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
8M
RADIO SHACK
A Division of Tandy Corporation
Fort Worth, Texas 76102
Printed in Korea
j
l!
!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.
©1994 Tandy Corporation.
All Rights Reserved.
Radio Shack is a registered trademark used by Tandy Corporation.
2
-----------_\._~~~~
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
3

-\
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.
4
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.
5

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.
6
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.
7

• 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
89

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:
)
1
1
l
.- -=
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
12
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.
13

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.
14
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.
15

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
Cj
~~
(j
16
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.
17

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.
18
NOTES
19