I have a 15 year old Raytheon set that has lived in Florida and Bahamian
waters all it's life. I often open it to grease the gears.

There is essentially NO corrosion of the kind you describe. I don't think
your problem is with the fresh water moisture. It sure sounds like an
electrolysis problem. Is your unit grounded per specs? Do you have
electrolysis problems in other parts of your boat?

Hope this info is useful.

"Larry W4CSC" wrote in message
...
"Lionheart" has just received her third Raymarine 2KW radome because
Raymarine couldn't save the corroded guts of numbers 1 and 2. It seems to
happen every year. The dome is NOT sealed, but has only 4 screws holding
the top to the bottom with a sort-of rubber seal between the flimsy halves
that are easily flexed. I don't think this is leaking, though. I think
the radome's little rubber tit drain vents the pressurized air inside the
dome out as it sits in the hot SC sunshine, then sucks in a big gulp of
99.9% humidity sea air as the sun sets. During the night, the colder dome
and POT METAL zinc chassis inside it condense the humidity into water that
corrodes the hell out of it all night until the sun rises in the morning.
As the POT METAL zinc chassis doesn't get sunlight, it is colder all
morning and the water condensation on it actually increases as the water
on
the now-heating dome vaporizes into 100% humidity inside the dome in the
morning. The water never drains out of this box as the bottom of it is
FLAT, not pitched towards the little rubber tit drain. Opening the dome
finds FRESH water sitting in the bottom, and condensing on all interior
parts. I tasted it and there's no salt taste. It has rained in
Charleston
VERY infrequently of late. This much water couldn't have survived the
long
periods of fair weather.

I'd like to hear from other Raymarine owners of 2KW and 4KW radomes that
have opened them after many months of on-mast service to see what they've
found inside. Our magnetrons have RUSTED. The unprotected pot metal
chassis is all corroded. If you remove the aluminum (more galvanic
action?) cover from the receiver cavity and its rubber seal, the INSIDE of
the pot metal chassis looks like a zinc that's been in the river....all
white corrosion and pitted. This is because this pot metal box ISN'T
sealed because it's open to the high humidity inside the dome where the
power and data connectors are sticking through....wide open.....

Take the dome off yours and let me know what you find. This swapping out
radomes every year is stupid!

Hello to all I remember. The Gulfstreamer Race from Daytona Beach to
Charleston was great, even though we all got becalmed 90 miles S of
Charleston for hours and hours in DEAD CALM and dropped out to motor home.
The big Amel Sharki ketch saw over 13 knots on the GPS all night before
that. We all had a ball!

"tkranz" wrote in
:

I have a 15 year old Raytheon set that has lived in Florida and
Bahamian waters all it's life. I often open it to grease the gears.

There is essentially NO corrosion of the kind you describe. I don't
think your problem is with the fresh water moisture. It sure sounds
like an electrolysis problem. Is your unit grounded per specs? Do
you have electrolysis problems in other parts of your boat?


There aren't any "gears". The new 2KW radomes have a flat piece of PC
board with a phased array of stripline antennas on them. It sits on a pin
where the RF enters from the waveguide. Around that is a pulley with a
rubber O-ring that's driven from a stepper motor pulsed by the PC board
inside the potmetal box. The motor is the same one used to pull the
printhead back and forth in a PC printer. The pulse rate sets the rotation
rate of the pc board antenna. No gears, it's cheap.

The water in the dome is fresh water. I've tasted it. It's condensate
from the air breathing in and out of the dome every day with no way of
escaping until the flat bottom of the dome is flooded enough to drain out
the tiny rubber tube grommeted into a hole in the flat bottom.

Too bad Raytheon isn't making good radars any more for small boats. Looks
like yours is much more sophisticated than ours.

On Sat, 29 Jan 2005 03:17:10 GMT, Larry W4CSC wrote:

"tkranz" wrote in
:

I have a 15 year old Raytheon set that has lived in Florida and
Bahamian waters all it's life. I often open it to grease the gears.

There is essentially NO corrosion of the kind you describe. I don't
think your problem is with the fresh water moisture. It sure sounds
like an electrolysis problem. Is your unit grounded per specs? Do
you have electrolysis problems in other parts of your boat?


There aren't any "gears". The new 2KW radomes have a flat piece of PC
board with a phased array of stripline antennas on them. It sits on a pin
where the RF enters from the waveguide. Around that is a pulley with a
rubber O-ring that's driven from a stepper motor pulsed by the PC board
inside the potmetal box. The motor is the same one used to pull the
printhead back and forth in a PC printer. The pulse rate sets the rotation
rate of the pc board antenna. No gears, it's cheap.

The water in the dome is fresh water. I've tasted it. It's condensate
from the air breathing in and out of the dome every day with no way of
escaping until the flat bottom of the dome is flooded enough to drain out
the tiny rubber tube grommeted into a hole in the flat bottom.

Too bad Raytheon isn't making good radars any more for small boats. Looks
like yours is much more sophisticated than ours.

You still need to find the problem. Every radar I have seen, Furuno or
Ratheon, has the drain tube in the bottom, so the interior is open to
the atmosphere, but protected from splash.



Rodney Myrvaagnes NYC J36 Gjo/a


"Biologists think they are chemists, chemists think they are phycisists,
physicists think they are gods, and God thinks He is a mathematician." Anon

Rodney Myrvaagnes wrote in
:


You still need to find the problem. Every radar I have seen, Furuno or
Ratheon, has the drain tube in the bottom, so the interior is open to
the atmosphere, but protected from splash.

Well, the problem must be with the design. There's been three DIFFERENT
radomes, the first two all got water in them. Raymarine said in "some
environments this happens". Sounds crazy. Charleston SC must be one of
them. I'm convince the same thing is happening inside the dome as a half
empty gas tank, which will just fill with water around here. Sucks in 100%
humid air at dusk, condenses all night, then the dense air blows back out
the drain hole when the sun shines on it until the sun set again when the
process repeats. A vented gas tank does the same thing, especially if its
sitting out in the sun with little gas in it.

The cure is to SEAL the dome. That's pretty hard to do with such thin
plastic and only 4 little screws holding the top to the bottom around the
seal, which only grips the bottom well. I'm for putting in a Muffin fan to
dry it out while its sitting at the dock. Hell, none of it's sealed,
anyways.....