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Microwave oven HV supply?

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MikeMl

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What is the approximate DC HV voltage that the magnetron in a microwave oven operates at?

What is the efficiency of the magnetron, i.e. how many Y watts from the transformer does it take to get X watts of oven rating?

What is the magnetron filament voltage? current?
 

MikeMl

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No, I fished a non-working microwave out of the dumpster today. Just wondering what I could use the hv tranny for. The windings all check ok for continuity. So does the diode. I didn't want to blow up my multimeter measuring the hv dc without having some idea what to expect.
 
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JimB

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From distant memory, a colleague of mine had the job of repairing a couple of microwave ovens for his wifes catering business.

The transformer put out about 1.8 to 2kV. The rectifier was actually a voltage doubler, the feed to the magnetron was from across the diode so there was a peak DC supply of about 5kV.

One thing I do remember and I am sure he does as well, when he tried to measure the magnetron supply using the company multimeter on the 2.5kV range, there was a bit of a flash-over in the meter, the internals of which were instantly toasted.:eek:

I have no idea what the heater voltage was, but I think the heater supply "floated" at the HT voltage.

These things can seriously bite you in the arse.:(

JimB
 

Nigel Goodwin

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The HT rectifier is a simple halfwave one, it's just that it's connected strangely - DC output is just under 3KV on load - using an old Avo8 on the 3000V range a microwave starts just off scale (but not bashing nastily on the end stop), and drops back to just below 3000V as the mag fires up. I've got an old Avo8 I use exclusively for that purpose.

The low voltage heater winding is very low, probably only a volt or two.

Safety wise - a microwave transformer is probably the most dangerous component you will ever come across - IT WILL KILL YOU, NO PERHAPS, NO MAYBES - DEAD!
 

MikeMl

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...
Safety wise - a microwave transformer is probably the most dangerous component you will ever come across - IT WILL KILL YOU, NO PERHAPS, NO MAYBES - DEAD!
Thanks Nigel,

but no less dead than the 3500V 1A supply I built for my 2kWpep RF amp for my ham station.

I was looking at the microwave tranny as a power transformer for a 1kW amp.
 

MikeMl

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Duplicate post
 
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Nigel Goodwin

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Thanks Nigel,

but no less dead than the 3500V 1A supply I built for my 2kWpep RF amp for my ham station.

I was looking at the microwave tranny as a power transformer for a 1kW amp.

I have a 10kV probe for my Fluke somewhere, so I will use that to check the secondary voltage.
Did you build two? :p

I've got a 30KV EHT meter at work.
 

HiTech

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This is a typical oven circuit:
 

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killivolt

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Foolishness.

I had this guy at work as I remember. I didn't really like him that much.

Anyway, one day we were talking as I was explaining the working of the Microwave to him I looked down and physically described where the mag was.

I said and be aware that thing it will bite........

This guy.

D,,,,,,u,,,,,,,m,,,,,,b,,,,,,,,,,,,,s,,,,,h,,,,,,,i,,,,,,,t.

Decides to stick his finger out pointing closer and closer to say " what you mean this little thing"

Suddenly an ark jumps off to his thumb through his hand and out his finger to the case.

Pulling it away I said............. see what I mean.:p

A very small hole was eaten through his hand and it left a white mark around the exit.

Somehow " Karma " play's with our Sorry " rotten " little life.

And this was guy was responsible for steeling my Fluke meters and my Tools.

I never found resolution but " Karma " made me feel a little better.:p

kv:D
 

sheldonstv

New Member
here are some microwave service manuals ..........
 

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unclejed613

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also be aware that there are two types of filter cap for the 5KV rail. one type has an internal 10meg bleeder resistor in it that discharges the cap within about 10-15 seconds. the other (older) type has NO bleeder resistor, and will hold a charge for quite some time. ALWAYS discharge the cap when working on the inside of the oven. i've fixed a few ovens in my day, as well as a lot of TV.s and computer monitors, and it's my habit to put a 'gator clip across the cap terminals or between a CRT anode cap and it's ground strap if the unit is going to spend any time on the shelf waiting for parts. i've been bit by caps and CRTs that had been previously discharged and subsequently recharged because of dielectric absorption.

i've heard about people at the service center where i work that were killed working on microwave ovens. they got careless while power was applied
 
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