ZETRON Viavi 3920 Operating manual

Appendix C: Viavi
3920 Test Procedures
MAINTENANCE GUIDE
www.zetron.com
™

Contents
ii
Appendix C: Viavi 3920 Test Procedures | MT-4E ANALOG & P25 DIGITAL RADIO SYSTEMS
Appendix C: VIAVI 3920 TEST PROCEDURES
MT-4E TESTING WITH THE 3920 BY VIAVI � � � � � � � � � � � � � � � � � � � � � � � �1
General Set-up and Connections � � � � � � � � � � � � � � � � � � � � � � � � � � � �2
Uploading Zetron Configurations to the 3920 � � � � � � � � � � � � � � � � � � � � � � � � 2
Radio Service Software (RSS) � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 3
Control Cards � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 3
Adapters, Cables and Extender Cards � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 3
Zetron MT-4E Radio System Test Sheet � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 3
Turning OFF the MT-4E Receiver and Transmitter Modules � � � � � � � � � � � � � � 4
Audio Connections � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 5
System Regulator Testing � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �6
System Voltage Testing � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 6
Receiver Testing � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �7
Receiver Analog Testing � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 7
Receiver Digital Testing � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 11
Receiver Bit Error Rate Testing � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 13
Receiver RF Preselector Alignment and Tuning � � � � � � � � � � � � � � � � � � � � � � 15
Receiver Reference Oscillator Adjustment � � � � � � � � � � � � � � � � � � � � � � � � � 17
Transmitter Testing � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �20
Transmitter Analog Testing � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 20
Transmitter CTCSS Testing � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 26
Transmitter Digital Testing � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 29
System Testing � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �33
Duplex Analog Testing � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 33
Duplex Digital Testing � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 36

01
Appendix C: Viavi 3920 Test Procedures
MAINTENANCE GUIDE | MT-4E ANALOG & P25 DIGITAL RADIO SYSTEMS
APPENDIX C: VIAVI 3920 TEST PROCEDURES
MT-4E TESTING WITH THE 3920 BY VIAVI
This Chapter contains instructions for Tuning, Testing, Maintaining and Servicing MT-4E Analog and P25 Digital
Radio Systems with the 3920 Service Monitor by Viavi.
This Chapter is intended as an aid to configuring and testing Zetron MT-4E radios using the Viavi 3920. Neither
Zetron or Viavi Solutions assume responsibility for damage caused to either unit as a result of misinterpretation
or misuse of this procedure. Zetron manufactured products are warranted against defective materials
and workmanship. This warranty does not extend to damage due to misuse, neglect, accident, improper
configuration or installation. Zetron and Viavi shall be released from all obligations under its respective
warranty in the event the Products are subject to misuse, neglect, alteration, accident, improper installation or
testing, or if unauthorized repairs are performed by the customer or others.
These procedures can be modified, changed and altered at any time to better suit your specific needs and
requirements. Refer to Zetron Instruction Manuals for complete radio system specifications.

02
Appendix C: Viavi 3920 Test Procedures
MAINTENANCE GUIDE | MT-4E ANALOG & P25 DIGITAL RADIO SYSTEMS
Uploading Zetron Configurations to the 3920
The 3920 allows for configuration files to be saved and recalled on the test set. These configuration files are
uploaded to the test set from a USB flash drive and can also be uploaded from your computer if the test set is
connected to your network�
The 3920 configuration files are available from Zetron website at www.zetron.com. The file can be downloaded,
then unzipped and copied onto a USB flash drive or transferred on the network.
To upload a file from a USB flash drive, insert the USB flash drive into the USB port and go to UTILS then File
Management. The Internal directory should be selected as Stores:/ and the External directory should be
selected as USB. Select the Internal Directory you would like to copy the files to (suggest Zetron, then select the
files on the USB and click File Copy. To select multiple files at once, hold the HOLD key.
To recall setups, double click on the UTILS button and select Store/Recall, or if you are using a mouse, right click
anywhere on the screen and select Store/Recall.
Please note that some of the setups that are recalled are generic and may need to be changed for your
specific receiver and transmitter settings.
The generic saved setups are as follows:
Audio = 1000 Hz @ 1.5 KHz deviation (for wideband set this to 3.0 KHz deviation)
CTCSS = 100.0 Hz @ 0.35 KHz deviation (for wideband set this to 0.5 KHz deviation)
NAC = 293
TGID = 1
General Set-up and Connections

03
Appendix C: Viavi 3920 Test Procedures
MAINTENANCE GUIDE | MT-4E ANALOG & P25 DIGITAL RADIO SYSTEMS
Radio Service Software (RSS)
Start the RSS program on the computer and ensure you are connected to the receiver or transmitter via the
type A to 5 pin mini-type B USB cable. Read the transmitter or receiver programming and familiarize yourself
with the settings (RF frequency, wide / narrowband, digital / analog, CTCSS / NAC, etc.).
Control Cards
Some Zetron MT-4E radio systems may have an AC-3E Audio Control Card or CI-BC-4E Base Control Card for use
in the radio system. The Control Cards connect to the receiver and transmitter balanced audio lines with an
unbalanced load, which could cause some measurements to be in error. If the radio system includes an AC-
3E Audio Control Card or CI-BC-4E Base Control Card, remove the control card from the rack for the individual
receiver and transmitter tests unless otherwise noted.
Adapters, Cables and Extender Cards
Various adapters, cables and extender cards are required for the different radio tests. Extender cards and
adapters are available from Zetron. The receiver reference oscillator and RF preselector filter tests require an
SMB - BNC adapter and a small SMB - SMB cable is required for the reference oscillator test as well. The SMB
adapters and cables are included in the A-TK-04 Tool Kit.
Zetron MT-4E Radio System Test Sheet
A Zetron MT-4E Radio System Test Sheet is included in Chapter 7 of the Maintenance Guide. It is recommended
that this test sheet be filled out each time the radio system is tested. If two or more pairs of transceivers are
tested, use a second test sheet to record the results. The test sheet will record settings for a single Tx and Rx
frequency, however other frequencies can be tested and recorded if desired.

04
Appendix C: Viavi 3920 Test Procedures
MAINTENANCE GUIDE | MT-4E ANALOG & P25 DIGITAL RADIO SYSTEMS
Turning OFF the MT-4E Receiver and Transmitter Modules
Turning the switch on the front panel of the MT-4E receiver or transmitter modules to the OFF position can cause
unwanted effects on other MT-4E receiver and transmitter modules.
When the MT-4E receiver and transmitter are connected directly together with the LVDS serial data RJ45 cable,
turning the MT-4E transmitter front panel switch to the OFF position will cause the MT-4E receiver module to turn
off. The MT-4E receiver modules A and D LEDs on the front panel will blink on and off when this occurs. Turning
the MT-4E receiver modules front panel switch to the OFF position will not cause any adverse effects on the
MT-4E transmitter. When turning the MT-4E receiver modules front panel switch from the OFF to NORM position
(or vice versa), it will cause the MT-4E transmitter to reboot. Remove the RJ45 cable to stop this interaction from
occurring. When connecting the LVDS serial data RJ45 cables to the CI-RC-4L repeater control card or CI-RC-
4M-G2 multiple link controller, the MT-4E receiver and transmitter modules are isolated from each other and the
modules can be turned on or off independently of each other.
When the MT-4E receiver and transmitter channel and bank select lines are connected together in parallel,
turning the MT-4E receiver or transmitter front panel switch to the OFF position will cause the channel and bank
select lines to be grounded. This will cause the other MT-4E module to operate on Bank B, Channel 1 regardless
of how the channel and bank select lines are set. If the bank select lines are not connected in parallel, only
the channel will be affected. The channel select lines are independent of the LVDS serial data RJ45 cables (the
cables will have no impact on the channel select).
When the MT-4E receiver and transmitter are connected to the antenna relay in the System Regulator module,
turning the MT-4E transmitter front panel switch to the OFF position will cause the MT-4E transmitter PTT OUT
line to be grounded, activating the antenna relay and causing it to be switched so that the transmitter is
connected to the antenna. This makes it impossible to test the MT-4E receiver through the antenna relay when
the MT-4E transmitter is turned off.
When performing maintenance on the Zetron MT-4E radio system it is best to simply remove the MT-4E receiver
or transmitter, that is not being tested, from the subrack and disconnect all RJ45 cables, rather than turning the
front panel switch to the OFF position. All Zetron modules are hot swappable. There is no need to disconnect
the power supply when inserting or removing the modules from the subrack.

05
Appendix C: Viavi 3920 Test Procedures
MAINTENANCE GUIDE | MT-4E ANALOG & P25 DIGITAL RADIO SYSTEMS
Audio Connections
The Receiver, Transmitter and Auxiliary Balanced audio lines are available for connection on Zetron extender
cards or by connecting to the optional back panel A-PNL-AUX96-3 screw-type terminal connector. The
extender cards have solder points available on each signal line that can have a small test point (5059-
TP110300) that is supplied with the extender card, soldered to them for easy connection with clip-on type clips.
Recommended Test Points are:
Audio Control Card and Base Control Card Extender Card pins (EC-96D1 and EC-96K-1.22): Auxiliary 1 Audio
Output = B11 and A11
Auxiliary 2 Audio Output = C1 and C3 (Audio Control Card); C2 and C4 (Base Control Card) Auxiliary 1 Audio
Input = C19 and C20
Auxiliary 2 Audio Input = B14 and A14
Receiver and Transmitter Extender Card pins (EC-48RD and EC-48RK-1.22):
Rx Balanced Audio Output = B26 and Z26
Tx Balanced Audio Input = B18 and Z18
Tx Subtone Input = B22 and Ground (B32)
The test points can be soldered into the extender cards as shown in Figure C-1.
Figure C-1: EC-96D1 and EC-48RD Direct Connect Extender Cards with Test Points Added
test points soldered
onto extender card

06
Appendix C: Viavi 3920 Test Procedures
MAINTENANCE GUIDE | MT-4E ANALOG & P25 DIGITAL RADIO SYSTEMS
System Regulator Testing
System Voltage Testing
The first stage of testing a Zetron MT-4E radio system is to perform a basic system check on the supply and
regulated voltages. The System Regulator module is designed with a convenient and easy test point built into
the front panel. This test point allows a technician access to the DC supply and regulated voltages. Simply
connect a standard Digital Volt Meter (DVM) to the METER jacks on the front panel of the System Regulator as
shown in Figure C-2.
Figure C-2: System Regulator Voltage Testing
The FUNCTION rotary switch on the front panel of the System Regulator will allow you to test various points in the
radio system. Following is a list of System Regulator rotary switch positions, the functions they measure and the
parameters measured:
CANCEL
ms
AA
mA
XAM NIMXAM NIMDLOHDLOH LERLER
RANGE
RANGE
Hz
Hz %
%
ms
BdBd
BdBd
cd+cacd+ca
cd+cacd+ca
cd+cacd+ca
cd+cacd+ca
FF
SnSn
mA
AA
mAmA
mVmV
VV
mVmV
VV
OFFOFF
CC
AA
AA
AA MOCMOC VV
TEMPERATURETEMPERATURE
AmAm
AA
AutoHOLD LOGGING
SAVE
FAST MN MX
SETUP
YES
NO
DIGITAL MULTIMETER
CLEAR MEM
VIEW
DC
TRANSMITTER
CNTL
BUS
MIC
AD
RF OUT
ANALOG
NORM
OFF
DIGITAL
KEY TX
MICMODE
REF
IN
USB
FREQUENCY (MHz)
MADE IN CANADA
MODEL # CODE
RECEIVER
NORM
SQ. DISABLE
OFF
CNTL
BUS
AD
RF IN
REF
IN
USB
FREQUENCY (MHz)
MADE IN CANADA
MODEL # CODE
VOL
SYSTEM REGULATOR
METER
+
-
MADE IN CANADA
ON
OFF
SPKR
INT
EXT
EXT
SPKR
OFF
POWER
ON
2
1
5
4
3
67
8
11
10
9
FUNCTION
12
CONTROL
RX B
REPEATER
TX B
RX A
TX A
PULL DOWN
TO REMOVE
9
5
3
7
11
15
9
13
3
7
11
15
SWITCH A SWITCH B
1 Supply Voltage +10 Vdc to +17 Vdc (+13�8 Vdc nominal)
2 +9�5 Volts Regulated +9�5 Vdc (± 0�1 Vdc)
3 Rx A Audio Receiver A Audio (NOT Rx Balanced Output)
4Rx A Carrier Strength 0 Vdc to +5.0 Vdc based on received signal strength (0 Vdc is a low RF
signal level, +5.0 Vdc is high)
5 Rx B Audio Receiver B Audio (NOT Rx Balanced Output)is a low RF signal level, +5�0 Vdc
is high)
6Rx B Carrier Strength 0 Vdc to +5.0 Vdc based on received signal strength (0 Vdc is a low RF
signal level, +5.0 Vdc is high)
Enter the Supply Voltage and +9.5 Volts Regulated values on the MT-4E Test Sheet. Inject a -100 dBm carrier
signal into the Receiver and record the RSSI Voltage on the MT-4E Test Sheet. Enter the Date, Firmware Versions
and Serial numbers of the Receivers and Transmitters on the MT-4E Test Sheet. The Firmware Version and Serial
Number can be found by connecting the RSS and clicking on Rx ID or Tx ID. The Serial Numbers can also be
found on the side of the modules.
The standby current draw of the radio system should be measured for battery/solar powered systems. Connect
an ammeter to the power input line and measure the standby current draw and transmit current draw of
the system. Enter the Standby Current Draw and Transmit Current Draw readings on the MT-4E Test Sheet. The
maximum standby and transmit current draw is dependent on the radio system (number and class of receivers,
transmitter output power, amplifi ers, auxiliary equipment, etc.).

07
Appendix C: Viavi 3920 Test Procedures
MAINTENANCE GUIDE | MT-4E ANALOG & P25 DIGITAL RADIO SYSTEMS
Receiver Testing
Receiver Analog Testing
Connect the 3920 and Zetron Radio as shown in Figure C-3:
On the 3920, recall Zetron setup 01 (Rx Analog) from your internal drive. Enter the correct RF frequency and
ensure that the deviation level of the 1.0 KHz tone is set correctly for your receiver (wide/narrow). Enter the
correct CTCSS tone (if used) and deviation level for the tone. On the Zetron Radio system, ensure the receiver
is turned on and turn the System Regulator Speaker switch to ON and INT. Set the FUNCTION rotary switch to
position 3 for Rx A or position 5 for Rx B (depending on the receiver being tested), then turn the volume up until
the 1 KHz tone is audible.
In the Jumper Settings area of the Service section on the RSS, ensure that the “Subtones on audio path”
selection is set to “Don’t pass” as shown in Figure C-4. The 3920 will conduct all tests with CTCSS tones on the
audio, giving erroneous measurements, if the Subtones are set to “Pass”.
Figure C-3: Receiver Analog Testing
VOL
SYSTEM REGULATOR
METER
+
-
MADE IN CANADA
ON
OFF
SPKR
INT
EXT
EXT
SPKR
OFF
POWER
ON
2
1
5
4
3
67
8
11
10
9
FUNCTION
12
RECEIVER
OFF
NORM
SQ. DISABLE
BUS
CNTL
AD
RF IN
IN
REF
USB
FREQUENCY (MHz)
MADE IN CANADA
MODEL # CODE
F
U
S
E
P
A
M
M
C
O
HELP TAB
SELECT
UTILS
RETURN
BKSP ENTER
21
ABC
3
DEF
JKLGHIMNO
654
TUV WXYZPQRS
987
0.
#
GENANTT/R
125 W MAX
CH2 FCTN GEN / DEMOD OUTCH1 SCOPETEST PORT
INPUTS
CA
100V MAX
T II
AUDIO IN12
MAX REV PWR
10 W
CANCEL
+10 dBm MAX
MIC / ACC
CONFIG
TEST
*
_
HOLD
ASSIGN
DMM
V
/
CAT II
150 V MAX
3A
CAT I
MAX
TYPE F
3A, 250 V
35 VDC MAX
Computer running RSS
Rx Balanced Audio Output
(from pins B26 and Z26)
USB from
Computer to Rx
T/R port from 3920 to RF IN on Rx
AUDIO IN 1
Figure C-4: RSS Subtone Settings

08
Appendix C: Viavi 3920 Test Procedures
MAINTENANCE GUIDE | MT-4E ANALOG & P25 DIGITAL RADIO SYSTEMS
Audio Distortion:
To check receiver distortion, inject -70 dBm RF carrier level into the receiver and measure the audio distortion
on the meter as shown in Figure C-5. The high limit is set to 2.0 %.
Figure C-5: Receiver Distortion Measurement
Enter the Audio Distortion reading on the MT-4E Test Sheet.

09
Appendix C: Viavi 3920 Test Procedures
MAINTENANCE GUIDE | MT-4E ANALOG & P25 DIGITAL RADIO SYSTEMS
Figure C-6: Receiver Reference Sensitivity Measurement
Reference Sensitivity:
To check receiver sensitivity, monitor the audio SINAD meter while slowly reducing the RF carrier level as shown
in Figure C-6. The 12 dB SINAD point should be at an RF carrier level less than the specified Analog Sensitivity
point of the receiver. The high and low limits are set at 11.5 dB and 12.5 dB SINAD.
Enter the Reference Sensitivity (12 dB SINAD) reading on the MT-4E Test Sheet.
If the distortion or reference sensitivity measurements are not within Zetron published specifications, the RF
Preselector may need re-alignment. Refer to the Receiver RF Preselector Alignment and Tuning section.
Squelch:
Adjust the RF carrier level up and down until the receiver squelches and unsquelches. There should be
approximately 6.0 dBm of hysteresis between the squelch and unsquelch points. The squelch point can be
adjusted in the Squelch Levels area of the Service section on the RSS.
The Receiver operates on a Noise based squelch (default) or a Received Signal Strength based squelch
(optional). The squelch can be set globally for all channels, or on a per channel basis. To set the squelch Open
and Close points, inject an RF signal at the desired Open or Close level and click the Set button.
Enter the Squelch and Unsquelch readings on the MT-4E Test Sheet.

10
Appendix C: Viavi 3920 Test Procedures
MAINTENANCE GUIDE | MT-4E ANALOG & P25 DIGITAL RADIO SYSTEMS
Audio Level:
The audio level adjustment is not required when connecting the receiver in a repeater configuration using LVDS
Serial Data. The audio level adjustment can be done on both the Rx Balanced Audio Output and the Auxiliary
Balanced Output (1 and 2). The Auxiliary Balanced Output is only available on the AC-3E Control Card or CI-
BC-4E Base Control Card�
To adjust the receiver balanced audio output, ensure that the AC-3E Control Card or CI-BC-4E Base Control
Card is NOT plugged into the subrack, and inject -70 dBm RF carrier level into the receiver (no external load is
required as the internal 600 ohm load of the 3920 is used).
In the Audio Levels area of the Service section on the RSS, adjust the Rx Balanced Audio Output level
adjustment as shown in Figure C-7 until -8.0 dBm audio level (0.308 Vrms @ 600 ohms) is measured on the Audio
Level meter of the 3920 as shown in Figure C-5. The high and low limits are set at -8.5 dBm and -7.5 dBm audio
levels (these limits do not always load properly).
Figure C-7: RSS Receiver Audio Level Adjustment
To adjust the auxiliary balanced audio output, plug the AC-3E Control Card or CI-BC-4E Base Control Card into
the subrack using an extender card and connect the Auxiliary Balanced audio output to the Audio In 1 input
on the 3920 (no external load is required as the internal 600 ohm load of the 3920 is used). Auxiliary 1 audio
output is available on pins B11 and A11, and Auxiliary 2 audio output is available on pins C1 and C3 for the AC-
3E Control Card and pins C2 and C4 for the CI-BC-4E Base Control Card. Ensure that NO external devices (eg.
tone remote adapter or IP router) are connected to the auxiliary audio output. Adjust the Auxiliary Balanced
Audio Output level adjustment (R13 for Aux Out 1, R56 for Aux Out 2) for 0.0 dBm audio level (0.775 Vrms @ 600
ohms).
Enter the Balanced Audio Output Level and Auxiliary Audio Output Level (if used) readings on the MT-4E Test
Sheet.
There are no specific measurements to check Receive CTCSS, just verify that the receiver CTCSS is operating.

11
Appendix C: Viavi 3920 Test Procedures
MAINTENANCE GUIDE | MT-4E ANALOG & P25 DIGITAL RADIO SYSTEMS
Receiver Digital Testing
Connect the 3920 and Zetron Radio as shown in Figure C-8.
Figure C-8: Receiver Digital Testing
On the 3920, recall Zetron setup 02 (Rx Digital) from your internal drive. Enter the correct RF frequency, and
ensure that the RF Control is set to Phase 1 and it is set for the STORED SPCH test pattern (or optionally the 1011
test pattern)�
VOL
SYSTEM REGULATOR
METER
+
-
MADE IN CANADA
ON
OFF
SPKR
INT
EXT
EXT
SPKR
OFF
POWER
ON
2
1
5
4
3
67
8
11
10
9
FUNCTION
12
RECEIVER
OFF
NORM
SQ. DISABLE
BUS
CNTL
AD
RF IN
IN
REF
USB
FREQUENCY (MHz)
MADE IN CANADA
MODEL # CODE
F
U
S
E
P
A
M
M
C
O
HELP TAB
SELECT
UTILS
RETURN
BKSP ENTER
21
ABC
3
DEF
JKLGHIMNO
654
TUV WXYZPQRS
987
.
#
0
GEN ANTT/R
125 W MAX
CH2 FCTN GEN / DEMOD OUTCH1 SCOPETEST PORT
INPUTS
CA
100V MAX
T II
AUDIO IN12
MAX REV PWR
10 W
CANCEL
+10 dBm MAX
MIC / ACC
CONFIG
TEST
*
_
HOLD
ASSIGN
DMM
V
/
CAT II
150 V MAX
3A
CAT I
MAX
TYPE F
3A, 250 V
35 VDC MAX
Computer running RSS
Rx Balanced Audio Output
(from pins B26 and Z26)
USB from
Computer to Rx
T/R port from 3920 to RF IN on Rx
AUDIO IN 1

12
Appendix C: Viavi 3920 Test Procedures
MAINTENANCE GUIDE | MT-4E ANALOG & P25 DIGITAL RADIO SYSTEMS
Inject the correct NAC (and TGID if programmed) and ensure that the receiver is operating as shown in Figure
C-9. There are no specific measurements to make on this test, just verify that the receiver is operating.
Figure C-9: Receiver Digital Check

13
Appendix C: Viavi 3920 Test Procedures
MAINTENANCE GUIDE | MT-4E ANALOG & P25 DIGITAL RADIO SYSTEMS
Receiver Bit Error Rate Testing
Connect the 3920 and Zetron Radio as shown in Figure C-10.
Figure C-10: Receiver Bit Error Rate Testing
On the 3920, recall Zetron setup 02 (Rx Digital) from your internal drive. Enter the correct RF frequency, and
ensure that the RF Control is set to Phase 1 and it is set for the STD 1011 test pattern (the 1011 test pattern will not
operate correctly for this test) as shown in Figure C-11.
Figure C-11: Receiver Bit Error Rate Test Injection
VOL
SYSTEM REGULATOR
METER
+
-
MADE IN CANADA
ON
OFF
SPKR
INT
EXT
EXT
SPKR
OFF
POWER
ON
2
1
5
4
3
67
8
11
10
9
FUNCTION
12
RECEIVER
OFF
NORM
SQ. DISABLE
BUS
CNTL
AD
RF IN
IN
REF
USB
FREQUENCY (MHz)
MADE IN CANADA
MODEL # CODE
F
U
S
E
A
M
P
M
C
O
HELP
SELECT
TAB
UTILS
RETURN
BKSP ENTER
12
ABC
3
DEF
JKLMNOGHI
654
TUVWXYZPQRS
987
.
#
*
_0
GENT/R ANT
125 W MAX
CH2 FCTN GEN / DEMOD OUTCH1 SCOPETEST PORT
INPUTS
CA
100V MAX
T II
AUDIO IN12
MAX REV PWR
10 W +10 dBm MAX
CANCEL
MIC / ACC
CONFIG
TEST HOLD
ASSIGN
DMM
V
/
CAT II
150 V MAX
3A
CAT I
MAX
TYPE F
3A, 250 V
35 VDC MAX
Computer running RSS
USB from
Computer to Rx
T/R port from 3920 to RF IN on Rx

14
Appendix C: Viavi 3920 Test Procedures
MAINTENANCE GUIDE | MT-4E ANALOG & P25 DIGITAL RADIO SYSTEMS
In the receiver RSS, enter the Service section and click on “Bit Error Rate”. The receiver frequency should
automatically be shown in the frequency box. Select the Test Type to “Continuous” and Avg. Superframes to
“8”. Click on the “Start Test” button to start the BER test. You should get 0% BER at the -70 dBm default RF carrier
level�
Monitor the BER reading while slowly reducing the RF carrier level as shown in Figure C-12. The 5% BER point
should be at an RF carrier level less than the specifi ed Digital Sensitivity point of the receiver.
Figure C-12: RSS Receiver Bit Error Rate Test
Enter the Reference Sensitivity (5% BER) reading on the MT-4E Test Sheet.
If the BER measurements are not within Zetron published specifi cations, the RF Preselector may need re-
alignment. Refer to the Receiver RF Preselector Alignment and Tuning section.

15
Appendix C: Viavi 3920 Test Procedures
MAINTENANCE GUIDE | MT-4E ANALOG & P25 DIGITAL RADIO SYSTEMS
Receiver RF Preselector Alignment and Tuning
Tuning of the RF Preselector fi lter is typically only required when the Analog or Digital Sensitivity or Analog
Distortion do not meet published specifi cations, or when the receiver RF frequency is changed beyond the
band pass of the filter (typically 5 - 7 MHz in a VHF or UHF 400 MHz receiver). The UHF 700 / 800 / 900 MHz
receiver RF Preselector is Full Band and does not require any tuning�
Connect the 3920 and Zetron Radio as shown in Figure C-13.
Figure C-13: Receiver RF Preselector Tuning
The RF Preselector output is a small RF cable internal in the receiver that terminates in an SMB connector.
The SMB plugs into J3 on the Receiver Mainboard. Disconnect the SMB cable from J3 and use the SMB-BNC
adapter to connect this point to the ANT input on the 3920 as shown in Figure C-14.
Figure C-14: Receiver RF Preselector Connection
VOL
SYSTEM REGULATOR
METER
+
-
MADE IN CANADA
ON
OFF
EXT
SPKR
INT
EXT
SPKR
OFF
POWER
ON
2
1
5
4
3
67
8
11
10
9
FUNCTION
12
RECEIVER
SQ. DISABLE
OFF
NORM
BUS
CNTL
AD
RF IN
IN
REF
USB
FREQUENCY (MHz)
MADE IN CANADA
MODEL # CODE
F
U
S
E
P
A
M
M
C
O
HELP
SELECT
TAB
UTILS
RETURN
BKSP ENTER
21
ABC
3
DEF
JKLMNOGHI
654
TUVPQRS WXYZ
987
.
#
0
GENT/R ANT
125 W MAX
CH2 FCTN GEN / DEMOD OUTCH1 SCOPETEST PORT
INPUTS
CA
100V MAX
T II
AUDIO IN 21 10 W
MAX REV PWR
CANCEL
+10 dBm MAX
MIC / ACC
CONFIG
TEST
*
_
HOLD
ASSIGN
DMM
V
/
CAT II
150 V MAX
3A
CAT I
MAX
TYPE F
3A, 250 V
35 VDC MAX
GEN port from 3920 to RF IN on Rx
RF Preselector output from Receiver
to ANT input on 3920
J3
on 3920
To ANT input
RF Preselector
output

16
Appendix C: Viavi 3920 Test Procedures
MAINTENANCE GUIDE | MT-4E ANALOG & P25 DIGITAL RADIO SYSTEMS
On the 3920, recall Zetron setup 03 (Rx Preselector Tune) from your internal drive. If Trk Gen does not appear
on the lower left corner of the display, then the 3920 does not have the tracking generator option. Enter the
correct RF frequency as the Center Frequency (CF) and ensure the receiver is turned on. The filter waveform
should appear as shown in Figure C-15. Turn the Markers on to add optional markers to the spectrum analyzer if
desired�
Figure C-15: Receiver RF Preselector on the Spectrum Analyzer
To tune the RF Preselector filter, remove the dust caps on the variable capacitors and, starting from the
capacitor closest to the front panel of the receiver and moving back, tune the filter to its new frequency.

17
Appendix C: Viavi 3920 Test Procedures
MAINTENANCE GUIDE | MT-4E ANALOG & P25 DIGITAL RADIO SYSTEMS
Receiver Reference Oscillator Adjustment
Connect the 3920 and Zetron Radio as shown in Figure C-16.
Figure C-16: Receiver Reference Oscillator Testing
The reference oscillator test on the receiver requires a connection directly into the Synthesizer, which uses an
SMB connector. Disconnect the SMB cable from the LO output of the synthesizer and connect the small SMB-
SMB cable to the SMB jack that is mounted on the Synthesizer (beneath the RF Preselector). The SMB-BNC
adapter is required to connect this point to the ANT input on the 3920 as shown in Figures C-17 (VHF and UHF
400 MHz Receiver) and C-18 (UHF 700 / 800 / 900 MHz Receiver).
Figure C-17: VHF and UHF 400 MHz Receiver Reference Oscillator Connection
VOL
SYSTEM REGULATOR
METER
+
-
MADE IN CANADA
ON
OFF
SPKR
INT
EXT
EXT
SPKR
OFF
POWER
ON
2
1
5
4
3
67
8
11
10
9
FUNCTION
12
RECEIVER
SQ. DISABLE
OFF
NORM
BUS
CNTL
AD
RF IN
IN
REF
USB
FREQUENCY (MHz)
MADE IN CANADA
MODEL # CODE
F
U
S
E
P
A
M
M
C
O
HELP TAB
SELECT
UTILS
RETURN
BKSP ENTER
21
ABC
3
DEF
JKLGHIMNO
654
TUV WXYZPQRS
987
0.
#
GENANTT/R
125 W MAX
CH2 FCTN GEN / DEMOD OUTCH1 SCOPETEST PORT
INPUTS
CA
100V MAX
T II
AUDIO IN12
MAX REV PWR
10 W +10 dBm MAX
CANCEL
MIC / ACC
CONFIG
TEST
*
_
HOLD
ASSIGN
DMM
V
/
CAT II
150 V MAX
3A
CAT I
MAX
TYPE F
3A, 250 V
35 VDC MAX
Synthesizer L.O. output from Receiver
to ANT input on 3920
Computer running RSS
USB from
Computer to Rx
on 3920
SMB-SMB
cable
LO output of
synthesizer
To ANT input

18
Appendix C: Viavi 3920 Test Procedures
MAINTENANCE GUIDE | MT-4E ANALOG & P25 DIGITAL RADIO SYSTEMS
on 3920
SMB-SMB
cable
LO output of
synthesizer
To ANT input
Figure C-18: UHF 700 / 800 / 900 MHz Receiver Reference Oscillator Connection
On the 3920, recall Zetron setup 04 (Rx Reference) from your internal drive as shown in Figure C-19.
Figure C-19: Receiver Reference Oscillator Measurement