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legarem 23rd November 2011 05:24 PM


I have a Stax electret phono cartridge which use 2 x 2SK53 FETs inside it. I have to replace these FETs but can't find any data on this obsolete FET

I would be happy if someone can give me the data for this FET.

Thanks a lot

jacco vermeulen 23rd November 2011 06:10 PM

Get K118 replacements.

(or try order a couple of K53 for $1.30 each plus postage : Bastler-Shop)

legarem 23rd November 2011 07:22 PM


Originally Posted by jacco vermeulen (
Get K118 replacements.

(or try order a couple of K53 for $1.30 each plus postage : Bastler-Shop)

The K53 were not aging very well. They showed channel imbalance with time.
Do you have a place where I can buy K118 preferably in Canada or USA ?


jacco vermeulen 23rd November 2011 09:44 PM

Futurlec (NY), MCM electronics (not Newark), XS Micro, etc.
Mini means the small (head-chopped) plastic package, TO-92S, as the K53.

(or the Bay way)

legarem 24th November 2011 12:54 PM

I bought some K118 but I really need at least the pinout (GDS)of the K53. In my japanese Fet references, There's K52 and K54 but no K53.

As it is in the circuit, I'm really not sure that the K53 is a P or N FET

jacco vermeulen 24th November 2011 02:49 PM

1 Attachment(s)
Japanese Industrial Standard JIS : K is always N

Ah, you're saying you can't tell from the JFET connections in the CPY-2 ? :clown:

legarem 24th November 2011 05:19 PM

1 Attachment(s)
In fact, I had to open the cartridge which was full of glue inside. I worked with a needle to take out the glue. I cleaned perfectly the inside so I could replace the fets but the little wires that goes to the little circuit were broken during the process.

The Stax adaptor feeds 9.6V to left ground (LG) and right ground (RG)of the cartridge. The V+ goes to the (LG) and the ground of the supply goes to (RG)

From RG, two 30K resistors goes to right hot (RH) and left hot (LH)

I don't know if the two 30K resistors go to the drain or source of the fets.

On the 4 pins that go outside the cartridge, there's a ground that goes from the cartridge conductive body , There's LH and RH output signals, (which have 30K that goes to ground of the power supply.

The problems I have is that normally, the V+ goes to the Drain with the resistors. In this cartridge, the two resistors are connected to the ground of the power supply instead of the V+

I know that the bias leakage current affect the gain of this cartridge.

Best should be to draw the schematic if you have an idea how to connect the wires.

Thanks a lot

Mooly 24th November 2011 06:23 PM

Not sure if this helps you or not but the drain and source of a JFET are interchangeable as the device is symetrical.

This was something I long wondered over as I noticed circuits performed identically whichever way they were fitted.

The late and much missed Bob Pease confirmed that they are indeed symetrical and you can not tell which is Drain or Source for most JFET's

legarem 25th November 2011 02:53 PM

1 Attachment(s)
Finally with all the informations I had, I figured that the fets in this cartridge are used as source followers like it is on the shown picture.

Will the 2SK118 alone will be ok to do this task or I'll need a fet which has an incorporated diode as it it shown on the drawing ?

If I need another fet that the 2SK118, what are your recommendations ?

It must be really small with long leads (No SMD)


Mooly 25th November 2011 05:02 PM

The "diode" is a strange thing to actually draw on a JFET as it's present in any JFET due to the way it is constructed.

The 2SK118 should be fine.

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