Convert an old C-band satellite receiver into a FM video receiver capable of tuning between 950 and 2000 MHz.  This is useful for intercepting frequency modulated wireless camera feeds, performing TSCM sweeps or even monitoring amateur radio television (ATV) signals.

This will NOT receive conventional vestigial sideband modulated television signals.  You'll need to see this project - Frequency Agile NTSC TV Demodulator to do that.

The 70 MHz IF input allows for interfacing with the GBPPR Spectrum Analyzer to further cover the DC to 1000 MHz band.

The satellite receiver is a standard off-the-shelf receiver (Blonder Tounge in this case) modified for manual tuning by removing the PLL sythesizer section and adding a manual tuning potentiometer (with a 36 volt range).  It was also modified to fit into an ammo box to make it somewhat portable for mobile use.

The divide-by-128 MB506 prescaler output, which normally went into the sythesizer, was brought out to a front panel BNC connector.  By connecting this to a frequency counter and multiplying the output frequency by 128 and then adding 70 MHz, you will get the current received frequency.

Example:  Prescaler output is reading 9.21875 MHz.  Multiply this by 128 to get 1180 MHz.  Now add 70 to get a final frequency of 1250 MHz.  This was the frequency of my test transmitter.

Block Diagram

Pictures

• Picture 1  Overview.  I kept part of the satellite receiver's front panel because it was too hard to cut out by hand.
• Picture 2  Front panel view.  RF input, manual tune, 70 MHz IN & OUT, audio ouput, prescaler output, video output, ON/OFF switch, fuse and DC input.
• Picture 3  Internal view.  Mostly stock, except for extending the audio and video connections to the front panel.
• Picture 4  Internal view.  Shows the RF tuner, 70 MHz filter, power supply filtering and the 12V-to-36V converter.  The RF tuner's F connector was replaced with a panel mount BNC connector.
• Picture 5  Top view.  The tuner's connections are (left-to-right): LNB supply (not used), +12 VDC, AGC, Voltage Tune, 70 MHz IF and Prescaler Output

Notes

NS Microwave Surveillance Cameras