[Laser] led txr

[I]

John,



we use lenses (100mm glass, or A4 size fresnel) to focus the beam here, so the lensed products may be more intense, but not effectively brighter when focussed. Our signals, FM or SSB go out on a 25kHz or so sub-carrier, so we need a high speed detector. I am still amazed an ldr works at all. A laser might be fine at short range, but you try aiming it at distance, I have done it at 15km, nearly, but not quite impossible. Even aiming the led is difficult with its effective one tenth of a degree beamwidth (calculated and confirmed by measurement).


By the way, we were out again last night and successfully completed a 65km contact between me, G8CYW and G8KPD/G8PNN. Signals were still end-stopping on FM and SSB. We could even continue when the signal disappeared to the naked eye when mist formed, we held the link for about an hour.


Stuart, G8CYW