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MODEL 38A Repeater Panel


MODEL 38A Repeater Panel


The Zetron Model38 Repeater Panel is a flexible, remotely programmable repeater tone panel that converts any station capable of duplex operation into a full featured repeater. The Model38 is an ideal replacement for older card-per-user tone panels, eliminating time consuming trips to remote repeater sites as well as the high cost of individual tone cards for each customer.
With a Zetron Repeater Panel, a system operator can add or remove customers without traveling to the repeater site. Records of repeater system use may also be obtained with the touch of a key on the Zetron Model 8B Programmer/ Timekeeper. Up to 60 different customers or user groups can be accommodated by a single Model38. (With the 50 CTCSS/18 DCS option, up to 68 users can be accommodated.) The Zetron Model38 is an ideal choice for retrofitting existing repeaters or developing new shared systems.


ToneLock, a Zetron exclusive, eliminates repeater talkdown or dropout resulting from weak, fading signals, high modulation levels, or poorly processed mobile transmitter audio. A ToneLock equipped Model38 will recognize a CTCSS tone or digital code with a receiver quieting level of 3 dB SINAD. Typical programmable tone panels require a minimum of 8 dB SINAD before reliable tone decoding occurs. The Model 38 can even out perform traditional reed type decoders. The Model38 will not false on adjacent tones, even when receiving CTCSS tones transmitted with a phase reversal.
The Model 38 is available at no extra charge with 50 CTCSS tones and 18 digital squelch codes. This special software permits the use of the Model 38 in radio systems that use non-EIA CTCSS tones. This makes the Model 38 ideal for older radio systems that may use non-EIA tones. The Audio Quality of the Model38 is immediately obvious when upgrading older repeater panels or replacing other programmable panels.


The Airtime Keeper keeps track of all system use for customer billing purposes. Airtime totals can be retrieved by Morse code, by a Model8B Programmer/Timekeeper, or by using a pair of modems and any RS-232 equipped terminal or computer. Airtime data may also be retrieved with a directly connected Model8B Programmer/Timekeeper or an RS-232 equipped terminal, or computer.
The Airtime Hog feature penalizes long winded talkers on a per user basis. If a user exceeds a preprogrammed time limit, the user is prohibited from using the repeater for the programmed penalty period. Warning tones are transmitted when a penalty is imminent.

The Prepaid Airtime feature allows a customer to purchase a block of airtime in advance. As the customer uses the repeater, the amount of unused airtime decreases. When the supply of prepaid airtime is nearly gone, the customer hears a warning tone whenever a radio unkeys. If the customer does not purchase additional airtime, the customer�s tone reverts to reserved status when the original block of time runs out. This permits the system operator to pre-bill problem customers.

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 one second. This prevents prolonged repeater transmissions due to momentary mobile key-ups. The Stuck Mic feature identifies which radio fleet has locked up the repeater. When the repeater times out, the Model38 transmits a two-digit DTMF sequence corresponding to the programmed user number. This helps identify the source of intentional or accidental repeater jamming.


The Model 38 Repeater Panel can be interrogated and programmed from a DTMF radio, from a Zetron Model 8B, or from a computer that is either connected directly or operating through telephone or packet modems (see diagram). Programming by computer is easy because the Model 38 puts questions and lists of choices on-screen. Programming via the built-in RS-232 port does not require taking the unit out of service. This means your repeater stays on the air, even as customers are added or removed from the system.


  • Full remote control of repeater system
  • All 38 CTCSS tones / 22 digital codes standard
  • ToneLock ultra high performance tone decoding
  • Simple installation and programming
  • Efficient management of repeater system
  • Remote control by radio or telephone line
  • Programmable per user features
  • Automatic Morse code ID
  • Zetron performance, quality construction, and long term reliability


Frequency Range 67 to 250.3 Hz
38 CTCSS/22 DCS (Standard)
No. of Tones
No. of Digital Codes

No. of Tones
No. of Digital Codes

Input Impedance 100K-ohm AC coupled. For connection to unsquelched discriminator audio
Freq. Accuracy
Freq. Stability
Output Amplitude
Output Mode
Output Distortion
0.1 Hz
Crystal controlled
0.0 to 3.0 V p-p, selectable
Flat or de-emphasized
Less than 1%
Less than 1K-ohm AC coupled
Morse ID Freq. 1200 Hz; adjustable �800 Hz
Beep Frequency 1000 Hz; adjustable 400 to 3000 Hz
DTMF Encoder Standard DTMF tones
Connections Discriminator; Push-to-Talk; CTCSS, Output; Repeat Audio; Alarm Input/Remote PTT Input; Power; Ground
Connector Type Detachable screw terminal
Transmit SPDT relay
Adjustments Four adjustments from rear panel: Input Level; CTCSS Encode Level; Output Level; Squelch
Indicators Power; Carrier; Decode; Encode; Transmit; DTMF
Local Prog. Port Front-panel audio jack for local DTMF programmer
Serial Data Port
Baud Rate
RS-232 compatible levels:
Tx data, Rx data, common/gnd
Follows XON/XOFF protocol
Selectable: 150; 300; 600; 1200; 2400; 4800
Rear Switches Audio Input Level (high/low); Audio Input (flat/de-emphasized);
CTCSS Output Level (high/low);
CTCSS Output (flat/de-emphasized);
Audio Output Level (high/low); COR (internal/external); COR Polarity (positive/negative)
Repeat Audio Flat or de-emphasized
Long Digit Reset A single DTMF digit received by the
Model 38 for 15 seconds may be used to reset the Model 38 remotely.
ToneLock ToneLock decodes a CTCSS tone with a receiver quieting level of 3 dB SINAD after initial acquisition
COR Input Range Adjustable threshold of 0 to 7VDC.
Level must change by at least 1 volt between carrier and no carrier conditions
Squelch Tail Elimination Model 38 decodes mobile�s reverse phase burst, or digital turnoff code
Current Consumption 350 mA at 13.8VDC
Oper. Voltage Range 11VDC to 15.0VDC
Rack-Mount Size 1.7" x 19" x 4.8"
Weight 2.2 lb
Operating Temp 0 to 65 degrees C.
WISCO International, Inc. - MIAMI, FL U.S.A.
Fax: (954) 370-3997 | E-mail: wiscointl@wiscointl.com

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