Some photos of my demo at the national radio amateur camp in July 1997

Laser SSB/CW/FM demo in July 1997 !!!

Photos by OH6MVA

These photos were taken by OH6MVA during the SRAL annual ham radio camp this year:

The OPT210 based photodetector ( 110 k ) and upconverter to 144 MHz is mounted in a tin plate RF tight enclosure. The enclosure also houses an adapting lense and the full system is mounted onto the ocular holder and is then focused for maximum C/N at reception. The white car bonnet at the right belongs to a fellow ham I greatly admire, Karl Mohlin, SM3AKW, who also witnessed the excitement of laser comms.

Oh yeah, thats me ( 128 k ) standing behind the laser receiver setup and explaining the soul and life of my very own virtual optical tamagotchi. The telescope is of the Byelorussian variety and a very nice one it is too. My 25 mW HeNe laser also mounts nicely in place of the search scope so I can use the alignment screws to align the laser with the main telescope for two way comms experiments.

The two gentlemen studying the lasercom system behind me are my fellow excentrics Matti Aarnio, OH1MQK and Riku Kalinen, OH2LWO.

The Laser transmitter ( 151 k ), modulator and accompanying downconverter from 144 MHz is mounted in an ex-camera enclosere. This is a neat job with a 1/4 inch thread that matches a standard camera tripod. Although this method is by no means stable enough for the real thing, ( troposcatter QSO's ) it IS very good for short distance experimenting and setting up things like modulation depth, RF drive levels, checking beam characteristics and the like.

Closeup photo of RX ( 40k ) and closeup photo of TX ( 43 k ) units. The IF of these units is 144 MHz and is converted internally to and from a baseband of around 150 kHz ( - 3 dB ).