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Microwave oven

R

Richard G. Gould

Jan 1, 1970
0
It appears that our microwave oven has lost cooking/heating power over the
years. Is that possible: Can the magnetron put out less power as it ages?
How can one test the heating power of a microwave oven: Perhaps by heating
a known quantity of water to a desired rise in temperature over a prescribed
time period? Are there any such measures for a microwave oven of a known
original/rated power?

Rick
 
F

Franc Zabkar

Jan 1, 1970
0
It appears that our microwave oven has lost cooking/heating power over the
years. Is that possible: Can the magnetron put out less power as it ages?
How can one test the heating power of a microwave oven: Perhaps by heating
a known quantity of water to a desired rise in temperature over a prescribed
time period? Are there any such measures for a microwave oven of a known
original/rated power?

Rick

Notes on the Troubleshooting and Repair of Microwave Ovens

7.1) Testing the oven - the water heating test:
http://www.repairfaq.org/REPAIR/F_micfaq4.html#MICFAQ_017

- Franc Zabkar
 
G

GregS

Jan 1, 1970
0
I don't know where you get your information, but microwave ovens use
magentrons. A klystron is a rather different sort of microwave device. For
one thing, it's an amplifier, not an oscillator (unless you misalign it,
especially the B cavity).

I know about these things, because I used to install and align klystrons. I
could tell you a few "Jedi tricks".


I suppose they still use Klystrons as deep space power amplifiers such as in Apollo missions.
I think the standard power was 20 KW and made by Collins. A Hydrogen Maser
was also used as a low noise amplifier and was used as the primary frequency
standard, Cesium second. I just updated my learning from the web. A Cesium
standard is basically a Xtal oscillator buffered with a atomic feedback loop and
has poor short term stability. The Maser has the best short term stability and porr long term.

greg
 
G

GregS

Jan 1, 1970
0
The Apollo mission was not "deep space". Nevertheless, I installed several
Varian klystrons in NASA's STDN.

Well the moon was a bit farther away. I don't remember what things
were tracked by the maser. Maybe it was just a backup, but easily overloaded
on strong signals. All the 3 main 85 foot MSFN/STDN stations had masers.
After Apollo, ERTS or Landsat was the main preoccupation. Tracking the
Alsep packages on the moon was also done for a VLBI experiment.
After that the stations were also recording Helios orbiting the Sun, a
very week signal. You really had to play with it to get phase lock.

Here is a link to the NASA bible for the stations. Its a big file....
http://zekfrivolous.com/nasa/NASA-SP-87.pdf

greg
 
A

Arfa Daily

Jan 1, 1970
0
Richard G. Gould said:
It appears that our microwave oven has lost cooking/heating power over the
years. Is that possible: Can the magnetron put out less power as it
ages? How can one test the heating power of a microwave oven: Perhaps by
heating a known quantity of water to a desired rise in temperature over a
prescribed time period? Are there any such measures for a microwave oven
of a known original/rated power?

Rick

The waveguide on the output of the mag (and it is a mag - ignore what
clodhopper says below about it being a klystron) can become coated with
resolidified vapourised grease and clag from the food that's been cooked in
it - especially if it is a combination type that has a conventional oven in
it as well. This can result in substantially reduced microwave cooking
efficiency.

Arfa
 
B

Baron

Jan 1, 1970
0
Ron said:
It is possible (IME) for magnetrons to lose power over time, sometimes
the antenna cap gets eroded away and sometimes you find cracks in one
of the magnets.

Ron

Yes they do loose power over time ! It depends upon how fast the
filament/cathode looses the ability to produce electrons. Often
Thoriated Tungsten is used in the heater ! If it gets hammered it
rapidly looses emission.
 

neon

Oct 21, 2006
1,325
Joined
Oct 21, 2006
Messages
1,325
In article <[email protected]>, "William Sommerwerck" <[email protected]> wrote:
>>> It appears that our microwave oven has lost cooking/heating power over

>the
>>> years. Is that possible: Can the magnetron put out less power as it ages?
>>> How can one test the heating power of a microwave oven: Perhaps by

>heating
>>> a known quantity of water to a desired rise in temperature over a

>prescribed
>>> time period? Are there any such measures for a microwave oven of a known
>>> original/rated power?

>
>> It's not a magnetron, it's a klystron. It's a tube and tubes get weak.
>> But more likely, one of the power sources has become weak.

>
>I don't know where you get your information, but microwave ovens use
>magentrons. A klystron is a rather different sort of microwave device. For
>one thing, it's an amplifier, not an oscillator (unless you misalign it,
>especially the B cavity).
>
>I know about these things, because I used to install and align klystrons. I
>could tell you a few "Jedi tricks".



I suppose they still use Klystrons as deep space power amplifiers such as in Apollo missions.
I think the standard power was 20 KW and made by Collins. A Hydrogen Maser
was also used as a low noise amplifier and was used as the primary frequency
standard, Cesium second. I just updated my learning from the web. A Cesium
standard is basically a Xtal oscillator buffered with a atomic feedback loop and
has poor short term stability. The Maser has the best short term stability and porr long term.

greg
FANTASTIC YOU TELL ME THIS AFTER I SPEND MONEY FOR A CESIUM ATOMIC CYNCH WATCH. Stupid thing misses a second every 20 millions years. wasted my money again.
 
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