Lectrosonics UM400 User Manual
INSTRUCTION MANUAL
UM400
Frequency-Agile UHF Belt-Pack Transmitter
Featuring
Digital Hybrid Wireless™ Technology
(US Patent Pending)
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Purchase Date:
Rio Rancho, NM, USA
www.lectrosonics.com
UM400
2
LECTROSONICS, INC.
Frequency-Agile UHF Belt-Pack Transmitter
Thank you for selecting the Lectrosonics UM400 frequency agile, belt-pack transmitter. The UM400 combines over 80 years of engineering experience with the
very latest components, in a design that addresses the
most demanding professional applications.
The design of the UM400 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 development of the operational
features offered on the UM400. Two hundred fifty six
frequencies are user selectable in 100kHz steps to alleviate interference problems in traveling venues, and
the low frequency roll-off is user adjustable to adapt to
varying acoustic environments and preferences.
The UM400 is a rugged, machined aluminum package with a removable, spring loaded belt clip. The
input section provides a correct input tap for virtually
any microphone or line level audio source. Five volts
of bias voltage is available to power electret mics with
either positive or negative bias. Level indicating LEDs
are provided on the control panel to make level settings
quick and accurate, without having to view the receiver.
The battery compartment accepts any 9 Volt alkaline
battery and makes a positive connection via self-adjusting contacts. The antenna is a detachable, locking 1/4
wavelength flexible galvanized steel cable that connects
to a 50 Ohm SMA port on the transmitter.
Only the UM400 transmitter is covered in this manual.
Companion receivers are covered in separate manuals.
The UM400 will operate with any 400 Series Lectrosonics receiver and a variety of analog receivers in the
same frequency group.
Rio Rancho, NM
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UM400
4
LECTROSONICS, INC.
Frequency-Agile UHF Belt-Pack Transmitter
Table of Contents
General Technical Description ..............................................................................................................................................................6
Introduction ...........................................................................................................................................................................................6
Digital Hybrid Technology .....................................................................................................................................................................6
UM400 Block Diagram ..........................................................................................................................................................................6
No Pre-Emphasis/De-Emphasis ...........................................................................................................................................................7
Pilot Tone Squelch ................................................................................................................................................................................7
Input Limiter ..........................................................................................................................................................................................7
Wide-Band Deviation ............................................................................................................................................................................7
Long Battery life....................................................................................................................................................................................7
Frequency Agility...................................................................................................................................................................................7
Antenna.................................................................................................................................................................................................7
Controls and Functions .........................................................................................................................................................................8
Input Jack..............................................................................................................................................................................................8
Power ON/OFF Switch..........................................................................................................................................................................8
Power On LED ......................................................................................................................................................................................8
Audio Level Control...............................................................................................................................................................................8
Audio Level ...........................................................................................................................................................................................8
Modulation LEDs...................................................................................................................................................................................9
Antenna.................................................................................................................................................................................................9
Frequency Select Switches...................................................................................................................................................................9
Adjustable Low Frequency Roll-Off.......................................................................................................................................................9
Belt Clip.................................................................................................................................................................................................9
Battery Installation ...............................................................................................................................................................................10
Operating Instructions.........................................................................................................................................................................10
Selecting the Compatibility Mode........................................................................................................................................................10
Attaching a Microphone and Adjusting Gain....................................................................................................................................... 11
Operating Notes.................................................................................................................................................................................. 11
Adjusting the Transmitter Frequency...................................................................................................................................................11
Microphone Cord Termination.............................................................................................................................................................12
TA5F Connector Assembly .................................................................................................................................................................12
Mic Cord Stripping Instructions...........................................................................................................................................................12
5-Pin Input Jack Wiring ........................................................................................................................................................................13
Input Jack Wiring Diagram ..................................................................................................................................................................13
RF Bypassing......................................................................................................................................................................................13
Line Level Signals............................................................................................................................................................................... 14
Wiring Hookups for Different Sources ...............................................................................................................................................15
Replacement Parts and Accessories..................................................................................................................................................16
UHF Transmitter Antenna Specifications ............................................................................................................................................16
Troubleshooting....................................................................................................................................................................................17
Specifications and Features................................................................................................................................................................ 18
Service and Repair ...............................................................................................................................................................................19
Returning Units for Repair ..................................................................................................................................................................19
Rio Rancho, NM
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UM400
+5V Bias
Phase Locked Loop
Voltage
Controlled
Oscillator
Freq
Switches
11001001
A-D
Converter
Digital Signal Processor
11001001
D-A
Converter
Shunt
Limiter
Bicolor
Modulation
LEDs
Microprocessor
9V
Battery
Switching
Power
Supply
+3.3v
+1.8v
+9v
-3v
Hi/Lo
Pass
Filter
Audio
Encoded
Audio +
Pilot Tone
4MHz
Reference
Bicolor
Power
LED
Mic
Jack
Supply
Audio
Level
Input
Amp
5
4
3
2
1
Final
Amplifier
50
Isolator
LF
Roll Off
General Technical Description
Introduction
The 400 system uses 75 kHz wide deviation for an extremely high signal to noise ratio. The switching power
supplies provide constant voltages to the transmitter
circuits from the beginning (9.3 Volts) to the end (5.5
Volts) of battery life. The input amplifier uses an ultra
low noise op amp for quiet operation. It is gain controlled with a wide range dual envelope input compressor which cleanly limits input signal peaks over 30 dB
above full modulation.
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
to improve the signal to noise ratio, 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.
The Lectrosonics Digital Hybrid system overcomes
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 information via an analog FM wireless link. This proprietary
algorithm is not a digital implementation of an analog
compandor but a technique which can be accomplished
only in the digital domain, even though the inputs and
outputs are analog signals. (As of this writing, the patent is still pending, so we cannot reveal detailed information about the algorithm at this time.)
Channel noise still has an impact on received signal
quality and will eventually overwhelm the receiver. The
Digital Hybrid 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. As always, these
advantages come at a cost. The Digital Hybrid system
requires fairly intensive digital processing in both the
transmitter and the receiver. These processors cost
money, take up space and consume power. The Digital
Hybrid system also requires that the underlying RF link
be of excellent quality, with better frequency response
and distortion characteristics than that required by conventional systems.
Because it uses an analog FM link, the Digital Hybrid
enjoys all the benefits of conventional FM wireless
systems, such as excellent range, efficient use of RF
spectrum, and long battery life. However, unlike conventional FM systems, the Digital Hybrid has done away
with the analog compandor and its artifacts.
UM400 Block Diagram
<--See 5-Pin Input Jack Wiring for details.
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LECTROSONICS, INC.
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