Interesting they have a hard limit of 520 volts. There has to be some circuit inside to lower the b+ a bit. How else could you run much smaller tubes?
Here's a quote from another page I found:
"Yellow Jackets not only rearrange the pin locations of the tubes, but also provide the necessary plate voltage drop and current limiting on the screens as well as blocking the amplifier's grid bias voltage while configuring the EL84 in a Class-A, self-adjusting cathode-bias circuit. In other words, there are no adjustments to make and no modifications necessary."
jeff
astouffer,
1. Consider the addition of a few parts:
An added coupling cap from the amplifier tube socket g1 connection, to the EL84 g1.
An added EL84 g1 resistor (from EL84 g1 to the bottom of an added cathode self bias CCS).
An added voltage dropping resistor from the bottom of the EL84 cathode self bias CCS to the amplifier tube socket cathode connection.
An added bypass cap across the series connection of the added self bias CCS and added voltage dropping resistor.
An added screen resistor (and added screen bypass cap?).
Stuff all that in a round yellow tube, and call it a Yellow Jacket, and see what happens.
Does that describe a possible solution?
Question?
With all the voltage drop across the self bias CCS and voltage dropping resistor multiplied times the proper EL84 cathode current . . .
Which is hotter, the EL84 or the Yellow Jacket?
2. Or, for another completely different and better way:
An added plate voltage dropping resistor and an added bypass cap across the resistor.
An added screen voltage dropping resistor and an added bypass cap across the resistor.
An added self bias CCS with an added bypass cap across it.
An added coupling cap and an added g1 resistor to isolate g1 from the amplifier fixed bias.
The bottom of the g1 resistor connects to the bottom of the CCS.
Stuff all that in a round yellow plastic tube, and call it a Yellow Jacket.
I like this 2nd solution Much Better than the first solution.
1. Consider the addition of a few parts:
An added coupling cap from the amplifier tube socket g1 connection, to the EL84 g1.
An added EL84 g1 resistor (from EL84 g1 to the bottom of an added cathode self bias CCS).
An added voltage dropping resistor from the bottom of the EL84 cathode self bias CCS to the amplifier tube socket cathode connection.
An added bypass cap across the series connection of the added self bias CCS and added voltage dropping resistor.
An added screen resistor (and added screen bypass cap?).
Stuff all that in a round yellow tube, and call it a Yellow Jacket, and see what happens.
Does that describe a possible solution?
Question?
With all the voltage drop across the self bias CCS and voltage dropping resistor multiplied times the proper EL84 cathode current . . .
Which is hotter, the EL84 or the Yellow Jacket?
2. Or, for another completely different and better way:
An added plate voltage dropping resistor and an added bypass cap across the resistor.
An added screen voltage dropping resistor and an added bypass cap across the resistor.
An added self bias CCS with an added bypass cap across it.
An added coupling cap and an added g1 resistor to isolate g1 from the amplifier fixed bias.
The bottom of the g1 resistor connects to the bottom of the CCS.
Stuff all that in a round yellow plastic tube, and call it a Yellow Jacket.
I like this 2nd solution Much Better than the first solution.
Last edited:
Nobody does linear supplies anymore. Like this for example https://www.st.com/resource/en/application_note/cd00222186-super-widerange-buck-converter-based-on-the-viper16-stmicroelectronics.pdf
OK guys, I got the answer from Jolida:
"The plate voltage for the power tubes is 465 to 470 volts"
"The plate voltage for the power tubes is 465 to 470 volts"
And here are the results (before the house fire):
An externally hosted image should be here but it was not working when we last tested it.
Last edited: