[Amps] Old Moto RF Decks

[KA4INM radio]

   On 12/02/14 15:06, Manfred Mornhinweg wrote:

  /* snip */
> If you want to keep things simple, the easiest way to reduce IMD in
> solid state amps is to give them lots of negative feedback. To do that,
> you have to start with excess gain! 30 years ago that was somewhat hard
> to do. But nowadays there are FETs that have huge power gain in the HF
> range. Given that the typical ham needs an amp having just 12dB gain,
> you can burn up the FET's excess gain via negative feedback, getting
> improved linearity in a class AB amplifier.   /* snip */

   I agree with the need for feedback, but the operating mode with the 
best overall efficiency which is suitable for all modulation modes 
without switching is class "B" push pull operation.  Wide band solid 
state designs eliminates the only drawback to class "B" push pull 
operation with tubes which is the (double) band switching and tuning. 
Neutralization is a snap with cross neutralization and the maximum gain 
will be available for a little degenerative feedback.
   I have always considered class "AB" to be class "A" just without the 
linearity.
-- 
   Ron  KA4INM - Youvan's corollary:
                 Every action results in unwanted side effects.