BST 75-216 OPERATOR’S MANUAL (216 MHz) Synthesized Base Station Transmitter 357 West 2700 South • Salt Lake City, Utah 84115 • Phone: (800) 496-3463 • Fax: (801) 484-6906 • www.comtek.
TABLE OF CONTENTS Introduction ........................................................... 1 Equipment Placement ............................................... 2 Power Requirements ....................................................... 2 Remote Antenna ...................................................... 3 Screw-in Whip Antenna ............................................ 3 Audio Input Connections ............................................... 4 Audio Adjustments ...........................
INTRODUCTION BST 75-216 Synthesized Base Station Transmitter T his transmitter may be used for personal listening applications such as cueing and IFB, wireless automatic tour information systems, language interpretation, and for assistive listening for people with hearing loss. The BST 75-216 mini base station transmitter meets the highest professional standards while offering outstanding value and the most advanced technology available.
OPERATING INSTRUCTIONS Equipment Placement If the BST 75-216 base station is to be rack mounted, a remote antenna must be used. The base station should be mounted away from equipment that uses large power transformers to reduce 60 Hz hum possibilities. Special Note: When using the base station in close proximity to other audio equipment, ensure that the audio equipment is not susceptible to RF interference.
OPERATING INSTRUCTIONS Remote Antenna When the BST 75-216 base station transmitter is to be rack mounted for permanent installation, a remote antenna must be used. For high performance application when greater coverage is required, the Phase-Right or Mini-Mite 1/2 wave omni antenna should be used. These antennas must be placed vertically polarized up to 15 feet away from the transmitter with the coaxial cable supplied. The highest possible antenna placement away from any metallic object is best.
OPERATING INSTRUCTIONS Audio Input Connections The BST 75-216 base station transmitter uses an XLR-3F connector with a “Combo” phone jack. The XLR portion of the connector will accept a true balanced or unbalanced line level signal up to +20 dBm. The 1/4” phone jack portion of the connector may be used for AUX output level audio or may directly phantom-power most two-conductor electret microphones.
OPERATING INSTRUCTIONS Audio Processing Circuit The audio processing system incorporates a peak-level compressor to prevent over-modulation and reduce audio distortion at high levels. This compressor has a very fast attack time and a carefully controlled decay time to optimize the dynamic performance of the audio processing system. (The VU meter will indicate this compressor action when the red LEDs are illuminated.
BST 75-216 FRONT PANEL 1 2 3 4 5 6 1 OPTIONAL ANTENNA: Used for mobile type applications. 2 POWER SWITCH: Turns the transmitter on or off. 3 POWER LED INDICATOR: Illuminates when the power is on. 4 VU METER: Displays the audio level being used for modulation. (See Audio Adjustment Section.) 5 ANTENNA INDICATOR: Detects antenna problems: bad, or incorrect antenna, and open coaxial cable. 6 RACK-MOUNTING SCREWS: Used for mounting BST 75-216 to rack-mounting panels.
BST 75-216 REAR PANEL 7 8 9 10 11 12 7 DC INPUT JACK: Requires 12V DC at 200 mA source. (Positive or negative center pin.) 8 CHANNEL SELECTOR SWITCH: Selects the frequency on which the transmitter will operate. (See Frequency Information Section.) 9 EXTERNAL ANTENNA JACK: BNC connector provides a standard 50 ohm RF output for use with an external antenna. 10 RF POWER SWITCH: Adjusts the RF power output of the transmitter (High-100 mW, Mid-50 mW, Low-25 mW).
BST 75-216 FREQUENCY INFORMATION AVAILABLE 216 MHz “FLASH MEMORY” COMPANDED CHANNELS USER-SWITCHABLE SELECTED CHANNELS (STANDARD PROGRAM) CHANNEL FREQUENCY SWITCH POSITION CHANNEL #1 #2 #3 #4 #5 #6 #7 #8 #9 #10 41-216.025 42-216.075 44-216.175 46-216.275 49-216.425 51-216.525 55-216.725 57-216.825 59-216.925 60-216.975 41 42 43 44 45 46 47 48 49 51 52 53 54 55 56 57 58 59 60 Position #1 216.0250 216.0750 216.1250 216.1750 216.2250 216.2750 216.3250 216.3750 216.4250 216.5250 216.5750 216.6250 216.
BST 75-216 FREQUENCY INFORMATION Multiple Channel Operation When multiple transmitters (more than two) are used in the same proximity, intermodulation interference can occur. This condition is common to all radio receivers to some extent when multiple transmitters are used in the same operating area. The RF signals will “MIX” together generating additional signals.
BST 75-216 ACCESSORIES Included Accessories 1. C-75 Carrying case 2. BST-75 Operator’s manual 3. SLW 75-216 Short loaded whip antenna 4. AP-12VAC Power adaptor (115V AC Input) 5.
BST 75-216 ACCESSORIES Optional Accessories 1. Mini-Mite 1/2 wave omni antenna 2. Phase-Right coaxial antenna 3. PRA Phase-Right antenna mount 4. HM-100 Behind-the-neck directional boom microphone with 1/4” phone jack plug 5. RMK 75-4 Quad rack-mount face plate 6. RMK 75-2 Double rack-mount face plate 7.
BST 75-216 SPECIFICATIONS Audio Inputs: • Line level balanced input 0 dBm for 80% modulation (+20 dBm max, XLR-3F) • Unbalanced input with bias voltage for electret microphone (-35 dBv at 5 K ohms. 1/4” mono plug) Connectors: • XLR-3F Combo with 1/4” phone jack • Barrel type 5.5mm X 2.1mm power jack DC • BNC type RF output Modulation Limiter: Peak compressor type with high linear overload protection (25 dB).
WARRANTY AND SERVICE Warranty COMTEK transmitters and receivers are warranted to be free from defects in workmanship and material under normal stand-alone use and conditions for a period of two years from date of original purchase. Items such as headphones and earphones, neckloops, and cords are warranted to be free from defects in workmanship and material for a period of 90 days from the date of original purchase. Batteries are not covered by this warranty.
357 West 2700 South • Salt Lake City, Utah 84115 • Phone: (800) 496-3463 • Fax: (801) 484-6906 • www.comtek.