Mr. Pass I have just come across a Forte Model 6a. I think it is 200wpc and uses IGBT's.
Can I reduce the rails by half (by rewiring the Toroids in series) and bias it to 50 watts class-A?
I have done it in the Forte Model 3 with good results but that uses BJT's, I am worried playing with these IGBT's.
If so, what idle bias do you recommend going to with rails of approx +/-38vdc?
Thanks much in advance,
K-amps.
Can I reduce the rails by half (by rewiring the Toroids in series) and bias it to 50 watts class-A?
I have done it in the Forte Model 3 with good results but that uses BJT's, I am worried playing with these IGBT's.
If so, what idle bias do you recommend going to with rails of approx +/-38vdc?
Thanks much in advance,
K-amps.
Rule of thumb:
To stay in the same thermal envelope: When halving the PSU voltage, you can double the current.
The other alternative is to aim for a temperature which should not be more than 70 degC.
You might also want to do some reading up on IGBT's to evaluate their thermal stability. If I know NP, I suspect that the emitter resistors are large enough to offset any thermal runaway should the devices be so inclined.
Petter
To stay in the same thermal envelope: When halving the PSU voltage, you can double the current.
The other alternative is to aim for a temperature which should not be more than 70 degC.
You might also want to do some reading up on IGBT's to evaluate their thermal stability. If I know NP, I suspect that the emitter resistors are large enough to offset any thermal runaway should the devices be so inclined.
Petter
Thanks Petter,
Additionally I'd like more insights especially from NP. I suspect he knows something about this that I should know.
I just dont want to blow the IGBT's and have a worthless amp on my hands.
I agree with you on the value of NP's emitter resisters, probably a minimum of 0.47 ohms... right?
Additionally I'd like more insights especially from NP. I suspect he knows something about this that I should know.
I just dont want to blow the IGBT's and have a worthless amp on my hands.
I agree with you on the value of NP's emitter resisters, probably a minimum of 0.47 ohms... right?
K-amps said:Mr. Pass I have just come across a Forte Model 6a. I think it is 200wpc and uses IGBT's.
Can I reduce the rails by half (by rewiring the Toroids in series) and bias it to 50 watts class-A?
I have done it in the Forte Model 3 with good results but that uses BJT's, I am worried playing with these IGBT's.
If so, what idle bias do you recommend going to with rails of approx +/-38vdc?K-amps.
Should work just fine, although I don't have a schematic on
it, as it was after my time. I would just crank up the bias until
the sinks reach a continuous 50 deg C (touchable for 5 seconds).
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