[Amps] Microwave Oven Power Transformer

[Steve Thompson]

Various thoughts, in no particular order.

Typically, the secondary gives 2.2-2.5kV across the caps with FWB.

I've played with a handful of them. Hipot testing the secondary 
with the wire to the frame lifted all but one have made 8kV, 
plenty enough for FWB use as is. The one that didn't arced where 
the wire came out of the bobbin and some kapton tape on the frame 
there brought it to 8kVish as well.

They often run the cores at high flux, leading to high magnetising 
current and core heating. Removing the filament winding and adding 
some extra primary turns in the space can help.

Secondary resistance can be higher than is usual for a similar 
'regular' transformer. Duncan Amps PSU designer will let you see 
regulation etc. Watch the rms current and calculate the 
dissipation, it can soar as the load current increases.

Don't forget to remove the shunts!

<http://web.archive.org/web/20030627162157/http://www.vaxxine.com/phil/QEX_HV_Power_Supply.pdf>

Take care, and have fun.

Steve
> I need a small supply (~ 1.5KV) to run a Motorola UHF Amp (pair 8560's).
> 
> My old microwave oven croaked so I salvaged the power transformer. It
> looks OK, but I wonder if anyone has used one in a supply. I plan to float
> the XFMR on a plexi plate and use a FWB Rectifier.
> 
> Any thoughts on this ??
> 
> 73, Dick, W1KSZ