Michael Coslo wrote:

Should I put a 1:1 balun on the setup or not?

- 73 de Mike KB3EIa -

Mike,

I'm sure there are a lot of opinions but here is what I do. Assuming
your mobile antenna is pretty well matched and you are running 100W then
the differential current in the coax will be about 1.4A. I have an
industrial clamp-on current probe that connects to a small battery
powered RF power meter (you can use something else) and I would measure
the common mode current on the shield of the coax. If the common mode
current was greater than 10% of the differential current in the coax
(0.14A) on any band of interest then I would use a good quality 1:1
balun. Why 10%? I have no real reason but I have done many mobile
installations and have nearly 30K mobile qso's and have no equipment
interactions or problems.

Obviously if the common mode current is minuscule then there no value in
having a balun. Also using a balun will do no harm and only cost you a
fraction of a dB. in loss.

73,
Larry, W0QE