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In Reply to: RE: red plates ... bob and weave ... posted by rage on September 24, 2021 at 12:29:04
"2.5K seems to be a standard value for a 2a3 at 250V"
2.5k is the standard for a 2a3 at 250volts plate to cathode but at 60ma.
Dennis runs at 43ma.
"Paul Joppa may have eluded to successful use of 2.5K here"
In fact it is Paul's math I used to determine 3.9k.
Paul's math follows the Western Electric chart very well.
If you want the least HD (across the board) while still having some power, it's a good rule of thumb.
load impedance = (voltage / current) - (2.38 * plate resistance)
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Follow Ups:
It is all about the delta V caused by the load R and the delta-i through it. At lower current there is a larger voltage to swing across between idle B+ and where the load line hits 0V. keep in mind this same voltage ideally must be supported by R as you take the idle current towards zero. With too little R, the line is steep and you hit zero current way too soon compared to going the other way... :)
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
thanks tre', appreciate your well explained answer.
Edcor has the CXSE 3K that claims 41H of inductance.. I'd like to give that transformer a try as I hope it may be a good compromise between 2.5K and 5K... (their 5K is rated 50H!)
Edcor dos not say how they measure so you realy don't know what there datasheets mean. This is also true for Magnequest.
They don't give real measurements with a tube for instance (or with a specefic Ra).
If you want realiable measurements Tango is the ONLY manufacturure that dos give accurate measurements.For those who use Lundahl, Tribute or Monolith Magnetics.... Please publish your measurements so people here can learn how these transformers behave in real life. I guess only MM will do a decent job (but there site sucks, but is a lot better then Lundahl or Tribute)
Edits: 09/24/21
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