Actually that is not true with something like a Softrock. You would need one crystal for each ham band which is not that big of a problem. For a full coverage receiver a well behaved PLL that went in 50 khz steps would work.
Johan H. Bodin wrote: > Hi, > > yes, a pure and simple XTAL LO would be better than any synthesizer > but making a full coverage HF receiver that works with a soundcard > would require hundreds of XTALs!... > > On my lab bench, I use a HP8640B for LO but it cannot be accused for > beeing portable ;-) > > Maybe it is time to brush the dust off the old "CB style" synthesizer > which used two banks of crystals, with small/big steps, and mix/filter > the two oscillator signals to get the LO frequency. There will be some > unwanted mixing products, of course, but they are predicatble in a much > better way than a DDS "spur' forest". > > 73 > Johan SM6LKM > > > W2XJ wrote: > >>Programs like soft rock would be better with a crystal front end it >>seems to me. The computer does the actual tuning. Beside the spur >>problem a crystal has less phase noise. > > >
