Good questions. I had them myself, especially #2. Wes
--- On Thu, 4/14/11, John Ragle <tpcj1...@crocker.com> wrote: > The more I > have glanced through the specs for this device, the more > puzzled I have become. I grew up on signal generators that > put out a > (good approximation to a) sine wave. This device is > described as an RF > "square wave" generator, which I take to mean that the > output wave shape > is a trapezoid with very fast rise and fall times. As > everyone knows, > the harmonic content of an ideal square wave falls off as > 1/N. In other > words, this device is a harmonic generator, par excellence, > very rich in > harmonic content. To get a sine wave, one has to run it > through a > bandpass filter. In this case, the bandpass filter is the > receiver to > which you connect it. > > So there are two questions. > > 1. What is the "frequency?" This term usually refers to a > sinusoid, in > which case the answer is trivial. Presumably the > "frequency" meant here > is the fundamental component of the "square" wave, but the > true answer > depends on the shape of the on/off switching, which > presumably depends > on the "frequency" one has dialed into the device. Is one > getting more > or less a 1/N dependence on amplitude at all frequencies? > > 2. When one refers to the calibrated "levels" of output, is > one > referring to the level of the square wave or of its > fundamental > sinusoidal component? Clearly, these are related...but > which is meant? > What about the high frequency end of the operating range, > where the > spectrum may well depart substantially from 1/N (because > the trapezoid's > edges are less "sharp"). > > Neither of these questions has anything to do with the > "phase noise" > specification. > > John Ragle -- W1ZI > ______________________________ ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
