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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