Diode Sorting Fixture

 

Diode Sorting Fixture in use on the bench

On May 11, 2025 I finished building my diode sorting fixture using a LM317 constant current source. In the fixture is a 1N4003 diode being tested today on May 29, 2025. On the 11th I sorted 100 1N4148 diodes for future use in Diode Ring Mixers. From that sorting I got 16 batches of 4 diodes matched and 5 batches of 2 diodes matched. Once I started the process it didn't take long and it was well worth it! For the 1N4148 diodes my measured forward voltage was from .714 to .729 vdc.

Page entry from my Lab Notebook

Whenever I go to hamfests or thrift stores, I like to look for cheap enclosure possibilities. After gutting the parts inside I repurposed this mouse controller case  I bought several years ago. I owe credit for this project to "M0NTV Homebrewing" youtube channel. Nick M0NTV did a great job on explaining how to design and build a constant current source for diode sorting using the LM317 regulator.

https://www.youtube.com/watch?v=EkMpLKwNl2U

I decided to leave out the variable pot. Like Nick I planned my circuit to use about 10mA constant current. I used 2 64 ohm resistors in series to get 124 ohms and provide 10 mA of constant current. I adjusted my power supply to provide 5.24 vdc to the fixture.

Here are the parts I used to build the fixture:

LM317T - Tayda - A-177 - $.23

4-40x 1/4" machine screw and nut (to mount LM317T)

.1uF - A5E104 - junkbox - $.00

51 ohm - Mouser - 271-51-RC - 

1K - linear pot - Tayda - A-1962 - $.50

enclosure - used from Ohio Thrift store - $4.99

2 Red Binding Post - Tayda - A-3583 - $.25 ea

2 Black Binding Post - Tayda - A-3908 - $.25 ea

DC 2.1mm Jack DC-099 - Tayda - A-5245 - $.55

DC Power Cable 12V5A - 2.1mm - Centro Power - B07C7VSRBG - $.46

I enjoyed building another piece of test gear for the lab. Good luck on your build if you choose to make a diode sorting fixture.

73,

Alan, N8WQ

2N2/40 CW Transceiver - Part 1 - Introduction

Compiled and Edited by: O. Alan Jones, N8WQ

After over one year of procrastination (MARCH 2023), I finally got started on my build for the 2N2/40 CW Transceiver which was designed and built by Jim Kortge K8IQY.

https://www.k8iqy.com/qrprigs/2n240/2n240page.html

If you have not read Jim's article, you really should, it is a treasure trove of information. https://www.k8iqy.com/qrprigs/2n240/K8IQYs%20Original%202N2-40%20Article.pdf

I officially kicked off my adventure on March 10, 2025 and began to collate all the documentation I could find on the 2N2/40 transceiver.

Besides Jim's original article, you will also need to read the Winter 1998 Edition of the QRPp Journal of the Northern California QRP Club, Vol. V1, No. 4.  The article entitled "2N2/40 40M CW "Built It From Scratch" Transceiver, is found on pages 4-49.

The 2N2/40 is built in a sequence of steps:

T-R, SEQ 1 - RX/TX Driver, page 17

VFO, SEQ 2 - Varicap Tuned VFO, page 19

FE, SEQ 3 - Receiver "Front End", page 23

IF, SEQ 4 - Crystal Filter/IF Amp, page 25

DET, SEQ 5 - RX LO Oscillator and Product Detector, page 43

AUD, SEQ 6 - Receiver Mute and Audio Amplifier, page 31

TX, SEQ 7 - TX Local Oscillator, Mixer & Amplifier, page 35

PA, SEQ 8 - Transmit RF Driver, Power Amplifier & Output Filter, page 37

 

The BOM is found on pages 40 and 41 of Winter QRPp 1998.

 

I created my own parts list for each stage/sequence of the transceiver in Excel. I verified all part designators by comparing the schematics to Paul Harden's (NA5N) excellent drawings and the BOM. For my build of this transceiver the schematics will have priority though :)

 

I will continue this discussion in 2N2/40 CW Transceiver - Part 2 - Layout of Substrate

 

73,

O. Alan Jones, N8WQ