What is the typical output voltage of microwave xformers?
Are they quiet?
I was under the impression that microwave transformers are designed for very low duty cycles -- only on for a few minutes at a time. At least, that would apply to home microwave ovens.
So there are barely enough turns on the primary, they do tend to hum, and draw a fairly high (reactive) current even with no load and are therefore prone to heating through i squared r losses in the primary.
But the above comes mostly from hearsay, so I would defer to people who have actually used them in transmitters that are used extensively on the air.
If you keep the windings tight, they are not loud. I remove the magnetic shunts and put in some wood wedges to keep things tight for the high voltage applications. Also adding some primary turns as well to help the efficiency(?). The only one that has been noisy was one that did not have the usual type of laminations and I damaged them a bit during the rewind. It hummed quite a bit, but it was fixed by putting a bolt through the holes in the laminations and clamping them tight.
I ran two similar MOTs with parallel primaries and series secondarys into a half wave bridge. I had linked them together and used the link to form a center tap. This worked very well but the voltage output was a bit low so I built up a Full wave bridge. Running them off of 120v mains didn't cause the tranies any problem, but I would 'Brown Out' the mains on key down. Switching to 240 volts series series configuration should fix that up. I originally tested the output into a 4000 ohm load, The output was stable, and the trannies only got good and warm. The DC goes into a choke input filter, with a large (sized) bleeder and smallish filter cap. I have 7 henries of smoothing and 4uf at 5kv oil cap. FWB makes a 120 hz ripple, but this seems to work ok.
The only application where they have failed was in my Tesla Coil power supply. Too much High Voltage Feed back through the primary of the TC and caused the MOT secondaries to arc over and burnt.
Feeding them in reverse provides a handy sized emergency Welder FWIW.
Someday I will aquire a Pole Pig. Then Things will become Interesting Indeed.
