Re: phasing GDTs with MOSFETS

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Mitchell" <Electrontube-at-sbcglobal-dot-net> 

  Its very easy to screw this up which can cause a catastrophic faliure of
the MOSFETs in the bridge.  My motto is,  check the phasing, and then check
it again.  That was the problem with my first SSTC, as I had two GDTs and
the primaries got reversed, which messed up all the phasing (which I didn't
bother to recheck)

Regards - Jim Mitchell
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Monday, April 26, 2004 9:40 AM
Subject: Re: phasing GDTs with MOSFETS


 > Original poster: Jan Wagner <jwagner-at-cc.hut.fi>
 >
 >
 > On Sun, 25 Apr 2004, Tesla list wrote:
 >  > Original poster: Fucian-at-aol-dot-com
 >  > Hey all,
 >  > I was wondering how to phase my GDTs with my mosfets for my full bridge
 >  > sstc...
 >  > I have 2 GDTs...How should i go about doing this?
 >
 > The phasings of the two secondaries of a single GDT is the same as for a
 > half-bridge.
 >
 > For the full-bridge: 1 GDT to the left half of the bridge (left upper,
 > left lower). The other GDT flipped around - swap the primary leads -
 > connected to right half of the bridge (right uppper, right lower), done.
 >
 > If you measure with a dual channel oscilloscope on the lower left and
 > right mosfet gates (gate->source voltages, naturally) then if all is
 > correct they should be 180deg out of phase i.e. inverted wrt each other.
 > If not, just swap the other GDT's primary lead around again.
 >
 > cheers,
 >   - Jan
 >
 > --
 > ****************************************************
 >   Helsinki University of Technology
 >   Dept. of Electrical and Communications Engineering
 >   http://www.hut.fi/~jwagner/ - jwagner-at-cc.hut.fi
 >
 >