Lectrosonics UM400A-26, UM400A-21, UM400A-22 User manual
INSTRUCTION MANUAL
UM400a
Frequency Synthesized 100 mW UHF Belt-Pack Transmitter
Featuring
Digital Hybrid Wireless™ Technology
U.S. Patent 7,225,235
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Rio Rancho, NM, USA
www.lectrosonics.com
UM400a
2
LECTROSONICS, INC.
Frequency Synthesized UHF Belt-Pack Transmitter
Table of Contents
General Technical Description ..............................................................................................................................................................4
Introduction ...........................................................................................................................................................................................4
Digital Hybrid Technology......................................................................................................................................................................4
UM400a Block Diagram ........................................................................................................................................................................4
No Pre-Emphasis/De-Emphasis ...........................................................................................................................................................5
Pilot Tone Squelch ................................................................................................................................................................................5
Input Limiter ..........................................................................................................................................................................................5
Wide-Band Deviation ............................................................................................................................................................................5
Frequency Selection .............................................................................................................................................................................5
Controls and Functions .........................................................................................................................................................................6
Input Jack ..............................................................................................................................................................................................6
Power ON/OFF Switch .......................................................................................................................................................................... 6
Power On LED ......................................................................................................................................................................................6
Frequency Select Switches ...................................................................................................................................................................6
Audio Level Control ...............................................................................................................................................................................7
Modulation LEDs ...................................................................................................................................................................................7
Antenna .................................................................................................................................................................................................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 Cable Terminationfor Non-Lectrosonics Microphones ................................................................................................11
TA5F Connector Assembly .................................................................................................................................................................11
Mic Cord Stripping Instructions ........................................................................................................................................................... 11
Crimping to Shield and Insulation .......................................................................................................................................................11
Microphone RF Bypassing ..................................................................................................................................................................12
Line Level Signals ...............................................................................................................................................................................12
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
© Copyright 2008 Lectrosonics. Inc
Rio Rancho, NM
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UM400a
General Technical Description
Introduction
The UM400a transmitter combines 100 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 Wireless® 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 a Lectrosonics ISO9VOLT battery eliminator.
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
in the receiver, yet still sending the encoded informa-
tion 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.
No Pre-Emphasis/De-Emphasis
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.
UM400a Block Diagram
Bicolor
Modulation
LEDs
Phase Locked Loop
4MHz
Reference
Freq
Switches
A-D
Converter
11001001
Digital Signal Processor
Microprocessor
D-A
Converter
11001001
Voltage
Controlled
Oscillator
Encoded
Audio +
Pilot Tone
9V
Battery
Final
Amplifier
Switching
Power
Supply
Isolator
50
Bicolor
Power
LED
+3.3v
+3.2v
+1.8
+9v
+5v
-3v
v
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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.
Control Panel
The control panel includes four membrane switches and
an LCD screen to adjust the operational settings. Multicolor LEDs are used to indicate audio signal levels for
accurate gain adjustment and for battery status.
Wide-Band Deviation
±75 kHz deviation improves the signal to noise ratio and
audio dynamic range of a wireless system dramatically,
compared to other designs that use ±30 kHz to 40 kHz
deviation. Wide deviation combined with a high powered
transmitters makes a significant improvement in signal
to noise ratio and operating range.
Battery Options and Operating Time
Switching power supplies convert regulated battery
voltages to operate various circuit stages with maximum efficiency. With the variety of alkaline, lithium and
rechargeable batteries available today in the 9V format,
there are many choices to maximize operating time or
minimize cost as needed for any application.
Frequency Blocks
Lectrosonics established a “block” numbering system
years ago to organize the range of frequencies available from the low 500 MHz band to the upper 700
MHz band. Each block includes 256 frequencies in 100
kHz increments. The block number is part of a simple
formula to derive the frequency. The block number is
multiplied by 25.6 to produce the lowest frequency in
the block. For example, block 27 x 25.6 = 691.200.
Circulator/Isolator
The RF output circuit includes a one way circulator/isolator
using a magnetically polarized ferrite. This device greatly
reduces the RF intermodulation produced when multiple
transmitters are used in close proximity to one another
(several feet apart). The isolator also provides additional
RF output stage protection.
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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UM400a
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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 UM400a accommodates virtually every
lavaliere, hand-held or shotgun microphone available.
Different line level signals can also be accommodated.
(See Wiring Hookups for Different Sources.)
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.
Low Frequency Roll Off
Control
1.6 . . . . . . . . 100K
Frequency Select Switches
NOTE: While a NiMH battery provides long
operating time, it will give little or no warning
before it is depleted. If you use a NiMH battery in
the UM400a, we recommend trying a fully charged
battery in the unit, noting the length of time that it
will run the unit, and in the future use somewhat
less than that time to determine when the battery
needs to be replaced. Digital Hybrid receivers
include timers to accurate track battery usage.
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.
Frequency Select Switches
Two 16-position rotary switches adjust the center
frequency of the carrier. The left-hand switch 1.6 MHz
steps and the right-hand switch makes 100K steps.
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LECTROSONICS, INC.
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