--- Michael <[EMAIL PROTECTED]> wrote: > Hi, Folks, > > Let's cast our minds back to the days of AM > (Advanced Modulation, for > those who are unfamiliar with the abbreviation <G>) > rigs and RTTY. > > Now I know that simple AFSK would work - and provide > both sidebands > and the carrier and really torture any SSB or true > FSK rig going. > Not that I'm actually above such things but let's > discount that for a > moment and look at shifting the transmit carrier as > it's supposed to > be. Which is kind of where I'm having a small but > measurable > problem. That problem is that I cannot for the life > of me remember > how the old FSK exciters worked.
Shifting the VFO or the xtal oscillator with a reactance valve....or switching a small variable capacitor in and out (a 10 uufd APC. fr instance)with a diode... > And, of course, > everything I've > found on the web relates to all those new fangled > SSB thingies and > AFSK and all. > > So how, for example, did the MD-203 manage the T-195 > to make it a > RTTY transmitter (as in the AN/GRC-46)? > > The derisive laughter may now commence. I'm used to > it ... *sigh* Well, the old way may seem attractive, but has problems of its own. First, it will be hard to keep the expected shift as you move accross the band (maybe not a big problem with narrow RTTY bands), and will be hard to TRANSCEIVE with it. >From a purely theoretical standpoint, the old way FSK might not be "phase continuous", which will originate a slightly broader signal. GL, Jose, CO2JA __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
