[Amps] SB-1000 - 100ma minimum plate current.

[Vic K2VCO]

Tom Mandera wrote:

> I switch to OPR and key the exciter.  I'm supposed to see 50-80ma of
> plate, but I see 100ma immediately.

This refers to the plate current with ZERO drive, the STBY/OPR switch in the OPR position 
and the RELAY connector on the back shorted to ground. You can check this without an 
exciter connected.

> I heard the (tube?) sizzle (sounds like a good weld, not a good thing in
> a radio) while attempting to increase the exciter drive to hit 125ma of
> grid, and never reached it.

Probably an arc in the tank circuit or (hopefully not) the bandswitch, caused by 
underloading. Do NOT allow this to continue, it will do real damage!

Make sure that you adjust the load control high enough. When my SB-1000 is tuned to full 
output I have about 120 ma grid current. With less drive you should see less grid current. 
Too much is an indication of underloading.

The simplest way to learn to tune up an amplifier is to get an experienced ham to show 
you. It's easier than it sounds in the SB-1000 manual, which is very confusing. Just 
remember to keep the grid current down (and the plate current to 400 ma).

Incidentally, the RF output meter is very inaccurate and is useful only for relative 
indications (at least, that's how mine is).

-- 
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco