Can you help solve this mystery RFI?

[beachkat55]

Hello all. We've tried for weeks to solve marine band channels cutting out every 1-2 seconds on a Bearcat UBC125XLT. We regularly monitor Ch63 for inshore weather forecasts so this is a pain. NB: Airband receives without issue.

This is what's been tried: CloseCall & Priority settings switched off), replaced 10m R8X coax cable to roof based antenna (moonraker scanking) mast mounted 35ft up with clear view to sea. Plugs checked and waterproofed.

The really weird thing is that other scanners, when attached to the same setup, receive marine band clearly without the 'pulsed' cut-outs which sound much like a mic being clicked on and off and clip speech making it fairly unintelligible.

Any advice / theories greatly appreciated as can't afford an MFJ antenna analyser and no one seems to hire them out locally.

[ch25]

You have nearby transmitter like security monitoring.
Your scanner have sh1tty receiver, so strong nearby signal make it deaf.
As simple as it is.
Other radios have better front end so nearby rf make no difference.
Chris

[DX-Digger]

You need to find the frequency of the interfering signal then make a series resonant filter capacitor and inductor tuned to that frequency and connect it across your antenna socket effectively grounding that signal. However if the signal is very close to the marine channel 160MHz it will make your receiver deaf.
You could also do it with a coax 1/4 wave stub again tuned to the interfering signal so it acts as a trap for that signal. so if the interfering signal is on 150MHz cut a piece of coax about 32cms long you may have to trim it shorter for best match. Its cheap to do and could fix your issue.
But first you have to find the frequency of the interfering signal.
Have a search on youtube for tuned stub filters
Easiest fix use one of your other scanners that doesnt suffer with the interference

[beachkat55]

Thanks for the suggestions. After latest efforts, now seems improved

[Piggly]

What were your efforts that led to the improvement?