The heater in the magnetron tube takes a couple seconds to warm to the point
where it will emit electrons. You can hear it easily on the old transformer
microwaves, the fan starts and it begins to hum, then a couple seconds later
the hum gets much louder. That louder hum is when the magnetron tube starts
Newer microwaves with switching power supplies may delay turning on the HV
until the heater has warmed up, and they may not have that transformer hum,
so it may be harder to tell when the RF comes on.
On Wed, 30 Nov 2016 17:16:05 -0600, Jon Elson wrote:
+1, You are the only one who did not lambast the OP for using the term
'warm up' to mean 'cause the ambient MW intensity to reach its operational
When I am judging time for extremely small loads (like softening butter
without liquifying it), I allow 4 seconds for my oven.
I find that the hum does not get louder though. Instead, I notice that the
fan speed lowers a bit, presumably because the supply voltage for the fan
is then being loaded down by the power consumption by the magnetron.
In sci.electronics.repair, on Wed, 30 Nov 2016 23:20:17 -0500, Mike
Just for the record, I consciously used the phrase, because it reminds
me of simpler times, harmed only by the extra time it took to turn on
the radio or tv. (In the movies, sometimes they would turn something
on and it woudl start immediately. I did stay at a hotel once 8 years
ago that was also operating in the 30's and it still had the remote
speaker/channel selector for the central radio it used then. Each room
had one and the patron could swtich between two or three stations, and
adjust the volume, so when you turned it on, it went on immediately.
Unfortunately, the hotel finally closed.)
I'm pretty sure mine is less tnan 4 seconds becuase I really have used
7 seconds and found noticeable heating, more than I think 3 seconds
would have done, based on the prior 10 seconds.
BTW, if you get one of those slabs of chocolate chip cookies, precut,
they say to cook them in a hot oven of course, but 37 seconds per square
does a good job. Not like baked, but like a differen4 recipe.
Another reason to know the startup time is if I make two of them, it
only has to start-up once, so it needs less than twice the time, but the
instructions already say less than twice the time, and their
differential is greater than 4 seconds. I think there is some reason
for that other than start-up, warm-up time.
Stick a compact fluorescent light bulb in the Uwave. It wil normally glow as soon as the microwaves actually come into the oven from the magnetron. It should be less than 2 seconds from the time you push the start button.
My Panasonic inverter seems to take up to 3 seconds to get going. That
device has a variable supply, which it can control heat output. Most others
are instant on.
Food still is cooking when power is off. As it cools it's also heating
cooler areas. Usuall recommended to wait one minute before eating. Enclosed
containers also equalize heating by steam. The microwave is a bit over 2
inches in length, so not all parts receive equal heating. There is usually
the rotating plate, but some have rotating devices in waveguide to spread
out the waves to also help equalize.
+1 I was going to say the same thing. It depends on the microwave
but my Panasonic is just like yours. So, 5 seconds is really 2
seconds and 10 seconds is really 7 seconds.
To the OP, two 5's is definitely not the same as one 10. As others
said, you should be able to figure out the start-uip time for your
Heating improves the physical "eatability" of products and also beats the
crap out of bacteria. If you cook for under the prescribed time to suit your
tastes then you need to understand about the bacteria.. Don't poison
Sorry, can't help you with cooking times.
When I tested it long ago, it took 2 seconds for the radiation to start hitting.
So a 2 second heating did nothing, a 3 second heating was actually 1 second, but a 60 second heating was 58 seconds which is close enough.
My wife has a strategy. If it needs 10 seconds, she hits 11, which lets her hit the same button twice instead of moving over to the zero and maybe missing. Same for 22, 33, 44 seconds. They're all close enough.
The way I tested it was to put a piece of wire in and watch for it to spark. I used a twist tie, bent in a rabbit ear antenna shape, at approximately the half wavelength. don't try this at home.
I have an older microwave, that has only 700W. Most directions are for
higher power. I find most things are OK if I add 25% to the cooking
time. For example, if it says 3 minutes I use 3:45.
BTW, some people have said that if I got a new microwave, it would
probably fail before the old one.
24 days until the winter celebration (Sunday December 25, 2016 12:00:00
AM for 1 day).
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