From: Chris Wilson <dead.fets@gmail.com>
Date: Sun, 4 Jun 2017 12:10:11 +0100
Message-ID: <1142673460.20170604121011@gmail.com>
To: rsgb_lf_group@blacksheep.org
In-Reply-To: <15c725d9c9b.marcocadeddu@tin.it>
References: <15c725d9c9b.marcocadeddu@tin.it>
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Subject: Re: LF: For today the FETs survived... and are working!
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Status: O

Hello LF'ers,
04 June 2017

Marco,  do  you have the means of posting screen shots of the gare and
drain  wave forms?  I  am  always keen to see just what people consider
good and bad ones and a capture speaks a thousand words. Glad you seem
to be progressing with this now! Crossed fingers for you!  :)

This  is  a  capture  of  my latest amp on 52V @ about 18 Amps Gate is
lower trace, drain upper.

http://www.gatesgarth.com/capture.jpg


Best regards,
 Chris  2E0ILY                          mailto:chris@gatesgarth.com


> Good morning LF &VLF :-)

> I had not a big choice among available cores for the driver xfmr.. and
> finally I choose a BN43-202 with a lower AL but higher cross section. 
> Now the driver xfmr is wound 10T primary and 22T+22T of sec (it had to
> be 20T but the cutted wire allowed a couple of turns more ;-) )
> Now have provided much confortable test points for the gates too.
> So I wired everything and replaced the original 150µH coil with 
> 4x2200pF in the output tank and have again available(but not yet 
> connected) the 25T for the guard circuit.

> the gates now are switched with a square wave (a bit smoothed in the 
> rising side) swinging from + 20 to -10 V with respect to ground.

> The tx is running since about half an hour at 50Vdc and only the dummy
> load is warming a bit.
> With 7T/19T xfmr on the output it is puring 35Wout with 45W input

> Unfortunately I cannot rise the supply continously from 50V to the 
> final 180V.. so will let it to be used to eat 50V and later give 180V

> Cross your fingers!

> Marco IK1HSS


-- 
Best regards,
 Chris                            mailto:dead_fets@gmail.com