[Amps] wires through center of coax

[Ron Youvan]

Fuqua, Bill L wrote:

>  Question, how do you place a wire in an hollow conductor with out creating a path for RF current on the outside to the inside?

<  Answer, you put a shorted stub on each end of the part of the transmission line where you don't 
want the line exposed to the elements (frequently the short in an elbow using 6" or larger line, 
think of a "T" being used as a "L" with the other branch being shorted) and drill a hole through the 
outer in the center of short inside the inner (where the inner is silver soldered to the shorting 
flat) and mount a rubber cord gripper, same at the other end at the other stub.  I saw it done once 
and I thought is was a silly way to convey the AOL tower light cord (type SJ cordage) "around a 
difficult area" by going through the line.
   I would have put it in "water tight flexible" conduit with the conduit mounted in plastic or 
neoprene blocks secured with stainless steel hose bands.  The impedance of the ridged line is 
unaffected by anything within the inner conductor and the cordage experiences none of the high power 
UHF signal in the coax until you develop a bad bullet between the stubs.
   My reasoning is: if there is any problem with any part of this line 1,000 feet up on the tower 
you know the tower crew is gong to pull the AC line out of the RF line and run it in some kind of 
"flexible conduit" mounted in some haphazard manor.
-- 
    Ron KA4INM - I'm proud to be Chuck's pop!