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Summary of Contents for Lectrosonics UM250C
- Page 1 UM250C FREQUENCY-AGILE UHF BELT-PACK TRANSMITTER OPERATING INSTRUCTIONS and trouble-shooting guide LECTROSONICS, INC. Rio Rancho, NM www.lectrosonics.com...
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Page 2: Table Of Contents
TABLE OF CONTENTS INTRODUCTION ..................... 3 GENERAL TECHNICAL DESCRIPTION ............... 4 CONTROLS AND FUNCTIONS ................6 BATTERY INSTALLATION ..................8 OPERATING INSTRUCTIONS ................8 OPERATING NOTES ..................... 9 ADJUSTING THE TRANSMITTER FREQUENCY ..........9 MICROPHONE CORD TERMINATION ..............10 5-PIN INPUT JACK WIRING ................11 TROUBLESHOOTING .................. -
Page 3: Introduction
The design of the UM250C was the direct result of numerous conversations with users, staging and touring companies and dealers across the US. The specific concerns and needs brought up in these conversations led directly to the develop- ment of the operational features offered on the UM250C. -
Page 4: General Technical Description
+9VDC SHUNT TREBLE HP FILTER LIMITER DELAY Vreg +5VDC LIMIT Vreg PEAK AUDIO +3.6VDC INDICATOR & LIMITER DRIVER COMPANDED PRESCALER AUDIO DIVIDER VOLTAGE 50 CIRCULAR LOW PASS CONTROLLED ISOLATOR FREQ FILTER OSCILLATOR SWITCHES TRANSMITTER PHASE LOCKED LOOP UM250C Block Diagram... - Page 5 UHF Belt-Pack Transmitter NO PRE-EMPHASIS/DE-EMPHASIS The signal to noise ratio of the 200 system is high enough to preclude the need for conventional pre-emphasis (HF boost) in the transmitter and de-emphasis (HF roll off) in the receiver. Pre-emphasis and de-emphasis in an FM radio system usually provides about a 10dB improvement in the signal to noise ratio of the system, but the high frequency boost in the transmitter must be removed in a purely complementary manner or else the frequency response of the original audio signal will be altered.
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Page 6: Controls And Functions
LF ROLL OFF INPUT JACK The input on the UM250C accommodates virtually every lavalier, hand-held or shotgun microphone available. Line level signals can also be accommodated. Use a Switchcraft TA5F connector on the cord. See the separate sheet titled “Transmitter 5-Pin Input Jack Wiring” regarding the correct connections for various microphones, and other sources. - Page 7 USE ONLY THE SCREW THAT IS SUPPLIED The circuitry is tightly packed into this unit. A longer screw will permanently damage the transmitter! Use only Lectrosonics #28528 which is a Phillips head, 4-40 x 3/16", FL100 screw. Rio Rancho, NM – USA...
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Page 8: Battery Installation
BATTERY INSTALLATION The transmitter is powered by a standard alkaline or lithium 9 Volt battery. It is important that you use ONLY a LITHIUM battery for longest life. Standard zinc-carbon batteries marked “heavy-duty” or “long-lasting” are not ad- equate. Ni-cad rechargeable batteries will only provide a few minutes of operation, or less, and will run down quite abruptly. -
Page 9: Operating Notes
UHF Belt-Pack Transmitter 7) While speaking or singing at the same voice level that will actually be used, observe the MODULATION LEDs. Adjust the AUDIO LEVEL control knob until the LEDs begin to light. Start at a low setting where neither LED lights as you speak. -
Page 10: Microphone Cord Termination
MICROPHONE CORD TERMINATION TA5F Connector Assembly VIEW FROM SOLDER SIDE OF PINS 0.15" Heatshrink Tubing 0.3" Mic Cord Stripping Instructions Caution! Do not allow the shield wire to touch any metal part of the connector shell. The shield wire is the antenna on VHF models and poor operating range will result. -
Page 11: 5-Pin Input Jack Wiring
UHF Transmitter Equivalent Input Circuit VHF transmitters use the shield of the microphone cord as the antenna. The UM250C uses a 1/4 wave flexible wire to radiate the RF signal. There is really not much difference between these two approaches, with respect to the effect of the RF on the microphone capsule. -
Page 12: Line Level Signals
Leaded capacitors: P/N 15117 Leadless capacitors: P/N SCC330P All Lectrosonics lavalier mics are already bypassed and do not need any additional capacitors installed for proper operation. BODY GROUND Caution - When wiring the connector, do not use the connector body for any electrical connections. A common mistake is to use the connector body as an audio ground. -
Page 13: Troubleshooting
UHF Belt-Pack Transmitter TROUBLESHOOTING Before going through the following chart, be sure that you have a good battery in the transmitter. It is important that you follow these steps in the sequence listed. SYMPTOM POSSIBLE CAUSE TRANSMITTER BATTERY LED OFF 1) Battery is inserted backwards. -
Page 14: Service And Repair
There are no adjustments inside that will make a malfunctioning unit start working. LECTROSONICS service department is equipped and staffed to quickly repair your equipment. In-warranty repairs are made at no charge in accordance with the terms of the warranty. Out of warranty repairs are charged at a modest flat rate plus parts and shipping. -
Page 15: Specifications And Features
UHF Belt-Pack Transmitter SPECIFICATIONS AND FEATURES Operating frequencies: 537.600 to 588.700 MHz (blocks 21, 22) 614.400 to 793.500 MHz (blocks 24 thru 30) Frequency selection: 256 frequencies in 100kHz steps RF Power output: 250 mW Pilot tone: 32.764 kHz (± 2Hz); 5kHz deviation Frequency stability: ±... -
Page 16: Warranty
This warranty does not apply to used or demonstrator equipment. Should any defect develop, Lectrosonics, Inc. will, at our option, repair or replace any defective parts without charge for either parts or labor. If Lectrosonics, Inc. cannot correct the defect in your equipment, it will be replaced at no charge with a similar new item.
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