Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site mouton.UUCP Path: utzoo!watmath!clyde!burl!ulysses!allegra!mouton!karn From: karn@mouton.UUCP Newsgroups: net.ham-radio Subject: Re: TS-430 frequency display; mods Message-ID: <157@mouton.UUCP> Date: Sat, 22-Sep-84 15:43:25 EDT Article-I.D.: mouton.157 Posted: Sat Sep 22 15:43:25 1984 Date-Received: Wed, 26-Sep-84 03:58:13 EDT References: <12149@sri-arpa.UUCP> Organization: Bell Communications Research, Inc Lines: 22 I don't know about the TS-430, but on synthesized VHF radios such as the Kenwood TR-9000 (which I have) there is a mechanism which explains small frequency calibration errors. Very few radios are actually synthesized to such small frequency steps such as 100 hz; this makes the phase lock loop design much more difficult. Instead, they typically have two oscillators which are mixed to generate the final LO signal: a "coarse" synthesized generator which operates on, say, 10 khz steps, and a "fine" conventional analog VCO which is operated over a relatively small range (10 khz) with a control voltage generated by a D/A converter. This means that while the frequency accuracy over a wide range will be fairly good, there may be small (several hundred hertz) errors which cyclically repeat due to nonlinearities in the D/A converter or the VCO (which is often a crystal oscillator and a variable capacitance diode.) There can also be nonlinearities when tuning through a "coarse" frequency step, e.g., a 10 khz boundary on the TR-9000 when the PLL synthesizer changes its output by one step and the analog VCO must sweep from one end of its range to the other. This is particularly noticeable on the TR-9000 in lower sideband. Phil Karn