Lectrosonics UH400A User manual

UH400A
UH400TM
Frequency Agile Plug-On UHF Transmitter
Featuring Digital Hybrid Wireless™ Technology
U.S. Patent Pending
INSTRUCTION MANUAL
Rio Rancho, NM, USA
www.lectrosonics.com
Fill in for your records:
Serial Number:
Purchase Date:

UH400A/UH400TM
LECTROSONICS, INC.2
Thank you for purchasing the UH400A plug-on transmitter. This is the latest version of a long history of plug-on
transmitter models that began in the late 1980’s, serving ENG applications at television stations across the USA. In
the mid-1990’s, the first UHF versions became available and the use of plug-on transmitters in motion picture produc-
tion increased significantly. The current UH400A model has evolved to include every improvement and feature devel-
oped since the first model was introduced.
The UH400A is a rugged, machined aluminum package. Selectable voltage phantom power is provided allowing the
UH400 to be used with the widest variety of microphones. LEDs located on the UH400A front panel make quick and
accurate level settings without having to view the receiver. The battery compartment accepts any 9 volt alkaline or
lithium battery and makes a positive connection via self-adjusting contacts.
The UH400TM is a specialized version of the UH400A that is an integral part of a highly responsive, wireless test and
measurement system.
Only the UH400A and UH400TM transmitters are covered in this manual. Companion receivers are covered in
separate manuals. The UH400A and UH400TM will operate with any 100 Series, 200 Series, 400 Series, IFB Lec-
trosonics receiver in the same frequency group, or selected analog receivers from other manufacturers operating in
the same frequency range. (Contact factory for details.)

Frequency Agile Plug-On UHF Transmitter
Rio Rancho, NM 3
Table of Contents
General Technical Description ..............................................................................................................................................................4
Introduction ...........................................................................................................................................................................................4
Digital Hybrid Technology .....................................................................................................................................................................4
Input Limiter ..........................................................................................................................................................................................5
No Pre-Emphasis/De-Emphasis ...........................................................................................................................................................5
Pilot Tone Squelch ................................................................................................................................................................................5
Wide-Band Deviation ............................................................................................................................................................................ 5
Long Battery Life ..................................................................................................................................................................................5
Frequency Agility .................................................................................................................................................................................. 5
Controls and Functions .........................................................................................................................................................................6
Power Switch ........................................................................................................................................................................................ 6
Power ON/OFF LED .............................................................................................................................................................................6
Phantom Power Voltage Select Switch .................................................................................................................................................6
Frequency Select Switches .................................................................................................................................................................. 7
Input Jack ............................................................................................................................................................................................. 7
Modulation LEDs .................................................................................................................................................................................. 7
Compatibility Mode Indicators .............................................................................................................................................................. 8
Mic Level .............................................................................................................................................................................................. 8
Frequency Blocks and Ranges .............................................................................................................................................................9
Operating Instructions ........................................................................................................................................................................10
Attaching the Microphone ...................................................................................................................................................................10
Mic Level Operating Tip ......................................................................................................................................................................10
Adjusting the Transmitter Frequency ..................................................................................................................................................11
Battery Replacement ..........................................................................................................................................................................11
Using the Polarity-Reversing Barrel Adapter ....................................................................................................................................12
Accessories ..........................................................................................................................................................................................12
Troubleshooting ...................................................................................................................................................................................13
Specifications and Features ...............................................................................................................................................................14
Service and Repair ...............................................................................................................................................................................15
Returning Units for Repair ..................................................................................................................................................................15
The UH400 transmitter is FCC type accepted under Part 74: 470 - 608MHz and 614 - 806MHz

UH400A/UH400TM
LECTROSONICS, INC.4
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 trans-
mitter 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 for
enhanced 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 combina-
tion of power, bandwidth and resistance to interference.
The Lectrosonics Digital Hybrid Wireless™system
(hereafter called Digital Hybrid) 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.)
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 con-
ventional FM systems, the Digital Hybrid has done away
with the analog compandor and its artifacts.
Transmitter
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
Switching
Power
Supply
+3.3v
+3.2v
+1.8v
+6v
-3v
50 Isolator
Hi/Lo
Pass
Filter
Audio
Encoded
Audio +
Pilot Tone
11.3 MHz
Reference
Bicolor
Power
LED
Audio
Level
Input
Amp
INPUT
JACK
+5V / +15V / +48V
BIAS SUPPLY
<-- (See Input Jack under Controls and Functions for details.)
UH400A Block Diagram

Frequency Agile Plug-On UHF Transmitter
Rio Rancho, NM 5
Input Limiter
The 400 series transmitters employ a digitally-controlled
analog audio limiter just before the analog-to-digital
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, connected as a fast attack and
release limiter followed by a slow attack and release
limiter. The limiter recovers quickly from brief tran-
sients, so that its action is hidden from the listener, but
recovers slowly from sustained high levels, to both keep
audio distortion low and preserve short term dynamic
changes.
The Modulation LEDs indicate limiter activity. When the
-20 LED glows red and the -10 LED glows green with
occasional red flickers, this indicates that the limiter is
active and that the transmitter is fully modulated (audio
level is between +0 and +10 dB). When the -10 LED
glows solid red, this indicates that the level is +10 dB or
more into limiting. Occasional forays by the -10 LED
into the red are desirable for most applications, since
the distortion introduced by the limiter is so minimal and
full modulation is thus assured. We strongly recom-
mend setting the audio level of the transmitter high
enough so that the -10 LED occasionally flickers red.
Generally speaking, some limiting is desirable in normal
operation to improve the signal to noise ratio of the
system. The limiting action is not audible and does not
create distortion. A highly trained ear would hear only
the compression of the peaks in the audio signal, which
is desirable with most recorders and many sound
reinforcement systems.
No Pre-Emphasis/De-Emphasis
The signal to noise ratio of the 400 system is high
enough to preclude the need for conventional pre-
emphasis (HF boost) in the transmitter and de-empha-
sis (HF roll off) in the receiver. Pre-emphasis and de-
emphasis in an FM radio system usually provides about
a 10 dB 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.
Pre-emphasis can also cause distortion in the receiver.
As this signal is passed through the IF filters in the
receiver, distortion can be produced, most noticeably at
full modulation. De-emphasis cannot be applied until
the signal is converted into audio, so there is no way
around this problem short of eliminating pre-emphasis
altogether. Neither of these problems occur in the 400
system
Pilot Tone Squelch
The 400 system uses one of 256 different ultrasonic
tones between 25 and 32 kHz, that modulate the carrier
to operate the receiver squelch. The pilot tone fre-
quency is chosen according to which of the 256
channels has been selected by the frequency switch
setting. The basic benefit of the pilot tone squelch
system is that the receiver will remain muted until it
receives the pilot tone from the matching transmitter,
even if a strong RF signal is present on the carrier
frequency of the system. The 400 Series insires that all
transmitters in a system have different pilot tone
frequencies so that even spurious RF from the wrong
transmitters can’t open the receiver squelch.
Wide-Band Deviation
A ± 75 kHz deviation improves the capture ratio, signal
to noise ratio and AM rejection of a wireless system
dramatically, compared to the more commonly used ±
15 kHz deviation.
Long Battery Life
Switching power supplies throughout the design allow
over 4.5 hours of operation using a single 9 Volt alkaline
battery. (A 9 Volt lithium battery will provide over 12
hours of operation.) The battery contacts are spring
loaded to prevent “rattle” as the unit is handled.
Frequency Agility
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.

UH400A/UH400TM
LECTROSONICS, INC.6
This transmitter may be used with a wide variety of
microphones. The 3-pin XLR connector allows the
transmitter to be used with any dynamic microphone, as
well as many two wire positive bias lavaliere systems
(such as those systems supplied by Lectrosonics).
Power Switch
The three position PWR OFF/PHTM/NO PHTM switch
turns the unit on or off, and selects either phantom
power, or no phantom power. Regardless of which
position the switch is set, the pilot tone muting system
effectively prevents “thumps” or transients from occur-
ring during power up or power down.
The PHTM (center) position of the power switch turns
on the phantom power value selected by the Phantom
Power Voltage Select switch, while the NO PHTM (fully
on) position disables phantom power.
Note: In order to avoid ddamage to some
microphones, be careful to use the center (PHTM)
position only when necessary and keep the
Phantom Power Voltage Select switch in the 5 V
position. (See Phantom Power Voltage Select
switch.)
Power ON/OFF LED
This LED glows green when the battery is good. When
the lamp glows red, there are about 30 minutes of
operation left with the recommended lithium battery, and
about 20 minutes of battery life left with an alkaline
battery. The lamp will flash red when there are only a
few minutes of life remaining in either type of battery.
Note: A NiMH battery will give little or no warning
when it is depleted. If you wish to use NiMH
batteries in this unit, we recommend installing a
fully charged batteries, noting the length of time
that the batteries will run the unit and in the future
use somewhat less than that time to determine
when the battery needs to be replaced.
A weak battery will sometimes light the POWER LED to
the “good” green indication immediately after being put
in the unit, but will soon discharge to the point where
the LED will go red or shut down (just like a flashlight
with “dead” batteries). If the Power LED fails to light
when power is applied, replace the battery.
Phantom Power Voltage Select Switch
Note: The UH400TM can be used with the
Earthworks M30 Test Microphone if pins 2 and 3
are reversed. A barrel adapter is provided for this
purpose.
This switch selects from three phantom voltages when
the PWR switch is in the mid position. The voltages are:
• 5 Volts for lavaliere microphones,
• 18 Volts for some professional mics requiring high
current and for many common stage mics that will
operate over a wide phantom Voltage range of 12 to
48 Volts. With the proper adapter, this position can
also be used with T power microphones. See our
web site for details on finding or making the proper
adapter.
• 42 Volts for microphones that do in fact require a
supply greater than 18 Volts. (See below for a
discussion of why 42 and not a “true” 48 Volts.)
For longest battery life use the minimum phantom
voltage necessary for the microphone. Many stage
microphones regulate the 48 Volts down to 10 Volts
internally anyway, so you might as well use the 18 Volt
setting and save some battery power. If you are not
using a microphone for the input device, or are using a
microphone that does not require phantom power, set
the Power Switch to the NO PHTM position (No Phan-
tom Power). This is the fully up position of the Power
Switch. Phantom power should only be used with a fully
floating, balanced device such as most microphones
with a 3-pin XLR connector. If you use the phantom
power with an unbalanced device or if pins 2 or 3 are
DC connected to ground, then you will draw maximum
current from the power supply. The UH400A is fully
protected against such shorts but the 9 Volt battery will
be drained at twice its normal rate.
Controls and Functions
Top View Control Panel
–20
–10
POWER
ON/OFF
LED
PWR OFF
LEVEL
PHTM
NO PHTM 5V
18V
48V
MIC LEVEL
PHANTOM POWER
VOLTAGE SELECT
(RECESSED)
POWER
SWITCH
0
1
2
3
4
5
6
7
8
9
A
B
C
D
E
F
FREQUENCY
1.6MHz 100kHz
0
1
2
3
4
5
6
7
8
9
A
B
C
D
E
F
Side View
FREQUENCY SWITCHES
(BEHIND DOOR)
INPUT
JACK
INPUT
JACK
MODULATION LEDs

Frequency Agile Plug-On UHF Transmitter
Rio Rancho, NM 7
The transmitter can supply 4 mA at 42 Volts, 8 mA at 15
Volts, and 8 mA at 5 Volts. The 42 Volts setting actually
supplies the same voltage to a 48 Volt microphone as
the DIN standard arrangement due to a dynamic
biasing scheme that does not have as much voltage
drop as the DIN standard. The 48 Volt DIN standard
arrangement protects against shorts and high fault
current with high resistance in the power supply feeds
to pins 2 and 3. This protects the supply if the supply
current is accidentally shorted to ground and also keeps
the microphone from being attenuated by the power
supply. The UH400A improves on those functions and is
able to use less power from the battery by using
constant current sources and current limiters. With this
dynamic arrangement the UH400A can also supply
more than twice the current of competing 48 Volt plug
on units and provide four times the current to some very
high end 18 Volt microphones.
The 5 Volt setting is provided for lavaliere microphones
made by us and others. Do not power lavalieres from
the 15 or 48 Volt setting as the microphone will be most
likely destroyed. Lectrosonics makes an adapter,
MCA5X, that will adapt our standard TA5F 5 pin micro-
phones to the UH400A. This adapter also provides
protection against excessive phantom voltage. If
voltages higher than 5 Volts are applied to the adapter,
a Zener diode will shunt excess voltage to ground. The
microphone won't work until the voltage is correctly
reduced to 5 Volts. If you have an older lavaliere mic
that was wired directly to an XLR for use with the earlier
UH200's, we strongly recommend building our protec-
tion circuit into the XLR to prevent accidental destruc-
tion of the lavaliere.
Frequency Select Switches
Two 16 position rotary switches adjust the center
frequency of the carrier within the transmitter’s fre-
quency block and for setting Compatibility Modes.
The 1.6 MHz is a coarse adjustment and the 100 kHz is
the fine adjustment. Each transmitter is factory aligned
at the center of its operating range. The default position
of the frequency select switches is in the center of the
transmitter’s range.
Input Jack
Standard 3-pin Switchcraft XLR type. Pin 2 is signal,
pin 3 is a floating signal ground, and pin 1 is case
ground (see schematic below). The UH400A is
self-locking onto a standard microphone.
Note: If severe noise is experienced when the
microphone is moved with respect to the UH400A,
the cause is an unbalanced condition between
pins 2 and 3 of the microphone.
Modulation LEDs
The Modulation LEDs
indicate the proper setting
of the MIC LEVEL control.
There are two bicolor
modulation LEDs that can
light either red or green
depending on the amount
of gain applied. The
transmitter should be set
so that both LEDs glow
green, with the -20 LED
occasionally blinking red.
Frequency Select Switches
Left Switch
1.6 MHz
Right Switch
100 kHz
Top View
–10
–20
MODULATION LEDs
1
2
3
+5V / +18V / +48V
4.7uf
1uh
1uh
1uh
To Mic
Preamp
1000 I
100 pf
511
1000
Input Jack Schematic
Signal Level -20 LED -10 LED
Less than -20 dB Off Off
-20 dB to -10 dB Green Off
-10 dB to +0 dB Green Green
+0 dB to +10 dB Red Green
Greater than +10 db Red Red

UH400A/UH400TM
LECTROSONICS, INC.8
Control Panel
PWR OFF
LEVEL
PHTM
NO PHTM 5V
15V
48 V
MIC LEVEL
Compatibility Mode Indicators
The Modulation LEDS will blink when power is first
applied to the transmitter to indicate the selected
operating mode. Immediately after, all LEDS will blink
together red, then green, followed by the Modulation
LEDs (-20 and -10) blinking to indicate the operating
mode.
The –20 and –10 LEDs will blink:
• Once for 100 Series mode
• Two times for 200 Series mode
• Three times for mode 3
(Contact Factory for Details)
• Four times for 400 Series mode
• Five times for IFB Series mode
• Six times for mode 6
(Contact Factory for Details)
Mic Level
Used to adjust the audio input level for the proper
modulation.
Top View
–10
–20
POWER
ON/OFF
LED
MODULATION LEDs

Frequency Agile Plug-On UHF Transmitter
Rio Rancho, NM 9
Each UH400A transmitter is built to cover a pre-se-
lected range of frequencies (a “block”). The transmitter
will tune to any of 256 different frequencies within this
factory assigned block. (See Operating Frequencies
(MHz).)
The block number is determined by this formula:
25.6 × Freq. (MHz) = Lowest freq. (MHz) in the
block
To determine a block number from a frequency:
Freq. (MHz) divided by 25.6 = Block number
It is handy to remember these formulas, in case you do
not have a copy of the table. For example, suppose you
need to know which block covers 685.500 MHz, without
using the table:
685.500 divided by 25.6 = 26.77734375
The first two digits left of the decimal are the block
number. In this case, 685.500 MHz falls within block 26.
Part of block 23 is not used since it covers a 608 to 614
MHz band that is illegal for use with wireless micro-
phones.
Operating Frequencies (MHz):
Block 21 537.600 - 563.100
Block 22 563.200 - 588.700
Block 23 588.8 00- 607.900;
614.100 - 614.300
Block 24 614.400 - 639.900
Block 25 640.000 - 665.500
Block 26 665.600 - 691.100
Block 27 691.200 - 716.700
Block 28 716.800 - 742.300
Block 29 742.400 - 767.900
Block 30 768.000 - 793.500 (export only)
Frequency Blocks and Ranges
Use the two Frequency Switches to set the transmitter’s
carrier frequency to match the associated receiver. For
example, assume that the transmitter and receiver are
both assigned Block 25 and the receiver’s switches are
set to 658.400 MHz.
Subtract the lowest frequency for Block 25 from the
assigned frequency to determine the switch settings for
the transmitter.
658.400
-640.000
18.400
Divide the result by 1.6 and round down the nearest two
digits to determine the coarse Frequency Switch
setting.
18.4/1.6 = 11.5 or 11 (B on the switch dial)
Multiply the coarse Frequency Switch setting by 1.6 and
subtract that number from the original result to deter-
mine the setting for the fine Frequency Switch.
11 x 1.6 = 17.6
18.400
- 17.600
.800 or 8
Therefore, the Frequency Switch settings for this
transmitter would be B8.

UH400A/UH400TM
LECTROSONICS, INC.10
TO ATTACH
TO REMOVE
Pull on mic to insure locking.
Press firmly, listen for click.
Depress collar fully.
Hold the
transmitter
case and
rotate the
collar in the
direction
shown. Do
this over a
soft surface
as the
microphone
may pop off
suddenly
Click!
Operating Instructions
Attaching the Microphone
1. Insert the UH400A into the XLR connector on the
bottom of the selected microphone. Listen for the
“click” that indicates the transmitter assembly has
locked on to the microphone. Gently pull on the mic
to insure proper locking has occurred.
2. If necessary, set the phantom power voltage for the
mic. If the mic does not require phantom voltage,
set the Phantom Power Voltage Select switch to 5
VDC to reduce the possibility of damage to the mic
when the transmitter is powered up.
3. Set the MIC LEVEL control to minimum (fully
counterclockwise).
4. Turn on the transmitter by setting the Power Switch
to PHTM, if the mic requires phantom power, or to
NO PHTM, if the mic does not require phantom
power. (Refer to the specifications for the mic you
are using to determine if phantom power is re-
quired.)
5. Hold the mic as you will when you will be using it, or
if the mic will be stationary, such as attached to a
lectern or mic stand and speak or sing into it at the
same voice level that will be actually used during
the program.
5. Start with the Mic LEVEL control at maximum
counterclockwise, then observe the front panel
Modulation LEDs. Slowly turning the Audio LEVEL
control clockwise while talking into the mic at the
same level that will be used during the program.
Increase the Mic LEVEL control until the -20 LED
glows red and the -10 dB glows green with occa-
sionally red flickers. This indicates full modulation.
6. Once the gain has been adjusted, the remainder of
the audio sound system can be energized and
adjusted.
Mic Level Operating Tip
The LEVEL control should not be used to control the
volume of your sound system or recorder levels. The
LEVEL control matches the transmitter gain with the
user’s voice level and mic’s position.
If the audio level is too high — both red LEDs will
glow solid red. This condition may reduce the
dynamic range of the audio signal.
If the audio level is too low — neither LED will glow,
or only the –20 LED will glow green. This condition
may cause hiss and noise in the audio.
Different voices will usually require different settings of
the LEVEL control, so check this adjustment as each
new person uses the system. If several different people
will be using the transmitter and there is not time to
make the adjustment for each individual, adjust it for the
loudest voice.
Selecting the Compatibility Mode
This unit is capable of working with Lectrosonics 400
series digital hybrid receivers, 200 Series, 100 Series
and IFB analog receivers. It is also capable of working
with analog wireless receivers from other manufacturers
(contact the factory for details). The transmitter can be
easily set to the compatibility mode of the matching
receiver using the supplied screwdriver.
Note: The UH400A is supplied from the factory as
a 400 series transmitter
1. Ensure the battery is good. If the Power LED lights
up when the Power Switch is set to PHTM or NO
PHTM, the battery is good and correctly installed.
2. Turn off the transmitter.
Control Panel
PWR OFF
LEVEL
PHTM
NO PHTM 5V
15V
48 V
PHANTOM POWER
VOLTAGE SELECT
POWER
SWITCH

Frequency Agile Plug-On UHF Transmitter
Rio Rancho, NM 11
3. With a small screwdriver (included with your unit),
set the frequency change switches to CC. (for
Change, Change). To gain access to these
switches, slide the access door open with a finger-
nail.
4. Set the Power Switch to NO PHTM briefly – just a
couple of seconds for the front panel LED’s to light
up, then immediately turn the unit off.
5. Change the Frequency Select switches to one of
the following settings:
MODE SWITCH SETTINGS
100 Series 1,1
200 Series 2,2
Mode 3 (Other analog*) 3,3
400 Series (Digital Hybrid) 4,4
IFB Mode 5,5
Mode 6* 6,6
*Contact factory for details.
6. Turn the transmitter on, when the front panel LEDs
light up, immediately turn the unit off.
7. Change the switches to 0,0.
8. Energize the transmitter and verify the new compatibil-
ity mode. The front panel -20 and -10 LEDs will blink:
• Once for 100 Series mode
• Two times for 200 Series mode
• Three times for mode 3 (contact factory)
• Four times for 400 Series mode
•Five times for IFB mode
• Six times for mode 6 (contact factory)
The Compatibility Mode will remain set until changed
with the above procedure.
Adjusting the Transmitter Frequency
If you are experiencing interference from another signal
on your frequency, you may want to change the operat-
ing frequency of your system. This is done with the
Frequency Switches.
The left switch changes the operating frequency by 1.6
MHz per step and the right switch changes it 100 kHz
per step. If you are experiencing interference, change
the operating frequency in 100 kHz steps to find a clear
channel. If it is not possible to find a clear channel
using the 100 kHz switch, return it to its original position
and change the 1.6 MHz switch by one click then try the
100 kHz switch again.
Battery Replacement
The UH400A transmitter is powered by a standard
alkaline 9 volt battery. It is important that you use ONLY
ALKALINE OR LITHIUM batteries for longest life.
Standard zinc-carbon batteries marked “heavy duty” or
“long-lasting” are not adequate. They will provide only
about five minutes of operation. Similarly, ni-cad
rechargeable batteries only give one hour of operation,
and will also run down quite abruptly. Alkaline batteries
provide about 4.5 hours of operation while lithium
batteries will run the unit for about 12 hours.
To open the battery compartment, press upward on the
cover door in the direction of the arrow as shown in the
drawing. Only slight, sliding pressure is needed to open
and close the battery door.
Swing the door open and take note of the location of
the positive (+) and negative (-) terminals. Insert the
new battery correctly and close the cover by reversing
the opening procedure. Note that the battery door will
NOT close if the battery is inserted incorrectly, since the
terminals will hit a protective polarity barrier. Don’t force
the battery door closed. If it is difficult to close, the
battery is in backwards.
The battery life will be affected by the amount of
phantom power supplied to any microphones that
require it. A high drain 48 volt microphone can shorten
battery life by 40% or more. A light drain 18 volt micro-
phone will make little or no difference in battery life. The
only way to be sure is to test the transmitter and
microphone combination with a brand new battery.
CAUTION : Lithium batteries will expand and
swell if allowed to go into a deep discharge.
Be sure to remove them as soon as the battery
is depleted. Stuck lithium batteries can be
avoided by removing the label wrapping
around the battery before use. This will allow
the battery to swell but will still leave enough
room in the compartment for the battery to fall
out normally.
Battery Compartment Action
SWING OPEN
RELEASE
DOOR
OBSERVE
POLARITY
Frequency Select switches
Left Switch
1.6 MHz
Right Switch
100 kHz
012
3
4
5
6
7
8
9
A
B
C
D
EF012
3
4
5
6
7
8
9
A
B
C
D
EF

UH400A/UH400TM
LECTROSONICS, INC.12
Part #21750
Accessories
PHTRAN2
MC5AX
PHTRAN2
Cordura Pouch with belt clip and velcro flap.
MC5AX
TA5 to XLR adapter for connecting a lavaliere
microphone to the UH400.
Using the Polarity-
Reversing Barrel Adapter
The UH400TM transmitter comes with a
polarity-reversing XLR barrel adapter for
use with Earthworks M30 measurement
microphones. Simply connect the
adapter between the transmitter
and microphone.
Earthworks M30
Barrel Adapter
UH400TM

Frequency Agile Plug-On UHF Transmitter
Rio Rancho, NM 13
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.
2. Battery is dead.
No Transmitter Modulation LEDs 1. Gain control turned all the way down.
2. Battery is in backwards. Check power LED.
3. Mic capsule is damaged or malfunctioning.
4. Mic cable damaged or mis-wired.
5. Phantom power not enabled for mic that requires it.
Receiver RF Lamp Off 1. Transmitter not turned on.
2. Transmitter battery is dead.
3. Receiver antenna missing or improperly positioned.
4. Transmitter and receiver not on same frequency.
Check switches/display on transmitter and receiver.
5. Operating range is too great.
No Sound (or Low Sound Level), Receiver Mod Level LEDs Are On
1. Receiver output level set too low.
2. Receiver output is disconnected; cable is defective or mis-wired.
3. Sound system input is turned down.
No Sound (or Low Sound Level), Receiver Mod Level LEDs Are Off
1. Transmitter gain (audio level) set too low.
2. Faulty microphone
3. Phantom power not enabled for mic that requires it.
4. Not enough current to power microphone. (Earthworks M30 is
only known microphone we’ve found to exhibit this issue.)
DISTORTED SOUND 1. Transmitter gain (audio level) is far too high. Check mod level
lamps on transmitter and receiver as it is being used. (Refer to
the Operating Instructions section for details on gain adjustment)
2. Receiver output may be mismatched with the sound system or
recorder input. Adjust output level on receiver to the correct level
for the recorder, mixer or sound system.
3. Excessive wind noise or breath “pops.” Reposition microphone
and/or use a larger windscreen.
4. Transmitter is not set to same frequency as receiver. Check that
frequency select switches on receiver and transmitter match.
HISS AND NOISE – AUDIBLE DROPOUTS 1. Transmitter gain (audio level) far too low.
2. Receiver antenna missing or obstructed.
3. Operating range too great.
EXCESSIVE FEEDBACK 1. Transmitter gain (audio level) too high causing the limiter to
reduce the dynamic range which in turn causes feedback.
Check gain adjustment and/or reduce receiver output level.
(Refer to the Operating Instructions section for details on gain
adjustment)
2. Transmitter too close to speaker system.
3. Mic is too far from user’s mouth.

UH400A/UH400TM
LECTROSONICS, INC.14
Operating frequencies: 537.600 to 607.900 MHz; 614.100 to 793.500 MHz
Frequency selection: 256 frequencies in 100 kHz steps
RF Power output: 100 mW (nominal)
Pilot tone: 25 to 32 kHz; 5 kHz deviation (in 400 Series mode)
Frequency stability: ± 0.002%
Deviation: ± 75 kHz max. (in 400 Series mode)
Spurious radiation: 60 dB below carrier
Equivalent input noise: –118 dBV, A-weighted
Input level: Nominal 2 mV to 300 mV, before limiting; Greater than 1.0 V maximum, with limiting.
Input impedance: 1 k Ohm
Phantom power: Selectable; 5, 18, 48 VDC
Input limiter: Soft limiter, >30 dB range
Gain control range: 43 dB; semi-log rotary control
Modulation indicators: Dual bicolor LEDs indicate modulation of –20, -10, 0 and +10 dB referenced to full modulation.
Low frequency roll-off: –12 dB/octave; 70 Hz (35 Hz for UH400TM)
Controls: Control panel knob adjusts audio gain.
Rotary switches on bottom panel adjust transmitter frequency.
Audio Frequency Response: 90 Hz to 20 kHz, +/-1 dB (40 Hz to 20 kHz, +/- 1 db for UH400TM)
Note: The audio is deliberately rolled off at 70Hz using a 12 dB/octave filter on the UH400A. This filter cannot be disabled.
Signal to Noise Ratio (dB):
Note: The dual envelope “soft” limiter provides
exceptionally good handling of transients using
variable attack and release time constants.
Once activated, the limiter compresses 30+ dB
of transmitter input range into 4.5 dB of receiver output range, thus reducing the measured figure for SNR without limiting by 4.5 dB
Total Harmonic Distortion: 0.2% typical (400 Series mode)
Antenna: Built-in
Battery Type: 9V alkaline or lithium
Battery Life: 4.5 Hours with alkaline 9 Volt, 12 hrs with lithium
(Battery life will vary with battery brand, phantom power voltage setting and mic current drain.)
Weight: 6.5 oz. with lithium battery, no mic
Overall Dimensions: 1.5 x 1.5 x 4.2 inches (Not including microphone.)
Emission Designator: 190KF3E
Specifications subject to change without notice.
The FCC requires that the following statement be included in this manual:
This device complies with FCC radiation exposure limits as set forth for an uncontrolled environment. This device
should be installed and operated so that its antenna(s) are not co-located or operating in conjunction with any other
antenna or transmitter.
Specifications and Features
SmartNR No Limiting w/Limiting
OFF 103.5 108.5
NORMAL 107.0 111.5
FULL 108.5 113.0

Frequency Agile Plug-On UHF Transmitter
Rio Rancho, NM 15
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 the interconnect-
ing cables and then go through the Troubleshooting section in this manual.
We strongly recommend that you do not try to repair the equipment yourself and do not have the local repair shop
attempt anything other than the simplest repair. If the repair is more complicated than a broken wire or loose connec-
tion, send the unit to the factory for repair and service. Don’t attempt to adjust any controls inside the units. Once set
at the factory, the various controls and trimmers do not drift with age or vibration and never require readjustment.
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. Since it takes almost as much time and effort to determine what is wrong as it does
to make the repair, there is a charge for an exact quotation. We will be happy to quote approximate charges by phone
for out-of-warranty repairs.
Returning Units for Repair
For timely service, please follow the steps below:
A. DO NOT return equipment to the factory for repair without first contacting us by letter or by phone. We need to
know the nature of the problem, the model number and the serial number of the equipment. We also need a
phone number where you can be reached 8 A.M. to 4 P.M. (U.S. Mountain Standard Time).
B. After receiving your request, we will issue you a return authorization number (R.A.). This number will help speed
your repair through our receiving and repair departments. The return authorization number must be clearly shown
on the outside of the shipping container.
C. Pack the equipment carefully and ship to us, shipping costs prepaid. If necessary, we can provide you with the
proper packing materials. UPS is usually the best way to ship the units. Heavy units should be “double-boxed” for
safe transport.
D. We also strongly recommend that you insure the equipment, since we cannot be responsible for loss of or dam-
age to equipment that you ship. Of course, we insure the equipment when we ship it back to you.
Mailing address: Shipping address: Telephone:
Lectrosonics, Inc. Lectrosonics, Inc. [phone]
PO Box 15900 581 Laser Rd. [phone] Toll-free
Rio Rancho, NM 87174 Rio Rancho, NM 87124 [phone] Fax
USA USA
Web: E-mail:
www.lectrosonics.com [email protected]

March 30, 2006
581 Laser Road NE • Rio Rancho, NM 87124 USA • www.lectrosonics.com
[phone] • [phone] • fax [phone]• [e-mail]
LIMITED ONE YEAR WARRANTY
The equipment iswarranted for one year from date of purchase against defectsin
materialsor workmanship provided it was purchased from an authorized dealer. This
warranty doesnot cover equipment which has been abused or damaged by careless
handling or shipping. Thiswarranty doesnot apply to used or demonstrator equipment.
Should any defect develop, Lectrosonics, Inc. will, at our option, repair or replace any
defective partswithout charge for either partsor labor. If Lectrosonics, Inc. cannot
correct the defect in your equipment, it will be replaced at no charge with asimilar new
item. Lectrosonics, Inc. will pay for the cost of returning your equipment to you.
Thiswarranty appliesonly to itemsreturned to Lectrosonics, Inc. or an authorized
dealer, shipping costsprepaid, within one year from the date of purchase.
ThisLimited Warranty isgoverned by the lawsof the State of New Mexico. It statesthe
entire liablility of LectrosonicsInc. and the entire remedy of the purchaser for any
breach of warranty as outlined above. NEITHER LECTROSONICS, INC. NOR
ANYONE INVOLVED IN THE PRODUCTION OR DELIVERY OF THE EQUIPMENT
SHALL BE LIABLE FOR ANY INDIRECT, SPECIAL, PUNITIVE, CONSEQUENTIAL,
OR INCIDENTAL DAMAGESARISING OUT OF THE USE OR INABILITY TO USE
THISEQUIPMENT EVEN IF LECTROSONICS, INC. HASBEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES. IN NO EVENT SHALL THE LIABILITY OF
LECTROSONICS, INC. EXCEED THE PURCHASE PRICE OF ANY DEFECTIVE
EQUIPMENT.
Thiswarranty givesyouspecific legal rights. Youmay have additional legal rightswhich
vary from state to state.