AIS trouble. Radio?

[BocaIII]

Ka4wja is absolutely correct.
No noticeable difference between rg8x and the much more difficult to use LMR 400 for runs 75 ft or less.

I use both in my ham station, less than 100 ft to one of my antennas is rg8x.

To my VHF antenna for 2 m and 440 and the Marine band is a 300 ft run of LMR 400

SWR meter is your friend to determine the quality of your coax antenna system.

Capt Jack
W4GRJ

[Bluechart]

Have you checked for resistance (short) between the center pin and the outside of the connector? Just unscrew the connector from the back of the radio, and check. Most likely a short, like a coax shield strand touching the center pin at one of your connections.

[sinnerman]

How about getting a cheap VHF antenna and hot wiring it to the VHF/AIS radio.

Different antenna/ shorter cable run.

If it still has issues then the radio is the culprit.

My two cents

[CarlF]

1) I agree that it's most likely signal attenuation due to corrosion in a connection or the coax itself. At a minimium unscrew the connectors, clean them, and add a good contact cleaner - Craig Labs Deoxit is by far the best for RF connections. An absolute miracle. A weakened signal could "fade in and out". It's also possible that the PL259 solder joints were never well done. Maybe no one noticed. https://www.amazon.com/gp/product/B0...e?ie=UTF8&th=1

2) Could be an LED light at the masthead but would only happen when turned on.

3) Is there another antenna at the masthead? Vertical metal near the AIS antenna is a killer for AIS range - even if it's not powered. In this tests below range dropped from 30 miles to 8 miles when an unused antenna was introduced four feet away. https://www.milltechmarine.com/VHF-A...well_b_32.html

[Leakie Marine]

Originally Posted by wholybee

Enlist help from your HAM friend. 99% something is wrong with either the coax, connectors, or antenna.

RG8x is terrible coax. It is fine for short runs, but usually on a sailboat I recommend against it, since even with a small sailboat the run is fairly long to the top of the mast. Depending on length, you might be loosing 50%-75% of your signal.

Your HAM friend hopefully knows this, but with a lossy cable like RG8x, you can read a good VSWR on the meter, and still have serious problems. Hidden by the cable losses. So, just because the VSWR tests good, does not mean it is good. (but bad VSWR always means something is wrong)

It might be worth cutting off a connector, and seeing if there is any corrosion of the wire itself. If there is any sign of corrosion or water inside the coax, the whole run needs replaced. If you are not experienced putting on a new connector, know that it is very easy to mess up, and have it look fine, and work fine for 6 months before it stops working.

1%, Something is wrong (damaged) with the VHF radio. I can't think of any settings that would do this, but perhaps the internal switch or splitter burned up. It does happen that a radio fails, but reception issues are almost always an issue with the coax or antenna.

Sharing an antenna with both the VHF and AIS signals is fine. With a VHF that has a built in AIS receiver, I don't think it can be done any other way.

+10 to what Wholybee says. Very unlikely it has anything to do with network and highly likely to do with antenna or more likely the feeder (cable) If yo ucan use something like LMR400, huge difference to performance. splitters are Ok, I run separate antennas for Comms and AIS, it's nice to have a built in spare!