VHF interference buzz?...........

[GetReel]

My Icom picks up weather channels perfectly clear, my radio 'checks' report clear transmission but I'm getting a low hum on incoming VHF traffic, I can hear and understand the caller, but there is a low buzz over thier incoming transmission.

Any guesses?

[BigLew]

A poorly grounded motorized device; radome, pump motor, maybe. Possibly a poor connection on your depthfinder. Not "at" the connectors , but inside the connectors where the various leads are attached to their respective pins.

Did you assemble your VHF radio connector yourself or was it supplied already assembled? Either way possibly the outer coax shield is not well done. That can be tricky. If you antenna lead passes any motor or possibly a CRT display and has a poor connection of the shield (woven wire surrounding the inner core lead), you could be picking up some sort of RF signal being generated by some elctrical device onboard.

Two suggestions:
1. Try a different antenna, even if you have to borrow one for a couple minutes from a friend.
2. Get on a clear channel and have a friend transmit to you a slow count while you try turning off and on other electrical devices to see if one of them is generating the RF.
3. To keep in mind that the source is more than likely closer than farther way from the radio connections. That's not to say it can't possibly be at the other end of the boat.
4. If you have a friend who's a ham radio operator, asking if he might take a look at or have any suggestions.
5. As a last resort, or probably your best option is to get in touch with your marine electronics service person who has a great reputation.

[McGillicuddy]

Weather channels are not a valid indicator of your reception or transmission as NOAA transmits from the tallest towers on the tallest points. And probably even satellite, now.

Interference is likely electromagnetic pulsing from another piece of equipment or bad contact or ground. It could be a poor or intermittent wiring connection, or weak ground on any piece of equipment's wiring. Perhaps it's a shielding problem where the radio is too close to something else, or some wire is too close to its wiring, and radiating unwanted signal to your vhf.

Could be as simple as moving your radio away from your compass, or you might have to play with eleventeen wires to find the incompatible culprit. As Big Lew suggested it could be your antenna connection. Could even be your bilge pump going on. Or your bait pump. Or sonar pulses from your transducer. Or even from your engine harness wiring. I'd start by turning off everything. Turn on your vhf, and then power up everything else that has a switch, one at a time. If that doesn't give you a clue start the motor and repeat the sequence.

I once saw an article where a guy recommended using a little am/fm pocket radio as a divining rod to direct him to the problem. He'd wrap the radio in alum. foil except the antenna, set it between stations and probe each wire with the antenna. When the buzz changed that was the likely culprit. Place the 2 wires perpendicular to each other and the problem goes away. In which case those to wires will need to be separated.