JFET-only Circlotrons without negative feedback

Just sourced some used Toshibas from Pras1170! Thank you Pras! If anyone is looking for obsolete parts Pras is a great resource. I also bought some THF-51 from Pras not too long ago.

So jpatay, best schematic for the 2SK1530’s? Maybe post #103? Any changes to R4-R8 for the Toshibas?
 
On the circuit, the voltages may differ slightly. The current is regulated by changing the voltage -32 V. First, you need to set +0.5 V on the 2SK1530 gates without applying voltage to them. Резистор R4 должен выравнивать напряжение на затворах +0,5 В.
Then turn on the power to the 2SK1530 and set the current (for example - 200 mA) with a 10kΩ resistor in the -32V stabilizer. In order not to damage the 2SK1530, you need to successively put a 220 V, 100-150 W incandescent lamp in the primary winding of the transformer.
At a load of 6-8 ohms, it is more accurate to set zero voltage with resistor R4. Set the voltage across the 0.1 ohm resistor to 20 mV, this will correspond to 200 mA.
I think you know that.
Good luck!
 

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UTSOURCE is a company that has no stock. They look for cheap goods in the market, and then sell them on eBay. For rare transistors and integrated electronic components, almost all of them are for profit and profit. Then they choose to purchase printed fonts and sell them on eBay.

I know their store, their business model in China, I know very well

The distance between me and his shop is only 400 meters away

However, UTSOURCE is not all models, they are all sold counterfeit, because they know what models are profitable, scarce, and scarce transistors, and then they sell them with fake cheap quality.
 
Do you already have other transistors (J113, J111, 2SJ103 ...)?

Jpatay, yes I already have J113, J111, 2sj74-GR and 2sj74-BL, and planning on using 2sk209x4 in place of 2sk170’s.

Regarding power supply, how is yours set up? Can you use the same toroid for the whole amp or do I need one toroid for bias and a separate toroid for the outputs? I think I can get all the voltages I need with one 400VA toroid with 25v dual secondaries.
 
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and planning on using 2sk209x4 in place of 2sk170’s.

Regarding power supply, how is yours set up?
One toroid can be used. 250 W is enough. I used a non-working German amplifier in my prototype.
And I had to insert another small toroid to power the stabilizer, because I was too lazy to wind up the necessary windings on the large toroid.
It turned out ugly, but this is the first prototype. Now that the circuit is fully debugged, you can build everything from scratch as it should.
2sk209 Are they SOT-23? Or is there in TO-92?
 

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