This is a device we use to simulate the type of interference that may be experienced on radio communication links.  It's based around the local oscillator of a Sayno TV tuner, which is sweeped and mixed with random noise.  This creates a narrow band of RF noise & garbage, oscillating over a small range of frequencies.

You can then use the device to help design spread spectrum or other interference resistant radio communications links.  The government spends billions of dollars on this type of thing.

Further amplification is not recommended.

GBPPR Tactical Communications Jammer Schematic  (30k PostScript)

The below schematic is my attempt at the Racal JAMCAT, with only the white noise option.

GBPPR Co-Channel Jammer Controller Schematic  (25k PostScript)