Motorola GP340 Service Information

Receiver 2-3
3.0 Receiver
3.1 Receiver Front-End
(Refer to Figure 2-2 and the Receiver Front End schematic diagram)
The RF signal is received by the antenna and applied to a low-pass filter. For 300R1, the filter
consists of L101, L102, C102, C103, C104. The filtered RF signal is passed through the antenna
switch. The antenna switch circuit consists of two PIN diodes (CR101 and CR102) and a pi network
(C106, L104 and C107). The signal is then applied to a varactor tuned bandpass filter. The VHF
bandpass filter comprises of L301, L302, C302, C303, C304, CR301 and CR302. The bandpass
filter is tuned by applying a control voltage to the varactor diodes (CR301 and CR302) in the filter.
The bandpass filter is electronically tuned by the DACRx from U404 which is controlled by the
microprocessor. Depending on the carrier frequency, the DACRx will supply the tuned voltage to the
varactor diodes in the filter. Wideband operation of the filter is achieved by shifting the bandpass
filter across the band.
The output of the bandpass filter is coupled to the RF amplifier transistor Q301 via C307. After being
amplified by the RF amplifier, the RF signal is further filtered by a second varactor tuned bandpass
filter, consisting of L306, L307, C313, C317, CR304 and CR305.
Figure 2-2 Receiver Block Diagram
Demodulator
Synthesizer
Crystal
Filter
Mixer
Varactor
Tuned Filter
RF Amp
Varactor
Tuned Filter
Pin Diode
Antenna
Switch
RF Jack
Antenna
AGC
Control Voltage
from ASFIC
First LO
from FGU
Recovered Audio
Squelch
RSSI
IF
IC
SPI Bus
16.8 MHz
Reference Clock
Second
LO VCO
U301
IF Amp

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