AEG Microwave repair

[joebog1]

Mike,
The transformer is a lovely door stop. They have a MASSIVE airgap to stop saturation.
I collected quite a few with a view of the "ever popular spot welder ".
They also mostly have welded laminations, forget the magnetic short, I make millions of these, says the manufacturer.
So if you want the HT to slowely die in your 500 watt transmitter, be my guest.
By slowely die I mean you will have about 3 seconds of 1500 volts HT, that will go down to maybe 800 volts as the airgap works.
PLUS the iron is usually 3/4mm to 1 mm thick, not grain oriented, which does nothing for efficiency. Stacked E's to I's, and not interleaved.
A nice transmitter traffos will supply a stiff 1500 volts whatever the duty cycle.
Oh, and I recommend a vacuum rectifier, or a solid sand bridge.

Joe

[Mike Watterson]

It is a doubler circuit.
Sorry I had to look again at the circuit. The cap would not supply current after the initial charge unless the diode was the opposite way to the magnetron.
Remember the anode of the magnetron is at ground the filament is at HT Negative. There is NO shorts on the HT side.

I stared at the schematic again. It is a doubler with the Magnetron as second diode and load. I was confusing myself.

Also as the anode is needing a heatsink, like a TWT, it makes sense to run the anode earthed and the cathode/filament at -ve EHT.

[Mike Watterson]

Mike, 
The transformer is a lovely door stop. They have a MASSIVE airgap to stop saturation.
…
So if you want the HT to slowely die in your 500 watt transmitter, be my guest.
By slowely die I mean you will have about 3 seconds of 1500 volts HT, that will go down to maybe 800 volts as the airgap works.
…

Seeing as I live at the edge of a small housing estate rather than in a totally isolated dwelling I'm wary of having more than 100W RF at HF anyway. Still, interesting that the 4CX1000A could do 70 MHz, or maybe band II. I think given the spectrum allowed here in Ireland a 100W transvertor for approx 30 MHz to 69.99MHz might be more interesting. The FTdx10 receives on 30 MHz to 75MHz, but only transmits on the UK 50MHz and 70MHz bands. I think so-called "widebanding" just fills in between 1.8MHz and 30MHz, it doesn't affect Band I transmit. I also have an FT817ND and it inherently is unable to do even 70 MHz. It's curious too that for Band II it uses a domestic FM radio IC. I removed one extra capacitor not part of de-emphasis and then the existing rear connector for data modes drives a home brew RDS decoder and stereo decoder.

Perhaps ex-microwave oven transformers are only good for neon lights or microwave ovens or home-made radar (do not look into the waveguide or stand in front of dish). Or ballast!

Being that I'm not far from Shannon and can see the Atlantic approach radar on Woodcock hill a pair of receivers would implement passive radar. Point a fixed one at the real radar and have the 2nd on moving dish for reflection, so I've no plans to build a 2.45 GHz radar with microwave oven parts. I suspect the magentron inherently does kW pulses and 800W average power, which was hand for radar rather than the CW Klystrons.