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Tubes Asylum Questions about tubes and gear that glows. FAQ |
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Tubes Asylum Questions about tubes and gear that glows. FAQ |
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In Reply to: So I guess the logical question would be... posted by Ivan303 on December 14, 2014 at 08:05:49:
At 275vdc plate to cathode, about 63ma, but now the plate dissipation is 17 watts but the JJs can take that.
Otherwise 250 at 57ma.
Side note, The "classic" OP of 250 at 60ma really wants a load of 2.25k but tubes are forgiving.
But at 275vdc at 40ma into 2.5k, the HD at 3 watts output is high. About 13%
If you increase the load impedance to 5k, the HD at 3 watts drops to about 5.5%
The above is in line with the math and in line with the "Triode Loadline Simulator" and in line with Paul Joppa's formula.
The Triode Loadline Simulator is a little tricky to use. You have to start by reduce the yellow grid swing lines to get the OP* where you want it and at higher load impedance's you have to increase the Uamax voltage in the box below to make the higher load impedance's reachable on the graph.
Once you get your OP, you can then move the grid swing back out to match you intended use.
* note, it's not just the operating point, it's the operating condition.
Operating point usually means just the plate to cathode voltage and idle current.
Operating condition means plate to cathode voltage, idle current, load impedance and maximum intended grid swing under normal intended use.
Tre'
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- RE: So I guess the logical question would be... - Tre' 08:48:46 12/14/14 (0)
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