[Amps] GS-35b 2 meter amp - plate capacitor spacing from tube?

[TexasRF at aol.com]

Bill, with plate current that low, the plate load impedance is pretty high. 
 To match a higher impedance requires less coupling C. Less coupling C 
means you  need more tune C to keep the plate circuit in resonance.
 
If you increase the drive level, the plate current will rise and the plate  
load impedance will be lowered which will call for an increase in coupling 
C and  a reduction in tune C.
 
If you are unable to increase the drive power, then yes, you need to change 
 the tune C plunger to allow more tune C to be available.
 
73,
Gerald K5GW
 
 
 
 
In a message dated 6/10/2010 3:54:09 P.M. Central Daylight Time,  
billdz.geo at yahoo.com writes:

Any  Russian tube experts on this board?

Picked up a homebrew GS-35B 2 meter  amp, seems to be working OK, about 650 
watts out with 50 watts drive from my  FT-847.  The anode is tuned with a 
piece of copper that is pushed closer  to the tube or further away by a 
plunger controlled by a knob on the front  panel.  Power was still going up when 
the plunger reached its maximum  push on the copper, which leaves the copper 
about 3/4" (20mm) from the  tube.  Do you think perhaps the plunger needs 
to be extended to get the  copper closer to the tube for best output?  Plate 
voltage is 3300v, plate  current only about .23 amps.

73, Bill NZ5N/OM9ACA



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