Midland 91-1060-91-1110 Installation and operating instructions

SERVICE MANUAL ADDENDUM
P25/FM TWO-WAY
LAND MOBILE RADIO
BASE TECH III BASE/REPEATER
STATION
91-1060-91-1110
91-4050-91-4100
LOW CURRENT MODELS
VHF HIGH BAND
UHF BAND
Part Number: 680-100-2049
Revision A
1/12

Important Information
All rights reserved. No part of this publication may be reproduced, transmitted,
transcribed, stored in a retrieval system, or translated into any language without the
written permission of Midland Radio Corporation.
No part of any copyrighted computer programs contained in the products referred to in
this manual may be copied or reproduced without the express written consent of Midland
Radio Corporation.
Midland Radio Corporation reserves the right to change the products described in this
manual without prior notice.
© 2012 Midland Radio Corporation
This manual is designed to facilitate the set-up and service of the Midland 91-1060 / 1110
91-4050 / 91-4100 P25 Base Tech III series. As necessary, service manual supplements
will be published and distributed on the following forms:
Manual Addition (MA) For supplemental information useful in product
service or improvement. Printed on BLUE
paper.
Change Notice (CN) For details about changes made during
production by model and serial number. Printed
on YELLOW paper.
Manual Correction (MC) For correcting literature errors not related to
production changes. Printed on GREEN paper.
Technical Bulletin (TB) For solutions to field problems and tips for
performance improvement. Printed on PINK
paper.
Comments or suggestions concerning areas of manual improvement are welcome.
© 2012 Midland Radio Corporation ii

TABLE OF CONTENTS
Manual Supplement Information ii
Table of Contents iii
Acronyms and Abbreviations iv
GENERAL INFORMATION
Specifications 1-2
Accessories 3-4
PREPARATION
Alignment 5-12
CIRCUIT DESCRIPTION
Description 13-18
DIAGRAMS
VHF/ UHF General Block Diagrams 19-22
Front Panel Unit Schematic 23
Analog Logic Unit Schematic 24
VHF RX Main Unit Schematic 25
VHF RX VCO Unit Schematic 26
VHF TX Main Unit Schematic 27
UHF RX Main Unit Schematic 28
UHF RX VCO Unit Schematic 29
UHF TX Main Unit Schematic 30
Front Panel Unit Layout 31
Analog Logic Unit Layout 32
VHF RX Main Unit Layouts 33
VHF RX VCO Unit Layout 33
VHF TX Main Unit Layouts 34
UHF RX Main Unit Layouts 35
UHF RX VCO Unit Layout 35
UHF TX Main Unit Layouts 36
Chassis Exploded View 37
Palm Microphone Schematic 39
PARTS
Low Current Specific Parts List…………….. 40-56
Replacement Parts Ordering 57
iii © 2012 Midland Radio Corporation

ACRONYMS AND ABBREVIATIONS
Below is a list of common electrical abbreviations used in documentation.
CTCSS --------------------- Continuous Tone-Controlled Squelch System
DCS (or CDCSS) --------- Continuous Digital-Controlled Squelch System
EEPROM ------------------ Electrically Erasable Programmable Read Only
Memory
MIL SPEC ------------------ Military Specification
RX --------------------------- Receive
TX --------------------------- Transmit
SINAD ---------------------- The ratio in decibels of signal + noise +
distortion to noise + distortion
VCO ------------------------ Voltage Controlled Oscillator
TCXO ---------------------- Temperature Compensated Crystal Oscillator
PLL ------------------------- Phase Locked Loop
© 2012 Midland Radio Corporation iv

General Information
Low Current Base Tech 3.5
SPECIFICATIONS -VHF
General
Frequency Range: A Band: 136-156 MHz, B Band: 146-174 MHz
Number of Channels: 500 channels with name, 10 groups of 50 channels
Channel Spacing: FM 12.5 / 20 / 25 / 30 kHz
Digital C4FM
Operation Mode: Simplex / Duplex / Full Duplex/ Repeat
Antenna Impedance: 50 ohm unbalanced
Power Supply: DC 13.6 V, negative ground only
Consumption: <120mA Standby
@RX ~1 A
@TX ≤12 A (60W), ≤20 A (110W)
Environmental Conditions: -30 to +60 degrees C, 95% humidity @ 35C
Dimensions: 18.2” (w) x 3.4” (h) x 14.2” (d), (462 mm x 88 mm x 360 mm)
Weight: 24 lbs (11 kgs)
Transmitter
Output Power: (91-1060) 25-60 W, continuous
(91-1110) 5-110 W, continuous
Switchable Bandwidth: Full Sub Band
Maximum Deviation: ±5kHz (wide band), ±2.5 kHz (narrow band)
Frequency Stability: ≤1.5 ppm std, 10 MHz external optional
Frequency Response: +1 dB / -3 dB, 300-3000 Hz, 1 kHz reference
FM Hum and Noise: ≤50 dB @1kHz 70% mod., ≤50 dB Digital mode
Modulation Distortion: ≤3%
Spurious & Harmonics: ≤0.25µW (≥80 dBc)
Receiver
Switchable Bandwidth: Full Sub Band
IF Frequencies: 1
st IF: 48.4 MHz, 2nd IF: 455 kHz
Frequency Stability: ≤1.5 ppm
Sensitivity: ≤0.40 µV @ 20 dB N.Q., ≤0.30 µV @ 12 dB SINAD
≤0.30µV, Digital 5% BER
Squelch Sensitivity: ≤0.25 µV
Selectivity: ≥85 dB @ 25 kHz, ≥80 dB @ 12.5 kHz (TIA-603)
≥80 dB Digital
Intermodulation: ≥85 dB
Spurious Response: ≥100 dB
AF Response: +1 / -3 dB, 300-3000 Hz, 1 kHz reference
AF Distortion: ≤3% @ 1 kHz 60% mod.
Audio Output Power: 7.5 Watts @ 8 Ώ/ 10 Watts @ 4 Ώ
Signal to Noise Ratio: ≥50 dB @ 1 kHz 70% mod. (wideband), ≥45 dB (narrowband)
1© 2012 Midland Radio Corporation

General Information
Low Current Base Tech 3.5
SPECIFICATIONS -UHF
General
Frequency Range: A Band: 400-435 MHz, B Band: 440-475 MHz
C Band: 465-500 MHz, D Band: 485-520 MHz
Number of Channels: 500 channels with name, 10 groups of 50 channels
Channel Spacing: FM 12.5 / 20 / 25 / 30 kHz; Digital C4FM
Operation Mode: Simplex / Duplex / Full Duplex/ Repeat
Antenna Impedance: 50 ohm unbalanced
Power Supply: DC 13.6 V negative ground only
Consumption: <120mA Standby
@RX ~1 A
@TX ≤12 A (60W), ≤20 A (110W)
Environmental Conditions: -30 to +60 degrees C, 95% humidity @ 35C
Dimensions: 462 mm (w) x 88 mm (h) x 360 mm (d); 18.2” x 3.4” x 14.2”
Weight: 11 kg (24 lbs.)
Transmitter
Output Power: (91-4050) 25-50W continuous
(91-4100) 2-100W continuous
Switchable Bandwidth: Full sub band
Maximum Deviation: ±5 kHz (wide band); ±2.5 kHz (narrow band)
Frequency Stability: ≤1.5 ppm std, 10 MHz external optional
Frequency Response: Within +1, -3dB, 300-3000Hz
FM Hum and Noise: ≥50 dB @1 kHz 60% mod.; ≥50 dB Digital
Modulation Distortion: ≤3%
Spurious & Harmonics: ≤0.25 µW (-80 dBc)
Receiver
Switchable Bandwidth: Full sub band
IF Frequencies: 1
st IF: 73.35 MHz, 2nd IF: 455 kHz
Frequency Stability: ≤1.5 ppm
Sensitivity: ≤0.40 µV for 20 dB N.Q./ ≤0.30 µV for 12 dB SINAD
<0.30 µV Digital 5% BER
Squelch Sensitivity: ≤0.25 µV
Selectivity: ≥85 dB @ 25 kHz; ≥80 dB @ 12.5 kHz (TIA-603);
≥80 dB Digital mode
Intermodulation: ≥85 dB
Spurious Response: ≥100 dB
AF Response: +1 / -3 dB, 300-3000 Hz, 1 kHz ref.
AF Distortion: ≤3% @ 1 kHz 60% mod.
Audio Output (<2% distortion): 7.5Watts @ 8 Ώ/ 10 Watts @ 4 Ώ
Signal to Noise Ratio: ≥50 dB @ 1kHz 60% mod. (45 dB at narrow)
© 2012 Midland Radio Corporation 2

General Information
Low Current Base Tech 3.5
OPTIONS & ACCESSORIES
71-7220B 30 AMP Rack-mount Power Supply 220/110VAC
71-1230BM Battery Back-up Module for 7220B
71-0033 DC Power Cable, 48”
71-7801 External TX/RX Antenna Relay (Up to 400 Watts)
71-7751 Internal TX/RX Antenna Relay
71-8820D 31-1/2” Indoor Cabinet, complete with locking doors
71-8830D 40-1/4” Indoor Cabinet, complete with locking doors
71-8082 Slide Rails for TX/RX Unit
71-8834 Hardware Kit for Cabinets
71-8822-2AS Grounding Kit for 31-½” Cabinets
71-8822-2AT Grounding Kit for 40-1/4” Cabinets
71-8871 12-1/4” Blank Panel
71-8870 10-1/2” Blank Panel
71-8863 3-1/2” Blank Panel
71-8862 1-3/4” Blank Panel
91-1303B USB Programming Cable
91-1480CD Base Tech III Programming Software
71-2020E 16 Channel Tone Remote Termination
71-2022E E&M Expansion Kit used with 71-2020E in
71-8885A/D Option Shelf (only)
71-8885A Option Shelf with Slides / Easy Access & AC Supply
No Battery Charge
3© 2012 Midland Radio Corporation

General Information
Low Current Base Tech 3.5
71-8885AC Option Shelf with Slides / Easy Access & AC Supply
with Battery Charge
71-8885D Option Shelf with Slides / Easy Access & DC
Operation
71-7206 Tone Termination Lightning / Surge Protection
(2wire / 4-wire)
71-7207 AC Surge Protection Kit (115V only)
71-7655A RF Line Surge Protection
71-8880 90” Aluminum Rack
71-8881 Shipping Hardware Kit, 71-8880
71-8879 Radio Shelf Support Kit (Relay Racks Only)
71-2315 Palm Microphone
71-2316 Desktop Microphone
71-8155-1 VHF Duplexer (3-5MHz Separation) 350W, 150-160
MHz
71-8155-2 VHF Duplexer (3-5 MHz Separation) 350W, 160-174
MHz
71-8152-3 VHF Duplexer (2 MHz Separation) 350W, 150-160
MHz
71-8152-4 VHF Duplexer (2 MHz Separation) 350W, 160-174
MHz
71-8455A UHF Duplexer (3-5 MHz Separation) 350W, 440-
512 MHz
71-8455D UHF Duplexer (3-5 MHz Separation) 350W, 406-
430 MHz
© 2012 Midland Radio Corporation 4

Alignment Procedures
Low Current Base Tech 3.5
THIS PAGE INTENTIONALLY LEFT BLANK
5 © 2012 Midland Radio Corporation

Alignment Procedures
Low Current Base Tech 3.5
RECEIVER (RX MAIN UNIT)
1. Pre-selector and Post-selector Tuning
Both selectors have been pre-tuned at the factory, so no alignment is required.
2. FVR001 Tight Squelch Level
This potentiometer allows adjustment to the tight squelch level.
3. FVR002 De-mod out Bias Level
This potentiometer allows adjustment to the level of DC Bias on the De-Mod output.
4. L303 VCO Alignment
The VCO has been alignedat the factory to cover fullsub-band. However, if you need to re-adjust VCO
after a repair, set the VCO voltage to 10.5 V at the highest end of the sub band using L303. The VCO
cover must be removed for access.
Note that tuning slug may be glued and breakage could occur.
5. RX 0-dBm LevelAdjustment
This is 600 ohm audio available on pins 20 and 21 of the EXT Option port. It is electronically adjusted.
Ground TP-2 on theAnalog Logic Unit PCB, and power-up the radio. See Figure 3 on page 6. The
station is now inAdjust Mode. Release TP-2 from ground. The display should look as follows:
RXNS <Adjust>
TXN RX 0dbm Out
C0001 27 / 31 AA
Use the “A” and “B” keys on the front panel to adjust the level up or down. Pressing the “#” key will
change the mode you are adjusting. The “A” key will increase the level while the “B” key will decrease
the level. You will be able to monitor the output if the station is receiving a valid carrier and signaling.
Cycle power to the radio to return to normal operation.
NOTE: The other ADJUST Modes are in order of appearance:
RX 0 dbm
REPEAT DEVI
DIGITAL DEVI
ANALOG DEVI
TONE DEVI
CTC DEVI WID
CTC DEVI NRW
© 2012 Midland Radio Corporation 6