DDS can be good close in and when not stretched too far, but DDS is not
at all clean, there are so many spurs it usually takes a PLL (with the
attendant noisy VCO) to act as a spur filter. I'm going back to VCXO for
clean phase noise on my next 2m rig. Its under construction now, a kit
from Germany called Hohentwiel. Also has superb dynamic range and
reciprocal noise and S/N after detection by using crystal filters at
both ends of the single conversion IF.
73, Jerry, K0CQ
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Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
Reproduction by permission only.
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