… If you're really curious, you'll need to place an ammeter in-series with your screen, set for an Average reading, and play the amp as loud as you'll play it. ...
How to measure screen grid dissipation with reasonable accuracy though, what meter settings to use? ...
I have not done it, but Page 10 of
my meter's manual talks about its capability to make "Min Max Average" readings over time.
I haven't tried recording Average Screen Current in this manner, but I have used it in the past to observe Min/Max Voltage to catch peaks when a scope wasn't available.
And personally, I'd wind the amp up as loud as it went, and bash a guitar as hard as I can to generate my "Average Screen Current." Real life conditions oughta be less severe than that.
How to measure screen grid dissipation with reasonable accuracy though, what meter settings to use?
... DC readings will be ‘average’, rather than the rms that is required for the power calculation.
Perhaps you were more focused on "Voltage" and "Dissipation."
I think that's a recursive problem: I envisioned someone starting by dividing Screen Dissipation Rating by Average Current. Then start with Idle Volts and determine the Voltage Drop needed to land on the output of the last step. Voltage Drop / Average Max Power Screen Current gives a resistor value.
But Screen Voltage at the filter cap likely will drop some amount, and reduce Screen Volts below what is needed for protection. Now one might use that Min/Max/Average function again to identify Minimum Screen Volts with the new screen resistor in place & bashing at max volume.
The steps above will probably tell us we went too far with the initial screen resistor value, and now we might do a back & forth dance dialing it in by repeating all of the above steps.
Or we copy a resistor value off some amp until tube failures prove we need a higher resistance.
Topic: Tweed Deluxe - Power supply choke/resistor switching? (Read 3395 times)