Transformer?

[chuckb]

Hey guys, I have a Thordason 21F08 filament transformer that I would like to use for the 5v winding of my 5F6A Bassman. My PT doesn't have a 5v winding and I'm currently using SS rectification.I would like to use tube a rectifier though. The problem is that the filament tranny is 6.3vCT @1.2A , pri.117v 50/60cps. Is there any way I can use this tranny for this application?

Chuck.

[chuckb]

Anyone?

[Tom Phillips]

I say no. Check out the tube data sheets and you will find that in addition to the fact that the voltage is too high, the showstopper is that your transformer does not have the current capacity to run any of the popular rectifier tubes that you would want to use in the 5F6A.

[chuckb]

Hey Tom,
Thanks for your reply,much appreciated.I'll just shop around for the right 5v tranny I need.

Chuck.

[imaradiostar]

There are quite a few 6 volt rectifiers out there- why not use one?

jamie

[chuckb]

I'm not to sure which one I would need?

[Tom Phillips]

I was wondering which one Jamie had in mind. I don't know of a 6V rectifier that will meet the Bassman needs and is commonly available. 6X4 comes to mind but is, I believe, not up to the task and can be pricy. (Compare the specs to the 5AR4 GZ34 and you will see) Seems like a lot of effort just to use your existing transformer.
Jamie?

[chuckb]

Hey Jamie,
To much effort for me,I may just keep the SS rectification untill I come across and the proper 5v tranny.

Chuck.

[imaradiostar]

You're totally right. I missed that it is for a 5f6a. I'd go with a weber or similar 5 volt add-on transformer.

Jamie

[Tom Phillips]

Chuck,
I should have asked earlier but what is your ultimate reason for changing to a tube rectifier?
Do you want to lower your plate supply voltage and add more sag? That's part of what will happen if you change the rectifier and keep the same PT.
Regards,
Tom

[chuckb]

Hey Tom,
Yes, that's the reason for the change.

Chuck.

[imaradiostar]

zener voltage dropper (or mosfet+zener) plus a resistor for sag would get you in the ballpark and the parts count is low. Price is below any tube rect I know of too.

You could wire that Thorardson as a buck transformer to lower all the voltages in the amp by a percentage. Should give you about 95% of your current voltages.

jamie