My Next VHF Question

[lcookie]

I just installed a VHF radio on my boat and every time I transmit one of my depth finder/gps units does funny things. On low power transmissions the screen will flicker. On high power transmissions the screen will go dim until I complete my transmission. The unit does not lose power. The display is the only thing that is affected. The voltage does not drop and the unit functions properly during and after the transmission. I thought it could be the load the radio placed on the battery but I wired the radio to a separate battery and the same thing happened. I even doubled the distance from the antenna to the unit thinking that could be the problem but no change. This only happens with one of the units. I have several other units on the boat that are unaffected.

Anyone got some advice on this one?

 

[Bondo]

Re: My Next VHF Question

Ayuh,.... Check the Grounds on both,....

They need a good clean solid ground path....

 

[bruceb58]

Re: My Next VHF Question

The voltage does not drop and the unit functions properly during and after the transmission.

Measure the voltage at the depthfinder while you are transmitting and while you aren't to see if its a voltage drop issue.

Is your radio directly connected to the battery with both its positive lead and ground? If you are trying to reduce the voltage drop due to the radio, you have to have seperate ones of both. A shared ground could be the cause of your voltage drop.

 

[lcookie]

Re: My Next VHF Question

My dad had that problem on his big Lund Barron boat with another brand of Sonar. He had to add chokes to his power lines going to his VHF to reduce it down to a acceptable level.

I have seen interference on my boat's console 898 when I plug in my cell phone to charge. Not always but sometimes. The 12v plug is on the passengers console. Supprised me.





Thanks,

Two Radio Shack chokes cleared it right up.

 

[bruceb58]

Re: My Next VHF Question

Another thing I always do is twist my power/ground pair when I send it back to my battery. Take two wires and chuck them into a drill and have a helper hold the ends. Run the drill until you get the desired twist on the wire.

 

[Fireman431]

Re: My Next VHF Question

I get that on my fuel meter gauge when I transmit. It pegs the needle during transmissions and returnes when I release the PTT. It's a VHF wattage thing in my boat because the grounds are all bussed and solid. But I think it's coming from the VHF unit and not the antenna as the fuel meter is directly over the VHF housing.

 

[jhebert]

Re: My Next VHF Question

Most of these problems of interference to other devices when transmitting on a boat's VHF Marine Band radio are probably caused by the location of the antenna. Many small boats have the radio antenna located near other electronic devices, with the base of the antenna perhaps only a foot away. Move the radio antenna away from other electronics devices. The best method is to elevate the antenna above the other devices. Use a 4-foot extension mast and install a 3-foot base-fed whip antenna. See my article on this type of installation at

http://continuouswave.com/whaler/reference/VHFAntenna.html

I had the same problems as described by others before moving my antenna away from the other electronic devices.

 

[Fireman431]

Re: My Next VHF Question

Most of these problems of interference to other devices when transmitting on a boat's VHF Marine Band radio are probably caused by the location of the antenna. Many small boats have the radio antenna located near other electronic devices, with the base of the antenna perhaps only a foot away. Move the radio antenna away from other electronics devices. The best method is to elevate the antenna above the other devices. Use a 4-foot extension mast and install a 3-foot base-fed whip antenna. See my article on this type of installation at

http://continuouswave.com/whaler/reference/VHFAntenna.html

I had the same problems as described by others before moving my antenna away from the other electronic devices.

Hmmmm...my antenna base is 6'+ away and 3' higher. That's why I assumed it was from the radio itself.

 

[jhebert]

Re: My Next VHF Question

Hmmmm...my antenna base is 6'+ away and 3' higher. That's why I assumed it was from the radio itself.

Thanks for providing information on your installation. Information like that will help readers give more cogent answers for your situation.