DEVAR Inc. 706 Bostwick Ave., Bridgeport CT Tel , Fax

Transcription

1 DEVAR Inc. 706 Bostwick Ave., Bridgeport CT Tel , Fax INSTRUCTION MANUAL DUAL PLUG & SEND TRANSMITTER MODEL PS-2-B PS-2B Rev A

2 TABLE OF CONTENTS 1 General Description Theory Of Operation Loss of Power Installation 3 5 Antenna Installation 5 6 Non Line of Sight Transmission 9 7 Antenna Grounding. 9 8 Lightening Protection Specifications Troubleshooting.. 13 Fig. 1 Timing Diagram. 2 Fig. 2 Link Protocol.. 2 Fig. 3 General Dimensions. 4 Fig. 4 Field Wiring 5 Fig. 5 Antenna Installation.. 6 Fig. 6 Radio Transmission.. 7 Fig. 7 Earth Ground. 7 Fig. 8 Radio Grounding... 8 Fig. 9 System Wiring 12

3 1. General Description The Devar Plug and Send Wireless Monitoring System is designed to transmit one analog and three discrete (on/off) data signals over a non-licensed portion of the VHF radio spectrum. The system accomplishes this by broadcasting very short pulses of radio energy with the transmitted information encoded in the length of time between pulses. A Plug and Send System consists of transmitter and receiver units. A single transmitter may transmit the same information to more than one receiver or multiple transmitters may be used to transmit data from different locations to a single multichannel receiver. Each set of transmitters and receivers is assigned an address code. Transmitters and receivers will only communicate if they have the same address code. Transmitters are also assigned channel numbers ranging from 1 to 16, allowing up to 16 remote transmitters to communicate with a single multi-channel receiver. Two 8 position DIP switches located inside of the transmitting and receiving radios are used to set the address code to one of 65,536 possible values. The channel that the transmitter transmits to is also set by means of a DIP switch located inside of the radio. The 16 possible channels are divided into 4 banks of 4 channels per bank (e.g. channel 2 would be bank 1, chan. 2 and channel 5 would be bank 2, chan. 1). Address codes and channel values are set at the factory and normally do not need to be reconfigured in the field. The Dual Plug and Send Transmitter is powered by 117 VAC with an internal 12 volt battery backup. Each of the two input channels provide a 22 VDC output to power a 2-wire field transmitter and each of the two input channels accept a single 4 to 20 ma input as well as three discrete, contact, closure inputs. Two green LED s, one for each channel, located on the front door of the transmitter, turn on and off as data is transmitted to the receiver. The length of time that the LED is turned on is proportional to the value of the analog input and the length of time that the LED is turned off is related to the number of discrete inputs that have been activated. The radio does not transmit a continuous signal. It transmits momentarily when the LED turns on and again when the LED turns off, see figure 1. The receiver demodulates the signal coming from the transmitter and produces a 4 to 20 ma output that is equal to the 4 to 20 ma input at the transmitter. The receiver also provides three discrete, contact closure outputs corresponding to the discrete inputs at the transmitter. Three red LED s mounted on the door of the receiver turn on when discrete inputs are detected. A green LED, also mounted on the door of the receiver, turns on and off as data is being received from the transmitter. Unlike the green Led on the transmitter this LED only flashes, once when it detects the start pulse coming from the transmitter and twice when it detects the stop pulse. If no data is received from the transmitter for a period of 4.5 minutes, the green LED will stay on continuously indicating a loss of communication. Should the receiver fail to receive data from the transmitter the last valid update will be retained until communication is reestablished and new data is received. 1

4 2. Theory of Operation Data is transmitted as a series of time modulated pulses. At the start of the cycle the transmitter will transmit a 400 millisecond, 10 watt, MHz, digitally encoded pulse. This pulse marks the start of the transmission cycle and contains the address code and channel information of the transmitting unit. The transmitter will then transmit a second pulse marking the end of the cycle. The value of the 4 to 20 ma input signal is encoded in the time duration between the start pulse and the stop pulse. The status of the discrete inputs is encoded in the time duration between the stop pulse and the next start pulse, see figures 1 and 2. START PULSE STOP PULSE START PULSE STOP PULSE Analog Data Discrete Data Analog Data 3 to 21 ma 1 to 51 sec 0, 1, 2 or 3 Discretes 52 to 80 sec LED ON LED ON LED OFF Figure1: Timing Diagram DISCRETE INPUTS D3 D2 D1 ON PERIOD (Seconds) ANALOG DATA (4 to 20 Ma) OFF PERIOD (Seconds) = CLOSED CONTACT Figure 2: Link Protocol 2

5 3. Loss of Power The Plug and Send Transmitter is provided with a battery backup system to maintain communication in the event of a power failure. The batteries, which are charged by the internal power supply, provide power for the radio system and for the external two-wire transmitters. Fully charged batteries will provide power for approximately 35 hours. Actual operating time under battery power will depend on many factors including the age of the batteries, the number of times the batteries have been discharged and the distance to the receiver. AC power must be restored to the transmitter for a period of 24 hours to recharge the batteries. CAUTION: To power down the Plug and Send transmitter you must disconnect the batteries as well as remove the AC line power. NOTE: One of the discrete input channels may be used to transmit a loss of power alarm to the receiver. This can be accomplished by connecting an AC relay to the 115 volt power line and using the normally closed contacts as a discrete input. The contacts, which remain open while the relay is energized will close on loss of power and trigger a discrete signal. 4. Installation The Plug and Send Transmitter System consists of the Transmitter Unit, 50 feet of RG58 cable with UHF plugs on each end and a 17 foot antenna. The transmitter enclosure may be mounted indoors or outdoors. Electrical connections are made to terminal blocks located inside of the enclosure, see figure 4. A UHF jack at the bottom of the enclosure is provided for the antenna cable. Discrete inputs are implemented by connecting a set of dry contacts between the discrete input terminals and the common terminals. If the 4 to 20 ma input signal is coming from a powered source, it is wired between the plus input terminal and the common terminal. If the input signal is coming from a 2-wire transmitter being powered by the Plug and Send, the analog input is wired between the plus input terminal and the +24 volt terminal. Spare terminal 4 has no electrical connection and may be used as a tie point. 3

6 Three methods are available for mounting the transmitter housing, see figure 3. FIRST: The enclosure may attached to a Panel by screwing through the panel into four, 6 mm, threaded, inserts located at the four corners on the back of the housing. SECOND: The enclosure may be attached by drilling through the threaded inserts and screwing into the panel from the inside of the enclosure. Four plugs are provided to seal the openings inside of the enclosure, after it is screwed to the panel. THIRD: Four mounting lugs may be attached to the threaded inserts on the back of the enclosure, the mounting lugs are then screwed to the panel CHANNEL 1 CHANNEL FRONT VIEW SIDE VIEW MOUNTING LUG REAR VIEW Ø6 mm Threaded Insert (4) Places Figure 3: General Dimensions 4

7 JUMPER OR EXTERNAL ma METER - OUTPUT + OUTPUT + INPUT SPARE DIS VDC DIS. 2 DIS. 3 TRANSMITTER DRY CONTACT DISCRETE INPUTS TYPICAL WIRING FOR 2-WIRE TRANSMITTER Figure 4: Field Wiring 5. Antenna Installation The Plug and Send Transmitter is shipped with 50 feet of RG58 cable, a 17-foot, 3- piece, fiberglass, whip antenna and mounting hardware. If a cable length greater than 50 feet is required, the RG58 cable will be replaced with RG8 cable. The first step in antenna installation is selecting the best location. Although line of sight is not required, the greatest transmission range will be achieved if there are no obstructions between the transmitting and receiving antennas. The antennas may be mounted on poles, towers, tanks, rooftops or other structures, see figure 5. The antenna should be mounted at least 9 feet above the ground or the roofline. In general the higher the antenna is mounted above the ground the better it will perform, however the FCC limits the height of the transmitting antenna to 60 feet. When mounting the antenna to the side of a structure, a distance of at least 3 feet should be maintained between the antenna and the structure. Specific instructions for mechanically assembling and mounting the antenna are provided with the antenna. Caution: The distance between the antenna and any power lines should be at least twice the combined height of the antenna plus the mast. Note: It is important that the antenna be properly grounded for both safety and performance and it is strongly recommended that a lightning protector be installed between the antenna and the receiver, see figure 7. Caution: When installing the antenna, do not use calk or silicone sealant around any part of the antenna, this could prevent water from properly draining away from the antenna, causing improper operation or damage to the antenna. 5

8 GOOD INSTALLATION BAD INSTALLATION LINE-OF SIGHT BETWEEN THE TRANSMITTER AND RECEIVER ANTENNAS WILL PROVIDE THE BEST RANGE TRANSMITTING THROUGH STRUCTURES, METAL AND GEOGRAPHIC OBSTACLES WILL REDUCE RADIO RANGE MOUNT ANTENNA AS HIGH AS POSSIBLE GOOD ANTENNAS NEED GOOD GROUNDS 9 FT A GROUND PLANE WITH A RADIUS OF NINE FEET MINIMUM IS DESIRED AT LEAST 9 FEET ABOVE GROUND IS RECOMMENDED WHEN MOUNTING ON THE SIDE OF A STRUCTURE, USE A MINIMUM OF A 3 FOOT SPACER TO DISTANCE ANTENNA FROM STRUCTURE METAL ROOF POOR OK FAIR ANTENNA LOCATION IS OF PRIMARY CONCERN Figure 5: Antenna Installation 6

9 REFRACTED PATH DIRECT PATH H REFLECTED PATH REFRACTED PATH LINE OF SIGHT H OPTICAL HORIZON APPROXIMATE DISTANCE TO OPTICAL HORIZON AS A FUNCTION OF ANTENNA HIGHT RADIO HORIZON D = (H) 1/2 D = Distance in miles H = Hight in feet RADIO WAVE OBJECT SHADOW DIFFRACTION ZONE EFFECT OF OBSTRUCTIONS ON RADIO TRANSMISSION Figure 6: Radio Transmission MAST ANTENNA COAXIAL ANTENNA CABLE PLUG & SEND TRANSMITTER Connect a ground wire from the base of the mast to a suitable earth ground. If the mast is nonconductive connect the ground connection to the base of the antenna. All ground wires should be at least number 10 copper or number 8 aluminum wire. As a minimum, a suitable ground would consist of an 8 ft. copper or copper plated grounding rod driven fully into the ground. A piece of pipe, hammered or concreted into the ground, does not provide an adequate earth ground. EARTH Figure 7: Earth Ground LIGHTENING ARRESTOR Install a lightening arrestor between the antenna and the transmitter. The arrestor should be located close to the transmitter. If the transmitter is located inside of a building or inside of another enclosure, put the arrestor outdoors, close to point that the antenna cable enters the building. Connect the arrestor to a good earth ground. If necessary, drive a second 8 ft. grounding rod into the earth to ground the arrestor. 7

10 ANTENNA RADIO RADIO ANTENNA GROUND PLANE KIT 1. A grounded whip antenna can be pictured of as half a dipole with the earth acting as the other half of the antenna. 2. The whip antenna requires an electrical return path for the radio signal. If the earth is to be used as the electrical return a good ground connection must be established. A 6 to 8 foot copper or copper plated steel rod can be used to ground the antenna. An underground water pipe might also provide a good electrical connection to earth. A metal fence post will not provide an adequate ground.the surface area of a large metal object such as a water tank could also be used to provide a ground plane for the antenna. 3. It is not always easy to establish a good electrical return by grounding to the earth. 4. An electrical return can be provided by using a ground plane kit. Even though a ground plane kit is used the antenna must still be grounded to the earth. GROUND ROD Figure 8: Radio Grounding 8

11 6. Non Line of Sight Transmission Because the Plug and Send transmitter operates at MHz it is not restricted to line of sight operation as are other telemetry systems operating at higher frequencies, e.g. 900 MHz. Although the Plug and Send does not require line of sight, obstructions between the antennas will have an effect on the transmission. The amount of signal loss will depend on the nature of the obstruction, as well as the location of the obstruction with respect to the antennas, see figures 5 and 6. For example, transmitting through a heavily wooded area is generally not a problem, while transmitting over a mountaintop may not be possible. Metallic obstructions attenuate more signal than nonmetallic obstructions. A large factory building made of steel and concrete would block more signal than an equally large building made of wood. The location of the obstruction is also important. A large water tank located directly in front of the transmitting antenna may totally block the signal, while the same tank located half way between the transmitting and receiving antennas may not cause a problem. 7. Antenna Grounding A good earth ground is extremely important for both safety and for good signal transmission. The ground connection allows static electric buildup to drain off of the antenna and it provides a current path into the earth should the antenna be struck by lightening. The ground also provides the electrical return for the transmitted signal. This can be visualized by thinking of the whip antenna as being half of a vertical dipole with the earth being the other half of the antenna, see figure 8. For safety the base of the mast must be grounded to earth. The National Electrical Code requires using at least a number10 copper or a number 8 aluminum wire for this purpose. In most cases the mast can provide the ground connection to the base of the antenna. For a better signal return, connect a ground wire from the base of the antenna directly to the earth ground at the base of the mast. Use a heavy stranded copper wire. The braid from a coaxial cable makes a good ground connection. Caution: do not connect copper wire directly to galvanized steel. These metals will react with each other causing an unreliable connection. A ground can be made by driving an eight-foot, copper or copper plated, grounding rod into the earth. The quality of the ground will depend on the nature of the soil. Rocky or sandy soil has high resistance and provides a poor ground. Soil with a high mineral or ash content has low resistance and provides a good ground. To compensate for poor soil conditions; drive three or more ground rods, evenly spaced around the mast, into the earth. Each ground rod should be connected by a short, piece of heavy cable to a single ground point at the base of the mast. Other possible grounding methods include grounding to under ground water pipes or to grounded metallic structures such as large water tanks. 9

12 CAUTION: All ground connections must be made using an appropriate clamping method. Twisting a ground wire around the end of a grounding rod will not provide an acceptable connection. A ground plane may also be used to provide the electrical return for the radio signal. A ground plane consists of a conductive surface located below the antenna. The ground plane should have a radius of at least 9 feet, preferably 38 feet, around the base of the antenna. The antenna is then grounded to the ground plane. CAUTION: Although the antenna is connected to a ground plane, a ground connection is still required between the base of the antenna and the earth. One method of creating a ground plane is to attach a series of radial wires to the grounding rods at the base of the antenna. Use 8 or more wires radiating away from the base of the antenna like the spokes of a wagon wheel. These wires may lie on the ground or be buried one inch below the surface. Some mounting configurations will automatically provide a ground plane. The top surface of a large cylindrical tank or a flat metallic roof may be used as the electrical return for the antenna. In the rare case where a good electrical return cannot be established, a ground plain kit (option -GPK) may be provided. A ground plane kit consists of a set of four, 4-foot, radials that attach to the base of the antenna, see figure Lightening Protection The three points were lightening may enter the transmitter are, through the signal lines, through the power lines and through the antenna cable. It is recommended that a lightening arrestor be placed at each of these three entry points. Each lightening arrestor must be directly connected to a single earth ground. The lightening arrestors for the input signal cable and for the antenna cable should be positioned close to the transmitter. If the transmitter is mounted indoors or inside of another enclosure, mount the lightening arrestors just before the cables enter the building or the outer enclosure. This will often require driving an additional grounding rod just outside of the building at the point were the cables enter. If the input cable is shielded, connect the shield to the same ground as the lightening arrestors. NOTE: Even though the lightening arrestors for the cables are grounded, the mast for the antenna must still be grounded at its base. If the antenna is mounted on the roof of a building, run the ground connection from the base of mast to the earth, using the most direct path. Run the antenna cable down to where it enters the building and if possible maintain a separation of 4 to 6 ft. between the ground and antenna cables. The cables should be attached to the building using insulated spacers. Drive a second grounding rod into the earth at the point where the antenna cable enters the building. Mount the lightening arrestor just 10

13 outside of the building and ground it to the grounding rod using a short piece of heavy cable. A lightening arrestor should also be installed on the AC power lines going to the transmitter. Following the manufacturers instructions, connect the live, neutral and ground wires from the AC power line to the lightening arrestor and from the lightening arrestor to the transmitter. If the ground for the lightening arrestors for the antenna and signal cables is not the same as the ground for the electrical service for the building, e.g. you have driven additional grounding rods outside of the building, then connect these grounds together. 9. Specifications General a. Input channels. Two channels b. Inputs per channel... 2 analog and 3 discrete c. Analog inputs to 20 ma, (3 to 21 ma) d. Input resistance Ω e. Discrete inputs Up to 3 dry contacts per channel, 500 µa sink current f. Loop supply voltage. 24 volts, 90 Ω output resistance g. Loop supply limit.. 30 ma, typical h. Power requirement VAC, 50/60 Hz, 6 watt Max. momentary current draw: 2 Amp i. Internal battery... Two 12 volt, 4.5 amp-hours each j. Current draw from battery... 2 amp, momentary on transmit, 100 ma, average continuous k. Battery operation.. 35 hours, typical, new battery l. Battery charge time.. 24 hours, minimum m. Charge voltage to 13.9 volts n. Temperature range to 60 C System a. Resolution... 8 bits b. Accuracy % of span, with occasional excursions to 1% c. Signal coding.... Time duration, 56 to 128 sec. d. Address code.. 65,536 possible codes Radio a. Frequency MHz b. Transmit power watt c. Transmit time msec, pulse d. Antenna impedance. 50 Ω Mechanical a. Enclosure... Polycarbonate, NEMA 4X b. Weight lb. c. RF connector UHF 11

14 BATTERY 1 BATTERY 2 WHT/BLK - + WHT/BLK - + LED 1 WHT/RED # 18 BRN # 18 RED LED 2 WHT/RED # 18 BRN # 18 RED #18 RED #18 RED #18 BRN #18 BRN #18 BRN #18 RED #18 BRN #18 RED #18 RED ON ON ON GND +12V SENSE -SENSE +13.8V +13.8V ORN YEL SEE NOTES GND CH 1 GND CH 2 GND CH 3 GND CHANNEL SWITCH OPTION SWITCH A B ADDRESS CODE RIU 1 BASE BOARD 1 POWER SUPPLY BASE BOARD 2 RIU 2 CH 4 #18 GRN #18 BLK LINE NEUTRAL #18 WHT JUMPER OR EXTERNAL ma METER - OUTPUT + OUTPUT + INPUT SPARE DIS. 3 DIS. 2 DIS VDC + OUTPUT - OUTPUT SPARE + INPUT DIS. 3 DIS. 2 DIS VDC GND AC NEUTRAL 117 VAC LINE POWER TO ANTENNA DRY CONTACT DISCRETE INPUTS TRANSMITTER NOTES: 1. BROADCAST CHANNELS ARE SELECTED BY THE CONNECTING ORANGE AND YELLOW WIRES TO THE TERMINAL BLOCK INSIDE THE RADIO. 2. UNUSED CHANNELS IN THE RADIO ARE CONNECTED TO GROUND. 3. THE RECEIVER BANK AND ADDRESS CODES ARE SET USING THE DIP SWITCHES. 4. THE FACTORY DEFAULT CONFIGURATION TRANSMITS TO BANK 1, CHANNELS 1 AND 2 OF THE RECEIVER. + - Figure 9: System wiring TYPICAL WIRING FOR 2-WIRE TRANSMITTER A 4096 SWITCH 1 OFF ON OFF ON SWITCH 3 SWITCH 4 OPTION SWITCH RECEIVER BANK SWITCH 2 OFF OFF ON ON CHANNEL SWITCH ADDRESS CODE (BINARY CODED DECIMAL) BANK # OFF OFF SET SWITCHES 1 & 2 TO SELECT THE RECEIVER BANK THE TRANSMITTER ACTIVATES IN THE 8 AND 16 CHANNEL RECEIVERS, FOR ALL OTHER RECEIVERS SELECT BANK 1 SWITCHES 1, 2, 3, 4 = ON B SWITCH ON TO SELECT VALUES ON OFF 12

15 10. Troubleshooting PROBLEM ANSWER CHECK AC POWER THE TRANSMITTER DOESN T DO ANYTHING. THE TRANSMITTER WORKS BUT THERE IS NO DISPLAY. THE DISPLAY CHANGES BUT DISPLAYS THE WRONG NUMBERS. THE DISPLAY DOES NOT CHANGE. THE TRANSMITTER STOPPED WORKING FOR A PERIOD OF TIME THEN RESUMED WORKING YOU HAVE ADDED A NEW RECEIVER AND IT DOESN T COMMUNICATE WITH THE TRANSMITTER THE DATA DOES NOT UPDATE AT THE RECEIVER TRANSMITTER AND RECEIVER DO NOT COMMUNICATE CHECK DC POWER BY MEASURING THE VOLTAGE ACROSS THE BATTERY. IT IS APPROXIMATELY 13.8 VDC WITH AC POWER APPLIED. YOU MAY HAVE LOST AC POWER. THE BATTERY DOES NOT BACK UP THE INDICATOR/CONTROLLER. CHECK TO SEE THAT THE DISPLAY HAS BEEN CONFIGURED TO INDICATE IN THE PROPER ENGINEERING UNITS VERIFY THAT THE SIGNAL TRANSMITTER IS OPERATING PROPERLY BY MEASURING THE INPUT CURRENT WITH A MILLIAMP METER OR BY REPLACING THE SIGNAL TRANSMITTER WITH A MILLIAMP CALIBRATOR. VERIFY THAT THE SIGNAL TRANSMITTER IS OPERATING PROPERLY BY MEASURING THE INPUT CURRENT WITH A MILLIAMP METER OR BY REPLACING THE SIGNAL TRANSMITTER WITH A MILLIAMP CALIBRATOR. WITH THE SIGNAL TRANSMITTER CONNECTED, MEASURE THE LOOP EXCITATION VOLTAGE BETWEEN TERMINAL 5 () AND TERMINAL 6 (+24 VDC). THIS VOLTAGE SHOULD BE FROM 21 TO 24 VDC. IF THE VOLTAGE IS LOW DISCONNECT THE SIGNAL TRANSMITTER AND RE-MEASURE THE VOLTAGE. THE OUTPUT CURRENT IS LIMITED TO 30 MILLIAMPS. CHECK FOR LIGHTENING DAMAGE TO THE INPUT BY DISCONNECTING THE SIGNAL TRANSMITTER AND VERIFYING AN INPUT RESISTANCE OF 247 Ω, ± 1% BETWEEN TERMINAL 4 (INPUT +) AND TERMINAL 5 (). YOU MAY HAVE LOST AC POWER. CHECK THE BATTERY. YOU MAY HAVE A MARGINAL INSTALLATION. CHECK ANTENNA SETUP, E.G. LOCATION, HEIGHT AND GROUNDING. NOTE THAT A GOOD GROUND CONNECTION CAN DETERIORATE DUE TO CORROSION OR IMPROPER CABLE ATTACHMENT. CHECK THAT THE ADDRESS CODE OF THE RECEIVER MATCHES THE ADDRESS CODE OF THE TRANSMITTER YOU MAY HAVE LOST RADIO COMMUNICATION. CHECK THE GREEN LED ON THE DOOR OF THE RECEIVER. THIS LED WILL FLASH ONCE AT THE START OF A CYCLE AND TWICE AT THE END OF THE CYCLE. IF THE LED STAYS ON CONTINUOUSLY, YOU HAVE LOST RADIO COMMUNICATION. CHECK THE VOLTAGE ACROSS THE BATTERY. IT IS APPROXIMATELY 13.8 VDC WITH AC POWER APPLIED OBSERVE THE GREEN LED ON THE DOOR OF THE TRANSMITTER TO VERIFY CIRCUIT OPERATION. THE LED WILL TURN ON AT THE START OF EACH DATA CYCLE AND STAY ON FOR A PERIOD OF TIME PROPORTIONAL TO THE ANALOG INPUT. FOR THE ON- OFF TIMES SEE FIGS. 1 & 2. VISUALLY INSPECT THE ANTENNA AND THE ANTENNA CABLE AND CONNECTORS. VISUALLY INSPECT THE GROUND CONNECTIONS. 13

16 11. Troubleshooting (continued) TRANSMITTER AND RECEIVER DO NOT COMMUNICATE TRANSMITTER AND RECEIVER DO NOT COMMUNICATE (New Installation) COMMUNICATION IS INTERMITTENT VERIFY THAT THE RADIO IS PROVIDING AN OUTPUT TO THE ANTENNA BY USING ONE OF THE FOLLOWING METHODS: 1) CONNECT A WATT METER BETWEEN THE TRANSMITTER OUTPUT AND THE ANTENNA CABLE. WHEN THE RADIO KEYS THE OUTPUT SHOULD BE AT APPROXIMATELY 10 WATTS. AN INEXPENSIVE WATT METER CAN BE PURCHASED FROM ANY ELECTRONICS DISTRIBUTOR THAT HANDLES CB RADIO EQUIPMENT. NOTE THAT THE RADIO KEYS FOR ABOUT ½ SEC EACH TIME THE GREEN LED ON THE DOOR TURNS ON OR TURNS OFF. 2) LISTEN TO A CB RADIO TUNED TO CHANNEL 23. YOU WILL HEAR A SHORT BUZZ EACH TIME THE TRANSMITTER TRANSMITS. 3 MOVE THE RECEIVER CLOSER TO THE TRANSMITTER AND SEE IF THEY COMMUNICATE. THE MOST CAUSE OF NON-COMMUNICATION IS IMPROPER ANTENNA GROUNDING. MAKE SURE THE ANTENNA IS CONNECTED TO AN ADEQUATE GROUND PLANE, SEE SECTION 8. THE ANTENNA MAY BE TO LOW. TRY RAISING ONE OR BOTH OF THE ANTENNAS. THE ANTENNA MAY BE MOUNTED IMPROPERLY OR BE IN A BAD LOCATION, SEE SECTION 6. YOU MAY HAVE A MARGINAL INSTALLATION. CHECK ANTENNA SETUP, E.G. LOCATION, HEIGHT AND GROUNDING. NOTE THAT A GOOD GROUND CONNECTION CAN DETERIORATE DUE TO CORROSION OR IMPROPER CABLE ATTACHMENT. THE ANTENNA IS NOT OPERATING EFFICIENTLY. VISUALLY INSPECT THE ANTENNA AND CABLE. MEASURE THE STANDING WAVE RATIO USING A SWR METER. NOTE: INEXPENSIVE METERS ARE AVAILABLE THAT MEASURE BOTH POWER AND SWR. 14

17 WARRANTY DEVAR INC. WARRANTS THIS PRODUCT AGAINST FAILURE AS A RESULT OF DEFECTS IN MATERIAL OR WORKMANSHIP FOR A PERIOD OF TWO YEARS. Should this product prove to be defective in material or workmanship during the warranty period, Devar Inc. will, at its discretion, repair or replace the defective item at no charge to the customer. Products that are damaged by accident, misuse, fire, water, lightning or other acts of nature are not covered under this warranty. Also not covered, is damage, due to shipping, installation, incorrect wiring or any other cause not related to a product defect. Unauthorized product modification, repair or attempted repair, or serial number modification will void the warranty. 15

18