I want to build one, not buy one. I'd like to find plans for something meeting
the specs below.
However, I have made a little progress with this endeavor. I friend of mine is
nearing completion of his EE degree and needs a project, so I suggested this
idea. We'll see how it goes -- he seemed quite interested.
Joe, N3JI
"Carcia, Francis A HS" <francis.carcia@hs.utc.com> wrote:
metron did an 800 watt 12 volt unit. A couple friends run them.
-----Original Message-----
From: Joe Isabella [mailto:n3ji@yahoo.com]
Sent: Friday, April 22, 2005 1:57 PM
To: Amps
Subject: Re: [Amps] Elecraft Amplifier (was Re: Fwd:Re: More Rumors)
So all this talk here about FETs and such, where can a layman like myself
find plans for say, a 100W in/500-700W out 12V amp?? I'd like to build
something along those lines for my mobile, but don't have the time to invest
in learning to design my own...
Thanks, Joe
Dave Haupt wrote:
Will,
If you know anything about the Elecraft people, you
would know that they would never "get by" with
anything. Everything they do is top notch.
It is possible to parallel FETs, but you're asking for
a whole lot more work in the process of matching them.
Even if your curve tracer shows that they're
electrically matched, if they're not thermally
matched, then once the amps starts delivering power,
one device can begin to hog the current, and you see
IMD rise precipitously.
Directly parallelling FETs works marvelously well if
they're on the same die, or packaged on the same
thermal header (e.g. MRF154/MRF157), but if you care
about IMD, it's not advisable to directly parallel
separate FETs which may or may not have come from the
same die lot.
They are using the Advanced Power Devices. Head to
that company's webpage, and read up the app notes.
K4XU is the chief apps engineer there, and Dick is a
very sharp guy. Think of him as the next Helge
Granberg, except that he's also earned his stripes in
contesting, as well as having a great reputation in
both the commercial (e.g. medical) amplifier field and
broadcast amplifier field.
73,
Dave W8NF
Will wrote:
>Vic,
>How many devices and or push pull pairs did they use
>for the power
>involved? I
>do know using FET's you can get by with one push-pull
>circuit and
>paralell
>FET's on both sides. This is a big advantage over
>using transistors and
>having
>multiple push-pull circuits with splitters and
>combiners.
>Best,
>Will
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