Richard Ferch wrote: > > However, RTTY and many FSK or MFSK-type modes (including JT65A, I > believe) feature a single constant-amplitude carrier that is stepped > between tones. When there is only a single tone being transmitted at any > time, compression does not cause intermodulation; it causes harmonic > distortion (odd-order harmonics), which can be eliminated by filtering > (the transmitter's crystal filter). The net effect after both > compression and filtering should be a constant amplitude signal. I > believe this is why JT65A users can safely use compression. > Hmm. As I wrote in my blog a while back ( http://www.g4ilo.com/2009/10/embarrassing-moments-in-ham-radio-1.html ) I once inadvertently did an experiment that proved the crystal filtering does not do a perfect job of removing the harmonics of a distorted RTTY signal. And surely the amplitude is not constant as seen by the ALC due to the effect of the ripple. If it was constant the ALC wouldn't change so it would not cause any harmful effects.
But heck, I'm just a software guy. Hopefully someone like Lyle who actually knows what he is talking about will chip in on this. ----- Julian, G4ILO. K2 #392 K3 #222. * G4ILO's Shack - http://www.g4ilo.com * KComm - http://www.g4ilo.com/kcomm.html * KTune - http://www.g4ilo.com/ktune.html -- View this message in context: http://n2.nabble.com/JT65A-output-power-variations-tp3985152p3988430.html Sent from the Elecraft mailing list archive at Nabble.com. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
