How exact must Tetrode Screen Voltage be?

[Naysayer]

How much can the Screen Voltage vary?
Is it like the Control Grid where it must be exactly what datasheet states?
Or can it vary a bit like the other tube grids & filament?

Everything I find online concerns Screen Current and that's addressed by the control boards.
Datasheets state the same value regardless of the other conditions. Will +/- 5 volts matter much for grid-driven DC grounded K?
neil Happy New Year, Hope for Peace in Ukraine.

 

[Naysayer]

Found the Answer, I think.
Re-read the 2004 Pride DX-300 Review/Manual originally published on CBTricks.com. Page 32, section 4.4, Item 7 states Screen voltage at tube pins can vary +/-10%. That’s a lot but good news for me as I’m bit low.

 

[Beetle]

Plus or minus 0.042 ohms or so.

 

[nomadradio]

Nothing about a vacuum tube is exact, as a rule. Screen voltage will be regulated to improve linearity, but the improvement might not be a lot. Standard textbook screen voltage for the 4CX250B tube is 250 Volts. The Pride runs closer to 340. Part of what makes it a hot rod linear.

73

 

[Naysayer]

Thank you all for the feedback on this. I've been using old tubes (300y's) to set voltage & current limits. Had to order a new current meter that I'm waiting on to do final adjustments before I put new tubes in it (300a's).

 

[RK20]

Screen voltage being exact is not as important as it being stable over the audio cycle.
Variations in screen voltage will modulate the RF power output.
A regulated screen voltage supply is a good thing if possible.

 

[nomadradio]

A regulated screen voltage supply is a good thing if possible.

Improves IMD, if you care. AM ops typically do not. Sideband operators should.

73

 

[Naysayer]

Screen voltage being exact is not as important as it being stable over the audio cycle.
Variations in screen voltage will modulate the RF power output.
A regulated screen voltage supply is a good thing if possible.

I noted the minimal nature of the Screen supply design of the Tokyo HyPower 4cx diagrams when compared to the rest of their circuit. I'm learning less is more efficient when it comes to RF.