[Amps] SB-230 drive VS power output

[Ron Youvan]

On 03/26/13 11:55, K4MT wrote:

> I have been fighting with my SB-230. Initially I was getting 500 watts CW key down with about 85 watts drive and over 600 on my peak reading meter on SSB.
> I slowly lost gain and finally I was only able to get about 300-400 key down and about 450 ssb peak. I decided the 8873 may have died.
> Today I took the tube out and cleaned the Beryllium block and heat sink, and also cleaned a black badly tarnished grid ring and replaced both bypass caps. When I put it together with new thermal grease etc, I now am back to 500 watts cw and over 600 peak on SSb. This is with about 85 watts drive. Don't know what fixed it!?
> Is the normal for these amps as I can find no specs listing output power vs drive level.  I noticed at 100 watts drive there is noticeable flat topping but at 70-85 watts I get a nice clean scope display.

   Measuring the values of the two removed capacitors might shed light 
on the mystery.  The grid/s must be kept at RF ground for proper operation.
-- 
Ron - KA4INM