I asked this question of RayMarine support a few years ago. Here's
what I asked:

"I am curious as to the lifetime of the magnetron, or any other related
components. I often leave the radar in Standby Mode to save power and
magnetron wear, but have been advised that the magnetron is heated in
standby and thus can wear out. How many hours use might I expect, and
will standby reduce wear?"

Here's the response:

"The magnetron is being heated anytime the radar is in standby. This
will not, however, significantly impact the life of the magnetron.
Actual transmit time is what really wears out the magnetron. If you
are really concerned about it, you can turn off the radar scanner by
holding the CLEAR key in for about 10 seconds. this leaves the
display energized, and available for the display of chart or data.
You can turn the scanner back on at anytime by tapping the POWER key
while on the radar mode. You will have to wait 70 seconds for the
warmup sequence to complete. In an EMERGENCY you can always bypass
the magnetron warm-up by holding in the ENTER key for 5 seconds.

"For systems installed on recreational vessels, we usually see upwards
of 12,000 hours of magnetron operation. That averages out to about 4
years of heavy use. In many cases, however, we see magnetrons last 10
years or more."

If the magnetron lasts 10000 hours, and wear is only 20% in standby
mode, then that's 50,000 hours, which is a very long time for a
recreational sailor.

Bruce in Alaska wrote:
In article , Jeff
wrote:


Note that magnetron life (which is a finite resource) is not used up
by standby time.


Actually, the above is not an accurate conclusion. Magnitrons are
a special type of Vacum (sp) Tube, that use a Filiment Anode, that
is Pusled at High Voltage, to create the RF energy that makes the
Transmitter Pulses. There are specific operational time limits
on filiment life for Pulsed and nonPulsed situations. Operating a
magnitron, with just the filiments lite does degrade the life of that
filiment, and will cause it to fail. It just doen't happen as fast as
when the unit is being Pulsed with High Voltage Pulses. Operational Life
is in the range of 1000 to 2000 hours and of that time, most figure 20%
will be in Standby Mode (filiment lite/no HV Pulses). Increasing
the Standby Time will extend Operational Life, but definitly not
forever, and as the filiment ages, MultiPulse, and Frequency Drift will
become issues.


Bruce in alaska