SB-200 Questions

[Robert Keeble]

Hello group,
I recently acquired and SB -200 and it was shipped parcel. Arrived fine but the 572-b s were wrapped and stored on top of the fan and must have taken a lick and bent the blades down and I didn't notice it until I fired it up. Opened it back up to straighten the fan out and discharged the anode clip of the tubes to chassis like the book said. Really got a big pop when I did and an immediate black spot the size of a quarter at the lower side of the glass bulb  and a smaller one on the other tube.
    It seems like it may have damage the 572 tubes because after that incident, I can only load it up to about 250 watts and was able to reach 600 before that.

Also show no plate current at all at idle (exciter at minimum) and the book says the reading should be 90 ma. After adjusting tune and load for max reading out, I can increase exciter to max (100 w) and then retune the drive and load for max.   
 Finally retune the load control to keep plate within 500 ma range.

All the while, the grid reading is way down on the low side of the scale never getting over about a fifth of the way up the white scale.

Also, both of the 572 s plates begin to glow red to orange after  less than a minute!

I see similar results when using my Icom 746 or my SB-401 to excite the amp. (The amp also has the soft key installed)

I am thinking I need to replace the tubes but before I shed a c-note, I thought I would ask for some advice!

Thanks in advance for any wisdom that you all can share. 

Maybe I qualify for the "Stupid Ham Trick" award for ruining my tubes!  

Bob,  KG4NVX

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