USER MANUAL Push Back Gateway U9920-GPB (P/N: 40993G-01)

Push Back Gateway
(P/N: 40993G-01)
19541P-41 (06-12)
Cautions and Warnings
READ AND SAVE THESE INSTRUCTIONS. Follow the instructions in this installation
manual. These instructions must be followed to avoid damage to this product and
associated equipment. Product operation and reliability depends on proper usage.
APPEARS DAMAGED. Upon unpacking your David Clark product,
inspect the contents for shipping damage. If damage is apparent,
immediately file a claim with the carrier and notify your David Clark
product supplier.
ELECTRICAL HAZARD - Disconnect electrical power when making any
internal adjustments or repairs. All repairs should be performed by a
representative or authorized agent of the David Clark Company.
STATIC HAZARD - Static electricity can damage components.
Therefore, be sure to ground yourself before opening or installing
LI-POLYMER - This product is used with Li-Polymer batteries. Do not
incinerate, disassemble, short circuit, or expose the battery to high
temperatures. Battery must be disposed of properly in accordance
with local regulations.
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The U9920-GPB (40993G-01) Push Back Gateway is a portable wireless communication device
that when used in conjunction with one or more U9910-BSW (40992G-01) or U9912-BSW
Wireless Belt Stations provides communication for up to four users as well as an interface to an
aircraft intercom system. Only one gateway is required per system. Up to four belt stations can
be connected to one gateway.
Figure 1: Overview of Gateway
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Before a belt station and a gateway can be connected, they must first be linked. As a security
measure, the close-link feature requires devices to be in proximity of about 1 to 3 ft (0.3 to 0.9m)
in order to successfully link. This ensures that the units are not inadvertently linked with other
units on the premises.
Linking procedure:
1. Ensure power is on for both U9920-GPB and belt station (see Power-up/Power-down)
2. Ensure units are within 1 to 3 ft (0.3 to 0.9m) of each other.
3. Simultaneously (within 1-2 sec) press and release the PTT button on the U9920-GPB and
the belt station to link with.
4. Amber LED’s will flash on both devices. A momentary red LED indicates a successful
5. Upon successful link the U9920-GPB will attempt to establish a connection with the belt
6. Upon successfully establishing connection the LED on the gateway will flash a green
pattern corresponding to the number of belt stations connected.
Once linked, the devices will not need to be linked again unless they are purged (see
Each belt station is able to be linked to only one gateway at a time. A gateway can have up to six
belt stations linked and be connected to four of those six at one time.
Status Indications
The power button has a multi-color LED in the center which serves as a status indication for the
gateway. Table 1 below lists these states.
Table 1: LED Status Indications
LED Color
Blink Rate
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Initializing/power up
Connection Dropped
Connection Established
Low battery (approx. 1 hr remaining)
Link/Connection in Progress
PTT asserted
Connected (pattern indicates
number of belt stations connected)
To power up the U9920-GPB Push Back Gateway, press and hold the POWER button for
approximately two seconds. The LED will turn red and then begin flashing orange. If there are
linked belt stations within range, they will automatically connect to the gateway in a few seconds
after power up.
To power down the U9920-GPB, press and hold the POWER button for approximately two
seconds. The LED will turn red and then turn off. The gateway is now powered down.
Aircraft Interface
The U9920-GPB is designed for airport push back operations and can be connected to an aircraft
intercom system. Once connected, up to four belt station (U9910-BSW) users can communicate
to the pilot of the aircraft by pressing the PTT button on the belt station. A Push Back Cable is
required between the U9920-GPB and the aircraft (see below: Figure 2 – connection illustration,
and Table 2 – Push Back Cable matrix.)
Line up
Orange Dots and Twist
Figure 2: Push Back Cable Connection
Table 2: Push Back Gateway Interface Cable Matrix
Part Number
PJ-051 Plug (1/4”)
U-174/U Plug (Civilian Only)
Dual G.A. Plugs (PJ-055/PJ-068)
U-174/U Plug (Military Only)
The included lanyard, hook, and Remove Before Flight banner (see Figure 1) facilitate the
temporary mounting of the U9920-GPB to an aircraft. The hook position on the lanyard is
adjustable to accommodate a variety of different mounting techniques. In addition, the belt clip
can be used to clip the gateway to an access door. Care and judgment should be exercised when
clipping or hooking to any part of the aircraft so that damage does not occur to the aircraft or the
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If possible, orient the gateway in such a way that it is as far away from any metal parts as
possible. This will increase the wireless range and robustness of communications.
Aircraft Level Adjustment
Audio levels can vary between aircraft. To compensate for this, the U9920-GPB has a receive
level adjust knob (see Figure 1). Turning this knob will increase or decrease the audio level
coming from the aircraft and into the wireless intercom. By adjusting this knob, optimum
performance can be achieved.
Receive Level Adjustment Procedure
1. Connect at least one belt station to the U9920-GPB gateway and ensure sidetone is
present (see belt station User Manual).
2. Press and hold PTT
3. While holding PTT, begin speaking and slowly turn Receive Level Adjust knob on the
U9920-GPB gateway clockwise until you hear an echo of your own voice.
4. Turn the Receive Level Adjust knob slightly counter-clockwise until the echo stops.
5. Release PTT.
6. You may wish to verify communication with the pilot or someone hard-wired to the
aircraft’s intercom.
Note: It is highly recommended for wireless push-back systems that each headset user interface
through a non-VOX belt station (U9912-BSW), as extremely high and varying noise levels within
this environment can become challenging to the VOX feature, resulting in unwanted ramp noise
being present in a VOX belt station user's headset and causing him/her to frequently adjust the
VOX setting. VOX belt stations may be desired in more stable and less extreme noise
All connected belt stations will be able to communicate with each other through the U9920-GPB
while in range. Additionally, all belt station users will always hear any traffic on the aircraft
intercom. To speak over the aircraft intercom, the belt station user must press and hold his/her
PTT button. Multiple belt station users may PTT and thus speak over the aircraft intercom
simultaneously. Wireless intercom for all connected belt station users is also achieved in this
manner. For more information consult the user manual for the belt station.
The range of a belt station and a gateway can be up to 300 ft (100m). If you are in an
environment with metal or concrete walls, this range could be reduced. If the belt station enters
into a "fringe" reception area, a brief sequence of three beeps will be heard in the headset. This
is to serve as a warning of a possible disconnection if conditions are not improved. When
possible, the user should attempt to regain line-of-sight contact with the controller.
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When the belt station travels out of range of the gateway, a voice alert will indicate that the
connection has been lost. To reconnect, simply move back into range and connection with the
gateway will automatically be reestablished, also noted by a voice alert.
Low Battery
Under typical conditions, the battery in the gateway will last up to 24 hours or longer. The Status
LED turns red to indicate that the battery is running low. Additionally, a voice alert ("Gateway
Low Battery") is transmitted to all connected belt stations. This alert is not heard by the pilot of
the aircraft. At this point, approximately 1 hour of operation remains.
Auto Shut Off
The U9920-GPB will automatically shut off 30 minutes after the last belt station is disconnected.
In some circumstances it may be necessary to “purge” the U9920-GPB of some of its linked belt
stations. Typically purging is not necessary unless there are multiple gateways in the same
vicinity and you wish to remove a belt station from this gateway and link to a different gateway.
A gateway can link up to six belt stations where a belt station can be linked to only one gateway
at a time.
Full Purge
A full purge is a purge method which clears all links in the gateway. After this procedure no belt
stations will automatically connect to this gateway until linked.
Full Purge procedure
Power down gateway (see Power-up/Power-down).
Press and hold PTT button. Do not release.
Power up the gateway (see Power-up/Power-down).
Release POWER button.
Release PTT button.
Status LED will flash red to indicate successful purge.
Smart Purge
A smart purge is a purge in which only unwanted links are removed from the gateway. When this
procedure is complete, only belt stations that are connected to the gateway remain linked. All
other belt station links will have been removed (see the belt station User Manual for the
individual belt station purging procedure when remaining link purging may be necessary.)
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Smart Purge procedure
1. Ensure gateway is powered on and functioning.
2. Disconnect all belt stations to be purged (power off the belt stations).
3. Verify the number of green LED flashes on the gateway matches the number of
belt stations to be kept linked.
4. Press and hold LINK button on the gateway for 30 seconds until LED quickly
flashes red.
5. Release LINK button.
Battery Removal & Charging
All David Clark 9900-series wireless belt stations and battery operated controllers/gateways use a
3.7V Li-Polymer rechargeable battery. This battery is removed by loosening the battery release
screw (See Figure 1). The batteries are charged with the A99-04CRG 4-bay battery charger
(41034G-01). When installing a battery, take care to align the battery properly and fully tighten
the screw (see Figure 3).
Lift Door
Insert Battery
with Contacts
Figure 3: Battery Insertion/Removal
Table 3: Troubleshooting
Gateway will not turn on
Cannot link a belt station
Cannot speak to aircraft
Review Power-up/Power-down procedure
Ensure a fresh battery is installed
Review Registration procedure
Ensure units are within 1 to 3ft (0.3 to 0.9m) of
each other
Try a Full Purge
PTT not pressed
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Replacement Parts
Battery (P/N: 40688G-90)
Protective skin, orange (A99-02SKN, P/N: 40796G-03)
Aircraft Interface Cord, PJ-051 {1/4" plug} (P/N: 41035G-02)
Aircraft Interface Cord, U-174/U plug {Civilian Only} (P/N: 41035G-03)
Aircraft Interface Cord, dual General Aviation plugs {Saab, others} (P/N: 41035G-04)
Aircraft Interface Cord, U-174/U Plug {Military Only} (P/N: 41035G-05)
Care and Maintenance
The U9920-GPB is not user serviceable. Do not attempt to open the enclosure. If this product
requires service, please contact the David Clark Co. Inc. Customer Service department:
By Mail:
Customer Service
David Clark Company
360 Franklin Street
Worcester, MA 01604
If necessary, the U9920-GPB may be wiped down with a mild soap and water mixture. Although
it is a sealed device designed to withstand submersion in water to 1 meter, do not unnecessarily
submerse this product in water.
Avoid storage of this product in direct sunlight or high temperature environments.
Frequency Range
Average RF Power Output
1920 MHz - 1930 MHz (U.S. and Canada)
4 mW (100mW peak) (U.S. and Canada)
300 ft (100m) line-of-sight (nominal)
Battery Life
24 hrs continuous use (nominal)
Operating Temperature
-14°F to 113°F (-10°C to +45°C)
Storage Temperature
-4°F to 140°F (-20°C to +60°C)
Power Requirements
3.7V @ 100mA nominal
Battery Type
3.7V 2000mAh Li-Polymer
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FCC Part 15 Statement
This equipment has been tested and found to comply with the limits for a Class B digital device,
pursuant to Part 15 of the FCC rules. These limits are designed to provide reasonable protection
against harmful interference in a residential installation. This equipment generates, uses and can
radiate radio frequency energy and, if not installed and used in accordance with the instructions,
may cause harmful interference to radio communications. However, there is no guarantee that
interference will not occur in a particular installation. If this equipment does cause harmful
interference to radio or television reception, which can be determined by turning the equipment
off and on, the user is encouraged to try to correct the interference by one or more of the
following measures:
- Reorient or relocate the receiving antenna.
- Increase the separation between the equipment and the receiver.
- Connect the equipment into an outlet on a circuit different from that to which the receiver is
- Consult the dealer or an experienced radio/TV technician for help.
You may also find helpful the following booklet, prepared by the FCC: "How to Identify
and Resolve Radio-TV Interference Problems." This booklet is available from the U.S.
Government Printing Office, Washington D.C. 20402.
In order to maintain compliance with FCC regulations shielded cables must be used with
this equipment. Operation with non-approved equipment or unshielded cables is likely to result
in interference to radio & television reception.
Industry Canada Statement
This device complies with Industry Canada license-exempt RSS standard(s). Operation is subject
to the following two conditions: (1) this device may not cause interference, and (2) this device
must accept any interference, including interference that may cause undesired operation of the
Unauthorized Changes
Changes or modifications not expressly approved by David Clark Company, Inc. could void the
users’ authority to operate the equipment.
Usage Restrictions
Due to the UPCS frequencies used, this product is licensed for operation only in the United States
of America and Canada.
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