Cobra 29LTD Classic questions.

In a nutshell, if an antenna isn’t mounted correctly, your RF energy from the radio can’t flow out the antenna. So the RF signal will flow back on the outside of the coax to the radio ( common mode current) and your coax becomes part of the antenna system which isn’t good.
You can usually put ferrite beads on the coax or wrap the coax in 7 to 8 wraps (circles), and about 6 to 7 inch diameter. It’s is best to make the RF choke at the bottom of your antenna if possible. Here’s a great website that will answer a lot of your questions.

Common Mode Currents

It has been a lot of help for people with antenna problems.

 

Maybe, the bigger problem is that the coax is acting like the antenna and making a round trip from the radio to the antenna and back to the radio on the shielding of the coax, and this is where the inverter noise is being picked up. Chokes and a good ground will help.

 

The antenna needs to be moved above the roof line to transmit properly and the swr will probably go down. The inverter noise is being picked up by the antenna.

 

Moving it should be done after you put chokes on the coax. Eliminate one thing at a time.

 

It’s going to help if he’s offered sources.

 

OMG you guys ...

Parts and Accessories

 

Maybe I ”know” (sorta) but we KNOW that you know . . . as this is a foreign language to most.

I’d also recommend

www.palomar-engineers.com

I’ve ordered from both several times this year. And asked questions over the phone.

The products I’ve received (some related to CMC) have worked well enough I’ll call it a win to have spent the money.