Pub. 42004-324A
Extended Range
Page/Party® Systems
Confidentiality Notice
This manual is provided solely as an operational, installation, and maintenance guide and contains sensitive
business and technical information that is confidential and proprietary to GAI-Tronics. GAI-Tronics
retains all intellectual property and other rights in or to the information contained herein, and such
information may only be used in connection with the operation of your GAI-Tronics product or system.
This manual may not be disclosed in any form, in whole or in part, directly or indirectly, to any third party.
The GAI-Tronics Page/Party® system is a modular industrial communication system incorporating from
two to possibly hundreds of stations. Available in several forms, each station includes a handset, two
amplifiers (one for the handset and the other to drive one or more paging speakers), associated controls, and
a paging speaker (usually mounted separately). All stations are wired in parallel and additional stations
may be added at any time.
A GAI-Tronics Page/Party® system layout should be planned in advance of installation. Handset station
locations should be carefully selected, taking convenience, accessibility, and personal safety into account.
The quantity and location of paging speakers must be carefully considered, particularly in areas of high
ambient noise or reverberation.
The speaker amplifier built into each station will drive one horn-loaded paging speaker. If additional
paging speakers are needed, separate speaker amplifiers can be added to the system. In quiet areas such as
offices, several paging speakers can be connected to a single station. Refer to Publication 42004-135
Speaker Installation, or consult with a GAI-Tronics sales representative for additional system planning
All stations are wired in parallel. Good planning will minimize cable requirements for each installation.
GAI-Tronics can supply multi-conductor cable designed specifically for this application. The number, size
and color-coding of conductors are listed in the accompanying system connection diagrams. GAI-Tronics
standard cable has 600 volt insulation and is UL-rated for power cable tray use. Additionally, for ease of
installation GAI-Tronics’ cable is color-coded to match the termination points in our enclosures.
The maximum system cable length is 10 miles (16 km) end-to-end with the system’s Line Balance
Assembly located at the electrical center, i.e., cabling from the Line Balance may extend up to 5 miles to
the last station in any direction.
GAI-Tronics Corporation P.O. Box 1060, Reading, PA 19607-1060 USA
610-777-1374 „ 800-492-1212 „ Fax: 610-796-5954
Extended Range Page/Party Systems
Pub. 42004-324A
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The cable described above includes conductors to supply ac operating power to each station. All stations
operate from a common power source, enhancing reliability, particularly if no other ac load is placed on the
circuit, or branch line feeding the system. This configuration also allows easy transfer to a back-up power
source in the event of power failure. However, if preferred, each station may be individually powered from
a nearby nominal 120 volt, 50 or 60 Hz single-phase outlet.
Installation Procedure
STEP 1 — Electrical Noise Considerations
When planning your system, consider the following suggestions to avoid electrical noise caused by slip
rings and silicon control rectifier (SCR) power supplies.
Slip Rings - Use a Radio Frequency (RF) alternative and avoid using slip rings as audio conductors. Slip
rings are a source of electrical noise and are not reliable.
SCR Power Supplies - The Page/Party® system will be installed in areas where SCR power supplies are
used to power motors or other heavy equipment, consider using one or all of the following four
recommendations to reduce electrical noise.
Separation—Locate the Page/ system cables as far as possible from the SCR power supply input or
output cables. Electrical coupling between cables is reduced by the square of the distance between the
Shielding—Use shielded (Armored) system cables if the cable must be run in the same bundle or cable
tray with the SCR power supply cables. Shielded cables reduce capacitive coupling between SCR
power supply cables and Page/Party® audio cables.
Isolation—Two methods of power source isolation can be used to avoid electrical noise:
A. Use a low capacitance (primary to secondary) isolation transformer between the Page/Party® system
and the ac supply to the SCRs. This will electrically isolate the Page/Party® system’s ac power from
the noise generated by the SCR on the ac power feed. Also use an isolation transformer to isolate the
Page/Party® ac power from an ungrounded ac power source. Note: The neutral side of the transformer
output must be grounded in all instances.
The size of the isolation transformer should be based on the number of amplifiers used in the system.
If 10 or less amplifiers are used in the system, a 500 VA transformer is sufficient. If 11 to 20
amplifiers are used in the system, select a 1000 VA transformer. For systems with more than 20
amplifiers, the transformer should be sized to accommodate a load of 50 VA per amplifier.
B. A battery-powered 24 V dc Page/Party® system can be used as an alternative to the standard 120 V ac
system. In this instance, the battery/battery charger provides isolation from the SCR noise on ac power
systems. Cable shielding and separation as mentioned above still apply.
Note: Avoid battery chargers that utilize SCRs in their design.
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STEP 2 - Mounting of Station and Speaker Amplifier Enclosure
Each Page/Party® system station includes a plug-in amplifier that mates with a fabricated steel, cast
aluminum, or molded reinforced non-metallic enclosure. Each enclosure provides terminal blocks for
connecting inter-station cabling. Enclosures are packed separately from the plug-in amplifiers at the
factory, allowing the amplifiers to remain protected while the enclosures are installed and wired —
particularly important during system installation in areas under construction.
The 16-gauge steel enclosures do not provide any openings for conduits or cables because the location of
these will vary with each installation. Drill or punch the necessary conduit openings before mounting the
enclosure. Locate the openings on either the top or bottom of the enclosure, and toward the rear of the box.
Avoid the top center because of possible interference with the plug-in amplifier receptacle. A drill template
is supplied with each enclosure.
Cast aluminum enclosures are drilled and tapped on the top and bottom for specially-designed hub plates.
Unless special arrangements are made, these enclosures include plates for single 1¼-inch conduit. Plates
for single ½-inch or 1½-inch, or dual 1¼ inch are available.
Molded (non-metallic) enclosures are supplied without any conduit openings. Sealed threaded hubs, such
as Myers “Scru-tite,” are recommended. A drill template is supplied with each enclosure.
Use caution when drilling holes to avoid damaging internal electrical components and wiring.
The suggested mounting height for all station enclosures is 54 inches (137 cm). Subsets used with remote
amplifiers are supplied with 8-foot (244 cm) cables. Enclosures for remote subset amplifiers must be
mounted within reach of the 8-foot cable. Desktop or desk-edge stations enclosures are often mounted in
the knee-well of the desk.
STEP 3 - Mounting of Line Balance Assembly
Each GAI-Tronics Page/Party® system requires one Model 305-002 Line Balance Assembly. Its function
is to properly load the page and party line circuits. When using GAI-Tronics standard cable, select a
location that is:
near the electrical center of the system
adjacent to an indoor station in a relatively quiet area
no more than 5 miles from the most distant station
The line balance assembly has one electrical adjustment that must be made while using a station (see
below). The following is the preferred method for mounting the line balance assembly:
1. Suspend the assembly from the lower side of the indoor wall station using a 1-inch conduit nipple (not
2. Connect one twisted pair wire for the page circuit and another for each of the party lines between the
terminal blocks of the line balance assembly and the associated indoor wall station.
3. Make the wiring connections between the Model 305-002 Line Balance Assembly and the Model 702
and 703 Indoor Wall Station Enclosures in accordance with the wiring diagrams at the end of this
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Extended Range Page/Party Systems
STEP 4 - Installation of Inter-station Conduit and Cable
Inter-station cables are generally installed in cable trays or conduit. To assist in determining the conduit
sizes required, the outside diameters of the GAI-Tronics Corporation cables discussed in this publication
are listed below. Size and installation of conduit and cable must meet the requirements of applicable
electrical codes.
0.60 in. (15.1 mm)
0.68 in. (17.2 mm)
A ground conductor with green/yellow insulation, should be included with cable in any area where no
conduit, or non-metallic conduit is used. Non-metallic enclosures used with metallic conduit and cable
without a ground conductor require a bond between the conduit(s) and the ground terminal (terminal 3)
within the enclosure.
When using GAI-Tronics cable, attach wire lugs to each conductor and connect to the appropriate terminal
in accordance with either the color code shown on the applicable accompanying diagram or with special
drawings provided for this purpose.
Exception: Some cables have a spare orange conductor. Unless otherwise instructed, this should be
taped and not connected to the terminal strip(s) in the enclosures.
GAI-Tronics cable is considered to be a Class 1 cable (maximum voltage is less than 600 V). In a cable
tray, Class 1 cable may only be grouped with other Class 1 cables. However, long runs of GAI-Tronics
cable in proximity of 600 volt cables may cause an undesirable amount of hum to be induced onto the
Page/Party® system’s audio lines. To reduce undesired hum, separate the Page/Party® system cable from
the 600 volt cables by a minimum of 12 inches.
STEP 5 - Installation of Amplifiers and Subsets
One of the many features of GAI-Tronics Page/Party® system equipment is automatic speaker muting.
When the Push-to-Page switch is pressed at a particular station, the paging speaker connected to that
station is silenced, preventing acoustic feedback to the handset microphone. However, while the handset is
in use for the party line conversations, the paging speaker is “live” to permit broadcasts of page calls from
other stations.
For cases where the muting feature is not necessary or may be a disadvantage, it can be defeated as
outlined below.
1. Locate the lugged violet wire attached to terminal point 7 (MUTE) on the terminal block within the
enclosure of station to be modified.
2. Move the lugged violet wire to terminal point 8 (PAGE L1).
After making any necessary muting changes, unpack and install the amplifier for each station. Also,
unpack remote subsets (for desktop, desk-edge or flush-panel mount stations) and plug each into the bottom
of their respective amplifier enclosure.
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STEP 6 - Checkout and Adjustment
Verify all field-wiring connections (e.g., page line, party lines, mute, ac power and speaker) between
stations, and complete the line balance assembly installation before checkout begins. Ensure that all
handsets are on-hook.
1. Apply ac power, and check the station located next to the line balance assembly.
2. Press the PUSH-TO-PAGE switch on the handset and speak directly into the microphone. The broadcast
should be heard at all paging speakers in the system except those associated with the station under test.
If working properly, very little or none of your own voice (sidetone) is heard from the handset earpiece.
If the line balance assembly is not connected properly, there will be a high level of sidetone, perhaps
enough to cause feedback. Adjust the line balance assembly to optimize sidetone rejection on the page
line. If the system is complete when the first station is checked, adjust the line balance assembly as
noted below. Do not adjust station (amplifier) controls until the line balance assembly is adjusted.
3. Release the PUSH-TO-PAGE switch and check the party line(s) sidetone level by speaking into the
microphone of the handset. If working properly, very little or none of your own voice is heard from the
handset earpiece. This sidetone rejection will only occur if the line balance assembly is properly
connected because it contains a fixed resistor load for each party line. In addition, no party line
adjustments are provided. Check party line operation by conversing between two or more stations.
Adjustment of the Line Balance Assembly
To set the control for proper page circuit loading:
1. Remove the line balance assembly cover to expose the line balance control.
2. Lift the handset from the station located next to the line balance assembly and press the push-to-page
3. From the normal speaking distance (approximately ½-inch), blow steadily into the handset microphone
and adjust the line balance control to minimize side tone in the handset receiver. This adjustment needs
to be made only at the initial installation of the system. However, if in the future more than 10 speaker
amplifiers are added or deleted, repeat adjustment of page circuit loading.
4. After final adjustment, replace and secure the cover with the four mounting screws to discourage
tampering by unauthorized personnel and prevent entry of contaminants.
Each amplifier has a paging speaker volume control. It is accessible from the front panel with a
screwdriver, but is concealed behind the metal nameplate. To access it, simply loosen (but do not remove)
the two nameplate screws and pivot the nameplate around the left screw. This control is pre-set at the
factory to produce a moderate page level of approximately 4 watts of output power.
Each handset/speaker station amplifier has two additional internal controls: receiver volume control and
receiver sidetone control. Both controls are accessible from the rear using a small screwdriver through
holes provided on the chassis. A third hole allows similar access from the rear for the paging speaker
volume control. All controls are factory-adjusted for optimum performance in most industrial applications.
Do not readjust these controls to solve system problems until other possible faults are checked, such as a
missing, defective, or improperly connected line balance assembly. There is very little drop in receiver
(handset earpiece) volume level due to system cable losses. Generally, the only reason to reset the receiver
volume control is to compensate for extremely high ambient noise levels (up to 110 dB) or to meet
particular personnel needs.
For stations with cable lengths of 26,400 feet (5 miles or 8 km) or more from the line balance assembly,
receiver sidetone rejection is noticeably affected by cable impedance. Use the receiver sidetone control to
compensate for this by rotating the control clockwise.
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STEP 7 - Troubleshooting the System
Hum or Buzz
If hum or buzz is present on the page line, or on one or more of the party line(s), it is usually due to either
one of the inter-station cable conductors for the circuit being shorted to ground, or an unbalanced leakage
path to ground. Therefore, if the page and party line audio conductors are twisted pairs and there are no
leakage paths or short circuits to ground, induced voltages cancel-out across the paired conductors and do
not appear across the line.
To correct the problem, locate the source of the ground. Using an ohmmeter, check various junction points
of the system wiring to determine which direction the ground can be located. Locate the ground by going
from one junction point to another and disconnecting the affected circuit. Please note that the fault can be
within a plug-in amplifier. However, most ground faults occur due to improper terminations or from small
wire strands protruding from an improperly lugged wire.
Another source of grounds or near-grounded circuits is junction boxes filled or partially filled with water.
In many cases, dust or dirt deposits in the boxes can produce conductive and/or corrosive solutions when
combined with water. Thus, these deposits cause leakage between circuits and can corrode the wire and
Isolation of field wiring may be necessary for test purposes. If such isolation removes the line balance
assembly from the operating portion of the system, connect a 560-620 ohm, ½-watt resistor across L1 and
L2 of the affected page and party line circuits. Remove these resistors after completion of the tests.
Feedback or Distortion on the System
Each page and party circuit must be loaded to the optimum 600 ohms using the line balance assembly. If
the line balance is not connected, or is defective, the system will have excessive gain and will break into
feedback quite easily. Speech will also be distorted, and there will be a high level of sidetone in handset
Each party line is terminated with fixed a 620-ohm resistor in the line balance assembly. However, an
adjustment is provided for the page line to compensate for the number of speaker amplifiers connected to
the system page line. Improper adjustment will affect gain and increase the level of sidetone. Please refer
to specific instructions above for adjusting the line balance assembly.
Very Low Audio Level on One or More Lines at all Stations
It is possible for the system, or part of the system, to function with a short across the page or party line
circuits. If this occurs, the level of the system will be extremely low, decreasing to nearly zero in the
vicinity of the short circuit. Locate the short circuit in the same manner as locating a ground, by checking
junction points with an ohmmeter.
Cross Talk
Accidental crossing of circuits in a junction box will cause cross talk or interference. To check for this
condition, measure resistance between circuits of the interfering channels. The resistance should be infinite
or a very high value. Leakage or shorts to ground in two or more circuits can also result in cross talk on
those circuits.
In a multi-party line system, it is possible to have a small amount of cross talk between channels if line
balance resistors are opened or not connected. This condition can be detected by the presence of high
sidetone at handset receivers.
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Static Charges
In many installations, it is normal to read (measure) a static ac voltage from the conductors of the page and
party line circuits to ground. In many cases, this voltage may be as high as 50 volts or more. This voltage
is induced into the circuits by capacitance to the ac power circuit generally carried in the same cable or
from power cables paralleling communication cables. This voltage is inconsequential and can be ignored.
Problems will only occur if one side of the page or party circuit becomes grounded.
Audio Voltage
In a properly operating system, audio voltage read across any of the page or party circuits (L1 and L2) will
be approximately 0.5 to 0.75 volts ac on peaks when an audio signal is present, i.e., someone speaking into
a handset. The voltage will be proportional to the loudness of the person’s voice using the handset.
One Inoperative Station in a Working System
Except for a wiring error, an inoperative station indicates a defect in the amplifier at the station. This is
checked quickly by installing either a spare amplifier, or exchanging amplifiers from a known operating
Special Note Regarding Installation
GAI-Tronics Corporation 600-ohm Page/Party® system equipment is NOT approved for use in classified
areas, although under normal operation it does not produce arcs, sparks or heat that would ignite industrial
gases or dusts.
Proper installation is defined as (1) mounting and wiring per factory directions without unauthorized
modification, and (2) following all requirements set-forth by the U.S. National Electric Code (NEC),
articles 500-503, the National Fire Protection Agency (NFPA - 70), or Canadian Standards Association
(CSA) Electrical Code per CSA Standard C22.1. Installers must be familiar with the applicable codes, and
observe all established requirements. The most applicable parts of the Canadian Standards code are in
Section 18. Some, but not all, significant points are:
Conduits in a Class I, Division 2 area to or from a non-hazardous area or an adjacent Class I, Division
1 area must have approved seals in the boundary.
Conduits or raceways in a Class II, Division 2 or Class III area must have dust seals at entrances to
dust-tight equipment and at boundaries to other areas unless such conduits or raceways are also dusttight.
Explosion-proof (Division 1) equipment may be installed in a Division 2 area but must have the same
conduit and cable seals as if installed in the corresponding Division 1 area.
Sealing of multi-conductor cables or conduits containing multi-conductor cables in Class I, Division 1
or 2 areas must be around each conductor of the cable - except where type MI cable is used.
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Safe Power Connection/Disconnection
In order to satisfy Division 2 requirements, equipment must not create arcs or sparks during normal
operation, when completely installed and powered. Installing or removing an amplifier or connecting to a
live enclosure is not normal operation and can create arcs. To ensure personal safety, adhere to the
following cautionary note:
Do not insert or remove equipment from live enclosures, unless the area is known to be non-hazardous.
A separate power disconnect is highly recommended. It can be installed and safely used in either of two
1. An explosion-proof disconnect switch can be located in the Division 2 area.
2. An ordinary disconnect switch can be located in a non-hazardous area (outside the Division 2 area).
Either method will allow the use of the switch at all times. Connect field wiring as detailed in instructions
for the same equipment mounted in non-hazardous areas.
Power Distribution Recommendations
The ac power input current for a 700 Series Station (handset/speaker amplifier or speaker amplifier) is
0.46 amperes (50 VA or 27 watts) RMS at full power (12 watt RMS output) with 120 V ac line voltage.
The 14 AWG conductors used for power distribution in standard GAI-Tronics cable is rated at 15 amperes.
This limits the number of speaker amp stations per ac power feed to 32 units or less. Systems with more
than 32 stations will require splitting the ac power feeds into different branches.
Voltage drop must also be taken into consideration for long cable runs. The minimum operating voltage for
a GAI-Tronics station is 90 V ac, and resistance of 14 AWG cable is 26.8 ohms per loop mile. Thus,
length of the cable run must also be considered when designing and installing a system. Contact your
nearest GAI-Tronics representative if you require assistance with a system layout.
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Figure 1. Typical Multi Party Connection Diagram
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Figure 2. Typical Single Party Connection Diagram
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