I still remember my first 23cm transverter and my fear from frequencies above 1 GHz. What am I going to do? How am I supposed to measure, even how to tune anything on these high frequencies? It's not that long ago, about 15 years. Of course we managed that frequency. We also managed 10 GHz, later even 24 GHz. I have bought my 47GHz transverter from DB6NT. Now, these wonderful units from VK put us on 122 GHz ...
Harry WA0CNS and Herbert AF4JF made several short QSOs on 122GHz before making our 5.25 km contact on November 7th. See the posting here (click).
We have been playing with optical communications in the early days of the SLAMS group, see pictures here (click). The BARS group was also planning on some optical communications here (click), but we have never made a full bi-directional QSO until today (click here). Harry WA0CNS and Herbert AF4JF used the opportunity and tested their old equipment while waiting for other participants of the team meeting that we started holding in the Creve Coeur Memorial Park again. Witnessed by Ron KO0Z, our first QSO using red light took place. Harry used his station with two Fresnel lenses, TX with red LED diode wavelength 635 nm and RX with photo diode BPW34. Herbert used his old 5 mW red laser module wavelength 650 nm and a solar panel (!!) from old garden light as RX. No additional lenses used on Herbert's side. First QSO was difficult, especially aiming the stations at each other. We clearly have some work to do here, similar to our experience with 122GHz mentioned above. Using rifle scopes on these frequencies is a MUST!
Harry was actually using voice audio on transmit. That was surprisingly clear and easy to understand on Herbert's side. Herbert responded with 30% AM modulated CW (using shunt modulator).
Harry also built an optical beacon with infrared diodes (the little box on a smaller tripod on the right picture above). These diodes have lenses built in and the beam width is about 5 degrees. Built-in processor transmits beacon patterns and some text with Harry's callsign. I will try to record it and post the recording here next time.
So, what is next? Definitely attempt on longer distances on both, 122 GHz and 462 THz. We will keep working on mechanical stability, improving precise aiming and get more ready for next year.
73 Herbert
AF4JF
