Connecting a 6v6 output tube in triode mode?

[arwhite]

I've got a 5F1 champ that I built a while back. I'm trying to install a switch on it to switch between the regular 6v6 output tube connection and having the output tube connected in triode mode. I hooked it all up this afternoon and when I would switch to triode mode I would get a fairly loud hum through the speaker. I'm basically switching the screen grid connection of the 6v6 between the standard filter cap connection and being connected to the anode of the tube for triode operation. I've tried directly connecting to the anode as well as through 500 ohms of resistance. In each case I get the hum. Any ideas on what could be causing the hum? Is there a better way to connect it to get hum free triode operation?

[RedMan]

Single ended amps like Champs need extra filtering on the screens to keep em quiet. If your screens have much more than a hundred millivolts of supply ripple you'll get hum. In a push pull amp there's cancellation in the output. When you tie the screen to the plate you're getting all the ripple from the plate supply on the screens which is probably a few volts. I wouldn't add much more filtering with the tube recto but you can if you go to a SS recto.

[arwhite]

Redman, thanks for the info. I suspected it was something along those lines. I might try it on the deluxe kit I'm going to be building soon though since it is push-pull.