[TowerTalk] finding rf on coax

[David Voit]

I put up an end fed wire.   I have some interference with a smoke detector
and a cheap chinese keyer.  I am trying to understand what is causing the
problem.  It might be radiation from the coax or just the rf field from the
wire being close to the shack.  Commonly the explanations of rf on the coax
describe the symptoms but do not say how to verify that it is common mode
current causing the problem.  From what I read, the current will vary along
the coax and that it takes a complex set of components to measure it. I
want to verify or reject the existence of the problem so I can take the
correct steps.   and accurately measuring it is not important to me.  I
have an end fed wire with a 9:1 balun with about 15 feet of coax to the
banun and 90 feet of wire with no counterpoise.   The antenna article I
based it on stated no counterpoise was needed and nobody on the internet
makes stuff up. The antenna wire is maybe 10 feet from the smoke detector
as I have some limitations around my house and the wire is relatively low
above the roof.  It could be just a strong rf field and not common mode
interference.  Can I use something like an rf probe and a voltmeter to
verify that I have rf on the coax?  Is there another way to verify what the
cause might be?  Should I just pull the battery?

To be complete, I do have an earth ground just 6 feet from the rig.  The
transceiver is a ts 430s at 250 watts.



David Voit
WB6TOU