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Old 06-05-2012, 03:30   #1
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Radar Troubleshooting?

I am trying to get the boat prepared for my big adventure this summer -- sailing to Iceland and beyond the Arctic Circle.

I had thought I might replace my entire electronics suite, and had already chosen the equipment -- B&G Zeus plotters and a Simrad 4G radar.

But now I am not sure that I will have the money to do it all now -- there are so many other expenses. I might need to get a couple of more years out of the electronics.

I'm not really against keeping the existing electronics for a while - I like them. The network is built around Raymarine RL80CRC+ and RL70RC+ MFD's with the HSB2 high speed bus, and a 4kW large Pathfinder radar scanner. Everything works fine and is adequate for my purposes except for only two things:

1. Not AIS compatible; and
2. The radar doesn't work well.

I can solve the AIS problem by hooking up an AIS engine to a PC or to my IPad backup navigation system.

But what about the radar? I really want to have a well functioning radar for this trip.

My radar works -- so it's not a dead magnetron. But it is very, very weak. I hesitate to put any serious money into it, since it is near the end of its useful life. What could be wrong with it? I get weak and erratic returns from it. I can make out big ships only when they are 3 or 4 miles away, and even then they appear and disappear on the screen. No amount of fiddling with gain, sea clutter, etc. improves the situation. MARPA doesn't really work because I can't keep a lock on any target for long enough.

Any hints about what this might be? Is it something which might be worth repairing?
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Old 06-05-2012, 03:56   #2
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Re: Radar Troubleshooting?

Old magnetrons don't always just die, they just get weaker. Sound like time for a a new radar.
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Old 06-05-2012, 04:08   #3
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Re: Radar Troubleshooting?

Quote:
Originally Posted by SimonV View Post
Old magnetrons don't always just die, they just get weaker. Sound like time for a a new radar.
That's useful information -- so if one failure mode for the magnetron is that it gets weaker -- sounds like a new magnetron might possibly bring my old system back up to speed.

I want a new radar, but it means new MFD's, too. It's a lot of money -- and I might need to delay that expense, if possible.

A new magnetron is not very expensive. Buying and installing it myself will cost less than having the Raymarine techs just have a look at my system. Maybe it's worth taking a risk on a new magnetron's solving the problem?
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Old 06-05-2012, 06:50   #4
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Re: Radar Troubleshooting?

Yes, magnetrons get weaker over the years and your problem does sound like a tired magnetron. You can have it repaired (actually, replace that part of it) - but better to just buy a new dome unit for your existing display/controller.

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Old 06-05-2012, 07:13   #5
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Re: Radar Troubleshooting?

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Originally Posted by colemj View Post
Yes, magnetrons get weaker over the years and your problem does sound like a tired magnetron. You can have it repaired (actually, replace that part of it) - but better to just buy a new dome unit for your existing display/controller.

Mark
Bingo! Well, a new magnetron is surprisingly reasonable from JRC -- a few hundred dollars. But I don't think the entire radomes compatible with the RL80CRC+ are still made or sold? Buying a used one would seem to defeat the purpose of trying to have a fresh magnetron, not so?
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Old 06-05-2012, 07:30   #6
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Re: Radar Troubleshooting?

Just get your radar unit to another boat with a compatible magnetron. Connect and test. Then you will know if it is the unit's fault or the cable/magnetron.

If it is the cable/magnetron then start at the cable - they often chafe or become otherwise weakened - e.g. the connectors corrode.

If it is the magnetron then buy another on ebay. At times you can buy NEW ones there at a fraction of Raymarine asking price.

If the price of a new / sh ebay is not justified, shell out for a new Furuno 1623. You can always sell it off after your expedition. They get good resell values.

If you are going into ice/fog/rock/rain, then DO get the radar.

b.
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Old 06-05-2012, 09:54   #7
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Re: Radar Troubleshooting?

Quote:
Originally Posted by Dockhead View Post
Bingo! Well, a new magnetron is surprisingly reasonable from JRC -- a few hundred dollars. But I don't think the entire radomes compatible with the RL80CRC+ are still made or sold? Buying a used one would seem to defeat the purpose of trying to have a fresh magnetron, not so?
Dockhead,
Replacing the magnetron is relativity easy project so would agree with the suggestion to replace that part. Have replaced over 20 of them in microwaves and my airplane's radar. Not a difficult job as long as the power is off and you ground or short everything before you touch it. (important unless you are trying for a new frizzy hair style!) My airplane's magnetron is supposed to be replaced every 3000 hours of usage. So seems logical your boat's unit will also get weaker with time and usage.
Plenty of info avail on how to do it might be good idea to read it over. Google search on replacing radar magnetron lists 7,430 articles which is way more than you need! LOL!

Though not in the money saving venue feel must mention that since 90% of an iceberg is under water and you are going above the Artic Circle I would seriously consider a Forward Looking Sonar. Have one on my boat and just in a trip from the Med to Southern Florida 6 weeks ago (March) our sonar found and clearly warned the boat of 7 potential diasters.
4 underwater rocks, 2 containers 5 & 6 feet below the surface. In the case of the one @ 5' the underwater camera got the name and number and when the Captain called them they could care less. Told us it was now the property of their insurance company and they had no comment on how it was going to be taken care of. Captain logged the call and forwarded copy to our attorneys. Texas is one party state and call was from middle of ocean. The seventh contact was a whale! Did not know that it could detect them and would not have wanted to hit a whale even with a steel hull.

Icebergs would worry me with the greatest part of their mass underwater. Do believe a forward looking sonar esp one that reaches out 180 degrees would be a great safety addition for you. They are not exactly cheap IMHO but what is the safety of my family or me worth to me?
Realize not telling you something you didn't already know just prefer to error on the side of safety.

Have a Safe and Wonderful Trip!
Johnny
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Old 06-05-2012, 10:41   #8
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Re: Radar Troubleshooting?

Thanks for those tips! Maybe I'll take a crapshoot on a new magnetron for the existing system.

Concerning forward looking sonar - I actually have one of these - an Echopilot Gold. Damned if I can see anything but gibberish in the display. Maybe I just don't understand how to interpret it.
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Old 06-05-2012, 16:53   #9
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Re: Radar Troubleshooting?

G'Day Dockhead,

Don't know about Raymarine radars, but our Furuno has instructions for checking the magnetron's output. Involves measuring some simple voltages inside the radome as I recall. Perhaps yours has a similar check.

Cheers,

Jim
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Old 06-05-2012, 17:28   #10
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Dockhead,

The radar system you have is of good quality and design. If your radar is very very weak I would first suspect the cable from the scanner to the master unit. Ideally this is the unit at the nav station but not everyone does it that way. If the very tiny video cable has had water intrusion at either end it may greatly weaken the signal. There are ways to check the cable electronically but it is not something you can easily do yourself without going up to the radome. Suggest getting some friendly advice from a local Raymarine or other analog radar shop.

Magnetrons are hard to wear out. It's possible but not the first thing that pops onto the list of usual suspects.

Good luck,
Dan
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