Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!linus!decvax!ittvax!dcdwest!sdcsvax!sdcrdcf!hplabs!sri-unix!Halbert.PA@XEROX.ARPA From: Halbert.PA@XEROX.ARPA Newsgroups: net.ham-radio Subject: frequency synthesis Message-ID: <12693@sri-arpa.UUCP> Date: Thu, 4-Oct-84 17:39:47 EDT Article-I.D.: sri-arpa.12693 Posted: Thu Oct 4 17:39:47 1984 Date-Received: Sun, 7-Oct-84 21:36:56 EDT Lines: 12 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