BIRD 424-86A-03 User manual

YOU'RE HEARD, LOUD AND CLEAR.
8625 Industrial Parkway, Angola, NY 14006 Tel: [phone] Fax: [phone] [e-mail] www.bird-technologies.com
Installation and Operation Manual for
AutoQuad Tower-Top Amplifier System
Model 424-86A-03 and 424-86A-03-48
Manual Part Number
7-9322-5

Warranty
This warranty applies for one year from shipping date.
TX RX Systems Inc. warrants its products to be free from defect in material and workmanship at the time of shipment.
Our obligation under warranty is limited to replacement or repair, at our option, of any such products that shall have
been defective at the time of manufacture. TX RX Systems Inc. reserves the right to replace with merchandise of
equal performance although not identical in every way to that originally sold. TX RX Systems Inc. is not liable for dam-
age caused by lightning or other natural disasters. No product will be accepted for repair or replacement without our
prior written approval. The purchaser must prepay all shipping charges on returned products. TX RX Systems Inc.
shall in no event be liable for consequential damages, installation costs or expense of any nature resulting from the
purchase or use of products, whether or not they are used in accordance with instructions. This warranty is in lieu of all
other warranties, either expressed or implied, including any implied warranty or merchantability of fitness. No repre-
sentative is authorized to assume for TX RX Systems Inc. any other liability or warranty than set forth above in con-
nection with our products or services.
TERMS AND CONDITIONS OF SALE
PRICES AND TERMS:
Prices are FOB seller’s plant in Angola, NY domestic packaging only, and are subject to change without notice. Fed-
eral, State and local sales or excise taxes are not included in prices. When Net 30 terms are applicable, payment is
due within 30 days of invoice date. All orders are subject to a $100.00 net minimum.
QUOTATIONS:
Only written quotations are valid.
ACCEPTANCE OF ORDERS:
Acceptance of orders is valid only when so acknowledged in writing by the seller.
SHIPPING:
Unless otherwise agreed at the time the order is placed, seller reserves the right to make partial shipments for which
payment shall be made in accordance with seller’s stated terms. Shipments are made with transportation charges col-
lect unless otherwise specified by the buyer. Seller’s best judgement will be used in routing, except that buyer’s routing
is used where practicable. The seller is not responsible for selection of most economical or timeliest routing.
CLAIMS:
All claims for damage or loss in transit must be made promptly by the buyer against the carrier. All claims for shortages
must be made within 30 days after date of shipment of material from the seller’s plant.
SPECIFICATION CHANGES OR MODIFICATIONS:
All designs and specifications of seller’s products are subject to change without notice provided the changes or modifi-
cations do not affect performance.
RETURN MATERIAL:
Product or material may be returned for credit only after written authorization from the seller, as to which seller shall
have sole discretion. In the event of such authorization, credit given shall not exceed 80 percent of the original pur-
chase. In no case will Seller authorize return of material more than 90 days after shipment from Seller’s plant. Credit
for returned material is issued by the Seller only to the original purchaser.
ORDER CANCELLATION OR ALTERATION:
Cancellation or alteration of acknowledged orders by the buyer will be accepted only on terms that protect the seller
against loss.
NON WARRANTY REPAIRS AND RETURN WORK:
Consult seller’s plant for pricing. Buyer must prepay all transportation charges to seller’s plant. Standard shipping pol-
icy set forth above shall apply with respect to return shipment from TX RX Systems Inc. to buyer.
DISCLAIMER
Product part numbering in photographs and drawings is accurate at time of printing. Part number labels on TX RX
products supersede part numbers given within this manual. Information is subject to change without notice.
Bird Technologies Group TX RX Systems Inc.

Symbols Commonly Used
NOTE
ESD Elecrostatic Discharge
Hot Surface
Electrical Shock Hazard
Important Information
CAUTION or ATTENTION
High Voltage
Use Safety Glasses
WARNING
Bird Technologies Group TX RX Systems Inc.
Manual Part Number 7-9322
Copyright © 2006 TX RX Systems, Inc.
First Printing: March 2003
Version Number Version Date
1 03/04/03
2 08/01/03
3 04/26/04
4 02/15/06
5 08/09/06

Table o f C o n te n t s Manual 7-93 22 - 5 08/09/06
Table of Contents
General Description ............................................................................................ 1
Unpacking ............................................................................................................ 4
Pre-Installation Checkout ................................................................................... 4
Mechanical Inspection ....................................................................................... 4
Pre-installation Static Sensitivity Testing ........................................................... 4
Installation............................................................................................................ 6
Interference and Intermodulation Considerations .............................................. 6
Installing the System ..........................................................................................8
Installing the Tower-Top Box ............................................................................. 8
Installing the Multicoupling Amplifier .................................................................. 9
About Reserve Gain and Attenuation .............................................................. 10
Determining Needed Attenuation .................................................................... 10
Setting Reserve Attenuation ........................................................................... 11
About Multicoupler Gain and Attenuation .........................................................11
Setting Multicoupler Attenuation ..................................................................... 11
Post Installation Tests ...................................................................................... 11
Installed Sensitivity Test ................................................................................... 12
Calculate Cable Loss ......................................................................................12
Tri-Mode Test Port ............................................................................................ 13
Test Port Sensitivity with Dummy Load (Mode 1) ............................................. 14
Test Port Sensitivity with Antenna (Mode 0) ..................................................... 14
Spectrum Analysis ............................................................................................ 16
Antenna Sweep Test (Mode 2) .........................................................................16
Routine Operation ............................................................................................. 17
Signal Flow......................................................................................................... 17
Tower-Top Box ................................................................................................ 17
Multicoupling Amplifier ..................................................................................... 17
System Status Monitoring ................................................................................. 20
LCD Display .................................................................................................... 20
Status-Indicator LEDs ..................................................................................... 20
Form-C Contacts............................................................................................. 20
Alarms ................................................................................................................ 21
Warning ............................................................................................................ 21
Failure............................................................................................................... 21
System Troubleshooting ..................................................................................21
Performance Degradation ................................................................................. 21
Hardware Problems .......................................................................................... 21
Logic Circuit Failure .........................................................................................22
AC Line Fuse ................................................................................................... 22
Optional Preselector Filters.............................................................................. 23
Maintenance ....................................................................................................... 23
Recommended Spare Parts.............................................................................. 23
****Amplifier Replacement**** .......................................................................... 23
Tower-Top Box ................................................................................................ 23
Multicoupling Amplifier ..................................................................................... 24
Options ............................................................................................................... 25
Narrowband Preselector Filter ......................................................................... 25
Receiver Multicoupler Expansion Deck ........................................................... 25

Table o f C o n te n t s Manual 7-93 22 - 5 08/09/06
Figures and Tables
Figure 1: Front view of the tower-top box ............................................................ 1
Figure 2A: Top view of the multicoupler unit (MCA) ............................................ 2
Figure 2B: Front view of the MCA .......................................................................2
Figure 2C: Back view of the MCA ........................................................................ 2
Figure 3: Test equipment interconnection for “bench testing” ............................. 4
Figure 4: Cable connections for system components .......................................... 6
Figure 5: System installation guidelines .............................................................. 7
Figure 6: Tower-top box mechanical details ........................................................ 8
Figure 7: Application of rubber splicing tape ....................................................... 8
Figure 8: Alarm and power terminals ................................................................... 9
Figure 9: Installed sensitivity test........................................................................ 12
Figure 10: Measuring test port sensitivity with dummy load ............................... 13
Figure 11: Measuring test port sensitivity with antenna......................................14
Figure 12: Testing output spectrum .................................................................... 15
Figure 13: Maximum signal level mask .............................................................15
Figure 14: Antenna sweep test ........................................................................... 16
Figure 15: Block diagram of tower box ............................................................... 18
Figure 16: Block diagram of the MCA ................................................................ 19
Figure 17: Connecting the optional preselector ..................................................24
Figure 18: Optional 16-port expansion deck....................................................... 25
Table 1: System Specifications ............................................................................. 1
Table 2: Tower Box Specifications......................................................................... 3
Table 3: Multicoupling Amplifier Specifications ..................................................... 3
Table 4: Test Data Sheet....................................................................................... 5
Table 5: Optimum Reserve Gain Settings........................................................... 10
Table 6: Base Attenuation Settings .....................................................................11
Table 7: LED and alarm trouble shooting guide ..................................................20
Table 8: Current meter readings ......................................................................... 20
Table 9: Loss of Sensitivity troubleshooting guide .............................................. 22

TX RX Systems Inc. Manual 7-9322-5 08/09/06 Page 1
GENERAL DESCRIPTION
The AutoQuadTM Tower-Top Amplifier System pro-
vides the highest degree of reliability available in a
Tower-Top Amplifier (TTA) system. The AutoQuad
System uses quadrature-coupled amplifiers (also
called balanced amplifiers) to create a redundant
amplifier configuration in both the tower box and
the receiver Multicoupling Amplifier (MCA). Each
quad-amplifier provides two simultaneously used,
essentially parallel paths of amplification. Failure of
one of these paths of amplification results in an
overall gain reduction of only 6 dB in a quad-ampli-
fier.
The AutoQuad System also supplies automatic
backup-amplifier switching in the tower-top box.
Fault detection circuitry continuously monitors the
DC power operation of the primary quad-amplifier
and automatically switches to the identical second-
ary quad-amplifier if conditions indicate a primary
malfunction. If the
secondary quad-amplifier mal-
functions, operation switches to whichever quad-
amplifier is still providing some gain due to opera-
tion of one of its amplification paths. Fault detection
circuitry also provides at-a-glance status reporting,
with front-panel LEDs and a current meter. The
specifications for the AutoQuad system are listed
in Table 1.
Figure 1: Front view of the tower-top box (door removed for clarity).
3-18977
Input Switch
Amp A
3-18941
or
3-19285
Amp B
3-18941
or
3-19285
Door Clamp
3-19033
Output Switch
3-19029
Tr i - M o d e Te s t S w i t c h
8-21183
Surge Suppressor
(behind switch assembly)
Mounting Tab
(four total)
3-15878
Bandpass Filter
with Sample Port
Door Hinge
8-21205
Surge Suppressor
8-21206
Surge Suppressor
Noise Figure 5 dB max, <4 dB typ
Reserve Gain Fully settable by
electronic attenuator
Ship Weight 52 lbs (24 Kg)
Table 1: System specifications. Values are typical
unless noted otherwise.

TX RX Systems Inc. Manual 7-9322-5 08/09/06 Page 2
Figure 2B: Front view of the MCA.
Enter Button Scroll Button Display Contrast
Adjustment
Select
Switch
Amplifier
Alarm
Indicators
Display Tes t
Port
Performance
Data Tag
NOTE
Tool required for
button presses,
paperclip or stiff
wire works well
Figure 2A: Top view of the Multicoupling Amplifier (MCA). NOTE: 48 VDC converter used in model 424-86A-03-48.
3-19052
Daughter
Board
8-18150
Power Supply
3-18171
8-Way
Power Divider
3-18171
8-Way
Power Divider
3-18173
4-Way
Power Divider
3-19037
Quad
Amplifier
3-18000
Circuit
Board
* if so equipped
3-20015
Voltage
Limiter
Figure 2C: Back view of the MCA. NOTE: 48 VDC converter used in model 424-86A-03-48.
AC Cord Te s t Po r t
Line
Transmission
Line
To Additional 8-Way
Power Dividers on
Expansion Panel
Ground Alarm
Terminals
DC Power
Terminals To S t a ti o n
Receivers
To S t a t i o n
Receivers

TX RX Systems Inc. Manual 7-9322-5 08/09/06 Page 3
The quad-amplifier in the tower-top box amplifies
the weak received signal before the signal enters a
long and lossy transmission line, thus preventing
the line loss from degrading the signal-to-noise
ratio. Included in the tower-top box is a combline
preselector filter, amplifier “A” and amplifier “B,”
input and output switching circuitry, a tri-mode test
switch assembly and PolyPhaser surge suppres-
sors with DC bias-tap (see Figure 1). The specifi-
cations for the tower box are listed in Table 2.
The ground-mounted MCA shown in Figures 2A
through 2C is intended for 19-inch rack mounting.
It houses amplifier and signal distribution assem-
blies, current alarm monitoring, alarm indicators, a
power supply, and a current meter to provide visual
feedback on the system’s operating status. Also,
model 424-86A-03 houses a power supply, model
424-86A-03-48 houses a 48 VDC converter. The
specifications for the MCA are listed in Table 3.
Electrical Specifications
Frequency Range 806 to 824 MHz
Net Gain 20 dB
Noise Figure (typ /max) 2.8 / 3.8 dB
Backup Amplifier Switching Solid State RF Switch
Test Port Isolation 30 dB
Impedance 50 ohms
VSWR < 2.0 : 1
Preselector Type 10-Pole Combline Bandpass,
18 MHz BW
Loss < 1 dB
Rejection > 110 dB @ 776 and
851 MHz
LNA Type Quadrature-Coupled,
Modular
Gain 24 dB
Noise Figure 1.4 dB
1 dB Compression Point 27.5 dBm
3rd Order Input / Output IP 17 dBm / 41 dBm
Power Requirements 24 VDC @ 1.4 A (MCA)
Lightning Protection Impulse Suppressor on all
external connectors
Operating Temperature
Range
-30° C to +60° C
Mechanical Specifications
Enclosure NEMA 4x Stainless Steel
Connectors N -female
Dimensions (HWD) 24” x 6” x 6”
(610 x 152 x 152 mm)
Net Weight 30 lbs (13.4 Kg)
Table 2: Tower box specifications. Values are typical unless
noted otherwise.
Electrical Specifications
Frequency Range 806 to 824 MHz
Multicoupler Net Gain 0 dB min; 1 dB nominal
Preamplifier Type Quadrature-Coupled,
Modular
Gain 21 dB
Noise Figure 3 dB
1 db Compression Point 33 dBm
3rd Order Input / Output IP 27 / 48 dBm
Number of Outputs /
Split Loss
16 or 32 / 18 dB
Impedance 50 ohms
VSWR <1.5 : 1
Connectors To TTA N - female
To BTS BNC - female
Test Port Input BNC - female
Electronic Attenuator 3 - 35 dB in 0.5 dB steps
Alarm / Warning Contacts Two Form C Contacts
Optional Alarm & Control RS-232C
Power Requirements
Model 424-86A-03 90 - 240 Vac 50/60 Hz
Model 424-86A-03-48 36 to 76 VDC
Operating Temp Range 0° C to + 50° C
Mechanical Specifications
Enclosure Standard EIA 19” Rack Mount
Dimensions (HWD) 1 RU x 19” x 14”
(38 x 483 x 356 mm)
Net Weight 12 lbs (5.5 Kg)
Table 3: Multicoupling Amplifier specifications. Values are
typical unless noted otherwise.

TX RX Systems Inc. Manual 7-9322-5 08/09/06 Page 4
UNPACKING
Each major component of the TTA system is indi-
vidually packaged and shipped via motor freight or
UPS. It is important to report any visible damage to
the carrier immediately. It is the customer's respon-
sibility to file damage claims with the carrier within
a short period of time after delivery (1 to 5 days).
PRE-INSTALLATION CHECKOUT
The following pre-installation checks should be
performed after unpacking the system to verify
nothing has loosened during transit. Additionally,
the system should be made operational on the
bench with all components at ground level to verify
proper electrical performance.
Mechanical Inspection
Open the tower-top box by loosening all the door-
clamp locking screws and rotating the clamps to
release the door. Make sure that all the N and TNC
connectors are tight. In addition, it is advisable to
check the tightness of the hold-down screws for the
various assemblies to insure nothing loosened dur-
ing shipment.
Pre installation Static Sensitivity Testing
Hookup and test the entire system at ground level
to verify that all components are working properly
and to measure the system receiver sensitivity
before climbing. Short cables are used to intercon-
nect all components as shown in Figure 3. One
station receiver is selected and the test is per-
formed at this frequency. A data sheet is provided
in Table 4 on page 5 of this manual for recording
data collected during system testing. There is room
on each sheet for data recorded on multiple dates.
We suggest that you photo-copy the sheet and use
it for subsequent testing.
Test
Port
12 dB SINAD
Signal Generator
RX MCA
RF
Out
FRX MHz
3 KHz dev
1 KHz
No attenuation
Minimum length cables
Best possible sensitivity
Greater than -124 dBm
Less than -126 dBm typical
Daughter
Board
Input
Diagnostic Cable
Sampler
PortOutput
Preselector
Input
Switch
Output
Switch
Main Test Ant
Figure 3: Test equipment interconnection for “bench testing” of system components.
Connection to the appropriate power source is assumed.

TX RX Systems Inc. Manual 7-9322-5 08/09/06 Page 5
Date / Initial Date / Initial Date / Initial
Test Cable length/
type
Test Cable length/
type
Test Cable length/
type
RX Serial # RX Serial # RX Serial #
RX Frequency
(MHz)
RX Frequency
(MHz)
RX Frequency
(MHz)
RX Sensitivity
(dBm)
RX Sensitivity
(dBm)
RX Sensitivity
(dBm)
Static Sensitivity
(dBm)
Static Sensitivity
(dBm)
Static Sensitivity
(dBm)
Installed Sensitivity
(dBm)
Installed Sensitivity
(dBm)
Installed Sensitivity
(dBm)
Test cable Loss
(dB)
Test cable Loss
(dB)
Test cable Loss
(dB)
Test Port w/load
sensitivity (dBm)
Test Port w/load
sensitivity (dBm)
Test Port w/load
sensitivity (dBm)
Test Por t w/
Antenna (dBm)
Test Por t w/
Antenna (dBm)
Test Por t w/
Antenna (dBm)
Max Signal RX
band (dBm)
Max Signal RX
band (dBm)
Max Signal RX
band (dBm)
Max Signal TX
Band (dBm)
Max Signal TX
Band (dBm)
Max Signal TX
Band (dBm)
Max out-of-band
signal (dBm)
Max out-of-band
signal (dBm)
Max out-of-band
signal (dBm)
Date / Initial Date / Initial Date / Initial
Test Cable length/
type
Test Cable length/
type
Test Cable length/
type
RX Serial # RX Serial # RX Serial #
RX Frequency
(MHz)
RX Frequency
(MHz)
RX Frequency
(MHz)
RX Sensitivity
(dBm)
RX Sensitivity
(dBm)
RX Sensitivity
(dBm)
Static Sensitivity
(dBm)
Static Sensitivity
(dBm)
Static Sensitivity
(dBm)
Installed Sensitivity
(dBm)
Installed Sensitivity
(dBm)
Installed Sensitivity
(dBm)
Test cable Loss
(dB)
Test cable Loss
(dB)
Test cable Loss
(dB)
Test Port w/load
sensitivity (dBm)
Test Port w/load
sensitivity (dBm)
Test Port w/load
sensitivity (dBm)
Test Por t w/
Antenna (dBm)
Test Por t w/
Antenna (dBm)
Test Por t w/
Antenna (dBm)
Max Signal RX
band (dBm)
Max Signal RX
band (dBm)
Max Signal RX
band (dBm)
Max Signal TX
Band (dBm)
Max Signal TX
Band (dBm)
Max Signal TX
Band (dBm)
Max out-of-band
signal (dBm)
Max out-of-band
signal (dBm)
Max out-of-band
signal (dBm)
Tower Top Amplifier System Test Data Sheet (table 4)
System Model No.
System Serial No.

TX RX Systems Inc. Manual 7-9322-5 08/09/06 Page 6
1) The stand-alone receiver sensitivity is mea-
sured and recorded first.
2) Connect the equipment as shown in Figure 3.
Be sure that the signal generator is setup for 3
KHz deviation with a 1000 Hz tone.
3) Measure and record the system static sensitiv-
ity on both the MCA front panel and the data
sheet on page 5. The value should be better
than -124 dBm.
4) Use the amplifier select switch on the front
panel of the MCA to select the other tower top
amplifier and insure the static sensitivity value
remains nearly the same. This will insure that
both amplifiers in the tower top box are func-
tioning properly.
INSTALLATION
Interference and Intermodulation
Considerations
Although TX RX Systems, Inc. TTA systems are
designed for maximum interference immunity,
there are many factors that can lead to harmful
interference when using a tower-mounted ampli-
fier.
It is highly recommended that the receiving and
transmitting antennas be vertically separated to
maximize antenna isolation. Although most 800
MHz transmitters are connected to their antenna
through a combiner, it is quite likely that the com-
biner does not have enough transmitter noise filter-
ing to prevent desensitization of the receivers
unless there is significant antenna space isolation.
Large values of antenna isolation are most easily
realized when the antennas are separated verti-
cally. This antenna isolation also helps reduce the
possibility of intermodulation interference in the
receiving system.
One other important factor that can strongly con-
tribute to interference problems is excessive gain,
ahead of the receiver. Excessive gain can cause
overdrive to the station receivers when strong sig-
nals are present, making them more prone to inter-
modulation or carrier desensitization problems.
Receiver preamplifiers should not be used
Tower
Amplifier
Box
3-18375
Base Control Unit
3-18009 or 3-19720
To
120 VAC
Main
Transmission
Line
Test
Port
Line
Main
Transmission
Test
Port
Antenna
To
Station Receivers
To
Additional
8-Way Power Dividers
on Expansion Deck
To
Station Receivers
Figure 4: Cable connections for system components. NOTE: 48 VDC converter used in model 424-86A-03-48.

TX RX Systems Inc. Manual 7-9322-5 08/09/06 Page 7
DESIGN STANDARDS
Mainline grounded at top, base, shelter entrance and
every 75 feet
All external cable connections weatherproofed
Hoisting grips used every 200 feet per mainline
1/2" LDF 10 foot jumper cable from each antenna
to its mainline and tower-top amplifier
Lightning Protection on TX line
3/8" LDF Test Port Mainline
Installation must conform to R56 Standards
1/2" Superflex for all internal RF runs
DC Pickor Lightning Protection on each RX mainline
Motorola part no. DSISDC50LNZ30MA
1.
2.
3.
4.
5.
6.
7.
8.
9.
1/4" Superflex, N male to N male10.
System Engineer responsible for:
All mounting hardware
Wall feed-through hardware
RX TX
Tower Top
Amplifier
4
4
2
2
2
2
2
2
1
1
1
1
1
1
N
NN
8
6
7
7
5
10
5
N
N
Transmit
Combiner
RX
Multicoupler
and
Control
Panel
FROM
REPEATERS
TO
REPEATERS
BNC
Test
Port
Test
Port
Figure 5: System installation guidelines.

TX RX Systems Inc. Manual 7-9322-5 08/09/06 Page 8
because the receiver multicoupler, which is incor-
porated in the MCA, serves this purpose.
Installing the System
Figure 4 illustrates the cable connection points for
both the tower-top box and the MCA. Installation of
the AutoQuad TTA system should follow the
design standards listed in Figure 5. Lightning
surge suppressors are incorporated throughout the
system; refer to items 1, 6, and 7 listed in figure 5.
In addition, surge suppression is also provided for
all cable connections within the tower-top box.
Proper grounding techniques MUST BE observed
for these devices to perform properly. See the fol-
lowing sections for specific installation instructions.
Installing the Tower-Top Box
Figure 6 shows some of the mechanical features
of the tower-top box. Four mounting tabs are
welded to the back of the box to allow for fastening
to the tower.
Because of the varied tower types,
the customer must fabricate the interface brackets
between the tower and the box
.
1) Mount a receiving antenna on the tower.
21.06"
6.69"
Mounting Tabs
.312 Dia Thru
Mount Holes
4 Places
Figure 6: Tower-top box mechanical details.
Figure 7: Application of rubber splicing tape. NOTE: Additional waterproofing protection can be realized by
covering the rubber tape with either “Scotch Kote” or Vinyl Plastic Electrical Tape (“Scotch” brand 33+).
Ground Lug
Te s t Po r t
Transmission
Line
Antenna
Feedline
Main
Transmission
Line

TX RX Systems Inc. Manual 7-9322-5 08/09/06 Page 9
2) Run the main transmission cable as well as the
test port transmission cable up the tower.
3) Mount the tower-top box on the tower and con-
nect the antenna feedline, main transmission
line and test port line.
4) It is important to tighten the door-clamp locking
screws uniformly after installing the tower-top
box so that the door gasket seal is maintained.
Tighten each clamp about half-way, then start
back at the first clamp and fully tighten each
one in the same order. Tighten with a hand tool
only.
NOTE: To insure stability, it is impor-
tant to fasten the box to the tower
using all mounting tabs. The box must
be mounted with the connectors and
moisture relief valve facing down-
ward to prevent water entry. After connecting the
main transmission line and the antenna feedline,
we recommend that the connections be tightly
wrapped with rubber splicing tape (see Figure 7).
This will help prevent water entry into the cables.
Start the wraps on the cable several inches away
from the connector and wrap towards the connec-
tor, to prevent water from seeping in between the
wraps of tape. Cover the connectors completely
with tape.
Installing the Multicoupling Amplifier
The MCA is designed for indoor mounting in a
common 19-inch relay rack or cabinet. The follow-
ing steps are required for proper installation.
1) Install the MCA into the rack or cabinet with four
mounting screws. Connect the main and test
port transmission cables to the appropriate con-
nectors at the back of the unit.
2) If you have a supervisory alarm system, con-
nect its wiring harness to the terminal screws at
the back of the MCA. Refer to Figure 8.
3) For model 424-86A-03-48, connect the leads
from a 48 VDC source to the terminal screws
labeled “ + and - ” at the back of the MCA.
4) For model 424-86A-03, plug the MCA into a
suitable AC outlet. Connect the 24 VDC backup
voltage source to the “+ and -” terminal screws
at the back of the MCA. NOTE: It is recom-
mended that a 5 amp fuse be incorporated into
the output circuit of the backup power system
before connecting it to the MCA.
NOTE
These contacts
change state
when one of
the amplifiers
enters an alarm
condition
These contacts
change state
when one of
the amplifiers
enters a warn-
ing condition
For model 424-86A-03
connect 24 VDC backup
power supply here
OR
For model 424-86A-03-48
connect 48 VDC source here
Figure 8: Alarm and power terminals. Normally open or normally closed screw terminals are available.

TX RX Systems Inc. Manual 7-9322-5 08/09/06 Page 10
CAUTION: On units without the volt-
age limiter (part# 3-20015) the
backup voltage can not exceed 26.7
volts. Units which are equipped with
the voltage limiter the backup volt-
age can not exceed 30.0 volts.
5) Connect the station receivers and optional 16-
port receiver multicoupler expansion deck to the
output ports on the back of the MCA with high-
quality, double-shielded, 50-ohm coaxial cable.
We recommend using RG223 or RG142 dou-
ble-shielded cable for connecting to the station
receivers. This cable type is suitable for use
with BNC connectors. Flexibility in the jumper
cables prevent strain and possible damage to
the connections. We also recommend the use
of high-quality BNC connectors. Connectors
with gold-plated center pins are preferred.
Cable assemblies using these types of connec-
tors are available from TX RX Systems, Inc.
Unused receiver outputs need not be termi-
nated. However, unused expansion ports (the 2
left-most ports) should be terminated with 50
ohms until connected to an expansion panel
(refer to Figure 2C).
About Reserve Gain and Attenuation
Reserve gain (also referred to as MAIN gain) is
adjusted after installation to obtain the best perfor-
mance with a TTA system. The system’s dynamic
range is optimized when the reserve gain is set to
some nominal value. Reserve gain is defined as
the gain of the tower amplifier in dB minus the loss
of the main transmission line in dB. This is the gain
between the input of the tower top amplifier and the
input of the base amplifier.
It has been found in practice that different levels of
reserve gain are required for different types of
modulated signals to obtain the best performance.
Table 5 lists the optimum reserve gain settings for
various signal types. It should be kept in mind that
these values are not extremely critical. Systems
that depart from these gain settings can still give
reasonably good performance, but may degrade
somewhat when extremely strong and very weak
signals are present, as compared with an opti-
mized system.
The reserve gain attenuator is programmable and
needs to be adjusted to optimum levels for the type
of signals being processed. The default factory set-
ting for the reserve gain attenuator is 3 dB. Further
reduction of reserve gain may only be necessary
when the main transmission line loss is low; that is,
when line loss does not reduce the TTA gain
enough to obtain the desired reserve gain level.
Setting reserve gain properly is a two step process
including;
1) Determine the needed attenuation
2) Set the reserve attenuator
DETERMINING NEEDED ATTENUATION
To calculate if attenuation is needed to optimize
reserve gain use the formula;
Reserve gain (dB) = Gain TTA (dB) - Line loss (dB)
For example, if the TTA gain is 20 dB and the main
transmission line loss is 3 dB:
Reserve gain = 20 dB - 3 dB = 17 dB
If our system uses digital voice and data, we would
like a reserve gain as close to 10 dB as possible.
The amount of attenuation required is calculated
with the following formula.
Attenuation (dB) = Actual reserve gain (dB) -
Desired reserve gain (dB)
Attenuation = 17 - 10 = 7 dB
If the sign of the calculated attenuation had been
negative it would indicate that we could actually
use more gain! No attenuation would be required.
The amount of attenuation that can be achieved (0
to 15 dB in 1/2 dB increments) is adequate for main
transmission line losses of 0.5 to 14.5 dB and
allows the reserve gain to be set to its optimum
value over this range of cable loss.
Type of Signal Optimum Reserve Gain
FM Voice 13 dB
Digital 10 dB
Table 5 : Optimum Reserve Gain Settings.

TX RX Systems Inc. Manual 7-9322-5 08/09/06 Page 11
SETTING RESERVE ATTENUATION
Reserve attenuation is adjustable from 0 to 15 dB
in 0.5 dB increments. To adjust the reserve attenu-
ation perform the following steps.
1) Press and hold down the “ENTER” button for 15
seconds. This will place the MCA in the Test
Mode and the display will show the first Test
Mode menu choice
Calibrate LNAs .
2) Scroll through each of the test mode menu
choices by pressing the “SCROLL” button until
the display shows the
Set Attenuators menu.
3) Once the set attenuators menu is displayed
press the “ENTER” button. The display will now
show three menu choices. The active menu
choice is indicated by the “>” symbol next to the
menu title. You can move through the menu
choices using the “SCROLL” button. When the
MAIN menu choice is active you can change
the amount of reserve attenuation the system
provides by pressing the “ENTER” button.
Attenuation is increased in 0.5 dB increments
with each button press. The attenuation setting
works in a forward loop fashion, starting at 0
and increasing to 15, a button press after 15
returns the setting back to 0. After the reserve
attenuation is set to the desired value move the
“>” symbol to the OK menu choice and press
the “ENTER” button to exit back to the main
menu.
4) Exit the menu mode and return to normal oper-
ation by pressing down the front panel select
switch. The system will reset.
About Multicoupler Gain and Attenuation
Multicoupler gain (referred to as BASE gain) is also
adjusted after installation to obtain best system
performance. BASE gain allows for proper com-
pensation of the MCA-to-receiver cable loss and
should ideally be set to unity. It is defined as the
gain between the input of the base amplifier and
the input of the station receiver. Typically 2 to 3 dB
of attenuation is usually required for unity gain. The
default factory setting for multicoupler gain is 1 dB.
Use the attenuation values shown in Table 6 to set
the multicoupler gain to the correct value.
SETTING MULTICOUPLER ATTENUATION
Multicoupler attenuation is adjustable from 0 to 4
dB in 1.0 dB increments. To adjust the multicoupler
attenuation perform the following steps.
1) Press and hold down the “ENTER” button for 15
seconds. This will place the MCA in the Test
Mode and the display will show the first Test
Mode menu choice
Calibrate LNAs .
2) Scroll through each of the test mode menu
choices by pressing the “SCROLL” button until
the display shows the
Set Attenuators menu.
3) Once the set attenuators menu is displayed
press the “ENTER” button. The display will now
show three menu choices. The active menu
choice is indicated by the “>” symbol next to the
menu title. You can move through the menu
choices using the “SCROLL” button. When the
BASE menu choice is active you can change
the amount of multicoupler attenuation the sys-
tem provides by pressing the “ENTER” button.
Attenuation is increased in 1.0 dB increments
with each button press. The attenuation setting
works in a forward loop fashion, starting at 0
and increasing to 4, a button press after 4
returns the setting back to 0. After the multicou-
pler attenuation is set to the desired value move
the “>” symbol to the OK menu choice and
press the “ENTER” button to exit back to the
main menu.
4) Exit the menu mode and return to normal oper-
ation by pressing down the front panel select
switch. The system will reset.
POST INSTALLATION TESTS
These tests measure the full range of performance
from the maximum achievable to real-world perfor-
Set base attenuation to for cable loss of
3 dB 1 dB
2 dB 2 dB
1 dB * 3 dB
0 dB more than 3 dB
* factory default setting
Table 6: Base attenuation settings.

TX RX Systems Inc. Manual 7-9322-5 08/09/06 Page 12
mance in the presence of RF noise. Spectrum
analysis is included to determine if potentially
harmful signals are being delivered to the station
receivers. These tests are absolutely necessary,
not only to insure proper performance, but also to
serve as a bench mark for future evaluations and
troubleshooting. The post installation steps include
the following:
• Installed sensitivity test.
• Test port sensitivity with dummy load.
• Test port sensitivity with antenna.
• Spectrum analysis.
Installed Sensitivity Test
Important:
The installed sensitivity test should be
performed before the tower box connectors are
waterproofed so that they can be readily loosened
and reconnected. Taping and waterproofing fol-
lows successful completion of the post installation
tests.
The assistance of the tower climber is required
after the installation to perform the installed sensi-
tivity test. Instruct the climber to temporarily con-
nect the test cable to the antenna port. Temporarily
disconnect the test cable from the rear of the MCA
and connect it to the output of your signal genera-
tor. The correct connections are shown in Figure
9. Be sure that the signal generator is set up for 3
KHz deviation with a 1000 Hz tone.
• Record the Installed sensitivity as measured.
CALCULATE CABLE LOSS
The signal loss of the test cable can be calculated
based on knowledge of the static and installed sen-
sitivities previously measured. The relationship is:
Test cable loss (dB) = Static Sensitivity (dBm) -
Installed sensitivity (dBm)
For example, if the Static Sensitivity = -126 dBm
and the Installed Sensitivity = -119 dBm then:
Test
Port
12 dB SINAD
Signal Generator
RX MCA
RF
Out
FRX MHz
3 KHz dev
1 KHz
System fully installed
Main and base gain set
Test cable temporarily connected to
antenna port and Signal Generator
Installed sensitivity determined
- Pre-installed sensitivity = line loss
Daughter
Board
Input
Test Cable
Sampler
PortOutput
Preselector
Input
Switch
Output
Switch
Main Test Ant
Figure 9: TTA system and test equipment interconnection for the installed sensitivity test.

TX RX Systems Inc. Manual 7-9322-5 08/09/06 Page 13
Test cable loss = (-126) dBm - (-119) dBm = -7 dB
The test cable loss subtracts from the measured
sensitivity at ground level (static sensitivity) to yield
a lower sensitivity value yet accurate reference
sensitivity.
Tri-Mode Test Port
The test port provides an RF path from the BNC
connector on the front panel of the MCA to an iso-
lated 30 dB port at the antenna input of the TTA
preselector. The test port has 3 software selectable
modes of operation including;
Mode 0 (Default) connects the input of the tower
top preselector to the antenna and connects the
test port to the 30 dB port of the preselector.
Mode 1 (Desense) switches the input of the prese-
lector to an internal 50 ohm load. This allows
checking for external interference or desensitiza-
tion with minimal disruption to the system.
Mode 2 (Antenna Sweep) connects the test cable
directly to the antenna. This mode facilitates
sweeping the transmission line and antenna with
minimal disruption to the system.
Mode 0 is the systems default mode of operation.
To change the mode perform the following steps;
1) Press and hold down the “ENTER” button for 15
seconds. This will place the MCA in the Test
Mode and the display will show the first Test
Mode menu choice
Calibrate LNAs .
2) Scroll through the test mode menu choices by
pressing the “SCROLL” button until the display
shows the
Select Mode/LNA menu.
3) Once the select mode/LNA menu is displayed
press the “ENTER” button. The display will now
show three menu choices. The active menu
choice is indicated by the “>” symbol next to the
menu title. You can move through the menu
choices using the “SCROLL” button. With the
Test
Port
12 dB SINAD
Signal Generator
RX MCA
RF
Out
FRX MHz
3 KHz dev
1 KHz
Signal generator into test port
Base-line sensitivity measured
Daughter
Board
Input
Diagnostic
Cable
Antenna
Sampler
PortOutput
Preselector
Input
Switch
Output
Switch
Main Test Ant
Figure 10: Measuring test port sensitivity of the TTA system with the dummy load selected.

TX RX Systems Inc. Manual 7-9322-5 08/09/06 Page 14
“>” symbol next to the MODE menu change the
mode using the enter button. For additional
testing while in modes 0 or 1 the active amplifier
in the TTA can be changed also. Move the “>”
to the LNA menu and select either the A or B
amplifier. Note that mode 2 does not allow
amplifier selection.
4) Exit the menu mode and return to normal oper-
ation by pressing down the A/B amplifier select
switch. The system will reset itself to mode 0
with amplifier A active. This is the default mode
of operation.
Test Port Sensitivity with Dummy load (Mode 1)
Place the system into Test Port Mode 1. During
this test a 50 ohm load is switched into the input of
the tower top preselector. The equipment is con-
nected as shown in Figure 10. For future reference
record the length and type of diagnostic cable
used. The same length and type of diagnostic
cable should be used when performing all post
installation tests. (
Small diameter coaxial cable
used for diagnostic connections has relatively high
signal loss per foot at 800 MHz and higher. If differ-
ent cable lengths are used when making tests, it
will contribute to significant variability of the mea-
sured levels
).
• Record the test port sensitivity on the data
sheet.
This value represents the best possible sensitivity
measured though the test port and is always lower
than the value obtained in the Installed Sensitivity
test by a factor of approximately -30 dB which is
the coupling loss of the sampling port built into the
preselector in the tower box (the coupling loss can
vary from TTA to TTA by a factor of -28 to -32 dB).
Test Port Sensitivity with Antenna (Mode 0)
• Place the system into Test Port Mode 0. This is
the normal default mode of operation for the
system and connects the antenna to the input
of the preselector. The equipment is connected
as shown in Figure 11.
Test
Port
12 dB SINAD
Signal Generator
RX MCA
RF
Out
FRX MHz
3 KHz dev
1 KHz
Generator to test port
= Effective sensitivity
Enter on front panel
Daughter
Board
Input
Diagnostic
Cable
Antenna
Sampler
PortOutput
Preselector
Input
Switch
Output
Switch
Main Test Ant
Figure 11: Measuring test port sensitivity with antenna connected
(sensitivity less than or equal to sensitivity using a dummy load).