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.
How a Diode Ring Mixer works | Mixer operation theory and measurement – [Link]
Locally broadcast your cell phone through FM band using MAX2606 from Maxim:
This design idea presents an integrated IF voltage-controlled oscillator (VCO) that can retransmit the audio signal from a cell phone to the FM broadcast band. By placing the cell phone’s speaker near the microphone, the user can use the phone as a hands-free device while driving.
VCO enables a hands-free car kit for cell phones – [Link]
The light weight, compact size and low cost DSA800 family of spectrum analyzers from Rigol Technologies feature digital IF technology to provide the reliability and performance necessary for RF applications. The spectrum analyzers have a frequency range of 9 kHz to 1.5 GHz with a typical displayed average noise level (DANL) of ‑135 dBm. SSB offset phase noise is typically -80 dBc/Hz at 10 kHz, and the resolution bandwidth is adjustable from 100 Hz to 1 MHz. A preamplifier and AM/FM demodulation are standard with this instrument. [via]
Low-Cost Spectrum Analysers Feature 1.5 GHz Top End – [Link]