FREEWAY ATW-251 Owner's manual

200 Series Owners Manual v.1
7-6-06
Page 1 of 9
ATW-251 UniPak™ System
ATW-251/G Guitar System
ATW-251/H Headworn Microphone System
ATW-251/L Lavalier Microphone System
ATW-252 Handheld Microphone System
This device complies with part 15 of the FCC Rules. Operation is subject to the condition that this device
does not cause harmful interference.
This device complies with INDUSTRY CANADA R.S.S. 210, en conformité avec IC: RSS-210/CNR210.
Operation is subject to the following conditions: 1) This device may not cause harmful interference and 2)
this device must accept any interference received, including interference which may cause undesired
operation.
CAUTION! Electrical shock can result from removal of the receiver cover. Refer servicing to qualified service
personnel. No user-serviceable parts inside. Do not expose to rain or moisture.
The circuits inside the receiver and transmitter have been precisely adjusted for optimum performance and
compliance with federal regulations. Do not attempt to open the receiver or transmitter. To do so will void the
warranty, and may cause improper operation.
Notice to individuals with implanted cardiac pacemakers or AICD devices:
Any source of RF (radio frequency) energy may interfere with normal functioning of the implanted device. All
wireless microphones have low-power transmitters (less than 0.05 watts output) which are unlikely to cause
difficulty, especially if they are at least a few inches away. However, since a “body-pack” mic transmitter
typically is placed against the body, we suggest attaching it at the belt, rather than in a shirt pocket where it
may be immediately adjacent to the medical device. Note also that any medical-device disruption will cease
when the RF transmitting source is turned off. Please contact your physician or medical-device provider if
you have any questions, or experience any problems with the use of this or any other RF equipment.

200 Series Owners Manual v.1
7-6-06
Page 2 of 9
Introduction
Thank you for choosing an Audio-Technica professional wireless system. You
have joined thousands of other satisfied customers who have chosen our
products because of their quality, performance and reliability. This wireless
microphone system is the successful result of years of design and manufacturing
experience.
Each 200 Series professional VHF wireless system includes a receiver and either
a body-pack transmitter or a handheld microphone/transmitter on a specific
crystal-controlled frequency. ATW-251 UniPak™ body-pack transmitter systems
include models pre-packaged with either an AT-GCW guitar cable (/G), a PRO
8HEcW headworn microphone (/H), or a lavalier mic (/L) for particular
applications. All A-T Wireless Essentials™ microphones and cables, available
separately, are pre-terminated for use with any ATW-251 system.
Because 200 Series packaging is designed to hold all versions of the system,
some compartments in the carton are intentionally left empty.
The ATW-R250 receiver includes a space-saving switching power supply that
automatically adapts to changes in mains voltage. Unlike bulky linear power
supplies, this switching power supply is lightweight and compact; it uses only a
single outlet space.
The versatile ATW-T201 UniPak body-pack transmitter has both a high-
impedance input for instruments, and a low-impedance input with bias
connection for use with dynamic and electret condenser microphones. The ATW-
T202 handheld transmitter features a unidirectional dynamic microphone
element.
Both the body-pack and handheld transmitters use internal 9-volt batteries and
have Off/Standby/On switches, input Trim (level) adjustments and battery-save
switches.
Receiver Installation
Location
For best operation the receiver should be at least 3' (1 m) above the ground and
at least 3' (1 m) away from a wall or metal surface to minimize reflections. Keep
the receiver antennas away from noise sources such as digital equipment,
motors, automobiles and neon lights, as well as away from large metal objects. In
multi-channel systems, position receivers at least 3' (1 m) apart and keep
operating transmitters at least 6' (2 m) from the receivers to help assure
maximum RF performance.
Output Connection
The receiver provides unbalanced, aux-level output from a 1/4" TS (“mono”)
phone jack; an output cable is not included. Use a shielded audio cable with 1/4"

200 Series Owners Manual v.1
7-6-06
Page 3 of 9
phone plug to connect the receiver’s AF Out jack to the mixer/amplifier’s aux-
level input.
Power Connection
Connect the DC plug on the included AC power adapter to the DC power input
on the back of the receiver. Secure the cord over the cord hook on the back of
the receiver, to keep the plug from being detached by an accidental tug on the
cord. Then plug the adapter into a standard 120 Volt 60 Hz AC power outlet.
(Note that the receiver has no power Off/On switch. The receiver will be
energized whenever the power adapter is connected and plugged into the AC
outlet. Unplug the power supply from the AC outlet when the system is not in use
– both for safety, and to conserve energy.)
Antennas
A novel “dipole” antenna system on the receiver improves operation by providing
a “ground” element in addition to the usual “signal” element. Position the two
antennas at 90° in the form of a “V,” or position the left (“signal”) antenna
vertically and the right (“ground”) antenna horizontally, in the shape of an “L” (Fig.
B). Use the position that performs better in your operating environment. Be
certain to extend both antennas to their full 15" (38 cm) length by holding them at
their bases and pulling out on their caps. Both antenna elements may be
swiveled to the left and right, but do not attempt to rotate them in a
screwing/unscrewing motion. To do so may damage the antenna and/or receiver.
For best performance, locate the receiver so its antennas are in direct line-of-
sight to the transmitter’s likely operating position.
Receiver Controls and Functions
Front Panel Controls and Functions (Fig. C)
1. ANTENNAS: Position the “signal” antenna (1a) and “ground” antenna (1b) as
shown in Figure B.
2. POWER INDICATOR: Lights when power is supplied to the receiver.
3. RF INDICATOR: Lights to show presence of transmitter signal.
4. AF PEAK INDICATOR: Only lights when audio distortion is present at
maximum modulation. Not affected by position of Volume control.
Rear Panel Controls and Functions (Fig. D)
5. VOLUME CONTROL: Adjusts the audio level at the 1/4" output jack. Does not
affect AF Peak indicator.
6. DC POWER INPUT: Connect the provided docking power adapter, or other
12V DC source. (Receiver requires 200 mA.)

200 Series Owners Manual v.1
7-6-06
Page 4 of 9
7. AUDIO OUTPUT JACK: 1/4" TS (Tip-Sleeve) or “mono” phone jack. Use a
shielded cable to connect to an unbalanced aux-level input of a mixer or
amplifier.
8. CORD HOOK: Loop the cord around the cord hook to keep the DC plug from
pulling out accidentally.
Transmitter Setup
Battery Selection and Installation
An alkaline 9-volt battery is recommended. Make certain the transmitter power
switch is Off before installing or changing batteries.
When inserting the battery, observe correct polarity as marked inside the battery
compartment. The transmitter housings are designed to prevent incorrect
installation of the battery; do not force the battery in. Reversed batteries may
cause damage to the transmitter.
UniPak™ Transmitter Battery Installation
1. Slide off the battery cover as shown in Figure E.
2. Carefully insert a fresh 9V alkaline battery, observing polarity markings.
3. Replace the battery cover (Fig. F).
Handheld Transmitter Battery Installation
1. While holding the upper part of the transmitter body just below the ball-screen,
unscrew the lower body cover and slide it downward to expose the battery
compartment (Fig. G). Do not attempt to pull the lower body farther down, or to
gain access to the electronics.
2. Lift the white “battery keeper” arm until it sticks straight out from the mic body
(no higher). Then carefully insert a fresh 9V alkaline battery, observing polarity
markings.
3. Screw the body back together. Do not overtighten.
Battery Condition Indicator
The red battery condition indicator (Fig. I/J) should light strongly with a fresh
battery. As the battery weakens, the indicator will grow dimmer. When the
indicator becomes very dim or goes out, there is little life left in the battery.
Replace it at once for continued operation of the transmitter.
All transmitters feature battery-save switches (Fig. E/G). As supplied, the switch
is set in the High position for maximum range. Switching to the Low position

200 Series Owners Manual v.1
7-6-06
Page 5 of 9
increases battery life by reducing power. (Note: Effective range decreases when
the switch is set in Low position.)
UniPak™ Transmitter Input Connection
Connect an audio input device (microphone or guitar cable) to the input
connector on the bottom of the transmitter. The cable connector latches
automatically when inserted into the transmitter jack. To unlatch and remove the
connector, simply pull up on the connector’s knurled metal collar.
A number of Audio-Technica professional microphones and cables are available
separately, pre-terminated with a UniPak input connector (see “Optional System
Accessories” on page __
Transmitting Antenna
The UniPak transmitter includes a permanently attached flexible antenna. For
best results, allow the antenna to hang freely and full length from the bottom of
the transmitter. If the received signal is marginal, experiment with different
transmitter positions on your body or instrument; or try repositioning the receiver.
Do not attempt to remove, replace or change the length of the transmitting
antenna.
System Operation
Turn down the receiver volume control and the mixer/amplifier level before
starting up the wireless system. Do not switch on the transmitter yet.
Receiver on...
Plug the power supply into an AC power source. The green Power indicator on
the front panel will light.
Transmitter on...
When the transmitter is switched on, the receiver’s yellow RF signal indicator will
light. The transmitters have a 3-position power switch. When the switch is set to
“Standby” (ST or ST.BY), the transmitter produces RF with no audio signal.
When the switch is “On,” the transmitter produces both RF and audio. Excessive
audio input to the transmitter will cause the receiver’s red AF Peak indicator to
light.
Receiver Volume
Under typical operating conditions, the receiver's volume control should be
turned all the way up, with overall system audio gain adjusted at the mixer or
amplifier.
Input Level Adjustment

200 Series Owners Manual v.1
7-6-06
Page 6 of 9
Input trimmer controls in the transmitters enable you to maximize performance
for a particular microphone or guitar sensitivity, or to adjust for different acoustic
input levels.
Adjusting Input Level - UniPak Transmitter
Slide the battery cover off the top part of transmitter and remove the screwdriver
from its clip (Fig. E). Gently turn both the “MT” (Mic Trimmer) and “GT” (Guitar
Trimmer) controls to their full counterclockwise positions (toward “LO”).
• Microphone: Adjusting input level
Gently turn only the “MT” (Mic Trimmer) control all the way up (clockwise, toward
“Hi”). Check for excessive gain by speaking/singing into the microphone at
typically-loud levels while watching the receiver’s AF Peak indicator. If the AF
Peak indicator does light, turn the MT control slightly counterclockwise until the
AF Peak indicator no longer lights with maximum audio input to the transmitter.
• Guitar/Instrument: Adjusting input level
Gently turn only the “GT” (Guitar Trimmer) control all the way up (clockwise,
toward “Hi”). Check for excessive gain by playing at typically-loud levels while
watching the receiver’s AF Peak indicator. If the AF Peak indicator does light,
turn the GT control slightly counterclockwise until the AF Peak indicator no longer
lights with maximum instrument input to the transmitter. After adjusting input
level, return the screwdriver to its clip and reinstall the battery cover. No further
transmitter gain adjustments should be needed, as long as the input device and
the acoustic input level are not changed.
Adjusting Input Level - Handheld Transmitter
Unscrew the lower body cover and slide it downward, exposing the screwdriver
and Gain Trimmer control (Fig. H). Remove the screwdriver from its clip. Gently
turn the control to its full clockwise position (toward the side marked “H”), the
factory setting. Check for excessive gain by speaking/singing into the
microphone at typically-loud levels while watching the receiver’s AF Peak
indicator. If the AF Peak indicator does light, turn the Gain Trimmer control
slightly counterclockwise until the AF Peak indicator no longer lights with
maximum audio input to the mic/transmitter.
Return the screwdriver to its clip and close and secure the lower body. No further
transmitter gain adjustments should be needed, as long as the acoustic input
does not change significantly.
CAUTION! The small trimmer controls are delicate; use only the supplied
screwdriver. Do not force the trimmers beyond their normal 190o range of
rotation.
Return the screwdriver to its storage clip when not in use.

200 Series Owners Manual v.1
7-6-06
Page 7 of 9
Tips To Obtain the Best Results
1. Use only fresh alkaline batteries. Do not use “general purpose” (carbon-zinc)
batteries.
2. Position the receiver so that it has the fewest possible obstructions between it
and the normal location of the transmitter. Line-of-sight is best.
3. The transmitter and the receiver should be as close together as conveniently
possible, but not less than 6' (2 m).
4. Do not place the receiver antennas within 3' (1 m) of another receiver or
antenna.
5. The receiver antennas should be kept away from any metal.
6. A receiver cannot receive signals from two transmitters at the same time.
7. In the UniPak transmitter, the “MT” or “GT” input control not in use should be
set to minimum.
8. If the receiver output is set too low, the overall signal-to-noise ratio of the
system may be reduced. Conversely, if the volume control of the receiver is set
too high, it may over-drive the input of the mixer/amplifier, causing distortion.
Adjust the output level of the receiver so the highest sound pressure level going
into the microphone (or the loudest instrument playing level) causes no input
overload in the mixer, and yet permits the mixer level controls to operate in their
“normal” range (not set too high or too low). This provides the optimum signal-to-
noise for the entire system.
9. Turn the transmitter off when not in use. Remove the battery if the transmitter
is not to be used for a period of time.
10. Unplug the receiver from the AC outlet when the system is not in use.
System Operating Frequencies
Frequency Selection
Each transmitter/receiver system operates on a single factory aligned, crystal-
controlled frequency. Available frequencies are shown in the chart below.
Operating frequency is specified by a two character code, such as “T2,” in
addition to the actual frequency in MHz. The frequency of each transmitter
appears on a label on the outside of the unit. The frequency of each receiver
appears on a label on the rear panel of the unit and the frequency of each
system appears on the outer carton. For future reference, please record them in
the space provided below.
RF Interference
Please note that wireless frequencies are shared with other radio services.
According to Federal Communications Commission regulations, “Wireless
microphone operations are unprotected from interference from other licensed
operations within the band. If any interference is received by any Government or
non-Government operation, the wireless microphone must cease operation...”
If you need assistance with operation or frequency selection, please contact your
dealer or the A-T professional division.

200 Series Owners Manual v.1
7-6-06
Page 8 of 9
Extensive wireless information also is available on the A-T Web site at
www.audio-technica.com.
Application Freq. Code Freq. (MHz)
• Traveling frequencies: T2 169.505
(Normally work anywhere in the U.S.A. and T3 170.245
Canada.) T8 171.905
Systems on these frequencies may be combined for up to three simultaneous operating channels.
For future reference, please record your system information here (the serial numbers appear near the
screwdriver clip in each transmitter, and on the bottom of each receiver):
Operating Frequency
Freq. Code ______ ________ Frequency • MHz _ _ _ ._ _ _
Receiver
Model ATW-R250 Serial Number _ _ _ _ _ _ _
Transmitter
Model ATW-T20 _______ Serial Number _ _ _ _ _ _ _
½
Specifications†
OVERALL SYSTEM
RECEIVER
UNIPAK™ TRANSMITTER
HANDHELD TRANSMITTER
† In the interest of standards development, A.T.U.S. offers full details on its test methods to other industry
professionals on request.
Optional System Accessories
WIRELESS ESSENTIALS™ MICROPHONES AND CABLES
All Wireless Essentials accessories are terminated for use with ATW-T201 and other UniPak™ transmitters.
AT829cW Miniature cardioid condenser lavalier microphone. Includes clothing clip and windscreen.
Provided with ATW-201/L systems.
MT830cW Subminiature omnidirectional condenser lavalier microphone. Includes clothing clip and
windscreen.
MT830cW-TH “Theater” model, same as MT830cW except beige color mic and cable for concealment.
AT831cW Miniature cardioid condenser lavalier microphone. Includes clothing clip and windscreen.
AT851cW Surface-mount wide-range hemi-cardioid condenser microphone.
AT857AMLcW 19" gooseneck cardioid microphone. Mounts to 5/8"-27 thread. Includes windscreen.
AT889cW Headworn noise-canceling condenser microphone. Includes windscreen and cable clip.
ATM35cW Cardioid condenser instrument microphone. Includes AT8418 clip-on instrument mount.
ATM73cW Headworn cardioid condenser microphone. Includes windscreen.
ATM75cW Headworn cardioid condenser microphone. Includes windscreen.
PRO8HEcW Headworn hypercardioid dynamic microphone. Includes windscreen and cable clip.
Provided withATW-201/H systems.
PRO35xcW Cardioid condenser instrument microphone. Includes AT8418 clip-on instrument mount.
AT-GCW Hi-Z instrument/guitar cable with 1/4" phone plug. Provided with ATW-201/G systems.
XLRW Connecting cable for UniPak transmitter with an XLRF-type input connector, for Lo-Z
microphones with XLRM-type output terminations.
OTHER ACCESSORIES
AT8114 Foam windscreen for handheld transmitter.
AT8141 Water-resistant pouch for UniPak transmitter.

200 Series Owners Manual v.1
7-6-06
Page 9 of 9
AT8390 Shielded audio cable with 1/4" to 1/4" phone plugs. Available in a variety of lengths. (Also
available with one straight and one 90° phone plug as the AT8316.)
AT8456a Stand clamp for handheld transmitter, 5/8"-27 threads.
ATW-VP10 Vinyl pouch with belt clip to hold UniPak transmitter.
Receiver Power Supply
Antennas
Receiver Controls and Functions
Transmitter Controls and Functions