12B4 help needed

[PixelPlay]

I would love to see if Tubecad would work however I am not going to purchase it without knowing first. SW cad III seems to work though.

Cheers
Greg

 

[Brett]

I would love to see if Tubecad would work however I am not going to purchase it without knowing first. SW cad III seems to work though.

Cheers
Greg

I have every piece of TC software except the parts inventory one and it's excellent and low priced/great value and supports the site.

 

[PixelPlay]

Hey Brett
First off where are you in OZ?

As far as the software goes, I am not sure that it will run on a windows emulator on mac.

Cheers
Greg

 

[Brett]

Sydney

 

[PixelPlay]

Melbourne myself,
Brett if you had to choose a Tube Rectifier, what would it be for the 12b4?
I had a EZ81 however the heater is loose and needs to be replaced. I have a voltage of 6.6v from the transformer (6.3v used on the EZ81).
I am not restricted by the socket because that can change (no case yet), I would just like to know which rectifier pairs well / sounds good?

Thanks for your help
Greg

 

[Brett]

I only use damper diodes: 6CJ3 etc

 

[bequerel]

If I would like to try grid bias with the 12B4A can I just short the 12B4A cathode to ground, and connect a 9V battery between grid and ground? Will I need a coupling cap between the attenuator (w/fixed resistors) and the battery?

 

[SY]

Yes, through the grid leak resistor. And yes.

 

[bequerel]

Thanks SY. 🙂

Any suggestions regarding the value of the coupling cap? (Introducing a large value coupling cap is really not tempting.)

When you say "through the grid leak resistor", do you mean that the 1M resistor goes in series with the battery or in parallel (bet i mispelled that word again)?

 

[SY]

Reprieve here: in series. But you spelled "parallel" properly, so an "A" for effort!

If the resistor is 1M, a 0u1 cap will be fine.

 

[bequerel]

Got it! 🙂