User's Manual

Charge Pump and Loop Filter
Transistors Q2, Q4, Q10, and associated resistors and capacitors form
the charge pump and loop Filter. The phase detector output from IC1
pins 15 and 16 are combined by the charge pump to produce a 0 to
15V tuning voltage signal.
The signal is filtered by the loop filter (R13, C16 and C17) to remove
any residual reference Frequency harmonics from the signal. After
filtering the signal is applied to the voltage controlled Oscillator
module.
DC to DC Converter
The DC-to-DC converter converts the +7.5 V to a 14-16 V supply. This
is used to provide the Tuning voltage for the VCO. A wide voltage
range is required to allow for the wideband operation of the radio.
Q506 to Q508, and associated components, form a 200kHz oscillator.
The output of the oscillator is rectified and filtered by D503, D506,
C548 and C11. The resultant 16VDC is passed to R544 and then
becomes the supply rail for the charge pump.
Dual modulus prescaler
The prescaler divides the VCO frequency by 64 or 65.
Transmitter
The transmitter comprises:
VCO Buffer PA Module
Amp
PAGE 7
RF LPF
ANTENNA
SWITCH
Automatic
Power Control