductor on the inside of the hollow inner conductor you have created a new bit of transmission line, there are fields now between the new conductors and the inside on the inner conductor. That changes everything.
>
> 73
> Bill wa4lav
>