[Amps] SOTA Solid State amplifiers

Jim Thomson jim.thom at telus.net
Mon Oct 20 17:29:44 EDT 2014

Date: Mon, 20 Oct 2014 00:34:37 -0600
From: John Lyles <jtml at losalamos.com>
To: amps at 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.


##  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

## 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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