"tflfb" wrote in message ...

I have a 700 watt Microwave( Whirlpool ) oven above the kitchen
stove, its a micro/ exhaust fan combo.

Is it possible to have a bigger tube installed in order to up the
watts, to at least 1100.

Also the oven is 10 yrs old, takes forever as it is to heat anything.
There's a crack in the plastic trim on the door.( cosmetic)

I was never aware when I bought the oven that watts made a
difference when cooking.

A new oven is going to cost me at least $275, I will install
it my self.

Do you know how to install microwave tubes correctly? If you don't do
it correctly you can cause high levels of microwave leakage, and I do
mean high enough to cause skin burns and cataracts. And remember, you
cannot reliably measure leakage with a cheap meter! Some of those
meters will indicate tremendous leakage even with no microwave devices
nearby (not even phones), while others will show zero leakage even
when sitting inside a running oven. The only good meters are tuned
specifically for the 2450 MHz frequency used by ovens and cost at
least $300.

How much power is your oven putting out currently? You can measure
this with a thermometer, glass or plastic bowl, and exactly 1 quart or
1 litre of tap water. Fill the bowl with the exact amount, and stir
the thermometer in the bowl and record the temperature. Heat the
water at full power for exactly 60 seconds, and then again stir the
thermometer in the water and record the temperature. Assuming that
you used 1 quart of water and a Fahrenheit themometer, the power in
watts is 70 times difference of the beginning and ending temperature,
but if you used 1 litre of water and a Celcius thermometer, the power
in watts is 37 times the temperature difference.

Microwave ovens naturally decrease in maximum power with time, maybe
because the permanent magnet on the magnatron tube weakens, and it's
possible that a 10-year-old tube is putting out only 50-70% its
original power. Also the industry specifies microwave oven power
differently now, by something called the "IEC method," that seems to
give higher wattage numbers than the old method. You may want to test
a fairly new oven to see how close the method described above compares
to the IEC method.

Another way to boost microwave power is by increasing the size of the
high voltage capacitor, and at least one Japanese company changed
nothing else in their ovens rated from less than 500W to about 900W.
But if you try this yourself, don't go more than 20% over the original
size. After I changed the tube in our Sharp convection/microwave, I
decided to try this trick by replacing the original 0.8uF capacitor
with a 0.95uF, and I measured a proportional power increase. The new
tube lasted about as long as the original, 8 years. By the way, some
sources are far cheaper than others for microwave parts, and I've used
Wondral/EPS (1-800-227-0104) and MCM Electronics.
Also parts for some brands of ovens are much more expensive than
others, with Sharps being among the cheapest.