VHF radio cutting out.

[stav]

Sorry is three posts greedy??????

Ironically just when we have to give a transit report even for a jaunt around the bay here in Jersey the VHF has decided to play up.

It is a standard horizon 3500 with a RAM mic in the cockpit.

It has for a few weeks been saying battery low and chirping over the speaker when switched on. I checked the voltage at the power connector and it was either 12.4 or 12.6 volts (cannot remember but not a complete disaster).

Then it started cutting out when transmitting on hi power. On low power it is fine.

So checked the switch on the switch panel and found the spade connector on the back was cracked where it was crimped on and literally the smallest bit of metal was left connecting such that one wiggle it broke off. So I crimped on another spade connector but I didn't have a soldering iron with me to solder the tail first.

I thought it had fixed it but no radio still cuts out on hi power transmit.

The switch on the switch panel had a resistance of about 1ohm when closed.

Has something been damaged in the radio? Transistor/relay?

It has worked perfectly for 8 or so years.

Is it user serviceable? Or can anyone recommend a good electronic repair person.

Happy to give it a try to repair inside if it is doeable but really rate the radio when it works and would like a good fix.

What else to check?

Thanks in advance, again.

 

[VicS]

Id suspect the power supply

You report 12.4 (or 12.6) volts but is that when transmitting on high power or just when on standby'

You report a 1 ohm resistance for the switch on the panel......... that's the boats distribution panel presumably ?............... If that is so and your reading is correct that's enough resistance to cause your problems on high power

It'll take several amps on high power. "Several amps" X 1 ohm = "several volts" . ................ Volts drop in the power supply to the radio

 

[pvb]

Almost certainly a problem with the supply. Your radio consumes 5A on high power transmitting, so you need a decent power supply. First, you could wire it directly to the battery (ie bypass the switch panel) and try it again. If it's OK, then you'll know the wiring and/or switch panel is the culprit.

 

[stav]

Id suspect the power supply

You report 12.4 (or 12.6) volts but is that when transmitting on high power or just when on standby'

You report a 1 ohm resistance for the switch on the panel......... that's the boats distribution panel presumably ?............... If that is so and your reading is correct that's enough resistance to cause your problems on high power

It'll take several amps on high power. "Several amps" X 1 ohm = "several volts" . ................ Volts drop in the power supply to the radio

Hi VicS,

Yes voltage reading at standby, will have a look at voltage at switch (yes on distribution panel)when transmitting, good point.

 

[stav]

Almost certainly a problem with the supply. Your radio consumes 5A on high power transmitting, so you need a decent power supply. First, you could wire it directly to the battery (ie bypass the switch panel) and try it again. If it's OK, then you'll know the wiring and/or switch panel is the culprit.

Good idea to, will try that.

 

[PaulRainbow]

So checked the switch on the switch panel and found the spade connector on the back was cracked where it was crimped on and literally the smallest bit of metal was left connecting such that one wiggle it broke off. So I crimped on another spade connector but I didn't have a soldering iron with me to solder the tail first.

Good, don't solder wires that you are going to crimp, it's one or the other, not both.

 

[Howardp]

Have a look at the wires in the power supply to it, is the core still bright and clean (the copper bits) or black? Very common to get corrosion and your core looks black, that produces resistance and hence stops working properly. Simple to correct by changing the wiring.

 

[stav]

Thanks went for a sail this afternoon so before I went out by passed the switch and could transmit on hi power. So will look for a new switch for the switch panel but will also check the wires for corrosion in case. Thanks for the suggestions, really helpful!

 

[tim_ber]

Agree with all of above.

Had same situation and it was because of power.

So either battery is dropping voltage a lot when you try to transmit (poor battery) or wires are corroded or what not.

Just about wires... I was using a wireless keyboard at home, it would not work. Had left AAA batteries in and had corroded. Cleaned terminals and tried again, still no joy. Started to strip the red wire that went from battery compartment to keyboard switch and found that corrosion had crept along half of the 300mm wire. The copper had turned black on some strands as mentioned above.

So just 15cm of slightly corroded wire stopped the 3 volts getting to the switch. (3 volt has dropped to 2 volt or less in just a 30 cm wire)

New wired soldered in and keyboard good as new.

Will use tinned wire on boat from now on. Good lesson learned for me. Electricity is wonderful stuff but I am learning all the time.