RITRON, INC.
TABLE OF CONTENTS I DTX MODULES 1 INTRODUCTION 2 1.1 GENERAL 1.2 MODEL IDENTIFICATION 1.3 FCC REGULATIONS MODELS DTX-154 AND DTX-454 SPECIFICATIONS 2.1 GENERAL 2.2 TRANSMITTER 2.3 RECEIVER 3 DTX-154/454 INPUT/OUTPUT CONNECTOR 4 ACCESSORIES 5 OPERATION 6 5.1 CHANNEL SELECTION 5.2 POWER SUPPLY VOLTAGE 5.3 DUTY CYCLE/KEY-DOWN LIMITATIONS 5.4 OPERATING MODES 5.5 RNET COMPATIBILITY MODE PROGRAMMING 6.1 PC PROGRAMMING KIT 6.2 LOADING THE PROGRAMMING SOFTWARE 6.
8.1 DTX-160/260 RF BOARD 8.2 DTX-360/460 RF BOARD 8.3 CONTROL/LOADER BOARD 9 HARDWARE OPTIONS 10 ALIGNMENT 11 10.1 REQUIRED TEST EQUIPMENT 10.
1 INTRODUCTION 1.1 GENERAL The RITRON DTX Plus modules are programmable 2-way radios, which operate either in the VHF or UHF professional FM communications bands as well as a number of other bands in the 220 MHz and 350 MHz region. Each of eight channels can be programmed to contain a unique set of operating frequencies. The DTX Plus module is made up of two PC boards, an RF board and a control/loader board.
6=6 watts 9=10 watts F designates whether the control/loader board has a regulator and if so, at what current level: D=no regulator; the unit must operate from external, regulated +7.5 VDC and is limited to either 3 or 6 watts max. L=low current regulator; the power module is not regulated. Used for 10 watt version only. I=high current regulator; the unit operates from 10-15 volts at either 3 or 6 watts max.
these other forms of electromagnetic energy, which when used improperly can cause biological damage. Very high levels of x-rays, for example, can damage tissues and genetic material. Experts in science, engineering, medicine, health and industry work with organizations to develop standards for exposure to RF energy. These standards provide recommended levels of RF exposure for both workers and the general public. These recommended RF exposure levels include substantial margins of protection.
Instructions: • Transmit no more than the rated duty factor of 50% of the time. To transmit (talk or send data), assert the PTT input pin. To receive calls, un-assert the PTT input. Transmitting 50% of the time, or less, is important because this radio generates measurable RF energy exposure only when transmitting (in terms of measuring for standards compliance).
2 SPECIFICATIONS 2.
2.2 Supply Voltage 3 and 6 watt versions w/o internal regulator w internal regulator 10 watt version (DTX-460-0 only) 7.5 VDC 11 to 16 VDC 11.5 to 15 VDC RF Input/Output Connector BNC standard Power/Data Interface 15 pin subminiature D type Operating Temperature -30 to +60 C Maximum Dimensions (L x W x H) 3.6” x 2.3” x 1.0” including connectors Weight 6 oz.
2.3 RECEIVER Operating Bandwidth Up to span of the sub-band Sensitivity (12 dB SINAD @ 1 kHz w de-emphasis) 0.25 uV (-119.0 dBm) RF Input Impedance 50 ohms nominal Adjacent Channel Selectivity +/-6.25 kHz w very narrow IF +/- 12.5 kHz w narrow IF 45 dB min. 60 dB min. Spurious and Image Rejection IF/2 Image & other 60 dB min. 70 dB min. Intermodulation Rejection 68 dB min. FM Hum and Noise Very narrow channel (5/6.25/7.5 kHz) operation Narrow channel (12.5/15 kHz) operation 40 dB min.
3 DTX INPUT/OUTPUT CONNECTOR Connector Pinout Pin Number Name Description Comments 1 CS0 Channel Select low bit 2 CS1 Channel Select mid bit 3 CS2 Channel Select high bit 4 MIC IN Microphone Input 5 CSN High/Low Power or Channel 1/2 6 RAW SUPPLY Power Supply Input Positive Supply voltage input. 7 AUX IN Auxiliary Input Wideband input for data. 8 AUX OUT Auxiliary Output Wideband output for data. 9 PGN IN/OUT Programming I/O External programmer connects here. 10.
reference for all inputs. Pinout Description Pin Number Description 1 CS0-Least significant bit of the channel select lines. Active high 5 volt TTL/CMOS level. Internal 10 k pull-up to +5 volts. 2 CS1-Mid bit of the channel select lines. Active high 5 volt TTL/CMOS level. Internal 10 k pull-up to +5 volts. 3 CS2-Most significant bit of the channel select lines. Active high 5 volt TTL/CMOS level. Internal 10 k pull-up to +5 volts.
ohms. Therefore, it is not recommended that this output drive loads with less than 1000 ohms unless the resultant voltage drop is accounted for. 9 PGN IN/OUT-Connect via RITRON DTXP-PCPK PC Programming Kit to computer for programming the unit. 10 CTS-Clear-To-Send output from the unit which indicates that the unit is transmitting a carrier at the correct frequency and power level and is ready to accept an input signal to be transmitted.
4 ACCESSORIES Note: Programming kits are for use by authorized service/maintenance personnel only. The Programming Kit for DTX-154/454 radios (via compatible computer) is model DTXP-PCKT. It includes: 1) Programming software diskettes, 3.5” (qty 2). 2) 1 25 pin PC to 6 pin modular adapter cable with built-in interface circuitry. 3) 1 modular adapter to DB-15 connector cable with power cable. Factory programming of channels and features is also optional. Contact the factory for details.
5 OPERATION 5.1 CHANNEL SELECTION The DTX module supports eight channels. The desired channel is chosen via pins 1, 2, and 3 of the 15 pin connector as shown: Channel Pin 3 (CS2) Pin 2 (CS1) Pin 1(CS0) 1 2 3 4 5 6 7 8 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 0 = Logic low (0 to 0.3 VDC) 1 = Logic high (3.5 to 5.0 VDC or left unconnected) A logic low is a voltage level below 1 volt while a logic high is a voltage level above 3.5 volts.
5.3 CURRENT DRAIN VS SUPPLY VOLTAGE The current drain of the module is a function of the supply voltage, the RF output in transmit and the regulator option. The internal 7.5-volt regulator is a switching type such that the current drain actually decreases with an increase in supply voltage. Typical current drain values are shown in the table below: Receive Mode Supply Voltage 7.5 V 11.0 V 12.5 V 16.
5.4 DUTY CYCLE/KEY-DOWN LIMITATIONS The major heat generating component within the modules is the RF power amplifier which has a maximum temperature limit that should not be exceeded. In addition, the temperature within the module itself must be kept below the maximum temperature of the reference oscillator to ensure that regulatory frequency stability limits are observed.
5.5 OPERATING MODES 5.5.1 RECEIVE Carrier Detect and Squelch Operation The DTX is a transceiver; i.e. it can receive and transmit, although not at the same time. A carrier detect system exists within the unit to detect the presence of a carrier which controls the logic state of the DCD (data carrier detect) output. The RF levels at which this output changes state are programmable.
the MIC IN signal can achieve the same modulation with 4 mv rms in the low gain position and 0.5 mv in the high gain position. High/Low Power If RNet compatibility mode is not programmed into the unit, high and low power levels can be programmed into the unit on a channel by channel basis. High power is selected by placing the CSN input at a logic high state. Placing the CSN input at a logic low state chooses low power.
Self-quieting Frequencies(MHz) DTX-160 136.9500 143.1000 143.9938 144.0000 144.3750 149.2375 157.5000 158.3938 158.4000 158.4063 171.9000 172.8000 DTX-260 DTX-360 DTX-460 453.6000 453.9375 454.1625 455.4000 456.6000 457.7625 460.7938 460.8000 461.3625 461.4000 461.7000 464.4000 464.9625 465.1563 466.2000 468.0000 468.5625 469.
6 PROGRAMMING To program the DTX Module, the RITRON PC Programming Kit, DTXP-PCKT, must be used. 6.1 PC PROGRAMMING KIT The user should install the programming software on the host computer. The RITRON adapter cables connect the radio to a computer’s serial communications port. Once the cables are hooked up, the user runs the programmer software. This program transfers data between radio and computer memory. 6.1.
6.4 USING THE PROGRAMMING SOFTWARE Note: Power up the radio and connect it, via the programming cable, to the host computer before opening the programmer. Upon starting the programming software, a screen will appear with two buttons at the upper right, Program Radio and Programmer Configuration. Program radio reads the configuration of the radio and moves the user to the program radio menus which are described below.
5. Read Radio-Forces the programmer to do a read of the radio to update the programmer screens with the current state of the radio. This allows a radio to be connected to the programmer and powered up without closing and then reopening the programmer.
6.5.1 FREQUENCY SELECTION The Frequency page has fields for the transmit and receive frequencies for each channel. Channel information can be entered by clicking on the appropriate box and entering the desired frequency. The frequency chosen must be within the operating range of the radio and on a frequency for which the synthesizer is capable of channeling i.e. for VHF, divisible by 2.5 kHz and for UHF, divisible by 5 or 6.25 kHz.
RRCFSK, 4FSK, etc., DC coupling may be indicated, even if the output of the unit is not modified for true DC coupling to the output. AFSK modulation types such as Bell 202, etc. should use AC coupling. The factory default is AC. CSN Input-Selects whether RNET Compatibility mode is to be used. See section 5.6 for an explanation of this function. Normal operation is to set this for high/low Power. The factory default is high/low power mode.
Audio Input (TX) Gain-This input allows adjustment of the signal level to be applied to the modulation limiter and filter circuits from either the AUX IN or MIC IN inputs. At the maximum gain setting, the AUX IN signal input can achieve 60% rated modulation with about 25 mv rms input signal while the MIC IN signal can achieve the same modulation with 4 mv rms in the low gain position and 0.5 mv in the high gain position. The setting can vary from 0 for muted input to 32 for maximum gain.
This selection is used to load a previously saved radio configuration file to the radio connected to the programmer. This is of benefit when a number of radios are to set to the same frequencies and with the same switch settings. There are three options for this page, but none will copy the deviation and balance settings since these are unique to each radio, even if the actual deviation of a set of radios is identical.
II MAINTENANCE 10 IMPORTANT MAINTENANCE INFORMATION Surface Mount Repair: RITRON surface mount products require special equipment and servicing techniques. Improper servicing techniques can cause permanent damage to the printed circuit board and/or components, which is not covered by RITRON’s warranty. If you are not completely familiar with surface mount component repair techniques, RITRON recommends that you defer maintenance to qualified service personnel.
2) Board Separation Remove the two screws that secure the control/loader board to the rear bracket. The rear bracket stays connected to the RF board. Remove the two screws that secure the RF board to the front bracket. The front bracket stays connected to the control/loader board. These four screws are removed with a TORX T-9 driver. The two boards are held together by their interconnecting header/socket. Gently pry the two boards apart at the header/socket.
8 THEORY OF OPERATION 8.2 DTX-360/460 RF BOARD 8.2.1 RECEIVER RF amplifier and Bandpass Filters The incoming RF signal from the antenna connector passes backwards through the transmitter harmonic filter and to a diode switch. The diode switch, CR101 and CR201 route the RF signal to a lumped-element bandpass filter and then an amplifier Q101. The amplifier is followed by another lumped-element filter.
synthesizer. In most synthesizer designs, the divider must be an integer, which forces the reference frequency to be equal to the synthesizer step size. This synthesizer, however, uses a fractional-N technique to generate smaller step sizes. The reference frequency is derived by digitally dividing the frequency of the 14.4 MHz master oscillator. When locked, the VCO attains the same relative frequency stability as that of the master oscillator.
8.3 CONTROL/LOADER BOARD The control/loader board is responsible for controlling the operation of the RF board and for processing the audio input and output signals to and from the RF board and to and from the outside. Audio Chain The audio processing, both transmit and receive, is handled by the audio Codec IC, U302 and the DSP microcontroller U301. These devices handle pre-emphasis, modulation limiting, and lowpass filtering on transmit as well as de-emphasis and filtering on receive.
must be soldered in the C352 location. The DC voltage should be 2.5 volts nominal and very well regulated. Note: The FCC Type Acceptance obtained by RITRON is invalid once this modification is made. The user is responsible for obtaining type acceptance in a configuration which includes the device which is connected to the AUX IN input. 9.2 RF BOARD OPTIONS 9.2.
10 ALIGNMENT Warning: Alignment must only be performed by qualified and trained service personnel. The DTX module is aligned at the factory before shipment and should need no further adjustment. It is possible that the gain settings for the audio input and output signal paths may need optimized. The frequency trim, deviation, and balance should not need adjustment. The procedure for performing all of the alignment steps is detailed below.
The RX Frequency Trim trims the unit on frequency during receive. This setting, if incorrect, may degrade receive sensitivity, distortion, and possible recovered audio level, which in turn affects AUX OUT (RX) Gain and Audio PA Gain. The receive frequency trim is not affected by any other alignment step. To determine if the receiver is correctly trimmed to frequency, the 1 st local oscillator frequency must be measured.
10.2.5 TX LOW POWER AND HIGH POWER The transmitter output power level can be programmed on a per channel basis via the alignment page of the programmer. If RNet Compatibility has not been programmed on the settings page, both the low and high power levels can be set. If RNet Compatibility has been programmed, only high power can be set. The TX High Power and TX Low Power settings in the TX Power box act to select a common value for all channels.
An audio oscillator should be connected to the AUX IN input. The output waveform should be sine, the level at zero, and at a frequency of 500 Hz. Confirm that the Aux In Gain value is at least 10. On the channel drop-down menu, select lower band edge. Activate the PTT, and while observing the demodulated waveform on the oscilloscope, begin increasing the audio oscillator’s output level or the Aux In setting. The waveform should begin as a sinewave and at some point show clipping.
