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@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
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|