Power tube rating for Twin Jet

[Emg77]

Well this is the second time ive tried to replace the kt-88 's in this amp. First time I could only get it biased up to 25ma's. Now I can only it biased up to 20ma's. I need to get it biased up to around 44ma's based on the plate voltage being 545, My question is .... is there way to get more range out of the bias adjustment? or what rating do I neeed to know to be able to pick a tube to get into this range ? any help would be great. Thanks!!

 

[Ventura]

This sounds like a call to Jorge or Charlie at Boggy HQ. Should be a piece of piss to get that amp to that zone.

Was it modded to take EL34s before you bought it?? Might be a piggy back resistor/cap on the MB.

Mo

 

[leib10]

My KT88s are rated at about 48, and I'm able to get the bias in range easily.

 

[Emg77]

Yes as a matter of fact it is modded to take either el34 and kt88's it has a toggle to switch between I thoought the toogle was to switch resisters to allow the bias range to be capable of either. Maybe there is an issue with the mod!!!

 

[TheSneakyTruth]

Did it used to be able to be biased in the right range? If not, my guess is the tech who performed the mod threw in a wrong resistor.

 

[Ventura]

Yes as a matter of fact it is modded to take either el34 and kt88's it has a toggle to switch between I thoought the toogle was to switch resisters to allow the bias range to be capable of either. Maybe there is an issue with the mod!!!

There it is - does the range change when you toggle? If there's no change, the toggle is pooched. If the range is wrong, the resistor is either pooched or incorrect.