The
RF Limited TRB-1 Turboä
Echo Board
There are echo boards and there are echo boards, for
that matter there are copies of echo boards. The most popular is the
Connex board. Many truck drivers don’t even know that a Connex board is
an echo board. I’m not quite sure why this is so. However, I can take a
guess or two. The Connex radio has been around for many years and is known
as a higher-powered radio with echo. Some call the big radios. Before the
echo boards were available as add-on kits if you heard a radio with echo,
it was thought to be a high power or big radio. The echo, set properly,
does give the appearance of a base station in a big room sound, hence big
radio. The Connex board doesn’t increase the amplitude of modulation. It
creates the elusion of the signal coming from a larger than life source.
Now,
the TRB-1 Turboä
echo board does all that and much more. First, it has an audio output
adjustment that adjusts to a substantially higher output level than its
input source. Second, there is also audio tailoring done in the amplifier
stage as well as in the echo stage. Third, the board has an on-board
coarse echo volume adjustment. Forth, it is capable of
Reflex Echoä
& Endless Echoä.
Fifth, its capabilities include sound effects like Whammyä
& multi-tone Alien Voiceä.
Check the audio samples below.
| The RF Limited
TRB-1 PC Board |
 |
- This resistor is removed in installations where a resistor
is missing on the standard board.
- Remove the wire from this end of the standard board and
insert and solder it here.
|
| The TRB-1
Complete |
 |
The TRB-1 is designed to fit in place of the Connex type
board. The power, input, output, and the PA preamp jacks are plug compatible.
The potentiometer is a different value, so this must be swapped out if
you're replacing a standard echo board. Also the red wire for J4 must be
connected to a 13.8 volt switched source. The black wire can be cut off.
Connecting the black wire to ground could cause a ground loop creating
distortion or even a squeel.
The instructions supplied with the PC board are very good.
Although every radio couldn't be covered, they cover the most common radio
upgrade procedure and include 5 mic connector wire schemes that probably
cover 90% of the radios on the market.
One thing that has caused some confusion, there is a
connector on the J12 header. This connector has a gray shielded cable and
a single yellow wire. This can be unplugged and discarded. This J12 header
is only used in radios that already have an echo board installed and there
is an on-board public address pre-amp on the circuit board. If the old
board has a connector in this position, just insert it into the J12
position as part of the installation. On new installations, this position
has no function and isn't used.
In addition, some of the newer radios may have changed the
pin outputs of the J1 output and J2 input connectors. This will require
either rewiring the existing connectors or installing the supplied J1 and
J2 wiring harnesses. It's a little bit of work, but it's worth it.
A couple of tips when doing a new installation: Cut the
red wire off of the J1 connector, its just a duplicate of the white wire
on J1. Also, twist the two shields of the J1 and J2 connectors and connect
then to the ground pin of the mic connector.
| Mic Jack
Pin Function |
| Pin Number |
Cobra
Uniden
4-Pin |
Cobra
Uniden
5-Pin SSB |
HR-2510/2600
Lincoln
Emperor
5-Pin |
RCI-2950/2970
2985/2990/2995
Eagle
6-Pin |
Midland
AR-3300/3500
4-Pin |
| 1 |
Ground |
Audio |
Audio |
Ground |
Audio |
| 2 |
Audio |
Ground |
Ground |
Audio |
Ground |
| 3 |
TX |
RX |
TX |
TX |
RX |
| 4 |
RX |
PTT Common |
Up |
RX |
TX |
| 5 |
- |
TX |
Down |
Up |
- |
| 6 |
- |
- |
- |
Down |
- |
|
TRB-1 Pin Function |
| |
1 |
2 |
3 |
| J1 |
Audio Output |
Ground |
TX |
| J2 |
Audio Input |
Ground |
TX |
| J4 |
13.8 Volts |
Ground |
- |
Bob F
|