"Steve Lusardi" wrote in
:

At 6.36usec per radar mile, the pulse width must be less
than 1usec and the receiver must be on within nano seconds after the
pulse transmission in order to sense a close target.
Steve


The little 2KW Raymarine can see the docks three slips away from about 22'
up Lionheart's mizzen. It draws so little DC power its pulse width has to
be very narrow, indeed. I know of someone else who regrets putting the
radar atop the mast at 55' on a sloop because the bouys disappear about a
football field length away from the boat with the same radar.

This observation of the Raymarine 2KW is taken when the radar is new, not
after the internal condensation problems of Raymarine radomes has eaten
away the potmetal chassis, rendering it useless. I just put the third
radome up the mizzen.

By the way, for the Raymarine 2KW owners, the new radome has these little
plastic feet to hold the radome up off the mounting by about 1/2 inch. The
mounting bolts go through a hole in these feet. Looks like a patch for the
problem of stainless steel bolts and pot metal holes they screw into making
another galvanic battery to eat the chassis off from the bottom.

On Mon, 28 Mar 2005 05:12:28 -0500, Larry W4CSC wrote:


By the way, for the Raymarine 2KW owners, the new radome has these little
plastic feet to hold the radome up off the mounting by about 1/2 inch. The
mounting bolts go through a hole in these feet. Looks like a patch for the
problem of stainless steel bolts and pot metal holes they screw into making
another galvanic battery to eat the chassis off from the bottom.

Larry,
Do you think threaded nylon stand-offs with 1/4-20 nylon bolts
solve the problem?
Norm B

engsol wrote in
:

Larry,
Do you think threaded nylon stand-offs with 1/4-20 nylon bolts
solve the problem?
Norm B



Not at all. The condensation problems stem from the dome being open to the
air and exposed to the sun in a high humidity environment. It works the
same as a nearly-empty gas tank sucking in cold, wet night air when the sun
sets to condense inside all night and run down the walls, then blow air out
the little rubber tit at the bottom of the radome when the sun comes up,
boiling off what water it can in the heat of the day to create its own
rainstorm inside the OPEN pot metal chassis to eat away at the electronics
until the sun sets, again, to repeat the process.

The problem is not the bottom mounting, the problem is the "gas tank
effect" creating saturated hot air inside the dome because it's cheap to
make an unsealed dome that doesn't have to withstand a few pounds of
pressure......