Lectrosonics UM450 User Manual
INSTRUCTION MANUAL
UM450
Frequency Synthesized 250 mW UHF Belt-Pack Transmitter
Featuring
Digital Hybrid Wireless™ Technology
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Rio Rancho, NM, USA
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UM450
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LECTROSONICS, INC.
Frequency Synthesized UHF Belt-Pack Transmitter
Table of Contents
General Technical Description ..............................................................................................................................................................4
Introduction ...........................................................................................................................................................................................4
Digital Hybrid Technology
UM450 Block Diagram ..........................................................................................................................................................................4
No Pre-Emphasis/De-Emphasis ...........................................................................................................................................................5
Pilot Tone Squelch ................................................................................................................................................................................5
Input Limiter ..........................................................................................................................................................................................5
Wide-Band Deviation ............................................................................................................................................................................5
Batteries, Battery Life and External Power ...........................................................................................................................................5
Frequency Selection .............................................................................................................................................................................5
Antenna.................................................................................................................................................................................................5
Controls and Functions .........................................................................................................................................................................6
Input Jack..............................................................................................................................................................................................6
Power ON/OFF Switch..........................................................................................................................................................................6
Power On LED ......................................................................................................................................................................................6
Audio Level Control...............................................................................................................................................................................6
Modulation LEDs...................................................................................................................................................................................7
Antenna.................................................................................................................................................................................................7
Frequency Select Switches...................................................................................................................................................................7
Adjustable Low Frequency Roll-Off.......................................................................................................................................................7
Belt Clip.................................................................................................................................................................................................7
Battery Installation .................................................................................................................................................................................8
Operating Instructions...........................................................................................................................................................................8
Selecting the Compatibility Mode..........................................................................................................................................................8
Attaching a Microphone and Adjusting Gain......................................................................................................................................... 9
Operating Notes.................................................................................................................................................................................... 9
Adjusting the Transmitter Frequency.....................................................................................................................................................9
5-Pin Input Jack Wiring ........................................................................................................................................................................10
Microphone Cord Termination.............................................................................................................................................................11
TA5F Connector Assembly .................................................................................................................................................................11
Mic Cord Stripping Instructions...........................................................................................................................................................11
Microphone RF Bypassing.................................................................................................................................................................. 12
Line Level Signals...................................................................................................................................................................................
Wiring Hookups for Different Sources ...............................................................................................................................................13
Works with Servo Inputs Only:............................................................................................................................................................ 13
Compatible with Servo Inputs and other Lectrosonics Transmitters:...................................................................................................13
Replacement Parts and Accessories..................................................................................................................................................14
UHF Transmitter Antenna Specifications ............................................................................................................................................14
Troubleshooting....................................................................................................................................................................................15
Specifications and Features................................................................................................................................................................ 17
Service and Repair ...............................................................................................................................................................................18
Returning Units for Repair ..................................................................................................................................................................18
.......................................................................................................................................................................................... 4
© Copyright 2007 Lectrosonics. Inc
Rio Rancho, NM
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UM450
General Technical Description
Introduction
The UM450 transmitter combines a full 250 mW of
RF output with +/- 75 kHz wide deviation for extended
operating range and extremely high signal to noise ratio.
These key design features are coupled with the compandor-free Digital Hybrid WirelessTM audio chain and
packaged in the widely recognized Lectrosonics standard transmitter housing.
The unit is powered by a single 9V battery in the internal compartment, or from external DC using the supplied ISO9VOLT battery eliminator. Rechargeable 9 V
batteries and charger are also included with the unit.
Digital Hybrid Technology
All wireless links suffer from channel noise to some degree, and all wireless microphone systems seek to minimize the impact of that noise on the desired signal. Conventional analog systems use compandors for enhanced
dynamic range, at the cost of subtle artifacts (known as
“pumping” and “breathing”). Wholly digital systems defeat
the noise by sending the audio information in digital form,
at the cost of some combination of power, bandwidth and
resistance to interference.US Patent 7,225,135
Lectrosonics Digital Hybrid Wireless™ systems overcome channel noise in a dramatically new way, digitally
encoding the audio in the transmitter and decoding it
UM450 Block Diagram
No Pre-Emphasis/De-Emphasis
in the receiver, yet still sending the encoded information via an analog FM wireless link. This proprietary
algorithm is not a digital implementation of an analog
compandor but a technique that can be accomplished
only in the digital domain, even though the inputs and
outputs are analog.
Channel noise still impacts received signal quality and
will eventually overwhelm a receiver. Digital Hybrid
Wireless™ simply encodes the signal to use a noisy
channel as efficiently and robustly as possible, yielding audio performance that rivals that of wholly digital
systems, without the power and bandwidth problems
inherent in digital transmission.
Because it uses an analog FM link, Digital Hybrid Wireless™ enjoys all the benefits of conventional FM wireless systems, such as excellent range, efficient use of
RF spectrum, and resistance to interference. However,
unlike conventional FM systems, it does away with the
analog compandor and its artifacts.
The Digital Hybrid Wireless™ design results in a signal-tonoise ratio high enough to preclude the need for conventional pre-emphasis (HF boost) in the transmitter and deemphasis (HF roll off) in the receiver. This eliminates the
potential for extreme distortion on signals with abundant
high-frequency information.
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LECTROSONICS, INC.
Frequency Synthesized UHF Belt-Pack Transmitter
Low Frequency Roll-Off
The low frequency roll-off at the 3 dB down point is variable from 35 to 150 Hz Hz to control subsonic and very
low frequency audio content in the audio. The actual
roll-off frequency will vary slightly depending upon the
low frequency response of the microphone.
Excessive low frequency content can drive the transmitter into limiting, or in the case of high level sound systems, can even cause damage to loudspeaker systems.
The roll-off is normally adjusted by ear while listening
as the system is operating.
Input Limiter
A DSP-controlled analog audio limiter is employed before
the analog-to-digital (A-D) converter. The limiter has a range
of more than 30 dB for excellent overload protection. A dual
release envelope makes the limiter acoustically transparent
while maintaining low distortion. It can be thought of as two
limiters in series, a fast attack and release limiter followed by
a slow attack and release limiter. The limiter recovers quickly
from brief transients, with no audible side effects, and also
recovers slowly from sustained high levels, to keep audio
distortion low and while preserving short term dynamics.
Signal Encoding and Pilot Tone
In addition to controlling the limiter, the DSP also encodes the digitized audio from the A-D converter and
adds an ultrasonic pilot tone to control the receiver’s
squelch. A pilot tone squelch system provides a reliable
method of keeping a receiver output muted (squelched)
even in the presence of significant interference. When
the system is operating in the hybrid mode, a different pilot tone frequency is generated for each carrier
frequency to prevent inadvertent squelch problems and
simplify multi-channel coordination.
Microprocessor, PLL and VCO Circuits
A microprocessor monitors user command inputs from
the control panel buttons and numerous other internal
signals. It works intimately with the DSP to ensure the
audio is encoded according to the selected Compatibility Mode and that the correct pilot tone is added to the
encoded signal.
Batteries, Battery Life and External Power
Multiple switching power supplies, a DSP and microprocessor, and the high output power all add up to significant power requirements for operation. For this reason,
high capacity rechargeable batteries with charger and
a battery eliminator are included with the transmitter to
provide useful options and ensure that the transmitter is
usable right out of the box.
The supplied rechargeable LiPolymer 9V batteries provide about 3.5 hours of operating time per charge.
Alkaline 9V batteries will run the transmitter for about
an hour and a half.
Dry cell Lithium batteries are not recommended for
use in the UM450. This type battery has an upper limit
on the maximum current it can provide. The UM450
exceeds this limit, so it will only run the transmitter for
about a half hour, or even less depending upon the age
and state of the battery.
The ISO9VOLT battery eliminator is included to allow
powering the UM450 from an external DC power source
for extended operating times.
Frequency Selection
The transmitter section uses a synthesized, frequency
selectable main oscillator. The frequency is extremely
stable over a wide temperature range and over time.
Two rotary switches, located on the side panel of the
unit, provide 256 frequencies in 100 kHz steps over a
25.5 MHz range. This alleviates carrier interference
problems in mobile or traveling applications.
Antenna
The antenna on the UM450 consists of a rugged 1/4
wavelength stranded and galvanized steel cable, detachable via an SMA connector. The impedance of this
connector is 50 Ohms.
Compatibility Modes
Digital Hybrid transmitters were designed to operate
with Lectrosonics Digital Hybrid receivers and will yield
the best performance when doing so. However, due to
the flexibility of digital signal processing, the transmitters can also operate in various compatibility modes
for use with Lectrosonics 200 Series, Lectrosonics 100
Series, IFB and certain non-Lectrosonics receivers.
Contact the Lectrosonics sales department for a complete list of compatible non-Lectrosonics receivers.
Rio Rancho, NM
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UM450
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Controls and Functions
Input Jack
Power LED
Power ON/OFF Switch
AUDIO LEVEL Control
Modulation LEDs
ANTENNA Jack
Input Jack
The input on the UM450 accommodates virtually every
lavaliere, hand-held or shotgun microphone available.
Different line level signals can also be accommodated.
(See Line Level Signals and Transmitter 5-Pin Input
Jack Wiring.)
Low Frequency Roll Off
Control
1.6M 100K
Frequency Select Switches
NOTE: While a NiMH battery provides long
operating time, it will give little or no warning when
depleted. If you use a NiMH battery in the UM450,
we recommend trying a fully charged battery in
the unit, noting the length of time that the battery
will run the unit and in the future use somewhat
less than that time to determine when the battery
needs to be replaced.
Power ON/OFF Switch
Turns the transmitter on and off. Even when the switch
is turned off or on abruptly, the pilot tone muting system
prevents “thumps” or transients from occurring.
Power On LED
The Power LED glows green when the battery is good
and the transmitter is turned on. The LED will glow
yellow/orange as the battery voltage drops and finally
glows red when there are about 30 minutes of operation
left (when using the recommended battery). The LED
blinks red when there are only a few minutes of life left.
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A weak battery will sometimes light the Power LED to
the “good” green indication immediately after being put
in the unit, but will quickly discharge to the point where
the LED will go red or shut down (just like a flashlight
with “dead” batteries). If the lamp fails to light, the battery should be replaced.
Audio Level Control
The front panel AUDIO LEVEL Control is used to adjust
the incoming audio input level for proper modulation.
LECTROSONICS, INC.
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