Hybrid shunt reg split

[johnsonad]

A year ago I had asked about different configurations for the hybrid shunt reg set up in the Paramount.  Currently I'm running a 6SN7 in standard configuration.  My amps are on large chassis and I was thinking about splitting the shunt reg and driver into two tubes.  For the driver, I plan on first trying my current go to tubes, 2C22 and CV6 which are half of a 6SN7 variants but I would like to be able to try other single triode octal tubes potentially in the future.    Do you have a recommendation for a shunt reg  tube that draws 300mA or less current and would be easy to use and possibly small and cheap?  Worst case I use a metal can 6J5 of which I have quite a few of.

If I were to use a metal can 6J5, would I need to ground the can?

Thanks,

Aaron

[Paul Birkeland]

I tend to use the 6J6 as a generic tube for use with our hybrid shunt regulator when some flexibility is needed.  It draws a little more heater current than you requested, but you have the option of connecting one or two of the plates to the regulated B+ to adjust the cathode voltage to sit in the desired range.

Be sure to observe the 300V maximum plate voltage rating (the more contemporary Paramount soft-start circuit is regulated to 300V, so you're fine there), and the plate dissipation of 1.5W, which means that a maximum of 5mA per plate can be sunk through the 6J6.  If you need to sink more than 5mA, tie the second plate in and you can go to 10mA.

With 300V on the plate and 1mA-5mA of current on one plate, your cathode voltage will fall between 7V and 12V DC, which is a happy place for the TL431 to operate.

[johnsonad]

Thank you for the explanation PB!