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Thursday, January 28, 2016
QST de AA1TJ -- Please listen for Mike's Microwatts!
QST de AA1TJ... I've a 150uW transmitter built from a single unijunction transistor currently running as a beacon on 3552kHz. If my New England amateur radio pals would be so kind as take a listen for it I'd be most appreciative!
Thank you, Bill! 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."
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. Well done, OM!
Thank you, Bill! 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!
ReplyDeleteMission statement:
"...to boldly go where no unijunction has gone before."
Cheers,
Mike, AA1TJ
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. Well done, OM!
ReplyDelete73,
Mike, AA1TJ