high voltage warning on vhf

[mookieo2]

I finally installed a VHF and at speed it says High Voltage. I installed a new rectifier before the installation a few months back. The motor is a '79 140 seahorse. The volt meter on the dash reads about 16-18V I'm not sure if there is a regulator.

 

[Vic.S]

Re: high voltage warning on vhf

No there is no regulator. So the reading you see on your voltmeter is normal and is what the radio is objecting to.

You should be able to find a suitable add-on regulator, for example if you look at the parts list for 1980 models you will see that power tilt and trim models were fitted with a more powerful stator coil and also a regulator.

A regulator similar to that fitted to the later power tilt and trim models should solve your problem but I cannot help with the wiring I am afraid.

No doubt other solutions.

 

[petryshyn]

Re: high voltage warning on vhf

As Vic says, you can retrofit a regulator to the charging system.

There are other solutions "on the cheap"

-run with your lights on when you get the warning (free)

-install several diodes in series with the VHF power wire to drop some voltage ($5)

-if the current draw of the radio is 1 amp or less, you could install a 7812 regulator in series with the power wire. ($2)

It all depends on your electro-mechanical abilities.....

 

[Vic.S]

Re: high voltage warning on vhf

No so sure about the several diodes in series idea. Sure each one will drop about 0.6 to 0.7 volts ( provided you don't use Schottky diodes) but the drop is current dependent and a VHF, assuming we are talking about a 25watt marine radiotelephone, will draw several amps when transmitting. Might then drop the volts a bit too much. Normally one has to be very particular about a good power supply in order to get good transmitting performance.
Moreover when not running at speed no voltage reduction is required.

The transmitting current rules out the 7812 regulator. I guess.

In fact I think the big difference in current between standby/receive and transmit may make any regulator in the supply to the radio an unattractive idea.

 

[petryshyn]

Re: high voltage warning on vhf

Hi Vic

Actually, the drop across a conventional diode is quite stable once you are over a few milliamps. Thats why its a better choice over a resistor. He is probably only a volt or two over the warning threshold, so 2 or three diodes should suffice. At .50 apiece, its not a big investment to try. He'd only need 3-4 amp diodes.

Yes, putting in a charging system regulator is the good way to go, but pricey.....
It sure will be nice when they bring out a 7812 in a 5 amp configuration and price it at something reasonable!

 

[Vic.S]

Re: high voltage warning on vhf

Hi Vic

Actually, the drop across a conventional diode is quite stable once you are over a few milliamps.

Yes you are right .. I dont know what I was thinking of.

I checked the tech spec of my radio. It states the current when transmitting to be <6A so I think I'd use 6 amp diodes.
max Vf is stated to be <0.9V @ 6A for the ones I looked at so that's no problem.

Mine will take up to 15volts so he may need to drop 3 volts, but the diodes will have to be switchable otherwise the volts will be too low when the engine is not running or only running slowly.

Actually he is lucky he can use the VHF with the engine running. Too much interference on mine!

 

[boobie]

Re: high voltage warning on vhf

For your mtr OMC used to make an add on regulator kit part # 173640. May want to look into it.

 

[Vic.S]

Re: high voltage warning on vhf

For your mtr OMC used to make an add on regulator kit part # 173640. May want to look into it.

That is the same regulator which I mentioned earlier as being fitted to latter models with power tilt and trim.

It is the best solution but the snag is that it costs $168

I think I might try one of the cheaper alternatives first. Petryshyn's suggestion to try a string of diodes perhaps.

 

[Aratsman]

Re: high voltage warning on vhf

What about something like this?

http://h2oinstruments.com/shop/index.php?main_page=product_info&cPath=20&products_id=127

 

[Vic.S]

Re: high voltage warning on vhf

What about something like this?

http://h2oinstruments.com/shop/index.php?main_page=product_info&cPath=20&products_id=127

Isn't that a regulator for a conventional alternator ?

 

[Aratsman]

Re: high voltage warning on vhf

I believe so. Maybe it can be converted for this use.

 

[Vic.S]

Re: high voltage warning on vhf

I believe so. Maybe it can be converted for this use.

Shouldn't think so.
An alternator regulator works by controlling the field current to give the correct output volts from the main output terminal ( or at the battery, if battery sensed)