External Speaker Modification for
RT-1446/URC - Harris RF-350K:

This is a modification for using some of the internal wiring and
terminal block on the back of the transceiver for an external
speaker.   My radio came with an terrible sounding speaker, and
instead of wiring in a new one I decided to use an external, larger
speaker.  Good sounding speakers are often those that come with GE or
Motorola mobile radios (in a speaker your not looking for range but
clarity).

TB1 is the terminal block on the back of the radio.  Screw
9, the ninth from the top and fourth from the bottom is a spare.  It is
referred to as TB1-9 on the diagrams.  We are going to use this screw for
speaker audio.

There are two ways to do this.  You can just connect a wire
from the speaker, through the radio and hook it to TB1-9.  This is the
simplest way, but probably not the best as the wire will be in the way as your
move or remove various things around in the radio doing other stuff.  The
other way is rather elegant, but a bit more work.  You will probably want
to do this only if you plan on removing the A1A15 Interconnect PWB for some
other reason.  You will be installing a simple jumper on the A1A15, but the
board is a pain to take out.

The following diagrams will show the path of TB1-9 through the
various wiring in the radio.  The path is from TB1-9 through A1A16, the
Audio Interface PWB.  From A1A16 it goes into a wiring loom to the Exciter
PWB.  The path runs through the Exciter PWB back into the loom to the
Interconnect PWB.  Here, in the interconnect PWB the path ends and we need
to jumper it to where we want to go.

On A1A15 you will need to place a jumper wire between J7-18 to the spare on
P7-3.

From P7-3 the line goes back into the loom and to the A1A11A1 Front Panel
PWB, J6-3.  The last jumper brings the line over to the speaker switch,
J3.3.   Place a jumper from J6-3 to J3-3 and you can remove the
internal speaker.

The following additional sheet are provided for reference:

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