What tubes were in it to start with? I would have guessed EL34s.
I see the screen resistors are 470 ohms, so perhaps 6L6s?
Ah, I googled it, it came in either EL34s or 5881s.
As with any amp:
Load the heater winding down either with all 8 EL34s or equivalent load to see if the power transformer can handle the increased heater draw.
check to see that pin 1 is connected to pin 8. I'd increase the screen resistors to 1k 5W myself.
verify the bias adjstment has enough range.
I see the screen resistors are 470 ohms, so perhaps 6L6s?
Ah, I googled it, it came in either EL34s or 5881s.
As with any amp:
Load the heater winding down either with all 8 EL34s or equivalent load to see if the power transformer can handle the increased heater draw.
check to see that pin 1 is connected to pin 8. I'd increase the screen resistors to 1k 5W myself.
verify the bias adjstment has enough range.
Hi, I have 2 9200's, 1 9100, and a 20/20. The mentioned current draw of the heater current is one issue. The other issue is B+ current. The 5881's in my experience have an average Ip (Bias current) of 22 and the EL34's an average Ip of 26. So the El-34's will draw more B+ current. So the Bias supply circut will have to be modified to provide a higher Bias current aside from the Bias adjustments at the power tube circuts. The 9200 is a pretty reliable piece of equipment on 5881's , especially the WRT versions.
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