I was curious about this issue, so I sent a query to RayMarine a couple of years
ago. Here's what I asked, with reference to a SL72 radar:

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 I received:

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.

Jim McGowan
Senior Product Support Engineer

Raymarine Inc.
http://www.raymarine.com




By the way, the spec for my SL70 dome says that the power usage is 28 Watts
transmitting, 9 Watts standby. That's a pretty significant difference.

-jeff


"Bruce in Alaska" wrote
"Jeff Morris" wrote:
I often keep it in standby to save power and
magnetron time (they do wear out)

Just a point of note here. Leaving the radar in standby on most
civilian consumer radars does not save anything on Magnitron
Time. What wears out is the Filiment (heater) and that is
always ON whenever the Powersupply is on, even in Standby Mode.
To convise yourself of this, do this simple test. When you first
"Fire up" your radar, there is a timer that allows the Magnitron
to "Heat up and Stabalize", usually for three (3) minutes or so.
After that initial "Warm up Period", when going from "Standby"
to "Operate" does your radar require another "Warm up Period"?
If so, then you are correct on your Magnitron time statement.(Not very
likely to be this way) If not, then then "Standby" only save you
Transmit Power, and that's not really very much in most cases.
Most modern Magnitrons have between 2000 and 4000 hours of Service
Life and that is Filiment Life, really.

Bruce in alaska
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add a 2 before @