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MODEL 38 Max Repeater Panel


MODEL 38 Max Repeater Panel


The Zetron Model 38-MAX is a high capacity, remotely programmable, community repeater controller. It provides individualized repeater service for up to 160 different customer groups using 50 CTCSS tones and 110 DCS codes. This makes it the ideal panel for scan-based trunking applications.

In addition to a large user-group capacity, the 38-MAX offers other unique features to enhance repeater performance. An �airtime usage summary� provides a convenient method of determining the loading across every tone/code. A �dynamic conversation timer� automatically lengthens and shortens the maximum conversation limit in accordance with the rise and fall of traffic patterns.

A �dual time constant squelch� compensates for the difference in transmission strengths between nearby radios and distant or obstructed radios.

Performance Features

The Model 38-MAX is equipped with all of the performance features serious community repeater operators have come to demand. ToneLock 3dB SINAD decoding, a Zetron exclusive, eliminates dropouts resulting from weak,
fading signals, or high modulation levels. The usable range of the repeater will not be limited by the decode performance of the repeater tone panel when a Model 38-MAX is in control. The Model 38-MAX recognizes when a radio unkeys with squelch tail elimination, silently muting repeater receiver audio. The Model 38-MAX also transmits squelch tail elimination ensuring that listening radios quiet instantly without an annoying noise burst. High quality audio processing circuits in the Model 38-MAX are designed to ensure the best audio quality available.

Special Features

Individual station IDs may be programmed for each user, and a single system ID may be programmed for private carrier or cooperative applications. Automatic station ID means that users are no longer required to use valuable air time speaking their call sign. The Morse code ID feature automatically transmits a user�s call sign at the beginning of a transmission and at programmed intervals.

Courtesy beeps may be used to encourage unfamiliar radio users when to begin speaking, or tailbips (one beep per second) can occur during the repeater hold time.
The reserved user feature prevents a co-channel system operator from commandeering a temporarily unused tone or code. The Model 38-MAX reserves a tone or code by transmitting an alert signal and muting repeat audio when it detects the tone or code.
The privacy mode feature prevents users on different CTCSS tones or digital codes from assuming control of the repeater until after the transmitter hold time expires. This reduces or eliminates repeater barge-ins.
The anti-kerchunker filter cancels the transmit hold time and drops the repeater transmitter immediately if a mobile transmission lasts less than the specified time. This prevents prolonged repeater transmissions due to momentary mobile key-ups. The anti-kerchunker filter time is programmable.

The auxiliary relay provides a contact closure that can be programmed to close whenever a specific CTCSS tone or DCS code is received. Any individual tone or code, or group of tones or codes may be programmed to activate the relay.
Cross tone, cross code, and tone code encoding give the Model 38-MAX the most flexibility. This feature also permits multiple repeaters at different locations to be placed on a single frequency. Mobiles may roam between two or more systems, accessing each individual repeater with a different tone or code, and receiving on a common tone. The courtesy tone frequency may be set to a different pitch for each repeater to distinguish the repeater location or coverage.
Temporary cross-tone, or cross-tone defeat may be initiated using a DTMF keypad on a mobile or handheld radio. This feature provides a simple method for the repeater operator to communicate with any subscriber on the system. The site alarm feature will transmit a DTMF page with any CTCSS or DCS code, and an audible alert when the alarm input detects activity. The alarm may be used to alert the system operator of site conditions such as break-in, high temperature, or equipment failure.


Easy installation and setup ensures that a technician can install a Model 38-MAX in nearly any repeater or duplex station. Installers will appreciate the detachable screw terminal connector that makes the installation a snap. Factory wired cables and field proven application notes take the guesswork out of the installation procedure. Installation application notes are included in the instruction manual for the most popular repeaters from companies such as Ericsson/G.E., E.F. Johnson, Icom, Midland, Motorola, Regency, Repco, Standard, Tait, Uniden, and others. Only six connections are required in typical installations, and expert interface assistance is available from Zetron.


  • Three-year warranty and interconnect trade-up option
  • 160 user groups (50 CTCSS and 110 DCS)
  • ToneLock high performance decoding
  • Squelch tail elimination for proper operation
  • Airtime accumulation and prepay per user
  • Airtime usage graphs
  • Dynamic conversation limits
  • RS-232 and remote DTMF programming
  • Program or monitor while in use via RS-232
  • Per user programmable features
  • Site alarm and auxiliary relay
  • Privacy mode prevents �barge-ins�
  • Vacant tones and codes can be reserved
  • Courtesy tone and tailbips
  • Remote PTT input for wireline takeover


CTCSS tones 50 standard tones between 67 and 254 Hz
CTCSS bandwidth 1.0%
DCS codes 110, programmable as any octal code 000-777. Default settings for 104 standard DCS codes
DCS noise immunity Up to four bit errors in any position
Sensitivity ToneLock 3dB SINAD CTCSS, 5dB SINAD DCS
Squelch tail elimination Detects CTCSS reverse burst and DCS turnoff code
Input impedance 50K-ohm AC coupled. For connection to unsquelched discriminator audio
Frequency accuracy 0.05 Hz
Frequency stability Crystal controlled
Output amplitude 0.0 to 3.0 V p-p
Output slope Flat or de-emphasized
Output distortion Less than 2%
Impedance Less than 1K-ohm AC coupled
Squelch tail elimination DCS turnoff code sent, CTCSS encode drops minimum of 150mS before PTT, muting listening receivers
Morse ID frequency 1200Hz; adjustable �800 Hz
Beep frequency 1000 Hz; adjustable 400 to 4000 Hz
DTMF encoder Standard DTMF tones
Connections Discriminator audio, Receive carrier detect, Transmit audio, CTCSS/DCS encode, PTT, Power, Ground, Auxiliary relay output, Site alarm input
Connector type Detachable screw terminal
Transmit SPDT relay
Adjustments Rear panel accessible; Rx input level,
Tx output level, CTCSS/DCS encode level, Carrier detect threshold
Indicators Power, Rx carrier, Transmit, CTCSS DCS Decode, DTMF, Aux relay
Serial data port RS-232 compatible levels
Interface Tx data, Rx data, ground
Handshake XON/XOFF protocol
Baud rate Selectable: 150, 300, 600, 1200, 2400, 4800, 9600
RS-232 port fully operational while unit is active on the channel
Rear switches Audio input level high/low, audio input flat/de-emphasis, CTCSS/DCS encode level high/low, CTCSS/DCS encode flat/de-emphasis, audio output level high/low, COR internal/external, COR polarity normal/invert, COR pull-up on off
COR input range Adjustable threshold of 0 to 7 VDC.
Detection requires a 1 volt change between carrier and no carrier conditions
Current consumption 70 mA at 13.8 VDC (LEDs disabled), 100 mA typical
Operating voltage 11.0 VDC to 15.0 VDC
Rackmount size 1.7" x 19" x 4.8"
Weight 2.2 lb.
0 to 65� C.
WISCO International, Inc. - MIAMI, FL U.S.A.
Fax: (954) 370-3997 | E-mail: wiscointl@wiscointl.com

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