you have misdescribed what you were trying to build.
If you current limit at some remote location, eg. at a separate resistor, then the CCS does not operate. It effectively goes to full open trying to source the current it was designed for. In this situation, instead of having an output impedance in the hundreds of kilo-ohms or even Megohms you end up with just a few dozen ohms because the jFET is forced on to the wrong part of it's Id vs Vgs curve.
The current dropping resistor has to be inserted direct to the Source lead out.
Yes, thanks for pointing this out - I will fix the circuit to be a proper CCS with R after S, with R between S and G.
When you and other guys speaking about circuits will be more understand if you can draw a schematic.
CFH9
1)ripple on positive rail when peeceebee connected to power supply
2)ripple to negative rai when peeceebee >> >> >>
3)ripple to positive rail when CFH9 connected to the same power supply
4)ripple to negative rail when CFH9 >> >> >>
Somthing is wrong here!
Ringing?
1)ripple on positive rail when peeceebee connected to power supply
2)ripple to negative rai when peeceebee >> >> >>
3)ripple to positive rail when CFH9 connected to the same power supply
4)ripple to negative rail when CFH9 >> >> >>
Somthing is wrong here!
Ringing?
Attachments
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No,you mustn't take in account this 2MHz. This has been measured even when gnd clip and probe tip are connected together.(shorted probe) and not powered amplifier.
OK, I see... anyway, rather high-frequency thing.
You can try to catch it, syncing by the trigger at some low-time settings - then we will see the real frequency.
Looks like parasitic oscillation. The first suspects are the four MOSFETs. They have inches of supply rail traces with no adjacent ground track and no at-MOSFET decoupling.
Try installing a 100nF at each MOSFET's drain pin to power ground on PCB, four total.
I'm planning to build pair of these in CFH9 configuration but i'm having a trouble finding 2SC/KSA1381 / 2SC/KSC3503 devices. One local shop has 2SA1249/2SC3117 (datasheet: HTTP 301 This page has been moved ). Could these work on this amp?
Supply rails will be 53V as i have about 600VA centre tapped toroid with 38.5V secondaries at the shelf collecting dust. All other components are easy to find and i can atch my own pcbs with no trouble but those KSA transistors are giving me headache.
Supply rails will be 53V as i have about 600VA centre tapped toroid with 38.5V secondaries at the shelf collecting dust. All other components are easy to find and i can atch my own pcbs with no trouble but those KSA transistors are giving me headache.
Standard fare at Digikey:
KSA1381ESTU ON Semiconductor/Fairchild | Discrete Semiconductor Products | DigiKey
KSC3503DSTU ON Semiconductor/Fairchild | Discrete Semiconductor Products | DigiKey
Note, I have bought them from China (Aliexpress) and those work fine too - look visually identical, and I believe origin is from Asia (Korea?).
Maybe i should have mentioned my location which is Finland, so no Digikey here and shipping and customs fares cost about arm and a leg.
But i just found one supplier which i had forgot to check and they have them, so problem solved and time to start gathering other parts that i don't already have.
For $5 there's not much to lose, but $5 
You might be pleasantly surprised.
Btw, many many transistors and MOSFETs and JFETs from Ali work well. All IRFP240/9240's have been good (3 dozen at least). IRF610/9610 are good (1 dozen) Even the elusive 2sk170bl and 2SJ74bl work and measure well (40 so far all good). 2sk1058 and 2sj163 good (10 so far). 2sk2013 and 2sj313 good (20 so far all good). Don't flame me on this. Just reporting what I know and use.
Stay away from 2sc5200 and 2sa1943 though. Low prices in those are probably fake and not functional.
You might be pleasantly surprised.
Btw, many many transistors and MOSFETs and JFETs from Ali work well. All IRFP240/9240's have been good (3 dozen at least). IRF610/9610 are good (1 dozen) Even the elusive 2sk170bl and 2SJ74bl work and measure well (40 so far all good). 2sk1058 and 2sj163 good (10 so far). 2sk2013 and 2sj313 good (20 so far all good). Don't flame me on this. Just reporting what I know and use.
Stay away from 2sc5200 and 2sa1943 though. Low prices in those are probably fake and not functional.
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For $5 there's not much to lose, but $5
You might be pleasantly surprised.
Btw, many many transistors and MOSFETs and JFETs from Ali work well. All IRFP240/9240's have been good (3 dozen at least). IRF610/9610 are good (1 dozen) Even the elusive 2sk170bl and 2SJ74bl work and measure well (40 so far all good). 2sk1058 and 2sj163 good (10 so far). 2sk2013 and 2sj313 good (20 so far all good). Don't flame me on this. Just reporting what I know and use.
Stay away from 2sc5200 and 2sa1943 though. Low prices in those are probably fake and not functional.
I suspect most of their silicon and electrolytics are fake. They may work, but it doesn't make them genuine..