On Fri, 24 Jun 2005 20:05:29 GMT, 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

The bit that's pulsed in the magnetron is the cathode at the centrer
of the gadget.
The anode surrounds it, and is the machined copper piece with the
cavities.

But Bruce has it mostly right, I reckon

Brian Whatcott