Radio Shack HTA-20 User manual

RADIO SHACK LIMITED WARRANTY

This product is warranted against defects for 1 year from date of pruchase

from Rad.io Shack company-owned stores and authorized Radio Shack

franchisees and dealers. Within this period, we will repair it without charge for

parts and labor. Simply bring your Radio Shack sales slip as proof of

purchase date to any Radio Shack store. Warranty does not cover

transportation costs. Nor does it cover a product subjected to misuse or

accidental damage.

EXCEPT AS PROVIDED HEREIN, RADIO SHACK MAKES NO

WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WARRANTIES OF

MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.

Some states do not permit limitation or exclusion of implied warranties;

therefore, the aforesaid Iimitation(s) or exclusion(s) may not apply to the

purchaser.

This warranty gives you specific legal rights and you may also havo othar rights which

vary from state to state. We Service What We Sell

Cat. No. 19-1122

OWNER'S MANUAL

RADIO SHACK

A Division of Tandy Corporation

Fort Worth, Texas 76102

Printed in Korea

!ladle Ihaek®

FEATURES

Your Radio Shack HTA-20 VHF Amplifier with RX Pre-

Amplifier is a high-power, filtered VHF band amplifier

designed for use with transceivers in the 144 - 148 MHz

FM frequency band. When your transceiver transmits, the

amplifier amplifies the transmitted power.

Its features include:

Bipolar Transistor High Power Amplifier - increases a

normal transceiver's output power from 0.5 - 5 Watts up to

30 Watts.

Double Tuned Helical Band Pass Filter - reduces out-

of-band interference by allowing the received frequencies

in the 144 - 148 MHz band to easily enter the receiver but

attenuating all other frequencies.

Low Noise GaAs Field Effect Transistor (FET) Pre-

Amplifier - normalizes insertion loss and provides clean

received signal gain.

Note: This amplifier is designed to be used only with a

high-power antenna.

Radio Shack is a registered trademark used by Tandy Corporation.

-----------_\._~~~~

CONTENTS

Preparation 4

Mounting the Amplifier 4

Installing an Antenna 6

Making the Connections 7

Matching the Antenna's Standing

Wave Radio (SWR) 11

Operation 13

Troubleshooting 14

Maintenance 16

Caring for Your HTA-20 16

Replacing the Fuse 17

Specifications 18

PREPARATION

The most common place to mount an amplifier is under a

vehicle's dashboard. Choose a specific location where:

• You can easily reach the amplifier.

• The amplifier's wires and RF cables reach their con-

nection points and do not interfere with any of the vehi-

cle's moving parts.

• The amplifier is not directly in front of air vents.

MOUNTING THE AMPLIFIER

Warning: Mount the amplifier securely to avoid damage

to the amplifier or vehicle and to prevent injury to anyone

in the vehicle during sudden starts or stops.

Follow these steps to mount the amplifier.

1. Mark the positions for the screw holes using the supplied

mounting bracket as a template.

2. Drill the screw holes into the mounting surface at each

marked locations.

Caution: Be sure you do not drill into electrical wires

behind the mounting surface or into any of your

vehicle's moving parts.

3. Attach the mounting bracket to the mounting surface

using a Phillips screwdriver and the supplied mounting

screws and washers.

4. Attach the amplifier to the mounting bracket with the

supplied mounting knobs.

Note: The mounting knobs are large and slotted so

you can easily tighten them with either your fingers or

a large flat-blade screwdriver. Do not over-tighten.

INSTALLING AN ANTENNA

Be sure to use the amplifier only with a high power

antenna. Consult your local Radio Shack store for as-

sistance in selecting an appropriate antenna.

Caution: Due to the amplifier's high power output, a low

power antenna will get hot within a few minutes after

starting transmissions. An over-heated antenna causes

SWR (Standing Wave Radio) degradation which can

damage the RF power transistor, and in some cases,

damage or destroy the antenna.

• When selecting the antenna's mounting location:

• Mount the antenna vertically and as high as possible on

a vehicle.

• Mount the antenna and route the RF cable as far as

possible away from electrical noise sources (ignition

system, gauges, etc.).

Follow the mounting instructions supplied with the

antenna, then route the antenna's RF cable to the am-

plifier.

Caution: Do not run the cable:

• Over sharp edges or moving parts that might damage

the cable.

• Next to power cables or other communication unit's

antenna cables.

• Through the engine compartment or other areas that

produce extreme heat.

MAKING THE CONNECTIONS

Cautions:

• When used in a vehicle, the amplifier is designed to

work with a 12-volt, negative ground electrical system.

If you are unsure about your vehicle's electrical system

type, check with your vehicle's dealer.

• To avoid damage to the amplifier's RF power transistor

when you use a DC power supply instead of a vehicle's

12-voltelectricalsystem,useonly a powersupply(such as

Cat. No. 22-120)thatis fullyprotectedagainst over-voltage

and high frequency intrusion and is capable of supplying

high current.

• To prevent damage to your amplifier, do not apply power

to it until after you connect an antenna.

Notes: To achieve full rated power output when using:

• Your vehicle's electrical system, your vehicle should be

running so the nominal input power to the amplifier is

13.8V DC.

• A DC power supply, set the output to 13.8 volts.

1. Set POWER to the off position.

3. Push and turn counterclockwise the fuse holder in the

amplifier's red wire, pull the holder apart, and remove

the fuse.

4. Connect the amplifier's black wire to a metal part of

your car, such as your transceiver's ground source.

POWER

5. Connect the amplifier's red wire to a source of 12-volt

DC power, such as your transceiver's power source.

To Switched

12V DC

DC 13.8V ANT OUTPUT

@ r...i ~ ~ @

~ ~

POWER TX

off

2. Remove the power source by doing one of the following:

• Disconnect your car battery's negative terminal.

• Turn off the DC power supply.

Black Wire to Ground

6. Connect your transceiver's antenna RF cable to the

TX INPUT connector on the back of the amplifier. 7. Connect the antenna to the ANT OUTPUT connector

on the back of the amplifier.

• Reconnect your car battery's negative terminal.

• Turn on the DC power supply.

After making all the connections and before you begin

operating the HTA-20, test your transceiver and match

your antenna's SWR for top performance using an SWR

meter (not supplied).

MATCHING THE ANTENNA'S

STANDING WAVE RATIO (SWR)

8. Place the fuse inside the fuse holder, then push the

holder's ends together and tighten them by turning

the holder clockwise.

9. Reapply the DC power source by doing one of the

following:

)

.- -=

I'-J

I~===cil

I ~ (g) [g) g]l

I[Q] [Q] [Q] QJI'[g] IQ] [Q lQl

ANT OUTPUT TX INPUT

~ ~@

50 ohm RF Cable

Antenna

10 11

Notes:

• Make sure the SWR meter can measure the 144-

148 MHz frequency band and an output power of at

least 30 Watts .

OPERATION

To turn on the transceiver, set POWER to ON.

Set POWER on the amplifier to on. The POWER indicator

lights.

• Verify the SWR using the transceiver's low power

before turning on the amplifier to fine tune the SWR

at high power.

Use the instructions supplied with the SWR meter to

measure and adjust your antenna to the lowest SWR

value. Ideally, the SWR should be as low as 1.0:1. To

be acceptable, the SWR must be less than 1.3:1.

,I,

- c:::I - c:::I

POWER TX

POWER

[DON

When your transceiver transmits, its low-power signal is

sent to the HTA-20. The amplifier boosts the transmitted

power and sends the signal to the antenna for transmis-

sion. The TX indicator lights during transmission.

When your transceiver receives, the received signals are

routed through the amplifier's helical narrow band pass filter

to reduce undesirable out-of-band signal interference,

amplified by the low-noise GaAs FET pre-amplifier, then sent

back to the transceiver.

TROUBLESHOOTING

If your amplifier is not working as it should, follow these

suggestions to see if you can eliminate the problem. If you

cannot eliminate the problem, take the amplifier to your IOi

cal Radio Shack store for assistance.

Symptom Suggestion

No power to the

Check the red and black wires'

amplifier. connections.

Check the power source (either

vehicle battery or DC powersupply) and the in-line fuse

(replace only with an 8-amp fuse).

Cannot transmit and

Check all cables and insure they

receive. are securely connected between

the amplifier and the antenna

and transceiver.

Check all cables and wires for

short/open.

Output power is not

Check all cables for short/open

amplified. and be sure they are connected.

Symptom Suggestion

Output power is less

Check that the driving power

than the rated level. from the transceiver is within the

rated level (0.5 to 5 Watts).

Check the power source to

insure it is a 12 volt source.

MAINTENANCE

CARING FOR YOUR HTA-20

Your Radio Shack HTA-20 VHF Amplifier with RX Pre-

Amplifier is an example of superior design and craftsman-

ship. The following suggestions will help you care for your

amplifier so you can enjoy it for years.

Modifying or tampering with the amplifier's internal

components can cause a malfunction and void your

authorization to use it. If your amplifier is not performing

as it should, take it to your local Radio Shack store for

assistance.

REPLACING THE FUSE

Keep the amplifier dry. If it gets wet, wipe

it dry immediately. Liquids contain minerals

that can corrode electronic circuits.

Handle the amplifier gently and carefully.

Dropping it can damage circuit boards and

cases, and can cause it to work improperly.

Keep the amplifier away from dust and dirt,

which can cause premature wear of parts.

Wipe the amplifier with a damp cloth

occasionally to keep it looking new. Do not

use harsh chemicals, cleaning solvents, or

strong detergents to clean it.

1. Set POWER on the amplifier to off and turn off the power

source.

2. Hold the amplifier's in-line fuse holder by both ends,

push and turn it counterclockwise, then pull it apart.

3. Replace a blown fuse with an 8-amp fuse of the same

type and rating.

4. Push the holder's ends together and tighten them by

turning the holder clockwise.

SPECIFICATIONS

Frequency Band 144-148 MHz VHF Band

Frequency Mode F3 (FM)

RF Output Power 30 Watts

Input Power 0.5 - 5 Watts

Power Source DC 13.8V

Negative Ground Max Current 6 Amp Max

Spurious Level Less than - 60 dB

Net Gain (Receiver with Helical Filter) 0 dB

Receiver Bandpass Filter Double Tuned Helical

In/Out Impedance ,50 Ohm

In/Out Connector M Type

Dimensions (HWD) 1V2 x/3% x 6% Inches

Weight 13,4 Ibs

Specifications are typical: Individual units may vary.

Specifications are subject to change and improvement

without notice.

NOTES

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