Motorola Gm328 Gm338 Gm398 Detailed 6804112j18 E Manual

UHF Band 2 25-40W PCB / Schematics / Parts List4-13
* Motorola Depot Servicing only
Reference designators with an asterisk indicate 
components which are not field replaceable 
because they need to be calibrated with 
specialized factory equipment after installation. 
Radios in which these parts have been replaced in 
the field will be off frequency at temperature 
extremes.
R3151
0662057A73
10K
R3152 0662057A73 10K
R3153
0662057A73
10K
R3154 0662057A73 10K
R5001
0662057A97
97K
R5002 0662057A37 330...

4-14UHF Band 2 25-40W PCB / Schematics / Parts List
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 GM338
Mobile Radio
UHF B1 HIGH POWER LDMOS
(403-470MHz)
Service Information
Issue: December, 2003 

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programs contained in the Motorola products described in...

i
Table of Contents
Section 1 Model Chart and Technical Specifications
1.0 GM338 Model Chart............................................................................................. 1-1
2.0 Technical Specifications ...................................................................................... 1-1
Section 2 Theory of Operation
1.0 Introduction .......................................................................................................... 2-1
2.0 UHF (403-470 MHz) Receiver...

ii
Section 4 UHF PCB/Schematics/Parts Lists
1.0 Allocation of Schematics and Circuit Boards ....................................................... 4-1
1.1 Controller Circuits ........................................................................................... 4-1
2.0 UHF 25-40W PCB / Schematics / Parts List ........................................................ 4-3
UHF (403-470 MHz) 25-40W 8486127Z01 Top Side ............................................. 4-3
UHF (403-470 MHz) 25-40W 8486127Z01...

1-1
Section 1
MODEL CHART AND TECHNICAL SPECIFICATIONS
1.0 GM338 Model Chart
2.0 Technical Specifications
Data is specified for +25°C unless otherwise stated.
GM Series, UHF Band 1, 403-470 MHz
Mode Description
AZM25RKF9AA5GM338 403-470 MHz 25-40W Conv Pref (LDMOS)
Item Description
X GCN6114_ GM338 Control Head Direct Mount
XIMUE6012_Tanapa WM 403-470 MHz 25-40W
X RAE4151_ BNC 403-430 MHz, 
1/4 Wave Roof Mount
XRAE4152_BNC 450-470 MHz, 1/4 Wave Roof Mount
X RAE4153_ BNC 450-470 MHz, 3.5dB Gain Roof...

1-2Technical Specifications
*Availability subject to the laws and regulations of individual countries.Transmitter UHF
*Frequencies - Full BandsplitUHF 403-470 MHz
Channel Spacing12.5/20/25 kHz
Frequency Stability
(-30°C to +60°C, +25° Ref.)±2.0 ppm
Power 25-40W
Modulation Limiting
±2.5 @ 12.5 kHz 
±4.0 @ 20 kHz
±5.0 @ 25 kHz
FM Hum & Noise-40 dB @ 12.5kHz
-45 dB @ 20/25kHz
Conducted/Radiated Emission (ETS)-36 dBm 1 GHz
Adjacent Channel Power-60 dB @ 12.5 kHz
-70 dB @ 25 kHz
Audio Response (300 - 3000...

2-1
Section 2
THEORY OF OPERATION
1.0 Introduction
This Chapter provides a detailed theory of operation for the UHF circuits in the radio. For details of 
the theory of operation and troubleshooting for the the associated Controller circuits refer to the 
Controller Section of this manual.
2.0 UHF (403-470 MHz) Receiver
2.1 Receiver Front-End
The receiver is able to cover the UHF range from 403 to 470 MHz. It consists of four major blocks: 
front-end bandpass filters and pre-amplifier, first mixer,...

2-2UHF (403-470 MHz) Receiver
There are two 2-pole 44.85 MHz crystal filters in the high-IF section and 2 pairs of 455 kHz ceramic 
filters in the low-IF section to provide the required adjacent channel selectivity .The correct pair of 
ceramic filters for 12.5 or 25KHz channel spacing is selected via control line BWSELECT. The 
second IF at 455 kHz is mixed, amplified and demodulated in the IF IC. The processing of the 
demodulated audio signal is performed by an audio processing IC located in the...