Microwave oven

Discussion in 'Electronic Repair' started by Richard G. Gould, Oct 19, 2008.

  1. 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
     
    Richard G. Gould, Oct 19, 2008
    #1
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  2. Richard G. Gould

    Franc Zabkar Guest

    On Sun, 19 Oct 2008 02:22:41 GMT, "Richard G. Gould"
    <> put finger to keyboard and composed:

    >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
    --
    Please remove one 'i' from my address when replying by email.
     
    Franc Zabkar, Oct 19, 2008
    #2
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  3. Richard G. Gould

    GregS Guest

    In article <>, "William Sommerwerck" <> 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
     
    GregS, Oct 23, 2008
    #3
  4. Richard G. Gould

    GregS Guest

    In article <>, "William Sommerwerck" <> wrote:
    >> I suppose they still use klystrons as deep-space power amplifiers
    >> such as in Apollo missions.

    >
    >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
     
    GregS, Oct 24, 2008
    #4
  5. Richard G. Gould

    Arfa Daily Guest

    "Richard G. Gould" <> wrote in message
    news:RRwKk.2054$...
    > 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
     
    Arfa Daily, Oct 24, 2008
    #5
  6. Richard G. Gould

    Turbo_Boss

    Joined:
    Oct 24, 2008
    Messages:
    2
    Location:
    Panama Republic of Panama
    Check this web site:


    .repairfaq.org/sam/micfaq.htm
     
    Turbo_Boss, Oct 24, 2008
    #6
  7. Richard G. Gould

    Baron Guest

    Ron Johnson wrote:

    > 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.

    --
    Best Regards:
    Baron.
     
    Baron, Oct 25, 2008
    #7
  8. Richard G. Gould

    neon VIP Member

    Joined:
    Oct 21, 2006
    Messages:
    1,325
    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.
     
    neon, Oct 26, 2008
    #8
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