I have in mind something like this for power transformer 320-0-320, 5.0V@4A - 6,3@8A (custom made) any suggestions or is this one allright?
I have also used the Hammond 272JX in a 300B amp. It is only rated for 300-0-300 volts, but actually delivers 330-0-330 volts here. This is not uncommon for a Hammond transformer. A 372JX would be required in 230 volt countries.
A custom transformer would certainly work. You need a high voltage winding that delivers 330-0-330 volts at at least 175 mA. 320-0-320 volts would be OK. The 5 volt winding should be rated for 3 amps and the 6.3 volt winding should be capable of at least 4 amps.
It is permissible to slightly overspecify the current ratings but specifying too much current can be dangerous if the transformer delivers too much voltage with the actual load current. Using a 4 amp rating for the 5 volt winding could result in more than 5 volts to the 5AR4 which only draws 1.9 amps. The 6.3 volt winding is not as critical since the 300B filament supply is regulated. Too much voltage can cause the regulator to overheat. The high voltage should be close to 330-0-330 volts under load.
A custom transformer would certainly work. You need a high voltage winding that delivers 330-0-330 volts at at least 175 mA. 320-0-320 volts would be OK. The 5 volt winding should be rated for 3 amps and the 6.3 volt winding should be capable of at least 4 amps.
It is permissible to slightly overspecify the current ratings but specifying too much current can be dangerous if the transformer delivers too much voltage with the actual load current. Using a 4 amp rating for the 5 volt winding could result in more than 5 volts to the 5AR4 which only draws 1.9 amps. The 6.3 volt winding is not as critical since the 300B filament supply is regulated. Too much voltage can cause the regulator to overheat. The high voltage should be close to 330-0-330 volts under load.
I think this will be final: PT 330-0-330, 250mA, 5V@3A, 6.3V@5A
OPT 3.4K, 4-8 ohm and Choke DC 200 mA - 6 H - 150 ohm.
All transformers will be custom made, so i want to be sure before ordering. Any suggestions or is this OK?
THNX
OPT 3.4K, 4-8 ohm and Choke DC 200 mA - 6 H - 150 ohm.
All transformers will be custom made, so i want to be sure before ordering. Any suggestions or is this OK?
THNX
Those numbers look fine.abacus said:
What brand is OPT? I use Electra-print's 3K Ohm primary, 100mA current, 15w max power, 8 ohm secondary and I'm happy with it.
Your numbers look good. If you are having the OPT's custom wound, make sure that your winder understands the standing DC current requirement for SE OPT's. They should be gapped for about 75 mA of current and rated for at least 10 watts. A SE OPT that would do a 300B justice should weigh at least 3 KG.
If yours was the recent PC board order from Croatia, it was shipped this morning. Europe usually takes 10 days to 2 weeks depending on customs.
tubelab.com said:
Yes, this was my order. OPT's will be also custom made, no problem, winder knows the job.
Thanks for helping me in this project.
Regards
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