The March ST L-20C Transmitter with companion R-15C Receiver, form a high quality, frequency synthesized, point-to-point, line of sight, radio communications link. This system is available in the frequency band from 940 MHz to 965 MHz and will soon be available in all STL bands from 140 MHz and up.
WARNING THIS EQUIPMENT MUST BE OPERATED WITH A 3-PRONG GROUNDED OUTLET RECEPTACLE. FAILURE TO USE A PROPERLY GROUNDED OUTLET MAY RESULT IN IMPROPER OPERATION OR SAFETY HAZARD! LIMITED WARRANTY The Seller warrants that, at the time of shipment, the products manufactured by the Seller are free from defects in material and workmanship.
IMPORTANT NOTICE This equipment must be operated in a well-ventilated rack cabinet. Install rack-mounted equipment in a well-ventilated, well-grounded, and shielded rack cabinet. Do not locate solid-state equipment in a rack above tube-type equipment which produces high temperatures. Problems can also be avoided by locating this unit away from other equipment which has transformers that produce strong magnetic fields. These fields can induce hum and noise into the March equipment thus reducing performance.
Transmitter connections for Monophonic operation (Refer to Drawing 702-096) 1. Monophonic program audio output is connected to balanced audio input screw terminals. Use shielded wire, Program audio level required is +8 dBm, 600 ohms balanced and isolated from ground. For dual channel stereo repeat instructions at second transmitter. Audio processing requirements will be discussed in the “OPERATION”. section of this manual. 2.
The following suggestions are offered to help those responsible for antenna installations avoid costly errors in assembly and adjustment. March Electronics, Inc. assumes no responsibility for the installation and performance of antenna systems associated with its equipment.
transmitter is supplying power to it. The SWERVE should be less than 1.5 to 1 IF THE ANTENNA SYSTEM FAILS TO GIVE THE PREDICTED SIGNAL STRENGTH LEVEL, THE FOLLOWING ITEMS SHOULD BE CHECKED: . Check for correct assembly of antenna. . Check that antennas have same polarity. . Check orientation of antennas in both horizontal and vertical directions, 4.. Check SWERVE of both transmit and receive antennas, SWERVE should be less that . Check Fresnel zone clearance along radio path. .
OPERATION QUICK START Simply plug in the STL20C (here is no prows switch, The front panel meter ght will immediately come on. Within § seconds the AFC LOCK LED will begin flashing indicating has the synthesizer is In the process of locking on a frequency. Also, if the TRANSMIT switch is on, the red TRANSMIT LED will flush in unison with the AFC LOCK LED. Dining power up, the synthesizer will always lock on the frequency it was docked on when the 5TL-20C was inst powered up.
YU" on the meter corresponding to a axiom rated power output, LED Indicators {front panel) 1. AFC LOCK light « A solid green LED light is illuminated when the synthesizer VCO is locked an the desired output Frequency. If unlocked, or in the process of being locked the AFC LOCK LED flashes green. RF power output is inhibited until APC Lock is achieved. Initial power-up of the transmitter may require several seconds to achieve AFC Lock. 2.
below. 100% modulation when running frequency Teaspoon tests to prevent over modulation at the higher audio frequencies. With a: fl-quieting BF signal into the receiver, flat per-emphasis will produce a system signal-to-noise ratio approximately & 48 less than 78 se per-eophasls, Received signal levels less than full dieting may produce 3 difference of os much 2s 13 8 between flat and 75 ps per-emphasis, Power Adjust Pot Rotating the POWER ADJUST pot clockwise will sereneness the output power.
RF EXPOSURE WARNING This studio to apposition Hag unit (STL) contains a radio frequency (RF) transmigrate. During normal operation HU sends opt radio Incumbency (RF) sips.
The ST L-20C transmitter, R-15C receiver with the associated antenna system can be tested and compared with factory test date included in this manual The following procedures should be followed in order to obtain reliable and accurate results. Before audio tests or sub carrier tests are begun check the receiver “SIG. LEVEL" METER for required minimum signal. A conversion from VU to micro volts is given under OPERATION in the R-15 receiver manual. For a 950 MHz.
100% modulation at 400 Hz., then attenuate this level 20 dB. Set receiver output level to -10 dBm as the reference, then sweep the audio band for response. Response should be within the Limits sifted in SYSTEM SPECIFICATIONS. 14 COMPOSITE (STEREO) SEPARATION, NOISE, DISTORTION AND FREQUENCY RESPONSE.
SENDING AN INSTRUCTION Refer to drawing §97-6020-2. This section outlines how to send an instruction to the T/R SYNTHESIZER, The controls for sending an instruction all reside on the SYNTHESIZER CONTROL BOARD (800-377), These controls consist of three 8-pint dip switches labeled S1, 82, and $3, and one push button switch labeled $4. For the STL.
