Date: Mon, 20 Oct 2014 00:34:37 -0600
From: John Lyles <jtml@losalamos.com>
To: amps@contesting.com
Subject: [Amps] SOTA Solid State amplifiers
Manfred Mornhinweg, Warren Pratt and others have added some healthy and
interesting topics to this discussion on amplifiers. Whereas most of the
chatter is usually particulars of various brands of mostly tube
amplifiers and favorite tubes, I appreciate the addition of alternative
solid state amplifiers with very high efficiency, needing distortion
correction, but using inexpensive devices. There is another group online
on AM phone that does a lot of class E transmitter development, and they
too are using plastic switchmode devices in new ways. Thanks guys for
adding some fresh topics in here.
73
John
K5PRO
## agreed. My problem with the present crop of SS gear is they typ run 50% eff
at rated po. And that drops down to 35%, when run at 1/2 rated po.
## Although the MRF-150 is dated, the latest version, VRF-150G works
pretty good, imd wise, a huge improvement. A buddy built the arrl VRF-150G
amp and it works very well. Driven by a K3. K3 being run at 30 watts
out....which
is its imd sweet spot. Then a 6db pad into the VRF amp. The 200-250 w amp only
needs
aprx 7.5 watts to drive it. What might be tried next is to increase the NFB
in the SS amp
by 6 db.... then remove the 6db pad. On paper, this should improve the imd
by another
5db.
## The SS amp is used as an IPA to drive a YC-156. The K3 is not very clean at
100w.
Jim VE7RF
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