Intek M-490 Plus - DESCRIPTIONS OF EACH BLOCK; VCO and Varicap Diode Control

Model No: 3390 Drawring No:
Customer :
Title
M-490 Plus
Rev,Date:
31 27.90125 6882.5 17.20625 5580.25 13.950625
32 27.91125 6886.5 17.21625 5582.25 13.955625
33 27.92125 6890.5 17.22625 5584.25 13.960625
34 27.93125 6844.5 17.23625 5586.25 13.965625
35 27.94125 6898.5 17.24625 5588.25 13.970625
36 27.95125 6902.5 17.25625 5590.25 13.975625
37 27.96125 6906.5 17.26625 5592.25 13.980625
38 27.97125 6910.5 17.27625 5594.25 13.985625
39 27.98125 6914.5 17.28625 5596.25 13.990625
40 27.99125 6918.5 17.29625 5598.25 13.995625
3. DESCRIPTIONS OF EACH BLOCK
A. Introduction
The synthesizer is implemented with the following
Components:
PLL IC (IC6)
X-TAL (X2)
VCO, VARICAP DOIDE (D402)
IC101 is a cmos LSI that includes most of PLL block and driver, the Q401-Q406, C412, C415, C416,
C417 and L501, Varicap diode D402,D403 are clapp oscillator circuit to operate as a VCO of the
IC101. Q406 is a switching transistor to connect or disconnect the tuning capacitor in the VCO
oscillator tank circuit for transmitter or receiver. Q408 works as a buffer AMP for RX local frequencies
(16 MHz) and TX generating frequencies (13 MHz).
B. Reference frequency
The crystal, X2 (4.500 MHz) and other components at PIN 1 and 80 of IC101 can make a reference
frequency oscillator with internal amplifier.
C. VCO
Q503 and surrounding parts are consisting a clapp oscillator works as a VCO of IC101. the VCO can
be oscillate over the required of 13.4825 MHz to 17.29625 MHz
Created by: Approved by: Rev.No:
For Stage: Release Date: Page: 22 / 61