[Laser] led txr

[I]

First of all, to Des M0AYF:



i am in IO94CX, about 120 miles N of you. I have designed a transverter from 80m to produce and receive subcarriers for optical comms (see previous posts), it uses an MC1496 to mix a 3.58MHz xtal osc with rf around 3.605MHz to produce 25kHz SSB or FM and receive. The rx font end is a broadbanded RC coupled version of Clints (KA7OEI) wonderful receiver. The tx  LED is driven and biassed from the transverter at up to 1A current. It uses a golden dragon red LED RS part 665-6189. I use my FT817 as driver, on its half watt setting. Hopefully the design will be in RadCom in the new year.


I have also designed a LED transceiver using the same LED on tx and rx, also to be in RadCom. All this by following links from Tims excellent website (and a bit of experimenting). We worked 65km last week with end stopping signals.


Sorry, no website!


we may be out again next weekend to attempt 82km, NE England to N Yorks moors, weather permitting.


I have completed the construction of my extreme beacon using a 20W LED and 100mm lens to produce a 2 degree beam, modulated at 2.5Hz for visual recognition or 25kHz for reception peaking using transverter. Seeing a strobe over 65km enabled us to line up last week.


We used a smaller beacon to test rx sensitivity, 5mm LED driven from a 555 timer at 25kHz is audible from up to 1 km with no lens on tx.


Stuart, G8CYW