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Friday, January 29, 2016

AA1TJ's 150 Microwatts Heard at 112 Kilometers -- "To Boldly Go Where no Unijunction Has Gone Before."

AA1TJ reports: 

Breaking news from W1PID... "Mike! I just copied the beacon. I got 'VVV de AA1TJ 150 uw' and it faded out. 2146Z on 3551.95MHz" That's it! Jim copied a message produced by a lowly unijunction at a distance of 112km. How's that for cool! In a nutshell... the unijunction runs as an R-C relaxation oscillator at ~500kHz. A quartz crystal at the emitter frequency-locks the sawtooth waveform to 507kHz. The 7th harmonic is admitted to the antenna via a bandpass filter. The RF output to DC input conversion efficiency is all of 0.1%. Heat-sink? Check! Mission statement:
"...to boldly go where no unijunction has gone before."
Cheers,
Mike, AA1TJ


I think the really cool thing is that EM waves are once again flying out of the Vermont Hobbit Hole, propelled into space by the poet laureate of QRP.

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