Can't get Ruby Amp's buffer to work properly

[Cozybuilder]

I actually tried wiring one of those Mpf102 considering middle pin as gate, no more hum/noise, but quite a low output.
So this does not seem right either.

Indeed it doesn't.    Every pinout picture I can find the for MPF102 shows D-S-G.  The gate isn't in the middle.

Hmmm-

[davepedals]

I thinks I've built 5 rubys now, all of them worked, however I did the bassman mod a few nights ago and notice no real difference in the sound.  Strange.

[Borek]

Ok, so finally I measured resistances and did diode tests again.
For the whole package of chips.
So now I have the following:

Resistance between any pairing is 0L, but two of them that are around ca 40M.
The resistance seems to be directional.
Those two connection are the same that give me about 0.64 with diode testing.
All of the others, again 0L.
So this are the related connections:

middle pin (red cable) to right pin (black cable)

middle pin (red cable) to left pin (black cable)

I really don't knwo whats happening here. (I'm not using the sourface mount part )
If the resistance reading would be different, I would suggest a somehow rearranged pinout. But this leaves me pretty clueless.

[anotherjim]

Non-standard pins do exist. I don't think Fairchild did it with their own branded T0-92 parts, but other companies make them under license. Some buyers place big enough orders to have parts made anyway they want - surplus stock can find it's way to e-bay.
Do yours have the Fairchild "F"?

It's fairly common with SMD parts to have alternative pinout available because you can't just swing those around or cross the legs.
If you have some solder pad perfboard, a little 2x2 square makes an excellent adapter to mount SMD transistors on with offcut wire legs.

Given that it's supposed to be an N channel, which means the gate is P material, then diode test should show the leg that reads as a diode to the other 2 legs is the positive DMM lead. Is that so?

I don't know of any JFET that works on Enhancement mode (channel is normally high resistance "off"), they are all Depletion mode (channel is normally low resistance "on"). This means that given you have identified the gate, the other 2 pins should have low resistance between them. If they don't, either...
It ain't no JFET.
It's faulty.
There is negative voltage between the gate and any other pin.

[Borek]

Actually there is the Fairchild F on it.
It says
F BB12
MPF
102.

So from diode testing I'd guess that middle pin is gate, but as there is a very high resistance between any of the pins, I more feel like they sold some junk to me.
The BF454 on the other hand says zero resistance between source and drain - as should be. And it works. So I guess I have to stick to this. I just made it hole-through by soldering
some short jumper to it

[anotherjim]

So from diode testing I'd guess that middle pin is gate, but as there is a very high resistance between any of the pins, I more feel like they sold some junk to me.

Sorry to hear that - we've heard tales of counterfeit parts - what you got could be ordinary BJT transistors!

At least you got into learning some component testing skills!

[Borek]

Ok, so for protocol: bought them from Polida from Ebay - seems not exactly a first-timer with this company.

As I figure out, it should be no problem building the buffer with some J201? I can have them surface-mounted and converse them (also cheaper )
So that would be more comfortable than looking for working MPFs (which are only through-hole, I think).
So soundwise, there should be practically no difference, as it's only a buffer, or am I getting something totally wrong?
Thanks to you all for the help!

[antonis]

IMHO, any ordinary (general purpose) JFET is suitable for "isolation" use..