HTA-20  (190-1122)                 Preparation         Faxback Doc. # 14958

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 connection points and do
   not interfere with any of the vehicle'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

    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

    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 assistance 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 9 Standing Wave Radio)
          degradation which can damage the RD 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 amplifier.

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 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.

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

    *  Disconnect your car battery's negative terminal.

    *  Turn off the DC power supply.  
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.

5.  Connect the amplifier's red wire to a source of 12-volt DC power, such 
    as your transceiver's power source.

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 

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:

    *  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).

Notes:  Make sure the SWR meter can measure the 144 - 148 MHz frequency
        band and an output power of at least 30 Watts.

        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 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.


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