Motorola Gp328plus Gp338plus Gp338xls Detailed 6804112j28 G Manual

							Troubleshooting charts5C-35
5V
 at pin 6 of 
CR201
Is information
from µP U409
correct?
Is U201 Pin 18 
AT 4.54 VDC?
Is U201 Pin 47 
AT = 13 VDC
Is U241 Pin 19
4.3 VDC in TX?
Start
Vis u a l 
check of the 
Board OK?Correct
Problem
Check 5V 
Regulator
+5V at U201
Pin’s
13 & 30?
Is 16.8MHz
Signal at
U201 Pin 19?
Check FL201, C206, 
C207, C208, CR203 & 
R204
Are signals
at Pin’s 14 &
15 of U201?
Check 
L202Check Q260, 
Q261 & R260
U201 pin 2 at 
>3V in Tx and 
-30 dBm?
Are R231,R232,
R233,C231,C232,
& C233 OK?
Replace U201
If L261, C263 & C264
are OK, then see VCO
troubleshooting chart
Are Waveforms
at Pins 14 & 15
triangular?
Do Pins 7,8 & 9
of U201 toggle
when channel is
changed?
Check programming
lines between U409
and U201 Pins 7,8 & 9
Replace U201
Check uP U409
Troubleshooting
Chart
NO
YES
NO
YES
NO
YES
NO
YESNO
NO
NO
YES
YESNOYES YESNO
YES YES YES
NONO
NO
NO
YES
NO
YES YESCheck CR201, U210, 
U211, C258, C259 & 
C228
3.3V at U201 
pins 5, 20, 34 & 
36Check U248, 
L201 & L202
Is 
16.8MHz 
signal at 
U201 pin 
23?
Replace 
U201
YES
NO NO
YES
NO YES
Troubleshooting Flow Chart for Synthesizer 
						

							5C-36Troubleshooting charts
START
No LO?
Tx Carrier?
VCO OK
Check 
R260
TRB = 5V?Pin 10 
>1V?
L253 O/C?Change 
L253
Change 
U241
AUX 3 
High?
Check U201 
Pin 2 for 3.2V
Pin 19 =0V
AUX 4 
High?
Change 
Q261
V ctrl 0V 
or 13V?
L243 Open 
Circuit?
Change 
U241
Change 
L243
Change 
U201
Check for faulty parts or dry 
joints of L271, L273, C370, 
C386, R339 & L320 A
A
No
No Ye s
Ye s Ye s
No
NoYe sYe s
Ye s
No
Ye sNoNoYe sYe s
No
No
Check R245 for dry 
joint or faulty
No
Troubleshooting Flow Chart for VCO 
						

							5D-1
Section 5D
MODEL CHART AND TEST SPECIFICATIONS (330-400 
MHZ)
1.0 Model Chart
GP Series, 330-400 MHz
ModelDescription
AZH38PDC9AA3GP328 Plus 330-400 MHz 4W 16 CH 
AZH38PDH9AA6GP338 Plus 330-400 MHz 4W 128 CH 
ItemDescription
XPMUD1675GP328 Plus Super Tanapa 330-400 MHz 4W
XPMUD1676GP338 Plus Super Tanapa 330-400 MHz 4W 128CH
XPMUD1679GP328 Plus Tanapa 330-400 MHz 4W
XPMUD1680GP338 Plus Tanapa 330-400 MHz 4W 128CH
XJMHD4007GP328 Plus B/C Kit 330-400 MHz 4W
XPMHD4007GP338 Plus B/C Kit 330-400 MHz 4W 128CH
XPMHD4002GP328 Plus Front Housing Kit
XPMHD4003GP338 Plus Front Housing Kit
XXPMAD4009VHF 9 cm antenna (336-368 MHz)
XXPMAD4020VHF 9 cm antenna (370-400 MHz)
X6804022G48GP328 Plus User Guide
X6804112J64GP338 Plus User Guide
x = Indicates one of each is required. 
						

							5D-2Specifications (for GP328 Plus)
2.0 Specifications (for GP328 
Plus)
General
Tr a n s m i t t e r
Receiver
All specifications are subject to change without notice.
330-400MHz
Frequency:330-400 MHz
Channel Capacity:GP328 Plus : 16 Chan-
nels
Power Supply:7.5 Volts ±20%
Dimensions
   with Standard 
High  Capacity 
 
Lithium Battery:
   with Ultra High 
Capacity Lithium 
Battery:
101.5mm x 55.5mm x 
30.5mm
101.5mm x 55.5mm x 
35.5mm
Weight:
   with Standard 
High Capacity 
 
Lithium Battery:
   with Ultra High 
Capacity Lithium 
Battery:
250 g
270 g
Average Battery 
Life @ (5-5-90 Duty 
Cycle)
   Standard High 
Capacity Lithium 
Battery:
   Ultra High Capac-
ity Lithium Battery:
Low  
Power
>10 hrs
>14 hrs
High  
Power
>7 hrs
>10 hrs
Sealing:Meets MIL-STD-810-
C,D & E and IPX4
Shock:Meets MIL-STD-810-
C,D & E and TIA/EIA 603
Vibration:Meets MIL-STD-810-
C,D & E and TIA/EIA 603
Dust:Meets MIL-STD-810-
C,D & E and IP5X
Humidity:Meets MIL-STD-810-
C,D & E and TIA/EIA 603
330-400MHz
RF Output
Li Ion @ 7.5V:
Low
1W
High
4W
Frequency330-400 MHz
Channel Spacing12.5/20/25 kHz
Freq. Stability
(-30°C to +60°C)
0.00025%
Spurs/Harmonics:-36 dBm < 1 GHz 
-30 dBm > 1 GHz
Audio Response:
(from 6 dB/oct. Pre-
Emphasis, 300 to 
3000Hz)
+1, -3 dB
Audio Distortion:
@ 1000 Hz, 60%
Rated Max. Dev.

						

							Specifications (for GP338 Plus)5D-3
3.0 Specifications (for GP338 
Plus)
General
Transmitter
Receiver
All specifications are subject to change without notice.
330-400MHz
Frequency:330-400 MHz
Channel Capacity:GP338 Plus : 128 Chan-
nels
Power Supply:7.5 Volts ±20%
Dimensions
   with Standard 
High  Capacity 
 
Lithium Battery:
   with Ultra High 
Capacity Lithium 
Battery:
101.5mm x 55.5mm x 
33.0mm
101.5mm x 55.5mm x 
38.0mm
Weight:
   with Standard 
High Capacity 
 
Lithium Battery:
   with Ultra High 
Capacity Lithium 
Battery:
250 g
270 g
Average Battery 
Life @ (5-5-90 Duty 
Cycle)
   Standard High 
Capacity Lithium 
Battery:
   Ultra High Capac-
ity Lithium Battery:
Low  
Power
>10 hrs
>14 hrs
High  
Power
>7 hrs
>10 hrs
Sealing:Meets MIL-STD-810-
C,D & E and IPX4
Shock:Meets MIL-STD-810-
C,D & E and TIA/EIA 603
Vibration:Meets MIL-STD-810-
C,D & E and TIA/EIA 603
Dust:Meets MIL-STD-810-
C,D & E and IP5X
Humidity:Meets MIL-STD-810-
C,D & E and TIA/EIA 603
330-400MHz
RF Output
Li Ion @ 7.5V:
Low
1W
High
4W
Frequency330-400 MHz
Channel Spacing12.5/20/25 kHz
Freq. Stability
(-30°C to +60°C)
0.00025%
Spurs/Harmonics:-36 dBm < 1 GHz 
-30 dBm > 1 GHz
Audio Response:
(from 6 dB/oct. Pre-
Emphasis, 300 to 
3000Hz)
+1, -3 dB
Audio Distortion:
@ 1000 Hz, 60%
Rated Max. Dev.

						

							5D-4Transmitter
4.0Transmitter
4.1 General
(Refer to Figure 5-1)
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).
4.1.1 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 a 2 stage 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 330-400MHz.  
The  PRF1507 LDMOS PA is capable of supplying an output power of 7W with an input signal of 
0.3W.  The current drain would typically be 1300mA while operating in the frequency range of 330-
400MHz. The power output can be varied by changing the biasing voltage.
Figure 5-1: Transmitter Block Diagram
PCIC
Antenna
PA
Driver
VcontrolVcontrol
From VCO
  Jack
PA - F i n a l
StageAntenna Switch/
Harmonic Filter/
Matching Network 
						

							Transmitter5D-5
4.1.2 Antenna Switch
The antenna switch circuit consists of two PIN diodes (CR101 and CR102), a pi network (C107, L104 
and C106), and two current limiting resistors (R101, R170).  In the transmit mode,  B+ at PCIC (U102) 
pin 23 will go low and turn on Q111 where a B+ bias is applied to the antenna switch circuit to bias the 
diodes on.  The shunt diode (CR102) shorts out the receiver port, and the pi network, which 
operates as a quarter wave transmission line, transforms the low impedance of the shunt diode to a 
high impedance at the input of the harmonic filter.  In the receive mode, the diodes are both off, and 
hence, there exists a low attenuation path between the antenna and receiver ports.
4.1.3 Harmonic Filter
The harmonic filter consists of C104, L102, C103, L101 and C102.  The design of the harmonic filter 
for VHF is that of a modified Zolotarev design. It has been optimized for efficiency of the power 
module.  This type of filter has the advantage that it can give a greater attenuation in the stop-band for 
a given ripple level.  The harmonic filter insertion loss is typically less than 1.2dB.  
4.1.4 Antenna Matching Network
A matching network which is made up of L116 is used to match the antennas impedance to the 
harmonic filter.  This will optimize the performance of the transmitter and receiver into an antenna.
4.1.5 Power Control Integrated Circuit (PCIC)
The transmitter uses the Power Control IC (PCIC), U102 to regulate the power output of the radio. 
The current to the final stage of the power module is supplied through R101, which provides a voltage 
proportional to the current drain.   This voltage is then  fedback to the Automatic Level Control (ALC) 
within the PCIC  to regulate the output power of the transmitter.  
The PCIC has internal digital to analog converters (DACs) which provide the reference voltage of the 
control loop.  The reference voltage level is programmable through the SPI line of the PCIC.
There are resistors and integrators within the PCIC, and external capacitors (C133, C134 and C135)  
in controlling the transmitter rising and falling time.  These are necessary in reducing the power 
splatter into adjacent channels.
CR105 and its associated components are part of the temperature cut back circuitry.  It senses the 
printed circuit board temperature around the transmitter circuits and output a DC voltage to the PCIC. 
If the DC voltage produced exceeds the set threshold in the PCIC, the transmitter output power will be 
reduced so as to reduce the transmitter temperature. 
						

							5D-6Receiver
5.0 Receiver
5.1 Receiver Front-End
(Refer to 330-400MHz Receiver Front End Schematic Diagram on page 5D-22 and 330-400MHz 
Transmitter Schematic Diagram on page 5D-26)
The RF signal is received by the antenna and applied to a low-pass filter. For VHF, 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. 
Both the pre and post-RF amplifier varactor tuned filters have similar responses. The 3 dB bandwidth 
of the filter is about 50 MHz. This enables the filters to be electronically controlled by using a single 
control voltage which is DACRx .
Figure 5-2:  Receiver Block Diagram
Demodulator
Synthesizer
Crystal 
Filter Mixer Varactor 
Tuned Filter RF Amp Va r a c t o r  
Tuned Filter Pin Diode 
Antenna 
Switch
RF Jack Antenna
AGC
Control Voltage
from  ASFICFirst LO
from FGU
Recovered Audio
Squelch
RSSI
IFIC
SPI Bus 16.8 MHz
Reference Clock
Second
LO VCO U301IF Amp 
						

							Receiver5D-7
The output of the post-RF amplifier filter which is connected to the passive double balanced mixer 
consists of T301, T302 and CR306. Matching of the filter to the mixer is provided by C381. After 
mixing with the first LO signal from the voltage controlled oscillator (VCO) using low side injection, the 
RF signal is down-converted to the 45.1 MHz IF signal. 
The IF signal coming out of the mixer is transfered to the crystal filter (FL301) through a resistor pad 
and a diplexer (C322 and L310). Matching to the input of the crystal filter is provided by C324 and 
L311. The crystal filter provides the necessary selectivity and intermodulation protection. 
5.2 Receiver Back-End
(Refer to 330-400MHz Receiver Back End Schematic Diagram on page 5D-23)
The output of crystal filter FL301 is matched to the input of IF amplifier transistor Q302 by 
components R352 and C325. Voltage supply to the IF amplifier is taken from the receive 5 volts (R5). 
The IF amplifer provides a gain of about 7dB.  The amplified IF signal is then coupled into U301(pin 3) 
via C330, C338 and L330 which provides the matching for the IF amplifier and U301.
The IF signal applied to pin 3 of U301 is amplified, down-converted, filtered, and demodulated, to 
produce the recovered audio at pin 27 of U301. This IF IC is electronically programmable, and the 
amount of filtering (which is dependent on the radio channel spacing) is controlled by the 
microprocessor. Additional filtering, once externally provided by the conventional ceramic filters, is 
replaced by internal filters in the IF module (U301). 
The IF IC uses a type of direct conversion process, whereby the externally generated second LO 
frequency is divided by two in U301 so that it is very close to the first IF frequency. The IF IC (U301) 
synthesizes the second LO  and phase-locks the VCO to track the first IF frequency. The second LO 
is designed to oscillate at twice the first IF frequency because of the divide-by-two function in the IF 
IC.
In the absence of an IF signal, the VCO will “search” for a frequency, or its frequency will vary close to 
twice the IF frequency. When an IF signal is received, the VCO will lock onto the IF signal. The 
second LO/VCO is a Colpitts oscillator built around transistor Q320. The VCO has a varactor diode, 
CR310, to adjust the VCO frequency. The control signal for the varactor is derived from a loop filter 
consisting of C362, C363, C364, R320 and R321.
The IF IC (U301) also performs several other functions. It provides a received signal-strength 
indicator (RSSI) and a squelch output. The RSSI is a dc voltage monitored by the microprocessor, 
and used as a peak indicator during the bench tuning of the receiver front-end varactor filter. The 
RSSI voltage is also used to control the automatic gain control (AGC) circuit at the front-end. 
The demodulated signal on pin 27 of U301 is also used for squelch control. The signal is routed to 
U404 (ASFIC) where squelch signal shaping and detection takes place. The demodulated audio 
signal is also routed to U404 for processing before going to the audio amplifier for amplification.  
						

							5D-8Receiver
5.3 Automatic Gain Control Circuit
(Refer to 330-400MHz Receiver Front End Schematic Diagram on page 5D-22)
The front end automatic gain control circuit  is to provide automatic gain reduction of the front end RF 
amplifier via feedback. This action is necessary to prevent overloading of back end circuits. This is 
achieved by drawing some of the output power from the RF amplifier’s output. At high radio 
frequencies, capacitor C331 provides the low impedance path to ground for this purpose. CR308 is a 
PIN diode used for switching the path on or off. A certain amount of forward biasing current is needed 
to turn the PIN diode on. Transistors Q315 provides this current where upon saturation, current will 
flow via R347, PIN diode, collector and emitter of Q315 and R319 before going to ground. Q315 is an 
NPN transistor used for switching here. Maximum current flowing through the PIN is mainly limited by 
the resistor R319. 
Radio signal strength indicator, RSSI,  a voltage signal, is used to drive Q315 to saturation hence  
turning it on. RSSI is produced by U301 and is proportional to the gain of the RF amplifier and the 
input RF signal power to the radio. 
Resistor network at the input to the base of Q315 is scaled to turn on Q315, hence activating the 
AGC, at certain RSSI levels. In order to turn on Q315, the voltage across the transistor’s base to 
ground must be greater or equal to the voltage across R319, plus the base-emitter voltage (Vbe) 
present at Q315. The resistor network with thermistor RT300 is capable of providing temperature 
compensation to the AGC circuit, as RSSI generated by U301 is lower at cold temperatures 
compared to normal operation at room temperature. Resistor R300 and capacitor C397 form an R-C 
network used to dampen any transient instability while the AGC is turning on.