43 - Matching Diodes for Mixers

Nick M0NTV discusses the challenges of matching diodes for homebrew diode ring mixers. He builds and demonstrates an adjustable constant current source which is simple to construct and easy to use. Best of all - once set to the current level you want to test at - it requires no more tweaking. Just swap in the diodes and read their forward voltage drop on a DMM.

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IMPORTANT!
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Please note that there is an error in the left hand schematic at 22:10:19. The cathode of the diode
(D-) should NOT be connected directly to ground as shown here. It should only be connected to the switch. Apologies for this and many thanks to my friend Alan M0VLT for pointing it out and for building it himself! I have corrected this in the downloadable version.

Schematics and project layout diagrams can be downloaded here:
https://drive.google.com/file/d/1e-OV...

LM317 Datasheet can be downloaded here:
https://www.ti.com/lit/ds/symlink/lm3...

Grateful thanks particularly to Alan Wolke W2AEW for his excellent videos which really help amateurs (like me) to get a grip of RF electronics. Check out Alan's video on matching diodes here:
   • #302: Back to Basics: How to match diodes ...  

To find out more about the GQRP Club and SPRAT magazine please visit:
https://www.gqrp.com

Thanks for watching!
73

Nick
M0NTV