[Amps] Drake L4B to 6 Meters Help

[Ron Youvan]

   On 12/12/2016 10:01 AM, Michelle wrote:

>     I have converted a Drake L4B to 6 meters and I seem to be stuck at
750 watts output, I have tried a PI input (no change) , different tank 
coils
(less output), The current setup listed below I have checked both input and
output with a antenna analyzer at 50.125 and they both seem to be right on
spec. Thanks in advance for your comments.

> Plate volt 2300 under load
> plate current .650
> Grid 220
> Drive 100 watts
> Output 750 watts

> Input circuit T match (works as it should, flat match)
> Plate cap 3-30 pf vacuum variable
> Load cap 25-350 pf (original Drake plate cap) 1/3 meshed at max output.
> Tank circuit PI-L, L1 3 1/2 turns 1/4" copper tubing 1 1/2" id, L2 4 turns
16 ga 1" id.
> RF choke 42 turns of 22 ga on 1" porcelain form
> Bifilar choke Stock Drake 20 turns each leg of 10 ga on 5/8 ferrite rod
> All grid pins directly grounded to chassis
> Parasitic suppressors are 47 ohm 2 watt with 1 turn 16 ga
> T/R relay changed to vacuum relays

> What am I missing here? Has to be something really simple I'm overlooking,

> Thanks again for your comments,

   You don't say your modulation mode. (CW - FM or SSB whatever that is)
   I'm no expert, but you are achieving 50% efficiency, that doesn't
sound bad to me for 6 meters, to get more power out you need more
power in.
   I would double the plate Voltage.  That increases efficiency.
-- 
   Ron  KA4INM - Youvan's corollary:
                 Every action results in unwanted side effects.