Bird Technologies Group 5PI613805 SIGNAL BOOSTER User Manual 9408cvr 1 2

Bird Technologies Group SIGNAL BOOSTER 9408cvr 1 2

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5PI613805 User Manual HTML Version

USERS MANUAL

Part No.

61-38-05 UserMan page 1 of 38

Installation and Operation Manual

for the Two-Way Signal Booster System

Model Number 61-38-05

First Printing: June 2005

7-9408-1.2

Version Number Version Date

1 06/14/05

1.1 07/12/05

1.2 07/25/05

61-38-05 UserMan page 2 of 38

NOTE

WARNING

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 workman-

ship 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 damage 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 ex-

pressed 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 connection 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. Federal, 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 collect 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 purchase.

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 policy

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 supercede part numbers given within this manual.

Information is subject to change without notice.

Symbols

Commonly Used

CAUTION or

ATTENTION

High Voltage

Use Safety

Glasses

ESD

Electrostatic

Discharge

Hot Surface

Electrical Shock

Hazard

Important

Information

61-38-05 UserMan page 3 of 38

To satisfy FCC RF exposure requirements for transmitting

devices, a separation distance of 70 Centimeters or more

should be maintained between the UPLINK antenna of this

device and persons during device operation. To satisfy FCC

RF exposure requirements for transmitting devices, a sepa-

ration distance of 21.5 Centimeters or more should be main-

tained between the DOWNLINK antenna of this device and

persons during device operation. To ensure compliance,

operations at closer than these distances is not recom-

mended.

The antenna used for this transmitter must not be co-located

in conjunction with any other antenna or transmitter.

WARNING

For Class A Unintentional Radiators

This equipment has been tested and found to comply with the limits for a Class A digital device, pursuant to

part 15 of the FCC rules. These limits are designed to provide reasonable protection against harmful inter-

ference when the equipment is operated in a commercial environment. This equipment generates, uses,

and can radiate radio frequency energy and, if not installed and used in accordance with the instruction

manual, may cause harmful interference to radio communications. Operation of this equipment in a resi-

dential area is likely to cause harmful interference in which case the user will be required to correct the

interference at his own expense.

Changes or modifications not expressly approved by TX

RX System Inc. could void the user’s authority to operate

the equipment.

WARNING

This device complies with Part 15 of the FCC Rules. Operation is subject to the

following two conditions: (1) this device may not cause harmful interference and

(2) this device must accept any interference received, including interference

that may cause undesired operation.

61-38-05 UserMan page 4 of 38

Antenna System Installation

The antenna or signal distribution system consists of two branches. An uplink

branch typically uses an outdoor mounted, unidirectional gain antenna such

as a yagi and a downlink signal radiating system consisting of a network of

zero-gain whip antennas or lengths of radiating cable usually mounted inside

of the structure.

Even though the antenna system may not be supplied or installed by TX RX

Systems. The following points need to be observed because both the safety

of the user and proper system performance depend on them.

1) Antenna system installation should only be performed by qualified techni-

cal personnel.

2) The following instructions for your safety describe antenna installation

guidelines based on FCC Maximum RF Exposure Compliance require-

ments.

3) The uplink antenna is usually mounted outside and exchanges signals

with the repeater base station or donor site. It is typically mounted perma-

nently-attached to the building wall or roof. The gain of this antenna should

NOT exceed 10 dB. Only qualified personnel should have access to the

antenna and under normal operating conditions, no one should be able to

touch or approach it within 70 Centimeters (28 inches).

4) The downlink or in-building signal distribution system is connected to the

downlink booster port using coaxial cable. The distribution system may

use radiating coaxial cable or a network 1/4 wave whip antennas whose

gain does not exceed 0 dB for any radiator. These antennas should be

installed so that the user cannot approach any closer than 21.5 Centime-

ters (9 inches) from the antenna.

Table of Contents Manual 7-9408-1.2 07/25/05

61-38-05 UserMan page 5 of 38

Table of Contents

Section 1

Introduction ......................................................................................................... 1

Note About Output Power Rating ........................................................................ 3

Installation............................................................................................................ 3

Cautionary Notes ................................................................................................. 4

Pre-RF Connection Tests.................................................................................... 4

Test Equipment ................................................................................................... 5

Antenna Isolation ................................................................................................. 5

Procedure for Measuring Antenna Isolation ........................................................ 5

Increasing Isolation.............................................................................................. 6

Input Signal Levels .............................................................................................. 6

Procedure for Measuring Input Signal Levels...................................................... 6

Reduction of Incoming Signal Strength ............................................................... 8

Setting Signal Booster Gain ................................................................................ 8

Gain Reduction Methods ..................................................................................... 8

Bypassing Amplifier Sections ............................................................................ 9

Operation.............................................................................................................. 9

Signal Flow........................................................................................................... 9

System Components.........................................................................................10

Passive Filtering ................................................................................................ 10

DC Regulator (3-5969) ...................................................................................... 11

OLC Assembly (3-6280) .................................................................................... 11

Pre-amplifier Stage (3-11423) ...........................................................................12

Driver Amplifier Stage (3-11423) ....................................................................... 13

Hi Power Amplifier Assembly (3-11792)............................................................13

Signal Sampler (3-6999).................................................................................... 13

Signal Sampler (3-3569).................................................................................... 13

DC Junction Box (3-6254) ................................................................................. 13

Power Supply Assembly (3-15503) ................................................................... 13

Performance Survey.......................................................................................... 14

Field Adjustments ............................................................................................. 14

Filter Tuning....................................................................................................... 15

Helical Preselectors........................................................................................... 16

Required Equipment........................................................................................ 16

Tuning Procedure ............................................................................................ 16

Bandpass Filters................................................................................................ 17

Required Equipment........................................................................................ 17

Tuning Procedure ............................................................................................ 17

Pseudo-Bandpass Filters ..................................................................................18

Required Equipment........................................................................................ 19

Tuning Procedure ............................................................................................ 19

Notch Filters ...................................................................................................... 20

Required Equipment........................................................................................ 20

Tuning Procedure ............................................................................................ 21

Single Section Amplifier Subassemblies ........................................................... 22

Amplifier Tuning...............................................................................................22

Required Equipment........................................................................................ 22

Adjustment Procedure ..................................................................................... 23

Output Level Control (OLC)............................................................................... 25

Checking for Overload.....................................................................................25

Table of Contents Manual 7-9408-1.2 07/25/05

61-38-05 UserMan page 6 of 38

Maintenance and Repair ................................................................................... 26

Recommended Replacement Parts ................................................................. 26

Conversion Chart .............................................................................................. 26

Figures and Tables

Figure 1: Front view of typical 61-38-05 system ................................................... 2

Figure 2: Bottom view of the cabinet enclosure.................................................... 3

Figure 3: Top view of the cabinet enclosure......................................................... 4

Figure 4: Measuring antenna isolation ................................................................. 5

Figure 5: Measuring input signal levels ................................................................ 7

Figure 6: Observing RF power output .................................................................. 8

Figure 7: 1 stg/3 stg amplifier assembly 3-11423................................................. 9

Figure 8: OLC assembly 3-6280......................................................................... 12

Figure 9: Measuring signal booster gain ............................................................ 14

Figure 10: Surveying performance .....................................................................15

Figure 11: Preselector tuning ............................................................................. 16

Figure 12: Observing preselector return loss ..................................................... 17

Figure 13: Bandpass filter tuning........................................................................18

Figure 14: The pseudo-bandpass filter...............................................................18

Figure 15: Tuning for maximum return loss ........................................................19

Figure 16: Tuning for maximun attenuation ........................................................ 20

Figure 17: The notch filter................................................................................... 20

Figure 18: Tuning for maximum return loss ........................................................21

Figure 19: Tuning for maximum attenuation ....................................................... 22

Figure 20: Mechanical layout of single section amplifier ....................................23

Figure 21: Measuring amplifer gain .................................................................... 24

Figure 22: Meqsuring input return loss ...............................................................24

Figure 23: Measuring output return loss ............................................................. 25

Figure 24: Measuring reverse isolation ..............................................................25

Specifications .................................................................................................... 33

Power Conversion Chart................................................................................... 35

Notes................................................................................................................... 38

TXRX Systems Inc. Manual 7-9408-1.2 07/25/05 Page 7

61-38-05 UserMan page 7 of 38

INTRODUCTION

This publication, Instruction Manual 7-9408-1, con-

tains information to support the installation, opera-

tion, and maintenance of the model 61-38-05

signal booster system. Also included in this manual

are the procedures necessary for field adjust-

ments. It is assumed that procedures in this man-

ual will be carried out by a skilled electronics

technician who is familiar with the communications

system. This manual also gives an elementary

explanation of the operation of signal boosters and

signal distribution systems. For a more detailed

discussion of signal booster systems and design

methods, refer to the TX RX Systems Inc. publica-

tion "SEMINAR SUBJECTS" entitled "Repeater

Amplifier Systems: Principles and Applications" (lit-

erature number C2012J94). Contact your TX RX

Systems, sales representative if you wish to order

a copy.

The 61-38-05 booster family is designed to cover

the frequency range of 138 to 174 MHz in two non

contiguous bands, One version covers 138 to 144

MHz for operation in Canada and another version

to cover 148 to 174 MHz. This version is also used

to cover U.S. land-mobile frequencies from 150.8

to 174 MHz. Units for both bands share common

active circuitry but differ in the passive filter units

that duplex the downlink and uplink branches from

a common input or to a common output. Because

signal booster systems are often times subjected

to very demanding environments with extreme con-

ditions of temperature, moisture, dirt and corro-

sives, the system is housed in a high quality

(NEMA style) enclosure. This type of housing

maintains its dimensional stability and appearance

better than other materials. Figure 1 shows a front

view of the unit with the door opened.

The system uses linear RF active amplifiers, filters,

OLC (output level control) circuitry, and DC power

sources to adequately boost the level of the RF sig-

nals. Linear power amplifiers (Class-A) are used in

the amplifier stages of this signal booster system in

contrast to the highly efficient Class-C power

amplifiers used in the output stages of most FM

landmobile transmitters. Linear amplifiers are

biased for a relatively high continuous DC current

drain that does not change with changing RF drive

levels.

Class-A amplifiers generally have the lowest effi-

ciency of the various amplifier types, typically in the

range of 25-33%. They also draw relatively high

current levels on a continuous basis, making heat

dissipation an important factor. Their biggest

advantage is faithful reproduction of the input

waveform which results in the lowest levels of inter-

modulation distortion products (IM) of all the

classes of amplifiers. IM generation is a serious

design consideration when two or more channels

are simultaneously present in the same amplifier

stage.

Preselector filters are used in the system to provide

a number of functions including; reduction of the

level of undesired signals that may enter the sys-

tem and also help suppress any IM products that

may be inadvertently generated. They also pro-

duce a convenient impedance characteristic that

allows multiple branch paths to be tied together to

a common input/output port. This is accomplished

using critical length cables from the filter assem-

blies to a tee junction.

The output level of any signal passing through a

signal booster is determined by the input signal

level, the gain of the booster, and the maximum

output power per carrier rating of the booster. The

high power output stages used in the signal

booster may be damaged by excessive input sig-

nals. An output level control (OLC) circuit is added

to each amplifier chain to protect the amplifiers and

reduce spurious signals. The OLC circuit is

designed to maintain the maximum output level of

the booster during times of excessive input signal

levels.

OLC circuitry actuates when a predetermined max-

imum output level is reached. The output power

level in all OLC branches is sampled, and then fed

to a detector circuit which generates a DC voltage

proportional to the output power level. The DC out-

put of the detector is then applied to a control cir-

cuit which develops a voltage used to control a

variable electronic attenuator. The electronically

controlled attenuator is placed within the amplifier

signal path and reduces the incoming signal by an

amount necessary to keep the power from exceed-

ing the maximum safe level. The gain reduction

range is typically from 5 to 40 dB which is more

than adequate for most real life situations.

OLC circuitry should not be considered a panacea

for a poor system design. One undesirable affect of

OLC is that the signal level of all signals being pro-

cessed by the branch will be reduced when the cir-

cuitry is activated. This means that the

61-38-05 UserMan page 8 of 38

TXRX Systems Inc. Manual 7-9408-1.2 07/25/05 Page 8

Figure 1: Front view of a typical model 61-38-05 signal booster system.

Backup Battery

connects here

Filtering Filtering

Signal

Sampler

3-3569

Signal

Sampler

3-3569

Signal

Sampler

3-6999

Signal

Sampler

3-6999

OLC

Assembly

3-6280

OLC

Assembly

3-6280

1 stg/3 stg

Amplifier

Assembly

3-11423

1 stg/3 stg

Amplifier

Assembly

3-11423

High Power

Amplifier

Assembly

3-11792

High Power

Amplifier

Assembly

3-11792

Regulator

3-5969

Regulator

3-5969

Power Supply

Assembly 3-11503

RF In/Output

Connector RF In/Output

Connector

TXRX Systems Inc. Manual 7-9408-1.2 07/25/05 Page 9

61-38-05 UserMan page 9 of 38

performance of the system is actually decreased

on all other channels within the branch as long as

gain reduction is taking place. This implies that

OLC has been designed to handle short term or

transient overdrive episodes only.

Note About Output Power Rating

A single maximum output power rating does not

apply to broadband signal boosters because the

linear amplifiers (Class A) used in them may have

to process multiple simultaneous signals. Under

these conditions, the questions of power rating

becomes more complex.

When more than one signal is amplified, a number

of spurious signals will also appear in the amplified

output. They are referred to as intermodulation dis-

tortion products, more commonly called I.M. These

spurious products would not be present in a per-

fectly linear amplifier but as in all things, something

short of perfection is realized. The net result is that

the total power out in each signal will be somewhat

less than the single carrier rating in order to main-

tain adequate I.M. performance.

INSTALLATION

The layout of the signal distribution system will be

the prime factor in determining the mounting loca-

tion of the signal booster enclosure. However,

safety and serviceability are also key consider-

ations. The unit should be located where it cannot

be tampered with by unauthorized personnel yet is

easily accessible to service personnel using trou-

ble shooting test equipment such as digital multim-

eters and spectrum analyzers. Also consider the

weight and size of the unit should it become

detached from its mounting surfaces for any rea-

son.

Very little is required to install this signal booster.

The unit should be bolted in its permanent position

using lag bolts or other suitable fasteners. Make

sure there is an unobstructed airflow over the

external heatsinks. Safety and serviceability are

key considerations. The signal booster cabinet will

stay warm during normal operation so in the inter-

est of equipment longevity, avoid locations that will

expose the cabinet to direct sun or areas where the

temperature is continually elevated.

The signal booster is designed to be powered from

120 VAC and a conduit entry box is provided at the

bottom of the enclosure for bringing the AC line into

the cabinet. AC line connections should be made in

accordance with local electrical and building codes.

The battery backup system should also be con-

Figure 2: Bottom view of cabinet enclosure.

61-38-05 UserMan page 10 of 38

TXRX Systems Inc. Manual 7-9408-1.2 07/25/05 Page 10

nected at this time. The 3-pin MS style connector

for the backup power system is labeled and is

located on the bottom of the enclosure. A photo-

graph of the bottom of the cabinet is shown in Fig-

ure 2.

Connection of RF to the unit is made via “N” female

connectors located on top of the cabinet. These

connectors are individually labeled “High Frequen-

cies IN Low frequencies OUT” and “Low Frequen-

cies IN High Frequencies OUT”. Care should be

used when making connections to these ports to

insure the correct antenna cable is connected to its

corresponding input / output port or the system will

not work. The use of high quality connectors with

gold center pins is advised. Flexible jumper cables

made of high quality coax are also acceptable for

connecting to rigid cable sections. A photograph of

the top of the cabinet is shown in Figure 3.

CAUTIONARY NOTES

The following cautions are not intended to frighten

the user but have been added to make you aware

of and help you avoid the areas where experience

has shown us that trouble can occur.

1) Just like the feedback squeal that can occur

when the microphone and speaker get too close to

each other in a public address system, a signal

booster can start to self oscillate. This will occur

when the isolation between the input antenna or

signal source and the output antenna or signal dis-

tribution system does not exceed the signal

booster gain by at least 10 dB. This condition will

reduce the effectiveness of the signal booster and

possibly damage the power amplifier stages.

2) The major cause of damage to signal boosters is

the application of input RF power levels in excess

of the maximum safe input. This can happen inad-

vertently when connecting a signal generator with

full power out to one of the inputs or by a very

strong signal that is far stronger than expected.

The Maximum Safe Power input level for your unit

can be found on the laminated tag affixed to the top

of the cabinet near the RF input/outputs. Following

the pre-installation checks listed below will help to

avoid these two problems.

PRE-RF CONNECTION TESTS

Certain characteristics of the signal distribution

system should be measured before connecting it to

the signal booster. This step is necessary to insure

that no conditions exist that could possibly damage

the signal booster and should not be skipped for

even the most thoroughly designed system. Two

characteristics need to be measured; antenna iso-

lation and input signal levels.

Figure 3: Top view of cabinet enclosure.

TXRX Systems Inc. Manual 7-9408-1.2 07/25/05 Page 11

61-38-05 UserMan page 11 of 38

Test Equipment

The following equipment is required in order to per-

form the pre-installation measurements.

1) Signal generator for the frequencies of interest

capable of a 0 dBm output level. Modulation is

not necessary.

2) Spectrum analyzer that covers the frequencies

of interest and is capable of observing signal

levels down to -100 dBm.

3) Double shielded coaxial test cables made from

RG142 or RG55 coaxial cable.

Antenna Isolation

Antenna isolation is the signal path isolation

between the two sections of the signal distribution

system that are to be connected to the signal

boosters antenna ports. Lack of sufficient isolation

between the input and output antennas can cause

the amplifiers in the system to oscillate. This can

happen at a high enough level to damage the

power amplifier stages. In general, if one or both

antenna ports are connected to sections of radiat-

ing coaxial cable (lossy cable) via short jumpers of

non-radiating cable the isolation will be more than

adequate because of the high coupling loss values

that are encountered with this type of cable. When

a network of antennas are used for the input and

output, this problem is much more likely. Isolation

values are relatively easy to measure with a spec-

trum analyzer and signal generator.

Procedure for Measuring Antenna Isolation

1) Set the signal generator for a 0 dBm output

level at the center frequency of one of the signal

boosters passbands.

2) Set the spectrum analyzer for the same center

frequency and a sweep width equal to or just

slightly greater than the passband chosen in

step one.

3) Connect the test leads of the signal generator

and the spectrum analyzer together using a

female barrel connector, see Figure 4. Observe

the signal on the analyzer and adjust the input

attenuator of the analyzer for a signal level that

just reaches the 0 dBm level at the top of the

graticule.

INTERNAL

SIGNAL DISTRIBUTION

SYSTEM

SPECTRUM

ANALYZER

EXTERNAL

ANTENNA

SIGNAL

GENERATOR

ZERO LOSS

REFERENCE

ISOLATION (dB)

Figure 4: Typical test equipment setup for measuring antenna isolation.

61-38-05 UserMan page 12 of 38

TXRX Systems Inc. Manual 7-9408-1.2 07/25/05 Page 12

4) Referring to figure 4, connect the generator test

lead to one side of the signal distribution system

(external antenna) and the spectrum analyzer

lead to the other (internal distribution system)

and observe the signal level. The difference

between this observed level and 0 dBm is the

isolation between the sections. If the signal is

too weak to observe, the spectrum analyzer's

bandwidth may have to be narrowed and its

input attenuation reduced. Record the isolation

value. The isolation value measured should

exceed the amplifier gain figure by at least

15 dB.

It is wise to repeat the procedure listed above for

measuring antenna isolation, with the signal gener-

ator set to frequencies at the passbands edges in

order to see if the isolation is remaining relatively

constant over the complete width of the passband.

Also, the procedure should be repeated for each of

the remaining channels in the system.

Increasing Isolation

If the measured isolation does not exceed the

amplifier gain figure by at least 15 dB then modifi-

cation of the signal distribution system is required.

Alternately, the gain of the signal booster can also

be reduced to insure the 15 dB specification is met.

If the isolation cannot be increased then the

amount of gain reduction required is determined as

shown in the following example.

Input Signal Levels

Excessive input signal levels can damage the sig-

nal booster. Although this problem is less severe in

OLC protected branches, strong signals may cause

sudden reductions in gain and an associated

decrease in the desired output signal strength.

Even in the most carefully designed signal distribu-

tion systems, unpredictable situations can arise

that can cause this trouble. A few of the more com-

mon causes are:

a) Unintended signals entering the system. Prima-

rily caused by radios operating on channels that

are within the operational bandwidth of the sig-

nal booster. Sometimes this will be a transient

problem caused by mobile units when they

transmit while in close proximity to your system.

b) Hand-held and mobile units that approach

much closer than expected to one of the anten-

nas in the signal distribution system.

c) Unexpected signal propagation anomalies.

Building geometry can cause signal ducting and

other phenomena that cause signal levels that

are much stronger (or lower) than expected.

d) Lower than estimated signal attenuation causes

signals to be unusually strong. Higher losses

can also occur giving weaker signals than

desired.

e) Signal booster model with excessive gain. In

systems that have an existing signal booster, it

is sometimes assumed that an identical unit

should be installed when expanding the system

to provide extended coverage. In most cases, a

signal booster with far less gain than the first is

required.

f) Improper installation or application of signal

splitters or directional couplers in the signal dis-

tribution system. This is usually the cause of too

low a signal level but deserves mentioning here.

Signal splitting needs to be done with constant

impedance signal splitters so that the proper

power splitting ratios and VSWR are main-

tained. Using tee connectors by themselves is

inviting trouble. Directional couplers must be

connected with regard to their directionality and

coupling levels or improper system signal levels

may result.

Procedure for Measuring Input Signal Levels

1) Set a spectrum analyzer for the center fre-

quency of one of the branches (look at the

specification drawing for this information).

2) Set the analyzer sweep width so that the entire

passband frequency range can be observed.

EXAMPLE

Gain Reduction (dB) = Minimum Isolation (dB) -

Measured Isolation (dB)

If the measured isolation is -75dB and the mini-

mum isolation is -80dB then the amount of gain

reduction required is: -80dB - (-75) = -5 dB

TXRX Systems Inc. Manual 7-9408-1.2 07/25/05 Page 13

61-38-05 UserMan page 13 of 38

3) The analyzer input attenuator should be set to

observe input signal levels from approximately -

80 dBm to 0 dBm.

4) Connect the analyzer to the section of the sig-

nal distribution system that is going to serve as

the input for the branch you want to observe

(see Figure 5).

5) Record the power level (in dBm) of all carriers in

the passband frequency range that are signifi-

cantly greater than the noise floor displayed on

the analyzer.

6) Repeat steps 1 through 5 for the remaining sig-

nal booster channels.

7) To find the total power being applied to the

channel, the calculations listed below must be

performed. The conversion chart at the rear of

the manual can be used. Here are the steps:

a) Convert all values in dBm to Watts

b) Total the power for all carriers in Watts

c) Convert the total power in Watts to dBm

Repeat the calculation for all of the branches in the

system. For example: suppose we have a signal

booster with a maximum gain of 70 dB. After

checking the input signal levels, it was determined

that there are three signals that are significantly

greater than the noise floor displayed on the ana-

lyzer. These signals have strengths of -45 dBm, -

43 dBm and -41 dBm.

First we use the conversion chart at the end of this

manual to convert the power levels in dBm to watts

so that we can add them together. The power in

watts is written in scientific notation but the chart

uses computer notation. For example, in the chart,

an exponent may be written as E-08. In conven-

tional mathematical notation E-08 is written 10-8.

The total power must be written as a number

between 0 and 10 to use the chart. Look up

1.611E-7 in the Watts column. This number falls

between -38 and -37 dBm so we chose -37

because it is the next higher value.

Power (dBm) Power (watts)

-45 dBm 3.16 x 10-8

-43 dBm 5.01 x 10-8

-41 dBm 7.94 x 10-8

TOTAL 16.11 x 10-8

S p e c t r u m A n a l y z e r

R a d i o 1

R a d i o 2

S I G N A L D I S T R I B U T I O N S Y S T E M

Figure 5: Typical test equipment setup for measuring input signal levels.

61-38-05 UserMan page 14 of 38

TXRX Systems Inc. Manual 7-9408-1.2 07/25/05 Page 14

Reduction of Incoming Signal Strength

Reducing the strength of offending signals may

require some or all of the following steps:

a) The addition of extra filtering. Consult TX RX

System's sales engineers for help in this

respect.

b) Modification of the signal distribution layout by

changing the type or location of pickup anten-

nas. This has to be approached in an empirical

way, that is, change-and-try until you get the

desired results. Sometimes changing from omni

to directional antennas will correct the problem.

Setting Signal Booster Gain

The Pre-Installation checks as outlined earlier

should have been performed to determine if gain

reduction will be necessary for your installation.

This can be due to low antenna isolation or exces-

sive input signal levels, or both. The actual amount

of gain reduction is determined by the largest num-

ber required because of either low isolation or

excessive signal levels.

For example, if the results of the isolation measure-

ment indicated the need for a gain reduction of -10

dB but signal level measurements indicate a need

for only a -5 dB gain reduction; then 10 dB is the

number required since both conditions are satis-

fied.

Gain Reduction Methods

As shipped from the factory, the system was setup

for maximum gain. Gain reduction is accomplished

by adding fixed attenuator pads or where even

greater reductions are required by bypassing one

section in a multi-section amplifier stage. Bypass-

ing of amplifier sections is preferred for large gain

reductions so that excessive noise levels are not

produced. Use of attenuator pads alone will reduce

gain but the signal booster will also amplify the

noise generated in the lower level sections.

The addition of attenuator pads may be necessary

in order to achieve the proper signal levels in the

overall communications system. This is quite com-

mon as actual signal losses in a radiating cable

system can vary somewhat from predicted theoret-

ical values. Fine adjustment of gain in communica-

tions systems with cascaded signal boosters can

be very important to keep performance uniform

over the entire length of the system.

Figure 6 shows the use of a spectrum analyzer to

monitor signal levels in a signal booster. The ana-

lyzer connects to the signal sampler on the output

end of the branch to be tested. Attenuation is then

adjusted for the proper signal levels factoring in the

RF from Antenna or

Previous Repeater Amplifier

Signal Distribution System

FilterFilter

Sampler

Variable

Attenuator

Spectrum

Analyzer

10 dB Pad

Amp

Figure 6: Observing RF power output of a signal booster using a spectrum analyzer.

TXRX Systems Inc. Manual 7-9408-1.2 07/25/05 Page 15

61-38-05 UserMan page 15 of 38

-50 dB coupling loss of the signal sampler and any

additional loss produced by attenuator pads on the

analyzer input. A pad on the analyzer input can

help to minimize measurement errors due to

VSWR mismatch that occurs with some analyzers.

A pair of fixed attenuator pads (3 and 6 dB) are

supplied for the purpose of gain reduction. They

are mounted in clips to the top of the filter assem-

blies in the center of the unit. The pads’ attenuation

values are clearly labeled on the body of the atten-

uator. The correct position for adding fixed pads to

the system is at the input or output of the electronic

attenuator ports on the OLC assembly (shown as

the dotted outline symbols on the specification

drawing).

CAUTION: Any fixed attenuator pads

that are already connected into the

booster circuitry have been installed

at the factory and should not be

removed for any reason. Their func-

tion may be other than gain reduc-

tion.

BYPASSING AMPLIFIER SECTIONS

Sometimes the amount of gain reduction needed is

greater than the amount available with the fixed

attenuator pads alone. In this case, the first stage

of the three stage portion of amplifier assembly (3-

11423) in the uplink or downlink branch may be

bypassed. The individual stages of these multi-

stage amplifiers are connected together with short

lengths of coaxial cable. To bypass the first stage of

the driver amp remove the coax cable that inter-

connects the first and second stages of the driver

amplifier (see Figure 7). Move the input cable from

the input connector on the first stage to the corre-

sponding connector on the second stage of the

driver amp. The BNC RF input connector for each

amplifier stage is located furthest from the DC

input TNC connector. Keep in mind that the total

gain reduction is the sum of the added padding

plus the loss of gain for the bypassed amplifier sec-

tion. Quality 50 ohm terminations should be

installed on the open terminals of any bypassed

stage.

OPERATION

It is imperative that the pre-installation checks be

performed as outlined earlier. Failure to do so may

lead to unsatisfactory operation or damage to the

signal booster. All that is required in order to put

the system into operation after the installation is to

turn on the power supply assembly. The green LED

on the power supply will illuminate indicating nor-

mal operation. If the red LED on the power supply

assembly illuminates it indicates operation from the

backup power source.

SIGNAL FLOW

Signal flow through the system is illustrated using

the system block diagram that is shown in specifi-

cations drawing shipped with your system. The 61-

38-05 model signal boosters are composed of 2

branches, uplink and downlink. Because the uplink

Pre-Amp

(Single Stage)

Driver Amp

(3 Cascaded Stages)

Output

Input

Output

Input

Figure 7: 1stg/3stg amplifier assembly 3-11423.

61-38-05 UserMan page 16 of 38

TXRX Systems Inc. Manual 7-9408-1.2 07/25/05 Page 16

and downlink branches are physically identical,

both being constructed from the same set of sub-

assemblies, the signal flow discussion that follows

is applicable equally well to both branches. The

only difference between the two branches is the

tuning of their passbands.

Signals enter the system through the RF connec-

tors at the top of the cabinet. This is where the cus-

tomers antenna system is interfaced to the booster.

Input signals are immediately passed through pas-

sive filtering. The filter configurations can vary

slightly depending on the exact model of booster.

The filters provide the necessary isolation to allow

a pair of amplifier chains to be tied together provid-

ing bi-directional amplification with a single com-

mon input and common output connection. A

secondary but very beneficial effect of filtering is

instantaneous input and output frequency spec-

trum limiting which helps to prevent amplification of

unwanted channels. After filtering signals are then

applied to a preamplifier stage (the first section of

the multi-stage amplifier assembly 3-11423).

Following the preamplifier signals are applied to

the input of OLC (output level control) assembly 3-

6280. This assembly will attenuate the incoming

signals if necessary, to protect the final amplifier

from being overdriven by stronger than usual input

signals. The amount of attenuation is determined

by a reference voltage produced by a detector cir-

cuit built into the OLC assembly, which continu-

ously samples the output level of the final amplifier.

Once past the OLC assembly the signals are

applied to a driver amplifier composed of the final

three sections of the multi-stage amplifier assem-

bly 3-11423. The driver amplifier ensures that sig-

nals applied to the next stage, the final amplifier,

are at their optimum level and as free of any inter-

modulation distortions as possible. The high power

amplifier 3-11792 is a linear amp operated at con-

siderably less than it’s maximum output power to

insure maximum linearity.

Signals output from the high power amplifier stage

are routed to the detector input of the OLC assem-

bly by the first signal sampler 3-6999. The purpose

of the detected signal is to adjust the amount of

attenuation provided by the OLC assembly to the

incoming signal after the preamplifier stage. The

output of the high power amplifier is passed

through a second signal sampler 3-5969 that pro-

vides a -50 dB sampled signal as a convenience for

service technicians. The signals then pass through

passive filtering before leaving the signal booster at

the output connector located on the top of the cabi-

net. This is where the customers antenna system is

interfaced to the booster.

SYSTEM COMPONENTS

Each of the major system components used in the

model 61-38-05 family of signal boosters are briefly

discussed in the following text. Refer to the system

specification drawing that shipped with your system

during this discussion. The specification drawing

will include complete electrical and mechanical

specifications for your model. These include fre-

quency band, bandwidth, power gain and maxi-

mum power ratings. Recommended maximum

power ratings are shown for single signal and multi-

ple signal applications.

The functional block diagram included on the spec-

ification drawing shows all of the major subassem-

blies and their interconnections. Part numbers for

the major assemblies are also shown. We suggest

you look this drawing over carefully to fully familiar-

ize yourself with the unit.

Passive Filtering

The passive filters on the input and output ends of

each active section have one major purpose: they

provide the necessary isolation to allow a pair of

amplifier chains to be tied together providing bi-

directional amplification with a single common

input and common output connection. The filters

provide duplex operation and each one is tuned to

pass either the downlink or uplink frequency band.

They must provide a minimum isolation factor that

exceeds the amplifier gain by 15 dB in order to pre-

vent regenerative feedback and maintain spurious-

free operation. In the VHF spectrum, these filters

are usually constructed from cascaded coaxial

bandpass cavities or multistage helical bandpass

filters. Bandpass filters may be augmented by

notch filters using the same basic resonator style

(coaxial or helical). Notching filters allow the filter

response to be closely tailored to the specific isola-

tion requirements for the specific uplink and down-

link frequency band separation. Typical VHF

frequency pairs (repeater input/output frequencies

= Down/uplink frequencies) vary considerably in

frequency separation making flexibility in tailoring

the filter response a necessity for proper operation.

When necessary, single channel bandpass filters

may also be used as an augment to facilitate close-

spaced frequency operation without interference.

TXRX Systems Inc. Manual 7-9408-1.2 07/25/05 Page 17

61-38-05 UserMan page 17 of 38

Single channel bandpass filters are generally 4-

pole crystal filters using piezo-electric resonators.

A secondary but very beneficial effect of filtering is

instantaneous input and output frequency spec-

trum limiting which helps to prevent amplification of

unwanted channels.

While filtering can reduce or eliminate spurious

output signal, this is a tertiary function in the VHF

signal booster because this booster family uses

Class-A linear amplifiers that generate much lower

harmonic content than the typical Class C or D

amplifier used in typical landmobile transmitters.

The input and output filter assemblies used in the

model 61-38-05 signal booster systems are com-

posed of helical preselectors, 2” square bandpass

cavities, and 2” square notch cavities. These filters

all have a carefully shaped response curves that

define the pass windows for the booster.

The helical preselectors are composed of four cas-

caded helical cavities. The cavities are intercon-

nected with critical length cables to synthesize a

shaped response. The bandpass filters pass one

narrow band of frequencies (the passband) and

attenuate all others with increasing attenuation

above and below the pass frequencies. The inser-

tion loss setting determines the filters selectivity

and maximum power handling capability. Insertion

loss is set at the factory. The notch filters are used

to notch out a very narrow range of frequencies

and improve the skirt selectivity of associated

bandpass filters.

The filters used in the booster are factory pretuned

and do not require any adjustment. The filters are

easy to misalign. Being passive devices using sil-

ver plated contacts means they requires no mainte-

nance and will stay tuned indefinitely unless they

are physically damaged or tampered with. If it is

suspected that a filter is out of alignment, we sug-

gest returning it to the factory for re-alignment.

However, if the necessary test equipment is avail-

able then the tuning procedure outlined later in this

manual may be used to put it back on frequency.

DC Regulator (3-5969)

The DC regulator receives 24.7 VDC from the

power supply assembly through it's input 'TNC'

connector. Two regulator assemblies are used, one

for each signal branch in the bi-directional system.

each of the regulators provides two different output

voltages, +15 VDC and +21.7 VDC. A minimal volt-

age differential of 3 volts is required between the

input and the output of the 3-5969 regulator in

order to maintain proper operation. The regulator

assembly can provide up to 5 amps of total current.

The regulator circuit uses two conventional IC reg-

ulator chips. An LM338K is used to produce the

fixed 15 VDC, and an LM340K is used for the vari-

able output which is factory adjusted to +21.7 VDC.

Test jacks (red & black) are available on the regula-

tor chassis for measuring the input, fixed-output,

and the variable-output voltages. The regulator has

an access hole on the side of it's case for adjusting

the variable-output voltage. A thin blade screw-

driver is used to engage a trim-pot type variable

resistor R2 which is then rotated until the desired

output voltage is obtained. Adjustment of the regu-

lator is only required after making repairs to the

regulator circuitry.

OLC Assembly (3-6280)

The OLC assembly 3-6280 is used in both

branches of the system is divided into three

shielded compartments; one housing the RF to DC

converter, the second a DC control circuit, and the

third containing the PIN diode attenuator circuit. A

test point is provided for measuring the voltage that

is applied to the PIN diode attenuator. A second

test point allows measurement of the voltage sup-

plied by the converter to the DC control circuit (see

Figure 8). Regulated 21.7 VDC is supplied to the

"TNC" female connector to power the assembly.

The RF to DC converter receives RF from the sig-

nal sampler and produces a negative polarity DC

output voltage that is proportional to the RF signal.

A Schottky Barrier diode is used as the detector.

Because this detector circuit has a very high input

impedance, the magnitude of the voltage that it

produces will vary if the length of the coaxial cable

which connects it to the signal sampler changes.

Therefore, it is important not to change this length.

The voltage produced by the RF to DC converter is

directly proportional to the output signal strength of

the final amplifier. The voltage is supplied to the DC

control circuit at the non-inverting terminal of op-

amp IC2. A variable reference voltage is applied to

the inverting terminal of the same op-amp. Variable

resistor VR2 is used to set the magnitude of this

reference voltage and controls the level at which

gain reduction will start to occur. As the signal

strength increases the output voltage of the con-

verter, which is of negative polarity, becomes

61-38-05 UserMan page 18 of 38

TXRX Systems Inc. Manual 7-9408-1.2 07/25/05 Page 18

larger. This change causes the output of IC2 to

also become increasingly negative. This output

voltage is connected via diode D1 to bias the PIN

diode attenuator. As this voltage becomes more

negative, the attenuation is increased thus achiev-

ing a certain range of gain control. Diode D1

insures that the gain control voltage is always posi-

tive and never goes below 0 volts. In actual opera-

tion, OLC operation is set to commence when the

power output of the final amplifier reaches its maxi-

mum two-carrier level as shown on the specifica-

tion drawing.

Two other IC’s are mounted on the DC control cir-

cuit board. IC1 is a 10 volt regulator that supplies

DC to the other two chips. Variable resistor VR1 is

used to set this voltage. IC3 is a voltage inverter

that produces -4.5 volts which is applied to the op-

amp IC2. This negative bias allows the output volt-

age of IC2 to closely approach 0 volts.

The PIN diode attenuator board has two diodes

that are used in series to extend the attenuation

range. The diodes are always forward biased with

minimum forward resistance and insertion loss

occurring at about 20 ma of current.

Pre-Amplifier Stage (3-11423)

The pre-amplifier consists of the 400 milliwatt

amplifier stage connected to the input of the OLC

assembly. The preamp is the first stage of the four

identical stages found in the amplifier assembly 3-

11423. This amplifier stage is used to insure that a

sufficient signal level is applied to the OLC assem-

bly.

The 1-section/3-section amplifier assembly (3-

11423) is composed of four individual and identical

amplifier sections. Each of the individual sections

(part# 3-8089) are complete 400 milliwatt amplifi-

ers. The individual sections are mounted on a com-

mon mounting panel and have a common DC

distribution bus running internally between them.

Each section provides 18.5 dB of gain with a power

requirement of 21.7 VDC (nominal) and a typical

current draw of 121 ma. The maximum single car-

rier power output is 400 milliwatts.

Each 400 milliwatt amplifier section consists of two

circuits, the amplifier circuit (3-8087) and the bias

regulator circuit (3-10742). Both of these circuits

are housed in their own enclosures which are then

physically joined together to make up one section.

The circuits are electrically joined using feed-thru

capacitors Cf1 and Cf2.

The amplifier circuit uses a linear RF transistor Q1

(Phillips part# BFQ34/01) which is operated in a

class "A" configuration in order to keep any inter-

modulation distortion to a minimum. The RF tran-

sistor is biased for a nominal collector current of

121 ma. A bias regulator circuit is used to keep the

collector current constant with changes in tempera-

ture. Narrow band matching techniques are used in

this amplifier and it will require tuning if the transis-

tor or matching network components are replaced.

CONTROL

VOLTAGE

+15 VDC

OUTPUT INPUT

OLC Voltage

Adjust

10V Regulator

Adjust

RF from

Sampler

Detector

Voltage

Test Point

OLC

Voltage

Test Point

RF to DC

Converter

Pin Diode

Attenuator

Figure 8: OLC assembly 3-6280.

TXRX Systems Inc. Manual 7-9408-1.2 07/25/05 Page 19

61-38-05 UserMan page 19 of 38

The bias regulator circuit uses an Op-Amp compar-

ator IC1 to supply a variable bias current which var-

ies as required to keep the RF transistors collector

current constant. Current to the collector of the RF

transistor flows through resistor R1. The voltage at

the collector side of this resistor is applied to the

non-inverting input of IC1. Voltage divider R2 / R4

sets the desired reference voltage on the inverting

terminal of IC1. The variable output voltage at pin 6

of IC1 is then applied to the base of the RF transis-

tor. The bias on the RF transistor will now vary in

such a way as to keep the voltage at the collector

end of R1 equal to the reference voltage provided

by divider R2/R4, thus keeping the RF transistor's

collector current constant (121 ma nominal).

Repair or replacement of bias circuit components

does not necessitate retuning of the amplifier.

Driver Amplifier Stage (3-11423)

The remaining three stages of the amplifier assem-

bly 3-11423 are used to form a driver amplifier

which amplifies the passband signals to levels suf-

ficient for driving the input of the final High Power

Amplifier stage. Each of the three individual 400

milliwatt stages in the driver amp are identical and

were discussed in detail in the earlier sub-section

entitled "Pre-Amplifier (3-11423)".

High Power Amplifier Assembly (3-11792)

This amplifier stage uses a single ultra-linear RF

transistor. The 3.0 watt rating indicates the maxi-

mum safe output from this amplifier assembly

using a single carrier. The actual maximum allow-

able power output with multiple carriers is much

lower and is determined by the maximum allowable

intermodulation product level. It is also limited by

the collector to emitter breakdown rating of the RF

transistor.

This amplifier stage is physically mounted to the

inside of the heatsink located on the side of the

cabinet. The amplifier draws a nominal 420 ma. A

bias regulator circuit within the amplifier assembly

is used to keep the collector current of the RF tran-

sistor constant with changes in temperature. This

amplifier has a minimum gain of 18 dB, 19 dB typi-

cal. The amplifier uses narrow band matching tech-

niques and will require tuning if the transistor or

matching network components are replaced.

Signal Sampler (3-6999)

Following the output of the power amplifier assem-

bly is a -25 dB signal sampler. This sampler is used

to couple the output signal level back to the OLC

assembly.

Signal Sampler (3-3569)

This sampler is located at the output of the uplink

and downlink branches and is used for connecting

test equipment to the branch, such as a spectrum

analyzer. The 3-3569 signal sampler capacitively

couples signals to the sample port at a -50 dB

level.

DC Junction Box (3-6254)

This assembly has no internal components and is

used to couple battery backup voltage (supplied by

the customer) to the power supply.

Power Supply Assembly (3-15503)

The power supply assembly consists of two sub-

assemblies, an OEM power supply module and a

failure switching circuit. The switching circuit is

designed to pass the output from either the OEM

power supply or the backup batteries to the TNC

style output connectors which are labeled “24.7

VDC Output” located on the assemblies front panel

next to the fuses.

The output of the OEM supply (part# 8-15495) is

applied to the output TNC connectors through relay

K2 pins 9 and 10. The voltage feed is protected by

fuse F1 (10 amp). During normal operation relay

K2 is energized connecting pin 9 to pin 10. If AC

power is interrupted relay K2 becomes de-ener-

gized connecting pin 9 to pin 8 which is fed from

the battery backup. This will pass battery voltage to

the output TNC connectors.

With AC voltage applied to relay K2 pin 6 will be

connected to pin 7 completing the ground path for

the green LED D2. When K2 is de energized indi-

cating AC power failure pin 5 is connected to pin 6

completing the ground path for the red LED D1

indicating the unit is operating on DC backup volt-

age.

The Loss of AC Alarm Terminal block is provided

for customer convenience. Under normal system

operation, when the OEM supply voltage is active,

the NC terminal is shorted to the COM terminal

because pins 5 and 6 are connected by relay K1.

K1 is energized whenever the AC power supply is

active. When the system is running on battery

backup voltage the NO terminal is connected to the

COM terminal because pin 5 will now be con-

61-38-05 UserMan page 20 of 38

TXRX Systems Inc. Manual 7-9408-1.2 07/25/05 Page 20

nected to pin 4. Relay K1 is de-energized when the

AC power supply is off.

PERFORMANCE SURVEY

It is a good idea to document the performance of

the system after installation so that a reference

exists for future comparisons. This information can

make troubleshooting an interference problem or

investigation of a complaint about system perfor-

mance much easier. If there are coverage prob-

lems with a system, this survey will usually reveal

them allowing corrective measures to be taken

before the system is put into routine use. The fol-

lowing is an outline of how to do such a survey.

Because the nature of each installation can be

quite different, only a broad outline is given.

1) Measure the gain of the signal booster being

careful not to exceed the maximum input level.

Figure 9 shows this being done using a signal

generator and spectrum analyzer. This is basi-

cally a substitution measurement. Record the

measured values for each passband.

2) Each branch of the signal booster system is

equipped with a -50 dB signal sampler port fol-

lowing the final output amp (part of the OLC

assembly). This port is for the connection of test

equipment such as a spectrum analyzer and

will allow the observation of the amplifier output

at a considerably reduced output level. This

decoupling figure needs to be added to a mea-

sured signal value in order to arrive at the actual

signal level. OLC assemblies appear in sche-

matic representation on the specification draw-

ings.

3) With a spectrum analyzer connected to the sig-

nal sampler port for the branch under test (see

Figure 10), have personnel with handheld

radios move to predetermined points and key

their radios. Record the level of these signals as

observed on the analyzer and also record the

location of the person transmitting. In this way, a

map of the systems performance can be gener-

ated.

4) For branches that amplify signals coming from a

fixed antenna or station, record the level of all

the desired incoming signals for future refer-

ence.

FIELD ADJUSTMENTS

The following information is provided in support of

field support activities, including routine mainte-

nance, repairs, adjustments and tuning. It is

Sampler Sampler

Detector

Electronic

Attenuator

OLC Assembly

Filter Filter

Amp

Control

ZERO

REFERENCE

GAIN

10 dB Pad

SIGNAL

GENERATOR

SPECTRUM

ANALYZER

Figure 9: Test equipment interconnection for measuring signal booster gain.

TXRX Systems Inc. Manual 7-9408-1.2 07/25/05 Page 21

61-38-05 UserMan page 21 of 38

assumed that the procedures will be carried out by

a qualified electronics technician observing all

standard safety practices.

Filter Tuning

Filters used in TX RX Systems’ signal boosters are

passive devices of rugged electrical and mechani-

cal design. They are tuned at the factory for the

original design requirements and require no adjust-

ment or maintenance. These devices will stay prop-

erly tuned unless they have been physically

damaged or are tampered with. Filter tuning falls

into two categories; retuning to the original fre-

quency such as when a filter is being repaired or

replaced, or tuning to new frequencies.

A number of points need to be considered before

attempting to tune a signal booster to frequencies

different from the original.

1) The Frequency Range Specification for the 61-

38-05 signal booster family does not mean that

an individual signal booster is field tunable over

the entire indicated frequency range. This spec-

ification only indicates the frequency range for

which the 61-38-05 components are intended.

Many of the filter assemblies used in a particu-

lar booster maintain reasonable performance

over a range that is within ± 2% of the original

frequency. For greater changes in frequency,

the performance of the filters may degrade

severely. Therefore some filters may need to be

replaced or modified when large frequency

changes are made.

2) In a bidirectional system, will the new inbound

and outbound channels have the same fre-

quency separation from each other as the origi-

nal ones? Frequency separation in bidirectional

designs is one of the prime design criteria. If the

frequency separation decreases from the origi-

nal, the filters will provide less isolation so the

gain may also have to be reduced to prevent the

signal booster from oscillating. Increases in fre-

quency separation are more easily accommo-

dated.

3) If the bandwidth requirement increases, the

bandpass filters may not pass all of the new fre-

quencies. In most cases, the bandwidth of the

bandpass filters cannot be changed by the cus-

tomer.

Sampler Sampler

Detector

Electronic

Attenuator

OLC Assembly

Filter Filter

Amp

Control

10 dB Pad

SPECTRUM

ANALYZER

SIGNAL DISTRIBUTION SYSTEM

BOOSTED

RF SIGNAL

Figure 10: Test equipment interconnection for surveying performance.

61-38-05 UserMan page 22 of 38

TXRX Systems Inc. Manual 7-9408-1.2 07/25/05 Page 22

4) The amplifier assemblies may have to be

retuned.

5) The length sensitive interconnect cables may

need to be changed.

If you are not sure about tuning the signal booster

system to new frequencies then contact your TX

RX Systems, Inc. representative. Our knowledge-

able engineering and sales staff are happy to dis-

cuss what it will take to tune your system to the

new frequencies.

Helical Preselectors

The helical preselectors are composed of four cas-

caded individual helical cavities. The cavities are

interconnected with critical length cables to synthe-

size a shaped response. This filter assembly can

not be tuned by tuning the individual cavities, the

assembly must be tuned as a whole. The band-

width of the filter is determined by the critical align-

ment of internal “reactive” components. Bandwidth

is therefore fixed by construction in this type of filter

The helical preselectors are pretuned at the factory

for a specific bandwidth and no attempt should be

made to adjust the bandwidth.

REQUIRED EQUIPMENT

A two channel network analyzer that simulta-

neously displays both transmission and reflection

is best for properly tuning a preselector. A single

channel tracking generator / spectrum analyzer

combination may be adequate but insure that it is

accurate enough to verify factory specifications. A

return loss bridge would also be required when

using a tracking generator / spectrum analyzer.

Skill and experience are also needed and the per-

sonnel doing the work should be thoroughly famil-

iar with the test equipment.

TUNING PROCEDURE

The following is an outline of the general proce-

dure.

1) Connect test equipment as shown in Figure 11.

2) Set the analyzer to the desired center fre-

quency and desired bandwidth.

3) Loosen the tuning rod locking nuts.

4) If the preselector is severely out of tune, set the

analyzer for 10 dB/div vertical scale and alter-

nately adjust the tuning rods in pairs working

from the center to the end rods for maximum

signal at the center frequency. Start with the

center rods and then move to the outer rods.

5) Repeat step 4 tuning to maximize the signal at

the center frequency. The response should start

to take on the desired shape and symmetry.

Setup the analyzer for 2 dB/div and then re-

adjust the rods in the same fashion. Make sure

that the response is relatively symmetrical. Fine

adjust the tuning rods as necessary to adjust

symmetry.

6) When using the spectrum analyzer/tracking

generator, the equipment must be connected as

shown in Figure 12 in order to check the return

loss curve. The network analyzer will show the

return loss curve as a matter of course.

7) Lock all tuning rods after the desired response

is obtained. Note that a slight dissymmetry in

Analyzer

Input

Generate

Output

+30

+40

+20

+10

-10

-20

-30

-40

4 Section

Helical Preselector

Figure 11: Preselector tuning.

TXRX Systems Inc. Manual 7-9408-1.2 07/25/05 Page 23

61-38-05 UserMan page 23 of 38

either the transmission or reflection response

may be unavoidable.

Bandpass Filters

The bandpass filters pass one narrow band of fre-

quencies (the passband) and attenuate all others

with increasing attenuation above and below the

pass frequencies. The insertion loss setting deter-

mines the filters selectivity and maximum power

handling capability. Insertion loss is set at the fac-

tory.

Cavity tuning follows a two step process. First the

cavity is temporarily disconnected from the system

and rough tuned, this will ensure the response

curve is very close to it's ideal. Next the cavity is

reconnected to the system and fine tuned. This is

done in large systems such as the model 61-38-05

in order to eliminate any slight distortions which

could result from interactions with other cavities.

The pass frequency is the only field adjustable

parameter found in the individual Bandpass reso-

nant cavity filters. Adjustment of the tuning rod on

these filters will allow the passband to be centered

at the desired frequency. The insertion loss of each

cavity is not field adjustable.

REQUIRED EQUIPMENT

Due to the sensitivity of the adjustments, it is

strongly recommended that the proper equipment

be used when tuning the individual filters, other-

wise the filter should be sent to the factory or an

authorized representative for retuning. The follow-

ing equipment or it's equivalent is recommended in

order to properly perform the tuning adjustments.

1. IFR A-7550 spectrum analyzer with optional

tracking generator installed.

2. 7/16” wrench.

3. Double shielded coaxial cable test leads

(RG142 B/U or RG223/U).

4. Female union (UG29-N or UG914-BNC).

TUNING PROCEDURE

The following is an outline of the general proce-

dure.

1. Turn off the system power and disconnect the

cables that are attached to the cavity.

2. Setup the analyzer / generator for the desired

frequency and bandwidth (center of display)

and also a vertical scale of 2 dB/div. Set the

sweep width of the display to 100 KHz.

4. A zero reference must first be established at the

IFR A-7550 before making measurements. This

is accomplished by temporarily placing a

"female union" between the generator output

and the analyzer input.

5. The flat line across the screen is the generator's

output with no attenuation, this value will

become our reference value by selecting the

4 Section

Helical Preselector

Analyzer

Input

Generate

Output

+30

+40

+20

+10

-10

-20

-30

-40

Bridge

50 ohm Load

Figure 12: Observing preselector return loss.

61-38-05 UserMan page 24 of 38

TXRX Systems Inc. Manual 7-9408-1.2 07/25/05 Page 24

"MODE" main menu item and choosing the

"STORE" command. This will store the flat-line

value in the analyzer's internal memory.

6. Next select the "DISPLAY" main menu item and

choose the "REFERENCE" command. This will

cause the stored value to be displayed on the

screen as the 0 dB reference value.

7. The resonant frequency of the filter is checked

by connecting the tracking generator to the

input of the cavity filter assembly while the

spectrum analyzer is connected to the output,

as shown in Figure 13.

8. Insure the IFR A-7550 menu's are set as fol-

lows:

DISPLAY - line

MODE - live

FILTER - none

SETUP - 50 ohm/dBm/gen1.

9. Adjust the pass frequency by setting the peak

(minimum loss value) of the response curve to

the desired frequency (should be the center-

vertical graticule line on the IFR A-7550's dis-

play). The resonant frequency is adjusted by

adjusting the tuning rod, which is a sliding

adjustment (invar rod) that rapidly tunes the fil-

ter's response curve.

Pseudo-Bandpass Filters

The pseudo-bandpass filter passes a relatively nar-

row band of frequencies and rejects (notches out)

a relatively wide frequency band. These cavity fil-

ters are two inch square, helical type resonators

that include a tunable notching section, refer to

Figure 14. These filters are pretuned and require

no adjustment unless they have been damaged

and repaired or tampered with in some way. They

are passive devices that require no maintenance.

Female Union

Used to determine 0 dB reference

Analyzer

Input

Generate

Output

+60

+80

+40

+20

-20

-40

-60

-80

Tracking Generator

2" Sq. Bandpass

Cavity Filter

Figure 13: Bandpass filter tuning.

Sliding Main

Tuning Rod

(Passband)

Main Tuning

Lock Nut

Rejection

Notch Tuning

Capacitor

Input/Output

Connectors

Figure 14: The Pseudo-bandpass filter.

TXRX Systems Inc. Manual 7-9408-1.2 07/25/05 Page 25

61-38-05 UserMan page 25 of 38

REQUIRED EQUIPMENT

Due to the sensitivity of the adjustments, it is

strongly recommended that the proper equipment

be used when tuning the individual filters, other-

wise the filter should be sent to the factory or an

authorized representative for retuning. The follow-

ing equipment or it's equivalent is recommended in

order to properly perform the tuning adjustments.

1) IFR A-7550 Spectrum Analyzer / Tracking Gen-

erator combination.

2) Eagle Model RLB150BN3 Return Loss Bridge

(35 dB directivity).

3) Double shielded coaxial cable test leads

(RG142 B\U or RG223/U).

4) 50 Ohm load with at least -35 dB return loss

(1.10:1 VSWR).

5) Insulated metal blade tuning tool for adjusting

ceramic and/or piston variable capacitors.

Similar equipment from other manufacturers

should yield acceptable results.

TUNING PROCEDURE

The following general procedure assumes familiar-

ity with the use of a tracking generator.

1) Set the tracking generator to a center frequency

of the filter to be tuned. Set the tracking genera-

tor for 0 dBm output and a 10 dB/div scale.

Connect the equipment as shown in Figure 15

but leave the load port of the bridge uncon-

nected.

2) Set a 0 dB return loss reference. For the IFR A-

7550 perform the following procedure:

a) Make sure that the unit is in "LIVE" mode

when performing step 7.

b) From the Mode Menu, "STORE" the above

trace.

c) Switch to the Display Menu and select

"REF". The trace should appear at the 0 dB

level.

3) Connect the load port of the bridge to the filter

as shown in figure 15.

4) Adjust the cavity main tuning rod for maximum

return loss at the center frequency.

5) Set the tracking generator for the center fre-

quency of the filter and connect the test leads

as shown in Figure 16 but first temporarily con-

nect the leads together through a female barrel

connector and set a zero dB loss reference. On

the IFR A-7550 proceed as follows:

a) Make sure that the unit is in "LIVE" mode when

performing step 2.

LOAD

REFLECTED

SOURCE

Analyzer

Input

Generate

Output

+30

+40

+20

+10

-10

-20

-30

-40

RLB - 150 Bridge

2" Square VHF

Pseudo-Bandpass Filter

Tracking Generator

Tune

Figure 15: Tuning the Pseudo-bandpass filter

for maximum return loss.

61-38-05 UserMan page 26 of 38

TXRX Systems Inc. Manual 7-9408-1.2 07/25/05 Page 26

b) From the Mode Menu, "STORE" the above

trace.

c) Switch to the Display Menu and select "REF".

6) Connect the leads to the cavity as shown in fig-

ure 16 and use a tuning tool or small screw

driver to engage the notch tuning capacitor and

rotate it to obtain maximum attenuation at the

notch frequency.

7) Tighten the cavity main tuning locking nuts.

The cavity may be put back into the repeater ampli-

fier.

Notch Filters

The notch filter passes a relatively wide band of

frequencies while rejecting (notches out) a very

narrow band of frequencies. They are used to

improve the skirt selectivity of associated band-

pass filters. These cavity filters are two inch

square, helical type resonators that include a tun-

able notching section, refer to Figure 17. These fil-

ters are pretuned and require no adjustment unless

they have been damaged and repaired or tam-

pered with in some way. They are passive devices

that require no maintenance.

REQUIRED EQUIPMENT

Due to the sensitivity of the adjustments, it is

strongly recommended that the proper equipment

be used when tuning the individual filters, other-

wise the filter should be sent to the factory or an

authorized representative for retuning. The follow-

ing equipment or it's equivalent is recommended in

order to properly perform the tuning adjustments.

1) IFR A-7550 Spectrum Analyzer / Tracking Gen-

erator combination.

2) Eagle Model RLB150BN3 Return Loss Bridge

(35 dB directivity).

3) Double shielded coaxial cable test leads

(RG142 B\U or RG223/U).

Analyzer

Input

Generate

Output

+30

+40

+20

+10

-10

-20

-30

-40

2" Square VHF

Pseudo-Bandpass Filter

Tracking Generator

Tune

Figure 16: Tuning the Pseudo-bandpass filter

for maximum attenuation.

Sliding Main

Tuning Rod

(Notch)

Main Tuning

Lock Nut

Passband

Tuning

Capacitor

Input/Output

Connectors

Figure 17: The Notch filter.

TXRX Systems Inc. Manual 7-9408-1.2 07/25/05 Page 27

61-38-05 UserMan page 27 of 38

4) 50 Ohm load with at least -35 dB return loss

(1.10:1 VSWR).

5) Insulated metal blade tuning tool for adjusting

ceramic and/or piston variable capacitors.

Similar equipment from other manufacturers

should yield acceptable results.

TUNING PROCEDURE

The following general procedure assumes familiar-

ity with the use of a tracking generator.

1) Set the tracking generator to a center frequency

of the filter to be tuned. Set the tracking genera-

tor for 0 dBm output and a 10 dB/div scale.

Connect the equipment as shown in Figure 18

but leave the load port of the bridge uncon-

nected.

2) Set a 0 dB return loss reference. For the IFR A-

7550 perform the following procedure:

a) Make sure that the unit is in "LIVE" mode

when performing step 7.

b) From the Mode Menu, "STORE" the above

trace.

c) Switch to the Display Menu and select

"REF". The trace should appear at the 0 dB

level.

3) Connect the load port of the bridge to the filter

as shown in figure 18.

4) Adjust the cavity main tuning rod for maximum

attenuation at the notch frequency.

5) Set the tracking generator for the center fre-

quency of the filter and connect the test leads

as shown in Figure 19 but first temporarily con-

nect the leads together through a female barrel

connector and set a zero dB loss reference. On

the IFR A-7550 proceed as follows:

a) Make sure that the unit is in "LIVE" mode when

performing step 2.

b) From the Mode Menu, "STORE" the above

trace.

c) Switch to the Display Menu and select "REF".

6) Connect the leads to the cavity as shown in fig-

ure 19 and use a tuning tool or small screw

driver to engage the notch tuning capacitor and

rotate it to obtain maximum return loss at the

center frequency.

7) Tighten the cavity main tuning locking nuts.

The cavity may be put back into the repeater ampli-

fier.

LOAD

REFLECTED

SOURCE

Analyzer

Input

Generate

Output

+30

+40

+20

+10

-10

-20

-30

-40

RLB - 150 Bridge

2" Square VHF

Notch Filter

Tracking Generator

Tune

Figure 18: Tuning the Notch filter for maximum

return loss.

61-38-05 UserMan page 28 of 38

TXRX Systems Inc. Manual 7-9408-1.2 07/25/05 Page 28

Single Section Amplifier Subassemblies

Amplifiers with 400 Milliwatt RF power output rat-

ings are manufactured by TX RX Systems, Inc. for

use in the model 61-38-05 family of signal boost-

ers. These amplifiers utilize bi-polar transistors

operating as class-A linear amplifiers with varying

RF power output capability. They offer a good com-

promise between low noise figure and low levels of

intermodulation distortion. In addition, these ampli-

fiers use narrow band impedance matching cir-

cuitry which offers significant improvements in

noise figure compared to broadband designs. How-

ever, narrow band circuits necessitate having to

tune the matching networks to obtain best perfor-

mance. This tuning procedure needs to be done

when the RF transistor and/or matching network

components are replaced.

Each single amplifier section (see Figure 20) uses

a bias regulator circuit to keep the RF transistor

biased for constant collector current with changes

in temperature. The collector current remains con-

stant when these amplifiers are running properly.

The actual value of bias current will be different for

different types of amplifiers but can also vary

slightly if the power supply voltage varies. All ver-

sions of the current production bias regulators are

designed for fixed values of RF transistor collector

current.

The multi section amplifier assembly 3-11423 is a

combination of individual single section subassem-

blies (part # 3-8089) which have a 400 Milliwatt

output power rating per section. These single sec-

tion subassemblies are interconnected with short

lengths of double shielded coaxial cable for the RF

interconnection. The individual sections are

mounted on a common bracket with a DC distribu-

tion wire running internally between sections. A

multi section amplifier is tuned on a per section

basis. Never attempt to tune the interconnected

sections.

AMPLIFIER TUNING

Field repair and tuning of our amplifiers is sup-

ported by TX RX Systems Inc. and the following

procedure will allow satisfactory operation to be

obtained. At the factory, TX RX amplifiers are tuned

using two channel network analyzers that allow

adjustment of both gain, input/output return loss

and verification of reverse isolation. After this tun-

ing, the amplifiers are checked with an advanced

noise figure measurement system and are fine

tuned to obtain best noise figure. Because this

equipment is rarely available in even the most well

equipped service centers, we recommend return-

ing the amplifier to the factory for repair and retun-

ing if the specified noise figure has to be obtained.

In actual practice, most of the amplifiers retuned in

the field will exhibit noise figures that range from

being equal to the published specification or

exceed it by 0.5 to 2 dB. Low noise figure may be of

minimal importance in any system where very

weak signal sensitivity is not an issue.

REQUIRED EQUIPMENT

The following procedure was developed to be prac-

tical as a field bench service procedure. This pro-

cedure is intended for single sections only. All multi

section TX RX amplifiers are composed of cas-

caded single sections interconnected with short

lengths of double shielded coaxial cable. Individu-

ally tuned single sections do not require any further

adjustment when they are connected together

Analyzer

Input

Generate

Output

+30

+40

+20

+10

-10

-20

-30

-40

2" Square VHF

Notch Filter

Tracking Generator

Tune

Figure 19: Tuning the Notch filter for max attenuation.

TXRX Systems Inc. Manual 7-9408-1.2 07/25/05 Page 29

61-38-05 UserMan page 29 of 38

forming a multi-section subassembly. This proce-

dure requires the following equipment:

1) IFR A-7550 Spectrum Analyzer / Tracking Gen-

erator combination.

2) Eagle RLB150N3 Return Loss Bridge or equiv-

alent (35 dB directivity).

3) Double shielded coaxial cable test leads

(RG142 B\U or RG223/U).

4) 50 Ohm load with at least -35 dB return loss

(1.10:1 VSWR). JFW Industries model 50T-007

or equivalent.

5) Regulated DC power supply at the required

voltage.

6) Insulated metal blade tuning tool for adjusting

ceramic and/or piston variable capacitors.

Similar equipment from other manufacturers

should yield acceptable results.

ADJUSTMENT PROCEDURE

1) Set the tracking generator output level to -20

dBm, the desired center frequency and sweep

width of 20 MHz.

2) Connect the test lead together through a female

barrel connector to obtain a zero dB reference

level. On the IFR A-7550 proceed as follows:

a) Make sure that the unit is in "LIVE" mode

when performing step 2.

b) From the Mode Menu, "STORE" the above

trace.

c) Switch to the Display Menu and select "REF".

A display with a vertically centered trace should

be visible.

3) Connect the equipment as shown in Figure 21.

4) Remove the amplifier top cover. Engage the

Output Tuning Capacitors one at a time and

rotate them for maximum gain.

Figure 20: Mechanical layout of a single section amplifier subassembly.

Bias Regulator

Circuit Board

Output Tuning

Capacitors

RF Board

Input Tuning

Capacitors

61-38-05 UserMan page 30 of 38

TXRX Systems Inc. Manual 7-9408-1.2 07/25/05 Page 30

5) Engage the Input Tuning Capacitors one at a

time and rotate them for maximum gain.

NOTE: If the gain peaks at a level

about 60% of maximum, one of the

variable capacitors should be rotated

180° and steps 4 and 5 repeated.

6)Connect the return loss bridge to

the tracking generator as shown in

Figure 22 but do not connect it to the

amplifier. Leave the test port on the

bridge open.

7) Set up the 0 dB return loss reference. For the

IFR A-7550 do the following procedure:

a) Make sure that the unit is in "LIVE" mode

when performing step 7.

b) From the Mode Menu, "STORE" the above

trace.

c) Switch to the Display Menu and select "REF".

The trace should appear at the 0 dB level.

8) Connect the bridge and load to the amplifier as

shown in figure 22 and see if the input return

loss is down -16 dB or more. If it is, skip to step

10.

9) Alternately adjust the input tuning capacitors for

increased return loss. A return loss of -20 to -30

dB loss should be obtained with maximum loss

at the center frequency.

10) Reverse the connections as shown in

Figure 23 and see if the output return loss is -

16 dB or more. If it is, skip to step 12.

11) Alternately adjust the output tuning capacitors

for increased return loss. It should be possible

to obtain -20 to -30 dB loss with maximum loss

at the center frequency.

NOTE

GENERATE

OUTPUT

ANALYZER

INPUT

+40

+30

+20

+10

-10

-20

-30

-40

BRIDGE

AMPLIFIER

INPUT

OUTPUT

50 OHM

LOAD

Figure 22: Measuring input return loss.

GENERATE

OUTPUT

ANALYZER

INPUT

+40

+30

+20

+10

-10

-20

-30

-40

AMPLIFIER

INPUT

OUTPUT

Figure 21: Measuring amplifier gain.

TXRX Systems Inc. Manual 7-9408-1.2 07/25/05 Page 31

61-38-05 UserMan page 31 of 38

12) Due to interaction, tuning the output circuitry

affects the input tuning and vise-versa. Repeat

steps 8 through 11 until acceptable input and

output return loss occurs without further tun-

ing.

13) Connect the equipment as shown in Figure 24

but connect the test leads together through a

female barrel connector and repeat the zero

reference procedure of step 2.

14) Using the figure 24 connection, verify that the

reverse isolation is at least -20 to -22 dB. This

value will occur normally as the result of proper

tuning.

The greater the reverse isolation the better as this

value must exceed the gain of the amplifier or oscil-

lation may occur. If after proper tuning this value

remains low, it may indicate a bad bypass capacitor

or defective RF transistor.

Output Level Control (OLC)

The OLC circuits are preset at the factory to limit

the RF power output of the signal booster branch to

the maximum two-carrier level as indicated on the

specification drawing. DO NOT attempt to adjust

or change this setting. This setting will be ade-

quate for protecting the final amplifier stage and

limiting intermodulation products.

OLC voltage data sheets are included with the

equipment shipment and list the actual OLC volt-

age values in relation to the degree of overload

detected for your unit. These sheets also record

the measured 1 dB compression point for the

branch and the calculated output intercept point

based on this compression point data.

CHECKING FOR OVERLOAD

Measurement of the DC voltage developed by the

OLC circuitry is a way to determine the degree of

input signal overload. In normal operation, up to 10

dB of overload on an intermittent basis is consid-

ered acceptable in most installations. Higher levels

GENERATE

OUTPUT

ANALYZER

INPUT

+40

+30

+20

+10

-10

-20

-30

-40

AMPLIFIER

INPUT

OUTPUT

Figure 24: Measuring reverse isolation.

GENERATE

OUTPUT

ANALYZER

INPUT

+40

+30

+20

+10

-10

-20

-30

-40

50 OHM

LOAD

BRIDGE

AMPLIFIER

INPUT

OUTPUT

Figure 23: Measuring output return loss.

61-38-05 UserMan page 32 of 38

TXRX Systems Inc. Manual 7-9408-1.2 07/25/05 Page 32

generally cause noticeable gain reductions to other

channels on the system and may also exceed the

maximum input level.

Connect the positive lead of a multimeter set to

measure DC voltage on a 0-20 volt scale, to the

OLC voltage test point on the OLC assembly. Fig-

ure 8 shows the location of the test point on the 3-

6280 OLC assembly. The negative lead of the mul-

timeter is connected to the chassis. (The black test

probe jacks on the voltage regulator assembly are

convenient for this). Compare the measured volt-

age readings with those on the OLC test data

sheet to see what degree of overload, if any, is tak-

ing place. Refer to the section in this manual titled

"Gain Reduction Methods" to correct an excessive

overload condition.

MAINTENANCE AND REPAIR

Signal boosters manufactured by TX RX Systems,

Inc. can function reliably for 10 or more years with

little or no maintenance. However, if the amplifiers

are subjected to excessively high signal levels,

power surges or lightning strikes, failures may

occur. The following procedures may be followed

for detecting a malfunctioning unit or as part of a

periodic maintenance program.

1) Heat sinks for the power amplifiers should be

cleared of dust and debris.

2) Inspect the units to see that the LED DC indica-

tors are lit (remove any dust or debris that may

obscure the LEDs). This will verify that DC

power is flowing properly. Check all hardware

for tightness.

3) Compare system performance to initial perfor-

mance levels measured when the system was

first installed. The lack of signal can be traced to

a malfunctioning amplifier by progressive signal

monitoring from the output (far end) to the input

end of the system noting the area where the

signal returns to normal level. The next amplifier

toward the output end of the system will proba-

bly be the one that failed.

Measure the gain of each branch at any conve-

nient frequency in the working frequency bands

to verify that the gain specifications are being

met. If the gain values fall below that specified

for a given model check the following:

A) Open the signal booster cabinet and inspect for

any loose or broken connections or cables, and

repair as necessary.

B) Measure the output of the power supply and

power regulators to see that the proper operat-

ing voltage is being maintained.

C) If the operating voltage is proper but the gain is

still low, measure the gain of each amplifier

stage until the one with low gain is isolated.

Replace a low gain amplifier with a new ampli-

fier stage to correct the problem.

RECOMMENDED REPLACEMENT PARTS

One each of the following: Power Amplifier Assem-

bly 3-11792, 1stg/3stg Amplifier Assembly 3-

11423, Voltage Regulator Assembly 3-5969, and

Power Supply Assembly 3-15503.

CONVERSION CHART

A Power in Watts to dBm conversion chart is

included on the following three pages. Most of the

setup and conversion procedures refer to power

levels in dBm more often than in Watts. This is

much more convenient when dealing with the

power levels and gain figures of signal boosters.

The chart allows easy conversion between the two

scales when necessary.

TXRX Systems Inc. Manual 7-9408-1.2 07/25/05 Page 33

61-38-05 UserMan page 33 of 38

61-38-05 Signal Booster Family Specifications by Part Number

------------------------------------------------------------------- Part Numbers -------------------------------------------------------------------

Specification 61-38-05331 61-38-05251 61-38-04401 61-38-04359

Frequency Range (MHz) 138 - 144 148 -174 148-174 138 - 144

Minimum Guard Band (MHz) 5.85 9 3.04 4.02

Number of Passbands 2222

Pass Bandwidth 150 KHz 1 MHz 1.) 1.965 MHz Single Channel

2.) Single Channel 1.56 MHz

Maximum Gain (dB) 88 88 88 88

Maximum Input Signal Level (dBm) -20 -20 -20 -20

Maximum Output Power (1 carrier)Watts +28 +28 +26 +27

Gain Set Method--fixed-pads (dB) -3 , -6, -10 -3 , -6, -10 -3 , -6, -10 -3 , -6, -10

Gain Adjust Range (dB) 0, -3, -6, -9, -10, -13, -16, -19 0, -3, -6, -9, -10, -13, -16, -19 0, -3, -6, -9, -10, -13, -16, -19 0, -3, -6, -9, -10, -13, -16, -19

1 dB Compression Point (dBm) 31 31 31 31

3rd Order Output IP (dBm) 39 39 39 39

Output RF Sampler (dB) -50 -50 -50 -50

System Noise Figure (dB) without pads 6.5 6.5 6.5 6.5

Operating Temperature Range (°C) -30 to +60 -30 to +60 -30 to +60 -30 to +60

Nominal Impedance (ohms) 50 50 50 50

VSWR 2.0 : 1 2.0 : 1 2.0 : 1 2.0 : 1

Input / Output Connectors Type 'N' female Type 'N' female Type 'N' female Type 'N' female

RF Sampler Port Connectors BNC female BNC female BNC female BNC female

AC Input Voltage (VAC) 100-120 / 200-240 @ 50/60 Hz 100-120 / 200-240 @ 50/60 Hz 100-120 / 200-240 @ 50/60 Hz 100-120 / 200-240 @ 50/60 Hz

DC Backup Input Voltage (VDC) 24 - 29 VDC 24 - 29 VDC 24 - 29 VDC 24 - 29 VDC

Unit Current Drain 2 Amps DC, <0.5 Amps AC 2 Amps DC, <0.5 Amps AC 2 Amps DC, <0.5 Amps AC 2 Amps DC, <0.5 Amps AC

Housing G1: Painted Steel to NEMA 4 G1: Painted Steel to NEMA 4 G1: Painted Steel to NEMA 4 G1: Painted Steel to NEMA 4

G2: Stainless Steel to NEMA 4X G2: Stainless Steel to NEMA 4X G2: Stainless Steel to NEMA 4X G2: Stainless Steel to NEMA 4X

Nominal Size (in./ mm) 24 x 20 x 10 (610 x 508 x 254) 24 x 20 x 10 (610 x 508 x 254) 14 x 19 x 23 (356 x 483 x 585) 36 x 30 x 12 (915 x 762 x 305)

Net Weight (Lbs / Kg) 70 (31) 70 (31) 50 (23) 220 (96)

61-38-05 UserMan page 34 of 38

TXRX Systems Inc. Manual 7-9408-1.2 07/25/05 Page 34

61-38-05 Signal Booster Family Specifications by Part Number

---------------------------------------------- Part Numbers ----------------------------------------------

Specification 61-38-03324 61-38-04742 61-38-04744

Frequency Range (MHz) 138 - 144 138 - 144 138 - 144

Minimum Guard Band (MHz) 4.21 3 2.805

Number of Passbands 222

Pass Bandwidth 500 KHz/1.0 MHz 1.0 MHz Max 1.185 MHz

1.0 MHz 900 KHz/150 KHz

Maximum Gain (dB) 88 88 88

Maximum Input Signal Level (dBm) -20 -20 -20

Maximum Output Power (1 carrier) Watts +26 +26 +26

Gain Set Method--fixed-pads (dB) -3 , -6, -10 -3 , -6, -10 -3 , -6, -10

Gain Adjust Range (dB) 0, -3, -6, -9, -10, -13, -16, -19 0, -3, -6, -9, -10, -13, -16, -19 0, -3, -6, -9, -10, -13, -16, -19

1 dB Compression Point (dBm) 31 31 31

3rd Order Output IP (dBm) 39 39 39

Output RF Sampler (dB) -50 -50 -50

System Noise Figure (dB) (without pads) 6.5 6.5 6.5

Operating Temperature Range (°C) -30 to +60 -30 to +60 -30 to +60

Nominal Impedance (ohms) 50 50 50

VSWR 2.0 : 1 2.0 : 1 2.0 : 1

Input / Output Connectors Type 'N' female Type 'N' female Type 'N' female

RF Sampler Port Connectors BNC female BNC female BNC female

AC Input Voltage (VAC) 100-120 / 200-240 @ 50/60 Hz 100-120 / 200-240 @ 50/60 Hz 100-120 / 200-240 @ 50/60 Hz

DC Backup Input Voltage (VDC) 24 - 29 VDC 24 - 29 VDC 24 - 29 VDC

Unit Current Drain 2 Amps DC, <0.5 Amps AC 2 Amps DC, <0.5 Amps AC 2 Amps DC, <0.5 Amps AC

Housing G1: Painted Steel to NEMA 4 G1: Painted Steel to NEMA 4 G1: Painted Steel to NEMA 4

G2: Stainless Steel to NEMA 4X G2: Stainless Steel to NEMA 4X G2: Stainless Steel to NEMA 4X

Nominal Size (in./ mm) 30 x 20 x 8 (762 x 508 x 203) 30 x 20 x 8 (762 x 508 x 203) 30 x 20 x 8 (762 x 508 x 203)

Net Weight (Lbs / Kg) 75 (33) 75 (33) 75 (33)

TXRX Systems Inc. Manual 7-9408-1.2 07/25/05 Page 35

61-38-05 UserMan page 35 of 38

dBm dBw Watts Volts (50Ω)

80 50 100000 2236.07

79 49 79432.82 1992.9

78 48 63095.74 1776.17

77 47 50118.72 1583.01

76 46 39810.72 1410.86

75 45 31622.78 1257.43

74 44 25118.86 1120.69

73 43 19952. 62 998.81

72 42 15848.93 890.19

71 41 12589.25 793.39

70 40 10000 707.11

69 39 7943.28 630.21

68 38 6309.57 561.67

67 37 5011.87 500.59

66 36 3981.07 446.15

65 35 3162.28 397.64

64 34 2511.89 354.39

63 33 1995.26 315.85

62 32 1584.89 281.5

61 31 1258.93 250.89

60 30 1000 223.61

59 29 794.33 199.29

58 28 630.96 177.62

57 27 501.19 158.3

56 26 398.11 141.09

55 25 316.23 125.74

54 24 251.19 112.07

53 23 199.53 99.88

52 22 158.49 89.02

51 21 125.89 79.34

50 20 100 70.71

49 19 79.43 63.02

48 18 63.1 56.17

47 17 50.12 50.06

46 16 39.81 44.62

45 15 31.62 39.76

44 14 25.12 35.44

43 13 19.95 31.59

42 12 15.85 28.15

41 11 12.59 25.09

dBm dBw Watts Volts (50Ω)

40 10 10 22.36

39 9 7.94 19.93

38 8 6.31 17.76

37 7 5.01 15.83

36 6 3.98 14.11

35 5 3.16 12.57

34 4 2.51 11.21

33 3 2 9.99

32 2 1.59 8.9

31 1 1.26 7.93

30 0 1 7.07

29 -1 0.79 6.3

28 -2 0.63 5.62

27 -3 0.5 5.01

26 -4 0.4 4.46

25 -5 0.32 3.98

24 -6 0.25 3.54

23 -7 0.2 3.16

22 -8 0.16 2.82

21 -9 0.13 2.51

20 -10 0.1 2.24

19 -11 0.08 1.99

18 -12 0.06 1.78

17 -13 0.05 1.58

16 -14 0.04 1.41

15 -15 0.03 1.26

14 -16 0.03 1.12

13 -17 0.02 1

12 -18 0.02 0.89

11 -19 0.01 0.79

10 -20 0.01 0.71

9 -21 0.01 0.63

8 -22 0.01 0.56

7 -23 0.01 0.5

6-2400.45

5-250 0.4

4-2600.35

3-2700.32

2-2800.28

1-2900.25

Power Conversion Chart

dBm to dBw: Watts: Microvolts

61-38-05 UserMan page 36 of 38

TXRX Systems Inc. Manual 7-9408-1.2 07/25/05 Page 36

dBm dBw Watts uVolts (50Ω)

0 -30 1.0000E-03 223606.8

-1 -31 7.9433E-04 199289.77

-2 -32 6.3096E-04 177617.19

-3 -33 5.0119E-04 158301.49

-4 -34 3.9811E-04 141086.35

-5 -35 3.1623E-04 125743.34

-6 -36 2.5119E-04 112068.87

-7 -37 1.9953E-04 99881.49

-8 -38 1.5849E-04 89019.47

-9 -39 1.2589E-04 79338.69

-10 -40 1.0000E-04 70710.68

-11 -41 7.9433E-05 63020.96

-12 -42 6.3096E-05 56167.49

-13 -43 5.0119E-05 50059.33

-14 -44 3.9811E-05 44615.42

-15 -45 3.1623E-05 39763.54

-16 -46 2.5119E-05 35439.29

-17 -47 1.9953E-05 31585.3

-18 -48 1.5849E-05 28150.43

-19 -49 1.2589E-05 25089.1

-20 -50 1.0000E-05 22360.68

-21 -51 7.9433E-06 19928.98

-22 -52 6.3096E-06 17761.72

-23 -53 5.0119E-06 15830.15

-24 -54 3.9811E-06 14108.64

-25 -55 3.1623E-06 12574.33

-26 -56 2.5119E-06 11206.89

-27 -57 1.9953E-06 9988.15

-28 -58 1.5849E-06 8901.95

-29 -59 1.2589E-06 7933.87

-30 -60 1.0000E-06 7071.07

-31 -61 7.9433E-07 6302.1

-32 -62 6.3096E-07 5616.75

-33 -63 5.0119E-07 5005.93

-34 -64 3.9811E-07 4461.54

-35 -65 3.1623E-07 3976.35

-36 -66 2.5119E-07 3543.93

-37 -67 1.9953E-07 3158.53

-38 -68 1.5849E-07 2815.04

-39 -69 1.2589E-07 2508.91

dBm dBw Watts uVolts (50Ω)

-40 -70 1.0000E-07 2236.07

-41 -71 7.9433E-08 1992.9

-42 -72 6.3096E-08 1776.17

-43 -73 5.0119E-08 1583.02

-44 -74 3.9811E-08 1410.86

-45 -75 3.1623E-08 1257.43

-46 -76 2.5119E-08 1120.69

-47 -77 1.9953E-08 998.82

-48 -78 1.5849E-08 890.2

-49 -79 1.2589E-08 793.39

-50 -80 1.0000E-08 707.11

-51 -81 7.9433E-09 630.21

-52 -82 6.3096E-09 561.68

-53 -83 5.0119E-09 500.59

-54 -84 3.9811E-09 446.15

-55 -85 3.1623E-09 397.64

-56 -86 2.5119E-09 354.39

-57 -87 1.9953E-09 315.85

-58 -88 1.5849E-09 281.5

-59 -89 1.2589E-09 250.89

-60 -90 1.0000E-09 223.61

-61 -91 7.9433E-10 199.29

-62 -92 6.3096E-10 177.62

-63 -93 5.0119E-10 158.3

-64 -94 3.9811E-10 141.09

-65 -95 3.1623E-10 125.74

-66 -96 2.5119E-10 112.07

-67 -97 1.9953E-10 99.88

-68 -98 1.5849E-10 89.02

-69 -99 1.2589E-10 79.34

-70 -100 1.0000E-10 70.71

-71 -101 7.9433E-11 63.02

-72 -102 6.3096E-11 56.17

-73 -103 5.0119E-11 50.06

-74 -104 3.9811E-11 44.62

-75 -105 3.1623E-11 39.76

-76 -106 2.5119E-11 35.44

-77 -107 1.9953E-11 31.59

-78 -108 1.5849E-11 28.15

-79 -109 1.2589E-11 25.09

Power Conversion Chart

dBm to dBw: Watts: Microvolts

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dBm dBw Watts uVolts (50Ω)

-80 -110 1.0000E-11 22.36

-81 -111 7.9433E-12 19.93

-82 -112 6.3096E-12 17.76

-83 -113 5.0119E-12 15.83

-84 -114 3.9811E-12 14.11

-85 -115 3.1623E-12 12.57

-86 -116 2.5119E-12 11.21

-87 -117 1.9953E-12 9.99

-88 -118 1.5849E-12 8.9

-89 -119 1.2589E-12 7.93

-90 -120 1.0000E-12 7.07

-91 -121 7.9433E-13 6.3

-92 -122 6.3096E-13 5.62

-93 -123 5.0119E-13 5.01

-94 -124 3.9811E-13 4.46

-95 -125 3.1623E-13 3.98

-96 -126 2.5119E-13 3.54

-97 -127 1.9953E-13 3.16

-98 -128 1.5849E-13 2.82

-99 -129 1.2589E-13 2.51

-100 -130 1.0000E-13 2.24

-101 -131 7.9433E-14 1.99

-102 -132 6.3096E-14 1.78

-103 -133 5.0119E-14 1.58

-104 -134 3.9811E-14 1.41

-105 -135 3.1623E-14 1.26

-106 -136 2.5119E-14 1.12

-107 -137 1.9953E-14 1

-108 -138 1.5849E-14 0.89

-109 -139 1.2589E-14 0.79

-110 -140 1.0000E-14 0.71

-111 -141 7.9433E-15 0.63

-112 -142 6.3096E-15 0.56

-113 -143 5.0119E-15 0.5

-114 -144 3.9811E-15 0.45

-115 -145 3.1623E-15 0.4

-116 -146 2.5119E-15 0.35

-117 -147 1.9953E-15 0.32

-118 -148 1.5849E-15 0.28

-119 -149 1.2589E-15 0.25

dBm dBw Watts uVolts (50Ω)

-120 -150 1.0000E-15 0.22

-121 -151 7.9433E-16 0.2

-122 -152 6.3096E-16 0.18

-123 -153 5.0119E-16 0.16

-124 -154 3.9811E-16 0.14

-125 -155 3.1623E-16 0.13

-126 -156 2.5119E-16 0.11

-127 -157 1.9953E-16 0.1

-128 -158 1.5849E-16 0.09

-129 -159 1.2589E-16 0.08

-130 -160 1.0000E-16 0.07

-131 -161 7.9433E-17 0.06

-132 -162 6.3096E-17 0.06

-133 -163 5.0119E-17 0.05

-134 -164 3.9811E-17 0.05

-135 -165 3.1623E-17 0.04

-136 -166 2.5119E-17 0.04

-137 -167 1.9953E-17 0.03

-138 -168 1.5849E-17 0.03

-139 -169 1.2589E-17 0.03

-140 -170 1.0000E-17 0.02

-141 -171 7.9433E-18 0.02

-142 -172 6.3096E-18 0.02

-143 -173 5.0119E-18 0.02

-144 -174 3.9811E-18 0.01

-145 -175 3.1623E-18 0.01

-146 -176 2.5119E-18 0.01

-147 -177 1.9953E-18 0.01

-148 -178 1.5849E-18 0.01

-149 -179 1.2589E-18 0.01

-150 -180 1.0000E-18 0.01

Power Conversion Chart

dBm to dBw: Watts: Microvolts

61-38-05 UserMan page 38 of 38

TXRX Systems Inc. Manual 7-9408-1.2 07/25/05 Page 38

NOTES

Bird Technologies Group 5PI613805 SIGNAL BOOSTER User Manual 9408cvr 1 2

Bird Technologies Group SIGNAL BOOSTER 9408cvr 1 2

USERS MANUAL

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