#167

This video describes how a classic double-balanced diode-ring mixer operates. Very basic mixer theory is quickly reviewed, which describes how the sum and difference of the LO (local oscillator) and RF (Radio Frequency) inputs are generated at the IF (intermediate frequency) output. It is also noted that the sum and differences of the harmonics of the LO and RF are also present at the IF output. Math waveforms on the oscilloscope are used to illustrate the operation of the mixer, and the actual waveforms from the mixer are compared to the math waveforms and the differences are discussed. A detailed description of the operation of the mixer is presented, including the switching action of the diodes. Finally, the frequency components are are expected from the mixer are shown on the spectrum analyzer. For more information about how diodes are used as switches, please see the video at this link:
   • #82: How to use a Diode as a Switch /...  
Also, for another tutorial on mixers and their use in frequency conversion and translation, check out this video:
   • #83: Basics of RF Mixers in Radio Rec...  
And, here's a video that shows how I wound the trifilar transformers used in this circuit:
   • #166: How to wind a trifilar toroid t...  
And, here's a video that shows how I wound the trifilar transformers used in this circuit:
   • #166: How to wind a trifilar toroid t...  

A copy of the notes in this video can be found here:
http://www.qsl.net/w/w2aew//youtube/D...