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- UM250C
- Operating Instructions And Troubleshooting Manual
Lectrosonics UM250C Operating Instructions And Troubleshooting Manual
Summary of UM250C
Page 1
Um250c frequency-agile uhf belt-pack transmitter lectrosonics, inc. Rio rancho, nm www.Lectrosonics.Com operating instructions and trouble-shooting guide.
Page 2
2 the um250b transmitter is fcc type accepted under part 74: 470-608mhz and 614-806mhz table of contents introduction ..................................................................................................... 3 general technical description ...................................................
Page 3: Introduction
3 uhf belt-pack transmitter rio rancho, nm – usa introduction thank you for selecting the lectrosonics um250c frequency agile, belt-pack trans- mitter. The um250c combines over 80 years of engineering experience with the very latest components, in a design that addresses the most demanding professio...
Page 4
4 um250c block diagram general technical description the transmitter is comprised of a number of functional sub-systems as shown in the block diagram below. General the 200 series uses 75khz wide deviation for an extremely high signal to noise ratio. The transmitter circuits are all regulated to all...
Page 5
5 uhf belt-pack transmitter rio rancho, nm – usa 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 f...
Page 6: Controls and Functions
6 controls and functions 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”...
Page 7
7 uhf belt-pack transmitter rio rancho, nm – usa modulation leds indicate the proper setting of the mic level control. “-20” led -- flickers or glows when sufficient audio is present. “0” led -- lights up when the input level is high enough to cause limiting. The input limiter has a very high overlo...
Page 8: Battery Installation
8 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 p...
Page 9: Operating Notes
9 uhf belt-pack transmitter rio rancho, nm – usa 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. Gradually, t...
Page 10: Microphone Cord Termination
10 microphone cord termination 1 2 3 4 5 view from solder side of pins 0.3" 0.15" heatshrink tubing ta5f connector assembly 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 oper...
Page 11: 5-Pin Input Jack Wiring
11 uhf belt-pack transmitter rio rancho, nm – usa transmitter input jack 4 3 2 1 5 lectrosonics 1uh 10k 1k 5 100 4 3 2 1 330pf 330pf + 5v mic bias 5ma max to mic amp pos bias (or gnd) mic source load line in neg gnd (or bias) uhf transmitter equivalent input circuit 5-pin input jack wiring the wirin...
Page 12
12 rf bypassing some mics require rf protection to keep the radio signal from affecting the capsule, even though the transmitter input circuitry is already rf bypassed (see schematic diagram). If the mic is wired as directed, and you are having difficulty with squealing, high noise, or poor frequenc...
Page 13: Troubleshooting
13 uhf belt-pack transmitter rio rancho, nm – usa 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 in...
Page 14: Service and Repair
14 service and repair if your system malfunctions, you should attempt to correct or isolate the trouble before concluding that the equipment needs repair. Make sure you have followed the setup procedure and operating instructions. Check out the intercon- necting cords and then go through the trouble...
Page 15: Specifications and Features
15 uhf belt-pack transmitter rio rancho, nm – usa 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 dev...
Page 16: Limited One Year Warranty
Limited one year warranty the equipment is warranted for one year from date of purchase against defects in materials or workmanship provided it was purchased from an authorized dealer. This warranty does not cover equipment which has been abused or damaged by careless handling or shipping. This warr...