Yellow Jacket opinions

[Helmholtz]

Notice that there's a black lead on the Yellow Jacket base. I'll bet this is intended to be grounded/earthed to the chassis.

Good observation. I also think that the black lead is used to short-circuit any existing cathode resistor and use the internal resistor for biasing instead. This would allow for better center biasing.

[Chuck H]

Good observation. I also think that the black lead is used to short-circuit any existing cathode resistor and use the internal resistor for biasing instead. This would allow for better center biasing.

Right. And since guys are using these things in their Marshall heads I think there also must be a DC blocking cap for the grid in there as well.

[Helmholtz]

Right. And since guys are using these things in their Marshall heads I think there also must be a DC blocking cap for the grid in there as well.

Yes, it's descibed here: https://www.yellowjacketstc.com/detailed-information
Many different versions.

[shortcircuit]

After visiting the Yellow Jacket homepage , they make a yellow Jacket recommended for the Vibro Champ , it's not the one I have . Apologies for not going there first.
https://www.yellowjacketstc.com/ampl...ecommendations posted before seeing post #18,as stated before "one of those days" Please don't throw me in the storm drain

[Dave H]

I'd want to know more about what's inside that converter socket so I could equate the changes to real world circuit analysis before putting my stamp on using them.

I don't know how accurate this is. It's all I could find.
Looks like both the plate and screen voltage are reduced by 100V

[Helmholtz]

I don't know how accurate this is. It's all I could find.
Looks like both the plate and screen voltage are reduced by 100V

[ATTACH=CONFIG]56280[/ATTACH]

Do you have any idea which of the many Yellow Jackets converters this refers to? I understand that some of them reduce plate and screen voltage while others don't.

[Chuck H]

Good find. It seems that there are several models though. The site is rather ambiguous about the actual circuitry in each model.

It reads to me that the one they recommend for the Vibro Champ is just a pin converter. That's not a very good idea IMO. Running an el84 at 400+Vp - Vg2 with no screen resistor and a 470R cathode resistance?!?!

[Dave H]

Do you have any idea which of the many Yellow Jackets converters this refers to? I understand that some of them reduce plate and screen voltage while others don't.

From the descriptions of their web site I'd think it was a YJS

[Helmholtz]

I think model YJC with the ground wire and (probably) voltage reduction would be the best choice. Will reduce power, though.
Ground wire shorts the existing cathode resistor.