Motorola GP340 Service Information

Chapter 2
THEORY OF OPERATION
1.0 Introduction
This Chapter provides a detailed theory of operation for the 300-350MHz circuits in the radio. For
details of the theory of operation and trouble shooting for the the associated Controller circuits refer
to the Controller Section of this manual.
2.0 Transmitter
(Refer to Figure 2-1 and the Transmitter schematic diagram)
The transmitter contains five basic circuits:
1. power amplifier,
2. antenna switch,
3. harmonic filter,
4. antenna matching network,
5. power control integrated circuit (PCIC).
Figure 2-1 Transmitter Block Diagram.
2.1 Power Amplifier
The power amplifier consists of two devices:
1. 9Z67 LDMOS driver IC (U101) and
2. PRF1507 LDMOS PA (Q110).
The 9Z67 LDMOS driver IC contains 2 stages of amplification with a supply voltage of 7.3V.
This RF power amplifier is capable of supplying an output power of 0.3W (pin 6 and 7) with an input
signal of 2mW (3dBm) (pin16). The current drain would typically be 160mA while operating in the
frequency range of 300-350MHz.
PCIC
PA
Antenna Switch/
Driver
Stage
Harmonic Filter
Vcontrol
Vcontrol
From
Antenna
Matching
Network
Power
Amplifier
VCO
P A Final

Motorola GP340 Specifications

Power and Battery

power supply	Rechargeable Battery 7.5v
battery life with standard high capacity NiMH battery (low power)	11 hours
battery life with standard high capacity NiMH battery (high power)	8 hours
battery life with ultra high capacity NiMH battery (low power)	14 hours
battery life with ultra high capacity NiMH battery (high power)	11 hours
battery life with NiCD battery (low power)	12 hours
battery life with NiCD battery (high power)	9 hours
battery life with Li-lon battery (low power)	11 hours
battery life with Li-lon battery (high power)	8 hours

Operating Environment

operating temperature	-20°C to +55°C
sealing	Withstands rain testing per MIL STD 810 C/D/E and IP54
shock and vibration	Protection provided via impact resistant housing exceeding MIL STD 810-C/D/E and TIA/EIA 603
dust and humidity	Protection provided via environment resistant housing exceeding MIL STD 810 C/D/E and TIA/EIA 603

Transmitter Specifications

frequencies - full bandsplit	VHF: 136-174 MHz, LB1: 29.7-42 MHz, UHF: 300-350 MHz, LB2: 35-50 MHz, UHF1: 403-470 MHz
channel spacing	12.5/20/25 kHz
frequency stability	±2.5 ppm
power	136-174: 1-5W, 300-350: 1-4W, 403-470: 1-4W
modulation limiting	±2.5 @ 12.5 kHz, ±4.0 @ 20 kHz, ±5.0 @ 25 kHz
FM hum & noise	-40dB typical
conducted/radiated emission	-36 dBm <1 GHz, -30 dBm >1GHz
adjacent channel power	-60 dB @ 12.5 kHz, -70 dB @ 20/25 kHz
audio response (300-3000Hz)	+1 to -3 dB
audio distortion	3%

Receiver Specifications

frequencies - full bandsplit	VHF: 136-174 MHz, LB1: 29.7-42 MHz, UHF: 300-350 MHz, LB2: 35-50 MHz, UHF1: 403-470 MHz
channel spacing	12.5/20/25 kHz
sensitivity (12 dB SINAD) EIA	.25µV typical
sensitivity (20 dB SINAD) EN	.50µV typical
intermodulation EIA	70 dB
adjacent channel selectivity	60 dB @ 12.5 kHz, 70 dB @ 20/25 kHz
spurious rejection	70 dB
rated audio	0.5W
audio distortion @ rated audio	3% typical
hum & noise	-40 dB @ 12.5 kHz, -50 @ 20/25 kHz
audio response (300-3000 Hz)	+1 to -3 dB
conducted spurious emission	-57 dBm <1 GHz, -47 dBm <1 GHz

Weight and Dimensions

dimensions with standard high capacity NiMH battery	137 x 57.5 x 37.5 mm
dimensions with ultra high capacity NiMH battery	137 x 57.5 x 40.0 mm
dimensions with NiCD battery	137 x 57.5 x 40.0 mm
dimensions with Li-lon battery	137 x 57.5 x 33.0 mm
weight with standard high capacity NiMH battery	420 gm
weight with ultra high capacity NiMH battery	500 gm
weight with NiCD battery	450 gm
weight with Li-lon battery	350 gm