The RF Limited TRB-1 Turboń 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 donĺt even know that a Connex board is an echo board. Iĺm 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 doesnĺt increase the amplitude of modulation. It creates the elusion of the signal coming from a larger than life source.
Now, the TRB-1 Turboń 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 Echoń & Endless Echoń. Fifth, its capabilities include sound effects like Whammyń & multi-tone Alien Voiceń. Check the audio samples below.
TRB-1 Audio Samples
Reverb Slight Echo Repeat Echo
Endless Echo Whammy Effect Other Effects
High Alien Voice Medium Alien Voice Low Alien Voice
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
1 Ground Audio Audio Ground Audio
2 Audio Ground Ground Audio Ground
3 TX RX TX TX 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 -