[Amps] Henry 3 KD Premier with 8877

[Ron Youvan]

   Buzz WA4GPM Miklos wrote:

> Does anyone have any first hand experience with this amplifier?  I’m particularly interested in the 10 meter performance (Eb, Ib, Pi, Po).  Maximum power output at .9A of Ib is only 1200 watts with efficiency at 43%.  The lower frequencies are more typical for an 8877, ie, 1500 watts out with efficiency around 64% and Ib at .75A.  Any theories to explain the low efficiency on 10?

   Not me, but in general the:

CHARACTERISTICS             from the CPI datasheet
Plate Dissipation (Max.)       1,500 Watts
Screen Dissipation (Max.)      ---
Grid Dissipation (Max.)        25 Watts
Frequency for Max. rating (CW) 250 MHz
Amplification Factor           200

   The high gain and 250 MHz for full ratings suggests troubles related 
to 29 MHz is mostly related to the circuitry surrounding the tube.
   Designing an amplifier for a fixed 28 MHz operation results in a 
circuitry that is seldom copied in a 1.8 to 29.97 MHz multiband 
amplifier at 10 meters.  So compromises are problems at the higher 
frequencies where the preciseness of things become more important.
Efficiency suffers.

also:    Ep    A   Pdrive  Poutput
	3,500 1.0   64     2,075
-- 
   Ron  KA4INM - Youvan's corollary:
                 Every action results in unwanted side effects.