Radar Question

Wandering Sagebrush · Posted: Tue Jun 22, 2010 6:39 pm Post subject:

A couple of thoughts...

Ken, I suspect that you want to move your GPS puck either well above or well below the radar. I have both of my antennas on a 24" extension above the radome, with no problems.

Tom - I had a problem with my C80 intermittently shutting down (screaming alarms, etc.), and finally failing completely. It was usually happening after hitting a wake or chop and getting a little bounce to the boat. The problem turned out to be the Raymarine GPS antenna as the cause of the issue. I had over torqued the mount screws and cracked the antenna housing. That allowed water intrusion and who knows what else.

Hope that helps....

Steve

k3nlind · Posted: Wed Jun 23, 2010 1:33 am Post subject:

All this information is great and I sincerely appreciate the input. However, I know that there are no loose or corroded connections or wiring. The GPS does not work intermittently. It simply shuts down and stops working when the radar is activated. Actually, I can turn the radar on and the GPS continues to function. It is only when I press the transmit button of the radar that the GPS shuts down. Further, the JRC radar and the Lowrance GPS/Fish/Depth finder are separate units and are not connected to each other in any way.

I took measurements of the equipment. The radar dome is 18 inches in diameter. Before I moved it the radar dome was on a 4 inch mast and the GPS antenna was mounted about 4 inches below and 3 inches outside the radar dome circumference... approximately 5 inches apart, point-to-point. After the move, the GPS antenna is about 7 inches above and 2 inches outside the radar dome circumference... approximately 9 inches apart, point-to-point.

The only major difference that I can come up with is the lie of the wiring. Before the wiring was completely separate and now the wires use a common channel run through the radar mount to enter the cabin.

I uses the GPS today for five hours continuously displaying the water map and not a single glitch... I did not use the radar. If it were a fuse or bad connection I would have noticed it during that time.

BTW, we caught four large wipers... woo-hoo < Wink

tpbrady · Posted: Wed Jun 23, 2010 2:40 am Post subject:

Ken,

This is virtually identical to the problem I had with an LGC-2000 GPS module on an LCX 20. When it was mounted anywhere on the radar arch when I turned the radar on to transmit, the GPS would go offline. I had it beyond the distance recommended by Lowrance and it didn't matter. I moved the LGC-2000 to the equipment shelf inside the cabin and the problem went away. It worked just fine inside.

k3nlind · Posted: Wed Jun 23, 2010 3:44 am Post subject:

Thanx, Tom. That sounds like the same situation. Can you tell me did this occur many times and the GPS came back later? In other words did it happen to you more than once? I have still not attempted to run the radar again.

thanx,

Levitation · Posted: Wed Jun 23, 2010 7:45 am Post subject:

Yes fried does not unfry, but a scrambled data set on the GPS will cause it to take from ten minutes to an hour download a fresh ephemeris to finally figure out what day and time it is and then find the position... Likely, the radar energy is being picked up the GPS antenna and the resulting voltage overload got into the GPS unit and scrambled the ephemeris data in RAM...

Move the GPS antenna off the top and put it in the cabin or down on the deck temporarily, then turn the radar on and see if it loses data... Very likely it will be fine and you will need to find a permanent mount away from the near field of the radar antenna...

denny-o

tpbrady · Posted: Wed Jun 23, 2010 10:49 am Post subject:

Ken,

It happened several times. The only way to restore the GPS was to disconnect power to the unit or disconnect the LGC-2000 from the back of the LCX-20. It recovered each time.

Wandering Sagebrush · Posted: Wed Jun 23, 2010 1:29 pm Post subject: One more thought!

If moving the puck does not solve the problem, I would go back to the guesses about voltage. It could be that with the radar on, you're sucking enough voltage out of the system that a slightly corroded or loose connection could drop enough voltage such that the GPS lost it... The corrosion could even be in the wire itself.

My suspicion is that it is the gps puck location, but this is a possibility, too.

Steve

k3nlind · Posted: Wed Jun 23, 2010 2:19 pm Post subject:

OK, thanx to all...

I feel better knowing that someone else has lived through this and that it recovered every time. My fear is subsiding.

As I am sure that it has nothing to do with voltage or corrosion (although I am pleased to have received these informational inputs)... my path will be to move the puck.... and test.

I will post results when available, but it might be some time.

thanx again to all,