An experimental spectrum analyzer based around the work done by W7ZOI & K7TAU.

Mostly based on junk box or easy to find, low cost components - hence the sloppy design.  This is currently an in progress project.  It will probably never be finalized and always updated.

Prerequisite reading from the original W7ZOI & K7TAU QST articles : August 1998 and September 1998.

Block diagram overview (12k GIF).

Schematics

New Version

Rework of the original design using (mostly) the same components.  Does not have any spurs.

• Sweep & Sync Section  (72k PNG)
• 1st LO & Mixer Section  (65k PNG)  (PCB)
• 2nd LO & Mixer Section  (101k PNG)  (PCB)
• 3rd LO & Mixer Section  (65k PNG)  (PCB)
• 10.7 MHz IF Resolution Filters Section  (50k PNG)  (PCB)
• 10.7 MHz IF & Log Amp Section  (65k PNG)  (PCB)

See the Motorola MC3361 datasheet for a simple, narrowband FM demodulation schematic.  Use a LM386 for the audio amp.

Pictures

Original Version/Prototyping & Waveform

New Version

Tracking Generator Add-On

Block diagram overview (6k GIF).

Tracking generator pictures.

• Add-On GBPPR 0 - 1000 MHz Tracking Generator  (75k PNG)

Notes

• I found the main 1100 - 2100 MHz Z-Comm VCO in an old satellite receiver thingy.  A Mini-Circuits POS-2120W should be a good substitute.
• M/A-Com lowpass filters, Sirenza MMICs and WJ mixers and amplifiers can be ordered from Richardson Electronics
• 70 MHz IF SAW filters, CLV1137 VCO from SHF Microwave Parts
• 1100 MHz IF Toko BPF, 25 kHz 10.7 MHz resolution filter, LM833 and misc parts from Digi-Key
• Torroids from Kits and Parts
• AD603 and AD8307 from Analog Devices
• Mini-Circuits filters and mixers from RF Parts Co.
• There are about 4 million little quirks and bugs in this design

Links

• Homebrew 100 MHz spectrum analyzer
• W7ZOI/K7TAU Spectrum Analyzer Constructed by N8QOH
• Homebrew Spectrum Analyzer Project
• Tektronix TR503-Compatible Tracking Generator  by KE5FX
• Build a 1000 MHz RF Spectrum Analyzer Inexpensively  by Scotty Sprowls
• 100 MHz Spectrum Analyzer  by Iulian Rosu, YO3DAC / VA3IUL

Datasheets

• Z-Comm CLV1137 VCO  (46k PDF)
• BPM70MSA 70 MHz SAW Filter  (16k PDF)
• WJ AG101 70 MHz IF Amplifier Application Note  (150k PDF)
• M/A-Com FL07-0001 DC-1000 MHz Low Pass Filter  (52k PDF)
• Micrel MIC29152 LDO Voltage Regulator  (148k PDF)
• Motorola MC3361 NBFM IF Demodulator  (213k PDF)