Simplistic NJFET RIAA

[Salas]

But with 2SK117GR you should be reading 3-6mA and not 300-600mA. Did you insert the DMM in series mode with B+ at its red mA socket and the black common socket connecting at D pin?

 

[cutting42]

I think wrote the numbers wrong without the decimal point. I will double check tomorrow but I suspect divide them all by 100

 

[cutting42]

It is a brand new DMM, my old Fluke was away and I bought a new one with hfe and capacitance testing etc and this was the first time I used it. Probably user error.

 

[Salas]

OK. Double check tomorrow so we can opine on confirmed 2SK117GR IDSS figures about wise placement on the good old FSP.

 

[Salas]

Meanwhile for the current UFSP phono guise I just added two cautionary text lines in post #17791. The one with the DIP switches configuration info and schematics.

CAUTION! Don't switch S5-S12 when the phono is powered on.
CAUTION! Don't switch S1-S4 when the system volume is open.

I know its intuitive not to reconfigure a circuit with the power on and not to change cartridge loads with the volume up, but I better remind it.

 

[dewdrop]

good reminder

 

[cutting42]

OK, a double check and remeasure of a couple we have correct values (with the decimal point this time)


1/ 4.4ma
2/ 4.4ma
3/ 3.04ma
4/ 2.93ma
5/ 4.96ma
6/ 5.14ma
7/ 4.78ma
8/ 4.69ma
9/ 4.26ma
10/ 5.78ma

Based on some earlier responses I am thinking:

Q7 1,2
Q2x 3,4
Q3x 7,8
Q5x 5,6

 

[Salas]

I would alternatively suggest

Q5x 3,4
Q2x 5,6 R6x 47Ω
Q3x 1,2
Q7 7,8

My reasoning is to bias Q4x BJT lighter via small IDSS Q5x saving on dissipation. Because Q4x has high voltage across it but no means to moderate its current bias while Q2x has high voltage too but there is R6x to moderate it.

 

[cutting42]

OK, will do, many thanks

 

[cutting42]

I have 6 BC550C in the mini kit I purchased and the hFE are very close - 209 to 217 but are low to what you ask in the instructions (600), Will they be OK or should I order a few and try to find some higher hFE.

Thanks

 

[dewdrop]

Here's the 50VA Antek in a 2U Galaxy (124 x 230D):
Galaxy 2U w/Aluminum Covers – diyAudio Store

Fits, just. It's a very nice brick of a power supply in hand.

pfarrell, can you share the part number of the male and female power connectors? I will like to do the same as you.

 

[Tea-Bag]

I have 6 BC550C in the mini kit I purchased and the hFE are very close - 209 to 217 but are low to what you ask in the instructions (600), Will they be OK or should I order a few and try to find some higher hFE.

Thanks

If these came from my kits, this is very suprising. Did you measure the BC560c to see if they came in low as well?
I suspect the measurements are inaccurate for one reason or another. The OnSemi/Fairchild BC5X0c were all high Hfe.

 

[pfarrell]

@dewdrop
XLR 4 pin... there are several varieties...

NC4FD-L-BAG-1 | Neutrik

NC4MXX-BAG | Neutrik

 

[dewdrop]

Super pfarrell! Thanks for the quick reply

 

[cutting42]

If these came from my kits, this is very suprising. Did you measure the BC560c to see if they came in low as well?
I suspect the measurements are inaccurate for one reason or another. The OnSemi/Fairchild BC5X0c were all high Hfe.

Hi there. Yes they are your kits. The 560 also were around 200 so maybe it is the measuring at fault. It is a new DMM with hFE capability which I do not have on my old Fluke. Short of getting another DMM to cross check is there another route to measure the hFE?

 

[Tea-Bag]

@dewdrop
XLR 4 pin... there are several varieties...

NC4FD-L-BAG-1 | Neutrik

NC4MXX-BAG | Neutrik

Also check out from neutrik, aljordan turned me on to these. Can take large wire.

NL4MP
NL4FX

They can take an odd connector on the chassis side.
NLFASTON

 

[dewdrop]

Thanks teabag. Can't wait to get the kit!

 

[Salas]

Cheap alternative to Neutrik for umbilical power cable termination are aviation GX16-4 connectors. Not mechanically comparable, another thing.

 

[Salas]

Hi there. Yes they are your kits. The 560 also were around 200 so maybe it is the measuring at fault. It is a new DMM with hFE capability which I do not have on my old Fluke. Short of getting another DMM to cross check is there another route to measure the hFE?

Maybe the DMM tries them at 10 μΑ or something to save on its battery. They would usually need 1-2mA Ic to meet their spec.

IMHO don't get another DMM just for hfe, each one has its own arbitrary standard, get a dirt cheap component tester from eBay.
Which will be all around useful to you for identifying various components, it even has LCR functions. OK ballpark stuff but handy.

 

[cutting42]

Maybe the DMM tries them at 10 μΑ or something to save on its battery. They would usually need 1-2mA Ic to meet their spec.

IMHO don't get another DMM just for hfe, each one has its own arbitrary standard, get a dirt cheap component tester from eBay.
Which will be all around useful to you for identifying various components, it even has LCR functions. OK ballpark stuff but handy.

You have it spot on, I checked the detailed specs and the DMM has a limit of 2μA for hfe testing.

I will get a component tester as it would help me in general.

Thanks again