[Boatanchors] 866jr Pwr Supply Problem

[VE7SL at shaw.ca]

Hopefully someone on the list can offer some suggestions regarding my recent 
dilema.....I have been running some 866jr's with a small power supply to get 
about 325V out with a choke input filter. It seems to work fine. Since I was 
needing about 400V I unsoldered all of the xfrmr leads and soldered on the 
ones from my 'temporary' replacement xfrmr to see what it would produce. The 
xfrmr sits on the table with all leads being about 10" back to the chassis 
underside. All worked fine until I switched the 'standby' switch to 'off', 
lifting the center-tap from ground. There was an onrush of current through 
the 866's (visible increase in glow) momentarily, blowing the fuse on the 
xfrmr's primary side. Any ideas why this happens? I replaced the fuse and 
promptly repeated the experiment :-(

I'm thinking perhaps some sort of back emf as the field collapses within the 
larger (not by much) xfrmr and may have something to do with the long leads?

Steve / tnx


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