From: G0MRF@aol.com
Message-ID: <0.b84b3777.25964183@aol.com>
Date: Sat, 25 Dec 1999 10:49:23 EST
Subject: LF: FET's etc for LF.
To: rsgb_lf_group@blacksheep.org
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii; format=flowed
Content-Transfer-Encoding: 8bit
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org
Sender: <majordom@post.thorcom.com>

Hello Group

and a very merry Christmas to one and all.

If anyone is planning a little home construction over the holiday period you 
may like to look at a FET marketed by RS Components as an alternative to the 
IRFP450.

STW34NB20    RS catalogue number  313-2920.   

Voltage         500 V
Current         34 Amps
Power Diss      180 Watts
Rds  ON     0.08 Ohms
Package     TO247   as   IRFP450 etc.  Drain connected to tab.

Price #2.78  + VAT  in 1 off.

A small test circuit using two of these in class D comfortably produces 350 
Watts at 86% efficiency after the low pass filter.  I've tested with supplies 
from 24 to 60V and with qrss.
As the Rds on is less than a quarter of the IRFP450, the device may also be 
OK for lower Voltage operation.

I've also recently purchased a supply of  3C85 toroids from Philips.  
As there was a minimum order charge I've bought some of the 58mm cores and 
some smaller   15  x 8  x 5.5mm  (OD ID H) which are very useful for 
directional coupler elements. If a VSWR bridge is on your "to be built" list, 
and you need a core, let me know.

73   es a "bug free"  y2k

David   G0MRF