Re: Hexfet & Power FET finals.. thoughts?

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From: Jim Kortge, NU8N (jokortge@sun.lisp.com)
Date: Tue May 16 1995 - 22:05:55 EDT


Jay Coote wrote...
>
>Does anyone have comments on using n-channel HEXFETs such as the common
>IRF-511 for the final in a 1-5 watt QRP transmitter for the MF/HF bands?
>
>
Jay, I have an amplifier that I designed using a pair of MTP3055 MOSFET's.
It easily puts out 12-15 watts cw on 40 and 17 meters. I am running it
class AB2 in SSB operation driving it with one of my Mizuho rigs (about 2
watts output) running on the bike.

At Dayton, Doug, KI6DS, and I talked about refining the design and maybe
making a kit available via NorCal. Lots of work to do before a real kit
exists. In the meantime, I could send you a schematic of the design that I
am using, and you could cobble one together, with some effort. Let me know! :>)

I also tried other MOSFET's such as IRF510's 520's etc and didn't find that
I could get as much power out of them, as I could the MTP3055.
Also, I have the PSPICE model for that device (compliments of Motorola)
which makes modelling the circuits in PSPICE a lot easier.

That's my $ .02 worth.....good luck and have fun!!!

72/73.....Jim, NU8N

Jim Kortge, NU8N | Bicycle Mobile Hams
jokortge@lisp.com | __o of America
Fenton, MI |_`\<, Mizuho 17m/40m QRP SSB
.... .. .. . . . .. (*)/(*) . . . . . ..


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