[net.ham-radio] frequency synthesis

Halbert.PA@XEROX.ARPA (10/05/84)

Thanks, Phil, for your explanation of how certain VHF radios do
frequency synthesis. It was interesting and surprising to me, and
probably something to watch out for. However, I looked at the TS-430
service manual, and it (and probably similar HF radios) apparently do
not use an open-loop D/A design for fine frequency control. The TS-430
uses a 36 MHz master oscillator, and 3 PLL's, plus a plethora of
dividers and mixers to produce the necessary LO signals. (It's -quite-
complicated.) All the VCO's appear to feedback to the PLL chips. Fine
frequency steps (e.g. 10 Hz) are produced by dividing a signal
controlled in coarser steps.

--Dan