VHF Problems

[kennyh]

Hi all

I’ve an issue with my Icom M411 VHF (approx 10 years old) which appears to have problems with transmission.

Of course it could be the antenna (approx 2m fibreglass whip aerial mounted on the roof of a hardtop 30ft’er).

I’m going to have a close look at the cabling / connection to the VHF, but do you have any other advice on resolving? Any know issues with the M411 that could be causing the issue? Any thoughts on a replacement should I have no luck resolving?

 

[Momac]

Is it not transmitting at all or just poor range?

 

[jrudge]

Start with basics. Antenna and power

My boat is 24v. 12v dropped was on way out ( failed 10 min later) and the radio would not transmit due to low power. Then it went dead which made diagnosis simple !

 

[kennyh]

Is it not transmitting at all or just poor range?

Poor range appears to be the problem.

 

[matt8442]

Morning Kenny, if it's poor range, then could be the cabling between radio and antennae is damaged or poorly shielded? Another thing it could be is damaged antennae? I had a problem on my boat whereby I had fitted LED lights to the radar arch which when turned on would cause RF interference with the radio meaning poor transmissions and recieving. Have you perhaps fitted LEDs recently?

 

[CLB]

Any thoughts on a replacement should I have no luck resolving?

Just to answer that specific question. Standard Horizon all day long. Better radios IMHO, better value and excellent support if needed.

 

[SteveNotlob]

Poor range appears to be the problem.

Is it receiving distant vessels?
Older Icoms like yours had an issue with the receive IF Filter failing.
You could transmit OK but would struggle to receive anything unless moored alongside if you had squelch up.
Turning off the squelch will usually allow you to receive vessels up to a few hundred yards away but with 'hiss' in the received audio from weak signal.
Regards, Stephen

 

[rszemeti]

Either:

get a suitably qualified electronics wallah to look at it

or

buy a VHF power meter, then you can at least see what is going up the pipe and how much is coming back down.

Without a powermeter, it is like trying to fix electrics without a multimeter.

 

[kennyh]

Thanks all

All appears to be working now. I stripped and cleaned the antenna connection at the set and that seems to have fixed it.

 

[oldgit]

99% of radio problems involve electric not getting on very well with water.
Poor transmission usually 13.8V not getting to radio. Check fuse and fuse holders first.Then power connection on rear of radio.Any corrosion will increase resistance. Simply pulling fuses/ connections and putting them back in will clean surfaces, squirt of switch cleaner (NOT WD40) will delay future problems.
Remove pl 259 and check for gunge.Water will get into aerial cable RG58 and can travel amazing distances via Capillary action. Normally a bit of green gunge at plug/socket, in extreme cases copper braid will have dissolved in to black mush.
As for Standard Horizon,you will find them popular on boats where saving money is considered a priority, probably not many in the wheel houses of folks who earn their living on the water.
As for support. ICOM are the only company who can/will actually repair a 10 year old radio sometimes FOC as many on here know.
They have an actual repair workshop( with actual engineers) in Herne Bay and have been there for 50 years, in emergency a personal visit can save the day.
Try sending a 10 year old Standard Horizon back to the importer for repair, do let us know how you get on.