Last night I made tests with a K118 in amplification mode
This fet needs a low resistor value at the drain to get good results
I got symmetric clipping when I used a 1k resistor at drain with 8.5V supply
I got 4.5 volts at D with this circuit.
So the K118 needs a lot more current to work than the original K53. As the supply is battery powered, this can be a problem.
As a K156 is supposed to be the same as K53 but can't be find, someone proposed me a Fairchild FJN598J
What do you think about this one ?
This fet needs a low resistor value at the drain to get good results
I got symmetric clipping when I used a 1k resistor at drain with 8.5V supply
I got 4.5 volts at D with this circuit.
So the K118 needs a lot more current to work than the original K53. As the supply is battery powered, this can be a problem.
As a K156 is supposed to be the same as K53 but can't be find, someone proposed me a Fairchild FJN598J
What do you think about this one ?
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That's not a source follower... and I don't know how you are rigging these up to test but any stray leakage will be a major issue. I'm guessing you need point to point wiring in a "screened" area away from stray fields.
Does the FET still require the capacitance of the capsule (or equivalent) to stop the gate "floating" at AC ?
Does the FET still require the capacitance of the capsule (or equivalent) to stop the gate "floating" at AC ?
Unlucky, you got a high Idss one. Try some J201's totally cheap (just try eBay and see) and available and the max Idss is 1mA (the 2SK156 is 800uA max.).
BTW the 2SK156 has the extra diode in it, this to prevent long turn on if the gate sees a large negative transient. You could buy two cheap mic capsules, grind a TO92 package down to expose the lead frame, and cobble the FET out of the capsule and solder it on the ends of the leads.
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bdent.com has 2SK156 in stock but at $5.86@ They incorrectly list it as a power MOSFET but the datasheet they supply is the correct one (this happens a lot). It looks like a NOS/rare price to me though. I bought their last 25 2SK222's and they were real and pretty good parts (used in our Austin microphone experiment).
Hey, we could make this a NOS JFET thread.
No, but how about a trade JFET's for NOS Teledyne relays?
Anybody in the SF Bay area interested in sending out jfets for these projects? I did not realize that people have so much trouble getting acceptable jfets even with these minimal characteristics. I have avoided doing this, because I hate to address envelopes and go to the post office (a neurosis), but it would seem that many are in difficulty.
This FET is special, MAX Idss of 1mA, I don't think you would have these around anyway. Do you have any recommendations for types of battery that work best for battery powered preamps? They used to use mercury batteries but they are now banned.
Before buying the K156, I tried to bias the K118 with 1k at the source.
Results: To hear something (really weak) i had to use the preamp volume control at it's maximum level,
On the bench, the K118 seemed to have an amplification factor of about .6 with the 1K.
This thing is not funny to work inside as it is quite small and I can't measure anything.
Results: To hear something (really weak) i had to use the preamp volume control at it's maximum level,
On the bench, the K118 seemed to have an amplification factor of about .6 with the 1K.
This thing is not funny to work inside as it is quite small and I can't measure anything.
Yesterday, I began to order 5 of them to match a pair but backed off when they asked me $ 33 for shipping them by USPS priority mail. I really need them but i'm not enough crazy yet to pay such a non sense shipping price for five TO92 fets. Too bad.
How to open a stax electretet phono cartridge
I'm currently trying to repair a stax CP-Y cartridge. both 2SK53 j fet's need to be replaced.. I was able to remove the cantilever holder with the single screw. Can someone please tell me how to reach the inside for replacing the JFet's ?
Regards, Bart
I'm currently trying to repair a stax CP-Y cartridge. both 2SK53 j fet's need to be replaced.. I was able to remove the cantilever holder with the single screw. Can someone please tell me how to reach the inside for replacing the JFet's ?
Regards, Bart
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