DIY Front End 2022

Unbelievable!o_O
I made these pcbs in KiCAD one week ago. Delivered today!
I have to match some J113 s...
Cheers
Dirk
 

Attachments

  • Frontend_2022_pcb_THT.jpg
    Frontend_2022_pcb_THT.jpg
    75.4 KB · Views: 250
  • Like
Reactions: 4 users
Hello out there,

I did some homework: matching / measuring a lot of J113s. Although I had a lot of J113 measured before (data written down), It was a little pain
to get an octett out (Q1 and Q2 doubled up = 4 and the same for the other channnel = 8. And another quartett for the CCS (Q3/Q4). I have such
a damage :yes: Perhaps I need a therapy?
Waiting for some parts to be delivered...
Cheers
Dirk
 

Attachments

  • DIY_Frontend_2022-most_parts_stuffed.jpg
    DIY_Frontend_2022-most_parts_stuffed.jpg
    172.2 KB · Views: 177
  • Like
Reactions: 4 users
Hello mbrennwa,
I checked the 2SK240BL-datasheet. Gate pins are in the mid (D-G-S)
(D-G-S).
Doubled J113 have gate -pin on outside. (G-S-D)
(G-S-D)
So would only be possible with twisted legs.
Since you're comparing to doubled J113, are you considering paralleled parts? While it would certainly be an interesting idea to use paralleled 2SK170 (i.e., 4x 2SK170 or 2x 2SK240 per channel), I was not thinking of paralleled parts. My idea was to use one 2SK240BL part for the differential input.

No matter what, I guess I'll have to start matching my 2SK240BL parts...
 
I made a test PCB, too. But I could get the offset below 2VDC.

The Iq of first stage is about 3mA, the second stage CCS is about 9mA,

The first stage Jfets are matched to 0.01mA at Id 1.5mA and Vds 25.5V .

The VAS transistor tested are 2SA1382 and ZTX735 while waiting for KSA992.
 

Attachments

  • Pass 2022 FE test pcb.jpg
    Pass 2022 FE test pcb.jpg
    98.8 KB · Views: 125