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Message-ID: <lADzFKAjlzJ7MwYv@telemetry.demon.co.uk>
Date: Wed, 13 Jun 2001 10:58:59 +0100
To: rsgb_lf_group@blacksheep.org
From: "Tom Boucher" <tom@telemetry.demon.co.uk>
Subject: Re: LF: RE: 73kHz tests tonight
In-reply-to: <E159qJq-0006Ar-00@gemini.herts.ac.uk>
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In message <E159qJq-0006Ar-00@gemini.herts.ac.uk>, James Moritz
<j.r.moritz@herts.ac.uk> writes
>Only real problem so far was getting the gate driver to work - even 
>with both sections of a TC4427 driver IC in parallel, the drive 
>waveform had rather slow edges when feeding the 4 large-
>geometry FETs in parallel, so I ended up adding a "booster" with a 
>complementary pair of discrete MOSFETs in a circuit adapted from 
>one of IR's application notes. The driver transformer now seems to 
>be the limiting factor, but is OK for the time being.
>

Jim, Andy and group

My 136KHz full bridge PA uses one section of a TC4426 ac coupled to a
quintifilar (?) wound driver transformer and, like yours, the waveform
is rather rounded. My theory is that is not such a bad thing because it
provides some switch-on delay which prevents all 4 PA FETS being on
together.

I did try a single FET driver per Decca which took a lot of supply
current and although the drive waveform was better, the PA appeared to
be showing some instability tendency.

73, Tom