A propos of this -- what does it signify if the grid meter reads well below
zero when an SB-220 is idling at no drive?
73, Pete N4ZR
At 11:31 AM 1/16/2005, Vic Rosenthal wrote:
N7uvh@aol.com wrote:
Hi guys...
Been working on a sb220.. did the rectifer and choke mods. Replaced with
Harbah parts.
I have noticed that i don't have a idle plate and grid currant.
You should never have ANY idle grid current. If you do, your amplifier is
oscillating or something is wrong with the metering circuit. Zero signal
plate current should be about 160-200 ma (for two tubes) for good
linearity on SSB. If you are only running CW or RTTY, it will work fine at
zero, although it will take more drive.
i noticed that the right tube will glow some and the left tube does not.
One is weaker than the other or they are different brands (the Amperex
ones have significantly different characteristics). The one that is
glowing is doing most of the work. They can glow dull red, but if they
glow bright orange or yellow, you are exceeding the dissipation
rating. Or, maybe one is a carbon anode type and the other is metal.
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
_______________________________________________
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
|