Rebiasing an Armadillo 1x2 amplifier to Class AB

[350GA]

I apologize if this is in the wrong section. Not particularly sure where to post this.

Good afternoon everyone. My buddy acquired an Armadillo Toshiba 1x2290 x 2x2879 Class C base amplifier recently, but as expected, it sounds like garbage on SSB. It does however have SSB delay, but no switchable biasing.

My question is, does someone have a diagram or pictures of how to bias an amp like this for Class AB? Possibly making it switchable would be a major plus.

I have kinda figured out part of the process, which is adding about .7v to to the bases of the transistors to put them into AB operation, but I'm not 100% sure on the process to do so.

Any help is greatly appreciated!

 

[kopcicle]

https://www.worldwidedx.com/threads/quick-and-dirty-class-ab-mod-for-kl300p.93982/

keep in mind a 1 x 2 is not an ideal amplifier chain.
Low, low,low drive. Like 2 watts or less. Remember to close down ALC as well as AM power.

 

[350GA]

Would this same mod work with this amp even though it runs at 16v while keyed? The PS floats at 21v while idling.

I wasn't able to see the pictures clearly, but from what I gather, I'll have to separate the bases of each transistor from ground, then supply the .7v to each base leg, correct?

 

[kopcicle]

https://web.archive.org/web/2006051...ricks.com/Amp/palomar/tx5300/tx5300_page1.gif

input transformer > center tap of input transformer output...
Lower right hand side of schematic > bias supply...

I'm hoping it's just careless typing...

I'll have to separate the bases of each transistor from ground, then supply the .7v to each base leg, correct?

The bases are never grounded (not exactly true, see "common base")
It isn't voltage but current draw @ voltage.

2sc2290 is so nearly the MRF454 so that this is good reading.
http://www.communication-concepts.com/content/AN762/AN762_Application_Note.pdf
Okay, anything Helge wrote is worth reading.

even easier ^^^

Only if you really want to put in the work...
https://www.eeeguide.com/dc-load-line-of-bjt-biasing-circuit/

And, from a previous rant...
https://www.worldwidedx.com/threads/pill-factory.230557/#post-628379

...