Greetings All,
My first post here.
I am building the Nutube preamp kit and may have a packaging error.
I have begun the assembly of my preamp kit and on confirming the parts selection to the instruction sheet document I may have found a discrepancy.
The write up states that the jfets Q1 and Q2 are different and packaged accordingly.
However I have found that while the Q1 package contained 4, FKH35 J113 fets, the Q2 package contained 2, of FKH35 and 2, of WH44 J113 fets.
This raised a red flag for me and I would like some guidance on whether this is a packaging error or is there more detail needed on how to populate the PCB correctly?
All of their respective bias resistors checked out consistent at 149 ohms.
No response from the store at this time after asking about a week back.
Thanks for your guidance.
My first post here.
I am building the Nutube preamp kit and may have a packaging error.
I have begun the assembly of my preamp kit and on confirming the parts selection to the instruction sheet document I may have found a discrepancy.
The write up states that the jfets Q1 and Q2 are different and packaged accordingly.
However I have found that while the Q1 package contained 4, FKH35 J113 fets, the Q2 package contained 2, of FKH35 and 2, of WH44 J113 fets.
This raised a red flag for me and I would like some guidance on whether this is a packaging error or is there more detail needed on how to populate the PCB correctly?
All of their respective bias resistors checked out consistent at 149 ohms.
No response from the store at this time after asking about a week back.
Thanks for your guidance.
Hi. No worries. Those are batch numbers if you are reading them on the jfets themselves, but they are not what's important. Within the batch, there are many different ldss values among the same jfet, and what guys at diyaudiostore do, is match them by idss. So you may get different batch number, but i'm sure idss values are on point. If you are up to, there are ways to measure idss, you can send me a PM where i can explain in detail. What's important now is that you don't mix them same pile. Keep them in their separate bags.
I did keep them separate while reading the numbers (under a magnifier). Based on your response and trusting the individual who packaged it I believe I will proceed with the soldering this weekend. Being new to posting here I do not know how to send a PM but will work on that. It would be great to have a procedure for measuring idss values.
Thanks for your response. I really enjoy learning these new things.
Thanks for your response. I really enjoy learning these new things.
It's ok. I'll copy paste text here. Will be useful to have more info in search function. I'll lead you trough it if you need help. It is quite easy to setup on a breadboard.
-Get a 5 to 13 volt supply and a DC voltmeter (we used 12V)
-Connect the +V to the Drain
-Connect the Gate and Source together to a 100Ω resistor
-Connect the other lead of the resistor to ground
-Measure the voltage across the resistor, which gives the Idss (1 volt = 10 mA of current)
-Try to measure all devices under the same conditions, temperature, and duration of test (give it 1min to aclimate for each jfet, since it's a small amount you can spare a few minutes more, use airconditioning in room if possible)
J113 pinout is shown on this image for convenience.
Since you built speakers, it should be easy to fix up a breadboard jig. Write here if you don't understand some step.
-Get a 5 to 13 volt supply and a DC voltmeter (we used 12V)
-Connect the +V to the Drain
-Connect the Gate and Source together to a 100Ω resistor
-Connect the other lead of the resistor to ground
-Measure the voltage across the resistor, which gives the Idss (1 volt = 10 mA of current)
-Try to measure all devices under the same conditions, temperature, and duration of test (give it 1min to aclimate for each jfet, since it's a small amount you can spare a few minutes more, use airconditioning in room if possible)
J113 pinout is shown on this image for convenience.
Since you built speakers, it should be easy to fix up a breadboard jig. Write here if you don't understand some step.