HTX-404  (190-1140)            Operation                Faxback Doc. # 6175

Operating from Vehicle Battery Power

A DC power cord (Radio Shack Cat. No. 270-1533)  supplies 13.8 volts
(typical) to your HTX-404 and can operate your HTX-404 at 5 watts with the
LOW POWER button out.  Follow these steps to operate from vehicle battery
power.

1.  Plug the power cord's barrel plug into the HTX-404's EXT DC jack.

Caution:  Never plug the power cord into the rechargeable power pack's
          CHARGE jack.  Doing so can damage the power pack and the HTX-404.

2.  Plug the power cord's cigarette-lighter plug into your vehicle's
    cigarette-lighter socket.

If the HTX-404 does not operate, remove the power cord's plug from the
cigarette-lighter socket and check the socket for debris.  Clean the
socket, if necessary, and try again.

Operating from AC Power

Operation from AC power requires an adapter or power supply (neither is
supplied).  Operate the HTX-404 from AC power using either the 1-amp 12
-volt DC adapter (Cat. No. 273-1653) or our regulated 2.5-amp power supply
(Cat. No. 22-120).

The 1-amp adapter connects quickly and requires no soldering, but only lets
you operate your HTX-404 at 2 watts (typical power) with the LOW POWER
button out.  The 2.5-amp power supply operates your HTX-404 at about 5
watts with the LOW POWER button out and is better isolated from 60 Hz
noise.

To use the 1-Amp, 12-volt DC adapter:

1.  Connect the barrel plug with the tip set to positive.

2.  Insert the adapter's barrel plug into the HTX-404's EXT DC jack.

   Caution:  Never insert the adapter's barrel plug into the rechargeable
             power pack's CHARGE jack.  Doing so can damage the power pack
             and the HTX-404.

3.  Plug the adapter into an AC outlet.

To use the regulated 2.5-amp power supply, you need the following
materials.:

Power supply (Cat. No. 22-120)

Two-conductor 18-gauge wire (cat. No. 278-567)

DC power connector (cat. No. 274-1567)

Soldering Iron and Solder

Voltmeter or multimeter

Follow these steps to power the HTX-404 from the regulated 2.5-amp power
supply.

1.  Cut the two-conductor wire to the length power cord you need.

2.  Strip about 1/2-inch of insulation from each end of both conductors.

3.  Solder one end of the wire to the DC power connector, with the red lead
    connected to the center terminal, and the black lead connected to the
    outer casing.

4.  Melt a small amount of solder unto the other end of the wire.  Then
    connect the red lead to the power supply's + terminal and connect the
    black lead to the power supply's-terminal.

5.  Plug in the power supply and turn it on.  Use the meter to confirm that
    you have correctly wired the power connector with the tip positive and
    the outer case negative.

6.  Turn off the power supply and plug the power connector into the HTX-
    404's EXT DC Jack.

7.  Turn on the power supply.

Backup Battery

Your HTX-404 uses a lithium battery to keep stored options in memory when
you disconnect it from a power source.  This battery should last 3 to 5
years under normal conditions.  When the HTX frequently displays ER1, the
backup battery needs to be replaced.

Note:  To clear the ER1 error message, reset the HTX-404.

The backup battery is not user-serviceable.  Take the HTX-404 to your local
Radio Shack store to have the battery replaced by a Radio Shack repair
center.