ZETRON 38A User manual

ZETRON
Model 38A Repeater Tone Panel
Instruction Manual
Part No. 025-9043Y
Please check for change information at the end of this manual.
Copyright © 1986 - 1999 by Zetron, Inc.
All Rights Reserved

Zetron Master Product Manual
Model 38A Part No. 025- 9043Y
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Zetron QC Checklist
✔Unbroken numerical page sequence in each section.
✔Complete front matter consisting of:
Title Page
Table of Contents ( 3 pages)
Statements ( 3 pages)
Other special pages ( 1 pages)
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1-1 6-10
2-2 7-7
3-13
4-24
5-27
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✔No other inconsistencies, e.g., light print, missing sections, misaligned pages, bad binders.
Special notes to QC:

Table of Contents
1. INTRODUCTION
INTRODUCTION ...................................................................................................... 1-1
FEATURES ................................................................................................................ 1-1
2. SPECIFICATIONS
GENERAL.................................................................................................................. 2-1
CTCSS / DCS ............................................................................................................. 2-1
INTERFACE............................................................................................................... 2-2
3. OPERATION
OVERVIEW ............................................................................................................... 3-1
CTCSS TONES AND DIGITAL CODED SQUELCH (DCS) .................................. 3-1
HOW TONES/CODES ARE ENABLED .................................................................. 3-2
User Validation ............................................................................................... 3-2
Disabled Tones ............................................................................................... 3-2
Enabled Users, CTCSS / DCS Encode ........................................................... 3-2
Carrier Controlled Repeat (Open Repeater) ................................................... 3-3
Reserved Users ............................................................................................... 3-3
WHAT HAPPENS WHEN A MOBILE UNKEYS....................................................3-3
Airtime Accumulation .................................................................................... 3-5
Repeater Hold Time........................................................................................3-5
Timeout Timer ................................................................................................3-5
Timeout User Identification............................................................................ 3-5
DTMF Regeneration ....................................................................................... 3-5
Airtime Hog Penalty .......................................................................................3-6
Temporary Cross-tone or Cross-code Encoding............................................. 3-6
Temporary Defeat of Cross-tone or Cross-code Encoding............................. 3-6
Remote PTT Function..................................................................................... 3-7
Site Alarm ....................................................................................................... 3-7
CONSIDERATIONS WHEN USING DIGITAL CODED SQUELCH (DCS)......... 3-8
REVERSE FREQUENCY WORKING (OPTION) ................................................... 3-11
Programming................................................................................................... 3-12
4. PROGRAMMING
OVERVIEW ............................................................................................................... 4-1
PROGRAMMING MODES ....................................................................................... 4-1
DTMF Programming Via The Radio Channel................................................ 4-1
Programming Via The Model 8 Repeater Programmer / Timekeeper............4-2
Programming Via The RS-232 Interface ........................................................ 4-3
CRT Mode ...................................................................................................... 4-4
PROGRAMMING COMMANDS.............................................................................. 4-6
Program Mode Access .................................................................................... 4-6
User Commands.............................................................................................. 4-7
System Commands.......................................................................................... 4-13

Table of Contents
(Continued)
List And Airtime Functions ............................................................................ 4-20
Diagnostic Commands.................................................................................... 4-21
5. INSTALLATION
GENERAL.................................................................................................................. 5-1
REQUIRED EQUIPMENT ........................................................................................ 5-1
SCREW TERMINAL CONNECTIONS .................................................................... 5-1
INSTALLATION PROCEDURE............................................................................... 5-2
Installation Tips .............................................................................................. 5-2
ADJUSTMENT PROCEDURE USING THE DTMF PROGRAM MODE .............. 5-3
ADJUSTMENT PROCEDURE USING THE SITE ALARM INPUT ...................... 5-4
RADIO-SPECIFIC CONNECTIONS ........................................................................ 5-6
GE MASTR III Base/Repeater ....................................................................... 5-7
GE MASTR II Base/Repeater.........................................................................5-8
GE Exec II Base.............................................................................................. 5-9
ICOM IC-RP1510 Repeater............................................................................5-10
E.F. Johnson CR1010 Repeater ...................................................................... 5-11
E.F. Johnson CR1010 Repeater (Alternate Hookup)...................................... 5-12
E.F. Johnson Viking Universal Station........................................................... 5-13
Kenwood TKR-720 / TKR-820 Repeater .......................................................5-14
Motorola GR300 Repeater (or Two GM300 Radios)..................................... 5-15
Motorola MTR2000 Stations .......................................................................... 5-16
Motorola MSF 5000 Analog Repeater............................................................ 5-17
Motorola MSF 5000 Digital Repeater ............................................................ 5-18
Motorola MCR-100 / RADIUS R-100 ........................................................... 5-19
Motorola MICOR Single User Repeater ........................................................ 5-20
Motorola MICOR Community Repeater ........................................................ 5-21
Tait T800 Series Repeater............................................................................... 5-22
Tait T300 Series Radio ................................................................................... 5-23
TONE PANEL PERFORMANCE TEST................................................................... 5-24
RS-232 CABLE DIAGRAMS.................................................................................... 5-25
PROGRAMMING THE MODEL 38 VIA FRONT PANEL CONNECTOR............ 5-26
INSTALLING A NEW PROM................................................................................... 5-27
6. REPAIR
IN CASE OF DIFFICULTY....................................................................................... 6-1
SERVICE NOTES ...................................................................................................... 6-1
MODEL 38 REPEATER PANEL PARTS LIST (702-9075) .................................... 6-2
MODEL 38 REPEATER PANEL ASSEMBLY DIAGRAM.................................... 6-5
MODEL 38 REPEATER PANEL SCHEMATIC (008-9075) ................................... 6-6
MODEL 38 REPEATER PANEL SILKSCREEN (702-9075) .................................. 6-10
7. QUICK REFERENCE

Table of Contents
(Continued)
DTMF REMOTE PROGRAMMING MODE NOTES .............................................. 7-1
MODEL 38 SYSTEM PROGRAMMING LOG........................................................ 7-2
MODEL 38 CTCSS USER DATABASE PROGRAMMING LOG .......................... 7-4
MODEL 38 DCS USER DATABASE PROGRAMMING LOG ..............................7-6
MODEL 38 PROGRAM MODE COMMAND SUMMARY.................................... 7-7
CHANGE INFORMATION

1-1
1. INTRODUCTION
INTRODUCTION
The Zetron Model 38 is a flexible repeater panel that provides individualized repeater service
to up to 60 or 68 different customer groups. It is a complete interface between a transmitter
and receiver, providing CTCSS encode/decode, repeat audio processing, and all timer
functions. It can be remote-controlled from a variety of sources. The Model 38A is equipped
with an RS-232 serial port for connection to computers and modems. An internal database
keeps track of all airtime use and, for accounting purposes, downloads into a PC. Nearly all
of the Model 38’s functions can easily be customized for each of the 38 or 50 CTCSS tones
and 22 or 18 digital coded squelch codes.
FEATURES
• Supports 38 or 50 CTCSS user groups, with ToneLock™ high sensitivity decoding
• Supports 18 or 22 digital coded squelch (DCS) codes
• Programmable via RS-232 and DTMF
• Attributes are programmable for each user group
• Remote enable and disable of all tones and DCS codes
• Temporary enable and disable of cross encoding
• Automatic Morse code station identification
• Stuck microphone timeout and identification
• DTMF paging when site alarm triggered
• Vacant tones and codes can be reserved
• Airtime Hog Penalty mode
• Cross-tone, cross-code, tone-code encoding
• Courtesy beeps and tailbips
• Privacy mode to prevent “barge-ins”
• Airtime is tallied for each user group
• Prepaid airtime feature

2-1
2. SPECIFICATIONS
GENERAL
Radio interface Compatible with most any commercial FM two-way radio or
repeater.
User group capacity 38 CTCSS tones and 22 DCS codes, or 50 CTCSS tones and 18
DCS codes.
Airtime capacity 249 hours, 59 minutes, 59 seconds per user group.
Airtime retrieval RS-232 port, DTMF or Morse code over radio channel.
Station ID Callsigns configurable for each user group, with independent
activity timers.
Station ID frequency 1,200 Hz; adjustable ±800 Hz. (per FCC rules).
Courtesy tone
frequency
1,000 Hz; adjustable 400 to 3,000 Hz.
Indicators Power, carrier, transmit, decode, encode, DTMF.
Current consumption 350 mA at 13.8 VDC.
Operating voltage 11.0 to 15.0 VDC.
Rack space 1.7 x 19 x 4.8 inches.
Weight 2.2 lb.
Operating
temperature
0 to 65°Celsius.
CTCSS / DCS
CTCSS frequencies 67.0 to 254.1 Hz. Tables include all standard EIA frequencies
and extensions.
CTCSS sensitivity Better than 3dB SINAD.
CTCSS accuracy Better than 0.1 Hz.
Digital squelch codes Selectable, any octal codes between 000 to 777.
Squelch tail
elimination
Compatible with CTCSS reverse burst, DCS turn-off code, and
loss of carrier.

Section 2. Specifications
2-2
INTERFACE
Connections Rx audio, Tx key, CTCSS / DCS encode, Tx audio (mic), 12
VAC or DC power, ground. Optional carrier detect, alarm input
and aux output.
Connector type Detachable screw terminal.
Rx input impedance 50 KΩAC coupled. For connection to unsquelched
discriminator audio.
CTCSS / DCS output Level: 0 to 4 Volts p-p. Impedance: Less than 1 KΩAC
coupled.
Transmitter type Direct FM, or phase modulation. Flat or de-emphasized CTCSS
encode.
Transmitter keying SPDT relay.
Carrier detect Internal noise detector or external carrier detect input. External
input threshold adjustable 0 to 7 VDC.
Adjustments Four adjustments from rear panel: Rx input gain, CTCSS / DCS
encode gain, Tx audio output gain, and carrier detect threshold.
Configuration
switches
Eight switches on rear panel: Rx audio gain high/low, repeat
audio flat/de-emphasized, encode gain high/low, encode flat/de-
emphasized, tx audio gain high/low, COR source
internal/external, COR polarity positive/negative, COR pull up
on/off.
RS-232 serial data
port
Front panel DB9 connector (non-standard pinout). Interface
cables available.
Alarm / Remote PTT
input
Activated via contact closure to ground.
Cables, interface
notes
Available for most repeaters and two-way radios.

3-1
3. OPERATION
OVERVIEW
This section of the manual covers key ideas and features that define the operation of the
Model 38A Repeater Tone Panel.
CTCSS TONES AND DIGITAL CODED SQUELCH (DCS)
The Model 38 monitors the channel for CTCSS tones and/or DCS codes. When a tone or
code is detected, it is converted into a User-Number that contains the user privileges and
attributes. The DCS decode numbers are completely user programmable. Two versions of the
Model 38 are available; 38 CTCSS + 22 DCS users (see Table 3. -1), or 50 CTCSS + 18
DCS users (Table 3. -2).
When ordered with the 50 tone set, the unit has a narrower CTCSS decoder bandwidth than
the standard 38 tone version. The 50 tone version is not recommended for use with radios
that use tunable encoders, due to the possibility of the encoder becoming mistuned or drifting
onto adjacent tones.
Table 3. -1. User Number Cross reference Table: 38 Tone Version
User Tone User Tone User Tone User Code
1 67.0 16 114.8 31 192.8 46 DCS
2 71.9 17 118.8 32 203.5 47 DCS
3 74.4 18 123.0 33 210.7 48 DCS
4 77.0 19 127.3 34 218.1 49 DCS
5 79.7 20 131.8 35 225.7 50 DCS
6 82.5 21 136.5 36 233.6 51 DCS
7 85.4 22 141.3 37 241.8 52 DCS
8 88.5 23 146.2 38 250.3 53 DCS
9 91.5 24 151.4 39 DCS 54 DCS
10 94.8 25 156.7 40 DCS 55 DCS
11 97.4 26 162.2 41 DCS 56 DCS
12 100.0 27 167.9 42 DCS 57 DCS
13 103.5 28 173.8 43 DCS 58 DCS
14 107.2 29 179.9 44 DCS 59 DCS
15 110.9 30 186.2 45 DCS 60 DCS

Section 3. Operation
3-2
Table 3. -2. User Number Cross Reference Table: 50 Tone Version
User Tone User Tone User Tone User Tone
1 67.0 18 118.8 35 183.5 52 DCS
2 69.4 19 123.0 36 186.2 53 DCS
3 71.9 20 127.3 37 189.9 54 DCS
4 74.4 21 131.8 38 192.8 55 DCS
5 77.0 22 136.5 39 196.6 56 DCS
6 79.7 23 141.3 40 199.5 57 DCS
7 82.5 24 146.2 41 203.5 58 DCS
8 85.4 25 151.4 42 206.5 59 DCS
9 88.5 26 156.7 43 210.7 60 DCS
10 91.5 27 159.8 44 218.1 61 DCS
11 94.8 28 162.2 45 225.7 62 DCS
12 97.4 29 165.5 46 229.1 63 DCS
13 100.0 30 167.9 47 233.6 64 DCS
14 103.5 31 171.3 48 241.8 65 DCS
15 107.2 32 173.8 49 250.3 66 DCS
16 110.9 33 177.3 50 254.1 67 DCS
17 114.8 34 179.9 51 DCS 68 DCS
HOW TONES/CODES ARE ENABLED
User Validation
The Model 38 is always listening to the receive audio for the presence of an enabled user. All
38 or 50 CTCSS tones and 18 or 22 of the digital codes can be marked as enabled or disabled
(consult the programming section).
Disabled Tones
When a disabled CTCSS tone is detected, the time accumulator will keep track of the airtime
used by that tone. This feature lets the system manager gain information about the CTCSS
tones that are in use on the channel, perhaps by another repeater in the area. The Model 38
will accumulate airtime for all CTCSS tones, but not disabled DCS codes.
Enabled Users, CTCSS / DCS Encode
When an enabled tone or digital code is detected, the transmitter will be keyed. Depending
on programming, the system will: (1) encode nothing, (2) regenerate the received tone or
code, or (3) encode a different tone or digital code (cross-tone encoding).

Section 3. Operation
3-3
Carrier Controlled Repeat (Open Repeater)
The Model 38 can be programmed to activate based on just carrier. In this mode the Model
38 will provide simultaneous tone and open repeater operation; users that have CTCSS or
Digital Squelch encode operate normally, users that have no encode repeat also. This allows
a mix of CTCSS tone users with open repeat capability and is ideal when adding tone users
to an existing open repeater.
To enable carrier (COR) for repeat, a user number is identified as the “CARRIER” repeat
user. This allows all standard user-programmable attributes to apply to open repeat,
including; enable/disable for the carrier user, CTCSS or digital code encoding, airtime
accumulation, station ID, etc. If the COR user number is set to “0”, the carrier repeat
function is disabled.
Reserved Users
If a user is marked as “Reserved,” the repeat audio will be squelched and a beep tone sent in
place of voice communications. A chirp tone will be sent when the user unkeys to indicate
reserve mode. This mode allows the system manager to reserve CTCSS tones and DCS codes
for seasonal users, or to temporarily prevent communications for a delinquent account.
WHAT HAPPENS WHEN A MOBILE UNKEYS
When a mobile unkeys, CTCSS tone or DCS code is no longer detected, the Model 38 will
do the following:
Anti-Kerchunker Filter
The anti-kerchunker filter cancels the transmit hold time and drops the repeater
immediately if a mobile transmission is less than the programmed “anti-kerchunk”
time. This serves two main purposes:
• It will discourage users from “kerchunking” the repeater to death.
• It will make the repeater co-exist better on shared-channels. When a lot of CTCSS
tones are enabled on a single channel, it’s not uncommon for voice falsing of
active CTCSS tones on a co-channel repeater to occur. This is because a human
voice often contains frequencies in the CTCSS band. A radio user could be
talking and cause a co-channel repeater to key up over the conversation. When the
repeater transmit hold time is greater than about a second, this causes major
interference to the voice communication. With the anti-kerchunker filter enabled,
the repeater will key ONLY for the duration that the voice simulates CTCSS, not
the entire transmit hold time. The anti-kerchunker filter is disabled by
programming the time to zero.
Courtesy Tone
If the courtesy tone is enabled for the user group, a short beep will be sent. The beep
frequency may be set from 400 to 4000 Hz (default setting is 1000 Hz). A system
programmable setting called “tailbips” can be enabled to cause the courtesy tone to

Section 3. Operation
3-4
be sent every second during the transmit hold time. If a 400 Hz beep (low tone) is
heard just prior to the transmitter unkeying, a system memory error has been detected,
consult the repair section.
Prepaid Customer Low-Airtime Warning
The repeater operator (or owner) can allow a customer to purchase a block of airtime
in advance (see “Prepaid Users” in the programming section). These prepaid blocks
decrease as the customer uses the repeater. When the remaining airtime falls below
two hours, a low-airtime warning chirp will be heard when the user unkeys. The chirp
sounds like a fast “bee-doo-bee-doo-bee-doo”. If the airtime drops to zero, the tone is
“reserved” as described above. A prepaid user who falls all the way into the
“reserved” mode will still hear warning chirps upon unkeying.
Reserved User Mode
If a user is programmed as reserve tone mode, a “chirp” will be sent when the user
unkeys. This gives a positive indication that communication has not occurred.
CTCSS / DCS Encode During Transmit Hold Time
When a valid user unkeys, the CTCSS or DCS encode may either be left on during
the transmitter hold time or turned off. This feature is programmable for each user.
When using a control station phone patch through the repeater, the encode should be
turned off during Tx-hold. This allows the phone patch to know when the mobile has
unkeyed, as opposed to knowing when the repeater has dropped off the channel.
When using the repeater for dispatch only, the encode may be left on during the Tx-
hold time to keep the mobile decoders open. This feature eliminates the decode delay
observed in the mobile between transmissions, and is generally required in order for
the busy channel lockout feature to function properly in the subscriber radios.
Morse Code Station Identification
When an enabled user unkeys, the Model 38 looks to see how long it has been since
the station ID was last sent. If enough time has passed (initially 15 minutes,
programmable 1-99 minutes) then the call sign will be sent. Each user group has its
own call sign and individual ID interval timer. The Morse ID is sent at the selected
ID speed (15 to 25 words per minute). The call sign is sent at 30% deviation (meets
FCC Part 90 rules) such that voice communication can occur during the ID. Note: if
the Morse ID is not programmed, or the first character is a “space”, an ID will not be
sent. A single system ID may also be programmed for use in co-op and private carrier
applications.
Last User Identification via DTMF
The Model 38 checks to see if the user is configured to send “Last User ID”. If
enabled, the user number will be sent via fast DTMF. This allows the system manager
to identify which users are active on the system in real time. All that’s required is a
DTMF decoder with display capability, such as the Zetron Model 8 Repeater
Programmer / Timekeeper.

Section 3. Operation
3-5
Privacy Mode
Finally, the Model 38 checks to see if the user is set for “Privacy Mode”. If enabled,
then no other users (CTCSS or DCS) will be allowed on the system until the transmit
hold time has expired. This feature can prevent other user groups from “barging in”
on the conversation and taking over control of the repeater.
Airtime Accumulation
The Model 38 keeps track of the airtime used by each customer group on the channel. Both
enabled and disabled users are logged. The airtime is stored in “hours:minutes:seconds”
format and will hold up to 250 hours per user. The airtime counts may be retrieved over the
channel or via the RS-232 port. The airtime may be set to accumulate including or excluding
the repeater transmit hold time (see programming section).
Repeater Hold Time
The programmable repeater transmit hold timer is adjustable from 0.0 to 9.9 seconds. When a
mobile unkeys, the Model 38 will begin monitoring for a valid CTCSS tone or DCS code to
be received again. If a valid user is not detected within a timeout period, a reverse burst for
CTCSS or digital turn-off code will be sent then the encode will be turned off (if it was
previously on). After a 0.2 second delay, the transmitter PTT will be dropped. This method
will remove the second squelch tail heard by the mobiles when the repeater transmitter
unkeys. Repeater “tailbips” may be enabled to beep once every second during the repeater
hold time.
Timeout Timer
While mobiles are conversing through the repeater, a timeout timer is running. If a mobile
does not un-key within the timeout period, warning tones will be sent, and then the
transmitter PTT will be dropped. This is a “stuck mic” time-out feature.
Timeout User Identification
After a timeout occurs, the system may be set to transpond (via slow DTMF) the user number
of the mobile that is still keyed up. The repeater will key up every 15 seconds while the
mobile is transmitting and send the user number. This feature can be enabled or disabled by
the system manager.
DTMF Regeneration
The Model 38 may be used to regenerate DTMF tones over the radio channel for applications
involving mobile DTMF decoders or control station telephone interconnects (such as Zetron
Models 30 or 45). DTMF regeneration ensures that all DTMF signaling occurs at the same
tone level. DTMF regeneration can occur for any or all users. A user commands the repeater
to regenerate DTMF digits by sending a DTMF “*” for greater than 1 second. When the digit
is released, the Model 38 squelches the repeat audio and begins regenerating all DTMF tones
received from the user until no digit has been received for the interdigit timeout
(programmable; factory set at 4 seconds). All sixteen DTMF tones can be regenerated.

Section 3. Operation
3-6
Airtime Hog Penalty
The Airtime Hog Penalty feature allows the system manager to penalize “airtime hogs” so
that other users on the system have a chance to complete dispatch calls. This feature
disallows a user from conversing through the repeater for a penalty duration (programmable
10-9990 seconds) if the user has recently exceeded the maximum allowable conversation
time limit (1-99 minutes). While a user is being penalized, the system will ignore the user. A
long-winded talker who is approaching the end of the conversation time limit will start
hearing warning tones (sounding like “bee-doo”) 1 per second prior to cut-off. To avoid an
impending Hog Penalty, the user must let the repeater transmitter un-key for an “idle
duration” (1-99 seconds), giving another mobile a chance to use the system. If another user
keys up, or if the idle duration is met, the conversation timer is reset. The Hog Penalty is
programmable on/off for each tone, and all users have their own penalty timers in the case of
multiple hogs on the system.
Temporary Cross-tone or Cross-code Encoding
Temporary cross-tone or cross-code encoding allows the system manager to converse with a
subscriber on any CTCSS tone or digital code. This mode is a temporary cross-tone or cross-
code assignment that allows users on different tones/codes to communicate. It is accessed
with a DTMF command sequence, and can be enabled/disabled on a per-user basis. An alert
signal is sent during the transmitter hang time while the temporary cross-tone or cross-code
mode is active. Command sequence:
• If the DTMF regenerate mode is enabled for the user, a long “#” (greater than two
seconds) plus a tone or code number, then a “#” (# 12#) will activate cross
encoding.
• Any channel activity will encode the originating mobile’s tone or code.
• When the originating mobile transmits, the called mobile’s CTCSS tone or digital
code will be encoded.
• The Tx-hold time is set at 30 seconds during cross encoding.
• An “Eeddll-eeddll-eeddll” queuing tone will indicate cross encoding is active.
• A long “#” (greater than .75 second) will exit the mode.
Temporary Defeat of Cross-tone or Cross-code Encoding
In many dispatch systems the Repeater Panel is programmed to always perform cross-tone or
cross-code encoding, which enables the dispatcher to communicate with vehicles operating
on a different tone or code, but prevents the vehicles from communicating directly with each
other. The dispatcher is usually the center of all communications: when a vehicle needs to
relay information to another vehicle, the dispatcher must listen to one vehicle, then transmit
the information to the other vehicle. This method wastes airtime and increases the chance of
miscommunication. If the dispatcher temporarily defeats cross encoding, users can talk
amongst themselves, and the dispatcher doesn’t have to relay information. Temporarily
defeating cross encoding is achieved by a DTMF command sequence, and is enabled or

Section 3. Operation
3-7
disabled for each user with the “DTMF COMMANDS” enable function. An alert tone is sent
in the squelch tail while the cross encoding is active. Command sequence:
• If the DTMF regenerate mode is enabled for the user, a long “0” will enter the
car-to-car mode.
• The Tx-hold time is set at 30 seconds during the cross-tone mode.
• An “Eeddll-eeddll-eeddll” queuing tone will indicate that cross-tone encoding is
defeated.
• A long “#” (greater than .75 second) will exit the mode.
Remote PTT Function
The site alarm input may be used as a “Remote PTT” function. This feature is initiated by the
site alarm input being pulled to ground by a contact closure or other input. When the alarm
input goes active, any repeater activity will be suspended, then the programmed CTCSS tone
or DCS code will be encoded, the repeat audio squelched, and the transmitter keyed. This
condition will continue until the site alarm input is released.
This feature can be used for wireline control of the transmitter from a tone or DC remote
control, or by wiring the local mic PTT to this input, a method of local control to talk to
specific users. See the site alarm system programming section.
Site Alarm
The Site Alarm feature sends out an audible alert, DTMF page, and CTCSS/DCS encode in
response to a contact closure input. This can be used to monitor external functions such as
system break-in or power failure. The alarm DTMF code can be received by a Zetron Model
8 Repeater Programmer / Timekeeper for remote alarm monitoring. Whenever the alarm
input is held in the active state, a 2000 Hz confirmation beep tone is sent over the transmit
audio just prior to unkeying when the repeater is in use.

Section 3. Operation
3-8
CONSIDERATIONS WHEN USING DIGITAL CODED SQUELCH (DCS)
When a DCS radio unkeys, it sends a 134.4 Hz squelch tail elimination turn off code bit
sequence for about 120 milliseconds. To avoid potential problems, users should not be
installed on the adjacent CTCSS frequencies of 131.8 and 136.5 if possible.
When installing DCS codes for the first time, use this procedure:
1. Use a radio with a known digital code.
2. Use the DCS encode test mode in the Model 38 to generate the digital squelch code that
the mobile is set to. If the mobile does not unsquelch, use the Model 38 digital encode
invert selection. The mobile should unsquelch on either the normal or inverted code.
3. Set the transmitter CTCSS/DCS encode deviation using a CTCSS tone, not a DCS code.
Most deviation meters will give an inaccurate reading of DCS deviation.
4. Make sure Jumper JP3 is in the “B” position (factory default).
5. To setup a DCS user in the Model 38 database, select a user number above the last
CTCSS tone (38 or 50). Enable the user and set the DCS decode number. Key up the
mobile and verify that the Model 38 “decode” led follows the transmission. If the mobile
is not decoded, try inverting the Model 38 receive polarity.
6. Once a single mobile is working through the Model 38, additional mobiles may be added.

Section 3. Operation
3-9
Table 3. -3. Commonly Used DCS Codes, with Binary and Hex Shown
Code Binary Hex Code Binary Hex
023 11101100011100000010011 640E37 311 01110001101100011001001 498D8E
025 11010110111100000010101 540F6B 315 11011000110100011001101 598B1B
026 11001011101100000010110 340DD3 325 00110010110100011010101 558B4C
031 10100011111100000011001 4C0FC5 331 01000111110100011011001 4D8BE2
032 10111110101100000011010 2C0D7D 332 01011010100100011011010 2D895A
036 00010111110100000011110 3C0BE8 343 01010010111100011100011 638F4A
043 10110110110100000100011 620B6D 346 01110101001100011100110 338CAE
047 00011111101100000100111 720DF8 351 00011101011100011101001 4B8EB8
051 11111001010100000101001 4A0A9F 356 10101001010100011101110 3B8A95
053 01101010101100000101011 6A0D56 364 11010000101100011110100 178D0B
054 11011110100100000101100 1A097B 365 01011110000100011110101 57887A
065 10111010001100000110101 560C5D 371 00101011000100011111001 4F88D4
071 11001111001100000111001 4E0CF3 411 11101110110100100001001 484B77
072 11010010011100000111010 2E0E4B 412 11110011100100100001010 2849CF
073 01011100110100000111011 6E0B3A 413 01111101001100100001011 684CBE
074 11101000111100000111100 1E0F17 423 10010111001100100010011 644CE9
114 01101011110100001001100 190BD6 431 11011000101100100011001 4C4D1B
115 11100101011100001001101 590EA7 432 11000101111100100011010 2C4FA3
116 11111000001100001001110 390C1F 445 11110111000100100100101 5248EF
122 10111011010100001010010 250ADD 446 11101010010100100100110 324A57
125 00001111011100001010101 550EF0 452 10011111010100100101010 2A4AF9
131 01111010011100001011001 4D0E5E 454 10100101110100100101100 1A4BA5
132 01100111001100001011010 2D0CE6 455 00101011011100100101101 5A4ED4
134 01011101101100001011100 1D0DBA 462 01110101010100100110010 264AAE
143 01101111010100001100011 630AF6 464 01001111110100100110100 164BF2
145 01010101110100001100101 530BAA 465 11000001011100100110101 564E83
152 00111101100100001101010 2B09BC 466 11011100001100100110110 364C3B
155 10001001101100001101101 5B0D91 503 01111000110100101000011 614B1E
156 10010100111100001101110 3B0F29 506 01011111000100101000110 3148FA
162 11010111100100001110010 2709EB 516 10000011011100101001110 394EC1
165 01100011101100001110101 570DC6 523 01001110101100101010011 654D72
172 00001011111100001111010 2F0FD0 526 01101001011100101010110 354E96
174 00110001011100001111100 1F0E8C 532 00011100011100101011010 2D4E38
205 11011101001100010000101 508CBB 546 00110011110100101100110 334BCC
212 10110101011100010001010 288EAD 565 00011000111100101110101 574F18
223 11010001110100010010011 648B8B 606 10111011001100110000110 30CCDD
225 11101011010100010010101 548AD7 612 11001110001100110001010 28CC73
226 11110110000100010010110 34886F 624 00011110101100110010100 14CD78
243 10001011011100010100011 628ED1 627 00000011111100110010111 74CFC0
244 00111111010100010100100 128AFC 631 11100101000100110011001 4CC8A7
245 10110001111100010100101 528F8D 632 11111000010100110011010 2CCA1F
246 10101100101100010100110 328D35 654 10011000011100110101100 1ACE19
251 11000100111100010101001 4A8F23 662 01001000111100110110010 26CF12
252 11011001101100010101010 2A8D9B 664 01110010011100110110100 16CE4E
255 01101101100100010101101 5A89B6 703 01000101011100111000011 61CEA2
261 00101110111100010110001 468F74 712 00010111101100111001010 29CDE8
263 10111101000100010110011 6688BD 723 01110011000100111010011 65C8CE
265 10000111100100010110101 5689E1 731 00111100100100111011001 4DC93C
266 10011010110100010110110 368B59 732 00100001110100111011010 2DCB84
271 11110010100100010111001 4E894F 734 00011011010100111011100 1DCAD8
274 11010101010100010111100 1E8AAB 743 00101001101100111100011 63CD94
306 00011001111100011000110 318F98 754 01000001111100111101100 1BCF82

Section 3. Operation
3-10
Table 3. -4. Normal and Inverted DCS Codes
Normal Inverted Normal Inverted Normal Inverted
023 047 223 134 445 043
025 244 225 122 446 255
026 464 226 411 452 053
031 627 243 351 454 266
032 051 244 025 455 332
036 172 245 072 462 252
043 445 246 523 464 026
047 023 251 165 465 331
051 032 252 462 466 662
053 452 255 446 503 162
054 413 261 732 506 073
065 271 263 205 516 432
071 306 265 156 523 246
072 245 266 454 526 325
073 506 271 065 532 343
074 174 274 145 546 132
114 712 306 071 565 703
115 152 311 664 606 631
116 754 315 423 612 346
122 225 325 526 624 632
125 365 331 465 627 031
131 364 332 455 631 606
132 546 343 532 632 624
134 223 346 612 654 743
143 412 351 243 662 466
145 274 356 212 664 311
152 115 364 131 703 565
155 731 365 125 712 114
156 265 371 734 723 431
162 503 411 226 731 155
165 251 412 143 732 261
172 036 413 054 734 371
174 074 423 315 743 654
205 263 431 723 754 116
212 356 432 516

Section 3. Operation
3-11
REVERSE FREQUENCY WORKING (OPTION)
Reverse Frequency Working or “RFW” is a method of controlling a repeater from a control
station or fixed location mobile. The purpose is to replicate the service previously only
available using a direct audio connection from the radio operator to repeater site. This
connection would usually be a leased line for EIA tone or DC remote control.
The document from the (UK) Radio Agency RA263 titled “Reverse frequency working and
talkthrough for PMR (standard) licenses” fully details what is available and who can use it.
The following is a description of an implementation of this method of operation using the
Zetron Model 38.
The Model 38 equipped with the RFW option will operate as standard or RFW mode. RFW
mode allows the unit to act as a cross tone encoder and decoder as shown below.
RFW mode
Description Dispatcher radio setup Model 38 Mobile radio setup
Dispatcher to mobile call Tx CTCSS 01 →Rx 01 Tx 02 →Rx CTCSS 02
Mobile to dispatcher call Rx CTCSS 01 ←Tx 01 Rx 02 ←Tx CTCSS 02
In this mode the dispatcher can communicate with the fleet, but the fleet can not hear each
other.
In order for talkthrough to be used, the Model 38 is sent a 4 or 5 digit code in DTMF which
changes the mode of operation. In talkthrough mode, the radio fleet can talk to each other. In
order for the dispatcher to also communicate it must change its CTCSS encode and decode
tone to the same as the fleet. As it would be usual for only the dispatcher to have the ability
to switch talkthrough then this would be done at the same time.
Some radios have the ability to send a DTMF sequence when the channel is changed. This
would then completely automate operation. If the dispatch radio does not have a DTMF
capability, then a Zetron ZMX microphone could be used. This could have two speed dials
programmed to allow switching modes from a single button press.
Talkthrough mode
Description Dispatcher radio setup Model 38 Mobile radio setup
Mobile to mobile call Tx 02 Rx 02 Tx / Rx CTCSS 02
Dispatcher to mobile call Tx CTCSS 02 →Rx 02 Tx 02 →Rx CTCSS 02
Mobile to dispatcher call Rx CTCSS 02 ←Tx 02 Rx 02 ←Tx CTCSS 02

Section 3. Operation
3-12
Programming
In order for RFW to be used, two users must be enabled on the Model 38. An example of this
programming shown in Table 3. -5. The necessary system programming is shown in Table 3.
-6.
Table 3. -5. RFW User Programming
User 10 - Dispatcher User 15 - Radio fleet
1. User enable = On 1. User enable = On
2. Decode (DCS) = 91.5 Hz 2. Decode (DCS) = 107.2 Hz
3. Encode = 15 107.2 Hz 3. Encode = 10 91.5 Hz
4. Tx hold time = 0 4. Tx hold time = 20
5. CTCSS tail = On 5. CTCSS tail = On
6. Morse Id = DISPATCH 6. Morse Id = FLEET
7. Reserve mode = Off 7. Reserve mode = Off
8. Privacy mode = On 8. Privacy mode = On
9. Courtesy tone = Off 9. Courtesy tone = Off
10. Last user Id = Off 10. Last user Id = Off
11. DTMF function = Off 11. DTMF function = Off
12. Hog limit = 0 12. Hog limit = 0
13. Prepay mode = Off 13. Prepay mode = Off
14. Airtime = 000:00:00 14. Airtime = 000:00:00
15. Aux relay = Off 15. Aux relay = Off
Table 3. -6. RFW System Programming
System Programming
1. Timeout time = 3 16. Remote PTT = 0
2. Timeout ID = Off 17. DCStx invert = Off
3. AntiKerchunk = 0 18. DCSrx invert = Off
4. ID timer = 15 19. Password = 123
5. ID freq = 1200 20. Access alarm = Off
6. ID speed = 22 21. Remote type = 0 Morse
7. ID sys user = 0 22. COR user# = 0
8. ID periodic = Off 23. Min airtime = Off
9. Beep freq = 1000 24. Serial tone# = Off
10. Tail bips = On 25. CTCSS hold = 0
11. Hog idle = 5 26. Slow CTCSS = Off
12. Hog penalty = 30 27. Interdigit = 4
13. Alarm DTMF = 28. DCS bit errs = 2
14. Alarm tone = 0 29. CTCSS delay = 70
15. Alarm pwr up = Off 30. Reverse Chn = 9801
The RFW feature is enabled and disabled globally, that is, only one command is used for On
and Off, and all users which have a cross tone set will be effected by enabling RFW.