Comtek PR-75a User manual

OPERATOR’S MANUAL
357 West 2700 South • Salt Lake City, Utah 84115 • Phone: [phone] • Fax: [phone] • www.comtek.com
PR-75a
AutoSmart-TuningTM
Assistive Listening
Receiver

© 2004 COMTEK®All rights reserved.
Print Release Date 01-18-2007
WARNING: MODIFICATION OF THIS DEVICE
TO RECEIVE CELLULAR RADIOTELEPHONE
SERVICE SIGNALS IS PROHIBITED UNDER
FCC RULES AND FEDERAL LAW.
TABLE OF CONTENTS
Introduction ...........................................................
Controls and Indicators ...............................................
Setup and Operation .......................................................
Optional Accessories ............................................
Frequency Information ..........................................
Battery Information ...............................................
Belt Clip Removal and Installation ........................
Specifications .........................................................
Warranty and Service ...............................................
1
2
3-4
5
6-7
8-9
10
11
12

INTRODUCTION
Page 1
The PR-75a personal receiver is the newest generation of user-friendly,
high fidelity monitor receivers for
auditory assistance and other personal
communication applications. When
turned on, this unique receiver will
automatically tune itself to the closest
transmitter. If other transmissions
need to be monitored, a manual,
AutoSmart-TuningTM (AST) control
will cause the receiver to seek any
on-channel group frequency
transmission in the 72-76 MHz band.
PR-75a
AutoSmart-TuningTM
Assistive Listening
Receiver

PR-75a CONTROLS AND INDICATORS
Page 2
PR-75a Controls
nBATTERY COMPARTMENT:
The battery compartment
features a hinged battery cover
and a polarity protection design
to ensure that only proper
battery polarity can occur.
oAUDIO OUTPUT JACK:
This stereo/mono audio
output jack accommodates
any low impedance headphone;
also functions as automatic on/off
power switch when headphone is
plugged in and as rechargeable battery
charging access.
pVOLUME CONTROL:
This control has 50 dB of range to adjust the audio
output for a comfortable listening level
(clockwise for maximum level).
qPOWER / RECEIVER STATUS INDICATOR:
LED indicator will display these four functions:
a. Fast blinking ----- Seeking channel
b. Continuous -------Receiving signal
c. Steady slow flash -------- No signal
d. Rapid flash ------ Low battery
Additionally there is an audible
beeping to indicate a low battery.
rAutoSmart-TuningTM PUSHBUTTON:
This one-button tuning control (AST)
allows the receiver to seek other channels
within the frequency group to which it is tuned.
sDATA I/O PORT:
For channel programming or specialty channel sequencing.

Setup
a. Open the battery door on the receiver (see page 8) and insert two 1.5 V AA
alkaline batteries (Eveready E91 or equivalent). This type of battery will offer
up to 100 hours of operation. If a rechargeable battery is to be used, ensure
thatithasbeenallowedtochargeatleasttwelve hours to bring ittofull
charge (seepage9forbatterychargerinstructions).
The use of carbon batteries is not recommended.
b. Ensure that there is a signal on the air on a channel from A-J
(see frequency chart page 6). The PR-75a receiver must be within 150 feet
ofthe transmitter for best reception.
c. Plugging the earphone into the “Auto-On” output jack on the top of the
PR-75a receiver will automatically turn on the receiver and initiate the
AutoSmart-TuningTM process. (The LED will blink very rapidly during this
process.) The receiver will then tune itself to the closest on-air transmitter in
its vicinity. Based on the first channel found, the receiver will thendetermine
the channel group to which it belongs for multiple channel operation.
(The LED will illuminate continuously when a signal is being received.)
Pushing the AutoSmart-TuningTM button (AST) will cause the receiver to
seek another compatible channel being transmitted in the frequency group
being used.
NOTE: The headphone cord also functions as part of the receiver’s
antennasystem. For optimum performance, this cord should be fully
extended. Coilingorbunchingtheheadphone cord may reduce the range
of the receiver. Also, coil-cord type headphone cords are not
recommended. The receiver should be carried by the snap-on belt clip
(included) or inapocketor belt-clip pouch.
d. Set the audio output level control to a comfortable listening volume. This
control is turned clockwise for maximum output level.
PR-75a SETUP AND OPERATION
Page 3

Page 4
PR-75a SETUP AND OPERATION
MonitoringCapabilities
Because each monitoring application requires a different
headphone or transducer to best satisfy each listening
need, the PR-75a can source a strong audio signal
(200 mW) to either stereo or mono headphones
with an impedance as low as 16 ohm.
Ahearing aid type button receiver may
be used with an impedance as high as
2k ohm and still produce a strong
audio signal.
The PR-75a is ideal for use with the
COMTEK NTC-102neckloop
transductor and wireless IR-230
miniature universal-fit ear canal
inductor receiver or with hearing
aids having a “T” switch.
Canbe used with consumer or
professionalheadphones.
Canbe used with
hearingaidbutton
receiversfor assistive
listeningor acoustic
eartube for IFB
application. Canbeused to
driveneckloopfor
usewithIR-230
inductorreceiver or
hearing aids.

Page 5
PR-75a OPTIONAL ACCESSORIES
OptionalAccessories
1. NBC 9-3-1 Digital fast charger
2. NBC 3-1 3 volt 12 hour battery charger
3. NH 1600 Rechargeable Ni-MH battery
(1.2 volt 1700 mAh)
4. P-1 Universal pouch
5. BC-216 Snap-on belt clip
(supplied with PR-75a)
6. LS-3 High efficiency headphones
7. NTC-102 Neckloop transductor
(for use with hearing aids or IR230)
8. ET-4 SM-N Button receiver with acoustic ear tube
9. SM-N Button receiver earphone assembly
10. NBC 9-3-12 Digital 12 station fast charger
11. FP-75 Channel programmer

PR-75a FREQUENCY INFORMATION
Page 6
CHANNEL FREQUENCY
A
B
C
D
E
F
G
H
I
J
72.100MHz
72.300MHz
72.500MHz
72.700MHz
72.900MHz
75.500MHz
75.700MHz
75.900MHz
74.700MHz
75.300MHz
72 MHz WIDE-BAND
CHANNELS
CHANNEL FREQUENCY
A
E
H
J
72.100MHz
72.900MHz
75.900MHz
75.300MHz
GROUP FREQUENCY
CHART
GROUP 1
CHANNEL FREQUENCY
B
G
I
72.300MHz
75.700MHz
74.700MHz
CHANNEL FREQUENCY
C
F72.500MHz
75.500MHz
Custom Programming
The Data I/O port allows
special channel programming
with the FP-75 programmer to
create new dedicated frequency
groups. These frequencies can
then operate in sequence for
“roundabout” type channel
selection with the AST push
button. A dedicated single
channel can also be programmed.
GROUP FREQUENCY
CHART
GROUP 2
GROUP FREQUENCY
CHART
GROUP 3
AutoSmart-TuningTM Process
Plugging the earphone into the PR-75a receiver will automatically turn on
the receiver and initiate theAutoSmart-TuningTM process. (The LED will
blink very rapidly during this process.) The receiver will then tune itself to
the closest on-air transmitter in its vicinity. Based on the first channel found,
the receiver will thendetermine the channel group to which it belongs for
multiple channel operation.

Page 7
Multiple Channel Operation
When multiple transmitters (more than two) are used in the same proximity,
intermodulation interference can occur. This condition is common to all
radio receivers to some extent when multiple transmitters are used in the
same operating area. The RF signals will “MIX” together generating
additional signals. If these product frequencies are too close to a frequency
which the receiver can also respond to, you will experience intermodulation
interference which may cause undesirable operation.
Toavoid this type of interferencewhen multiple transmitters areused in the
sameproximity,transmittingfrequencies must be coordinated by selecting
fromfrequenciesinthesamegroup. (Seegroup frequency chart on page 6.)
When programming new customized frequency groups with the FP-75
channel programmer, COMTEK’s Frequency Selection Guide Software can
be used to determine appropriate frequencies. Contact COMTEK to obtain a
freecopy of the frequency selection softwareor download it from COMTEK’s
website at www.comtek.com/software.html
transmitterstransmitters
transmitters
Group 1
operating area
Group 2
operating area Group 3
operating area
Transmitter
separation
Transmitter
separation
Transmitter Proximities
For Multiple Channel
Operation
Frequencygroups being transmitted
should be separated by 2X
the operating area; and for
bestperformance, the
group operating areas
should have a 100 ft.
minimum separation.

PR-75a BATTERY INFORMATION
Page 8
Low Battery Indicator
The LED indicator on the PR-75a is a multi-function indicator which
includes low battery detection. When the receiver is operating normally,
the LED indicator illuminates continuously indicating that the receiver is
receiving a signal on the tuned channel. If
the battery is low, the LED will show a
steady fast flash indicating the battery
is low. Additionally, if the user is
monitoring,anaudible beeping sound
will be heard warning that the battery
will be dead soon. Replace a low
batteryimmediatelyasperformance of
the receiver will be unpredictable and
may vary from audio distortion to
completefailure to operate.
Battery Removal / Replacement
Battery indicator LED
Pull back battery door latch and allow
battery cover door to spring open. To
remove batteries, simply manipulate
the negative (-) end of battery out of
the compartment and remove.
To insert batteries, manipulate the
positive (+) end into place with correct
polarity as shown. Press batteries into
compartment and close battery door until
it snaps shut. Note: Battery polarity
mustbe correct for unit to operate.

IMPORTANT
Page 9
Battery Charging
1. Make sure that two AA size 1.2 volt Ni-MH rechargeable
cells are used with a minimum of 1400 mAh capacity.
(Alkaline batteries must not be charged.)
2. Note that the red charging indicator on the charger is “ON” when the
PR-75a is plugged into the charger through the audio output jack.
3. When using the NBC -3 charger allow the battery to charge for 12 hours
for a full charge. The unit must then be unplugged. When using
the NBC 9-3-12 or NBC 9-3-1 digital fast charger, the charger will
automatically end the charge cycle and the red LED will change to green.
With this charger, the unit may be left in the charger until the unit is used.
4. Periodically open the battery compartment on stored COMTEK units to
check for battery leakage. If a battery is leaking, it must be discarded,
and the battery compartment must be cleaned or returned to COMTEK’s
service department for repairs.
NBC-3
NBC 9-3-12
NBC 9-3-1

Beltclipinstallation
PR-75a SNAP-ON BELT CLIP
Page 10
Belt clip removal
Hook belt clip
retaining lip over
front case ridge.
Rotate belt clip down onto case.
Apply pressure on both sides
of clip, snapping clip retainers
into slots.
Clip retainer
Retainer slot
Belt clip removal indent
Flex out and pull down with
your thumb or a large coin
(quarter) to unsnap belt clip
from case.
STEP2:
STEP1:

PR-75a SPECIFICATIONS
Page 11
AudioOutput:
Headset output 200 mW average
(Impedance as low as 16 ohm)
Connectors:
Stereo/mono 3.5 mm audio output
connector and charging input.
2.5 mm stereo connector for I/O
data programming.
Indicators:
Multi-functionLED
a. Channel-seeking
b. Received signal
c. No signal
d. Low battery (also audible beeping)
Controls:
Volume control (50 dB range)
Automatic turn-on when headphone
is plugged in and turn-off when
headphone is removed.
One-button tuning control (AST)
AudioFrequency Response:
100 Hz to 10 kHz ±3 dB
Harmonic Distortion:
Less than 1% (1kHz tone 30 kHz
deviation)
Operating Radio Frequency:
72 to 76 MHz
Frequency synthesized 10-channel,
AutoSmart-TuningTM (AST)
•
•
•
•
•
Frequency Stability:
0.002% frequency synthesized
crystal controlled
RF Sensitivity:
1.3 µV for 38 dB of quieting
(average)
Ultimate Quieting:
Better than 75 dB related
to output
F.M. ModulationAcceptance:
Non-Companded F.M.
Deviation up to 40 kHz
Antenna:
Integral with headphone cable
(no external antenna)
Battery Life:
100 hours with alkaline batteries
Power Requirements:
2 AA 1.5 volt alkaline batteries
or rechargeable Ni-MH
(NH 1700)
FCC Compliance:
Complies with Part 15
of FCC rules for scanning
receivers.
Dimensions:
1 1 /16" x 21 /2" x 31 /4"
(27 mm x 57 mm x 83 mm)
NOTE: Specifications subject to
change without notice
•
•

357 West 2700 South • Salt Lake City, Utah 84115
Phone: [phone] • Fax: [phone]
Web Page: www.comtek.com
PR-75a WARRANTY AND SERVICE
Warranty
COMTEK warrants this product to be free from defects in workmanship and
material under normal use and conditions for a period of one year from date
of original purchase. Items such as batteries, neckloops, and cords are not
covered by the warranty. Damage due to misuse, ill treatment and
unauthorized modification and repairs are not covered by this warranty. COMTEK is
not liable for consequential damages arising out of any failure
of the equipment to perform as intended. COMTEK shall bear no responsibility or
obligation with respect to the manner of use of any equipment sold by it.
COMTEK SPECIFICALLY DISCLAIMS AND NEGATES ANY WARRANTY OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE
OF SUCH EQUIPMENT INCLUDING, WITHOUT LIMITATION, ANY
WARRANTY THAT THE USE OF SUCH EQUIPMENT FOR ANY PURPOSE
WILL COMPLY WITH APPLICABLE LAWS AND REGULATIONS.
ServicePolicies
Warranty repairs must be done by COMTEK. Only factory technicians are
authorized to perform warranty service on the PR-75a receiver. Before
returning the PR-75a for service, a Return Authorization Number should
be obtained from the service department by calling 1-800-496-3463 or
1-801-466-3463. Return the unit to the factory with the original or comparable
packing. COMTEK will pay for insurance and ground return shipping costs in
the United States for all warranty service.
Page 12
© 2004 COMTEK®All rights reserved.

357 West 2700 South • Salt Lake City, Utah 84115 • Phone: [phone] • Fax: [phone] • www.comtek.com