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Technical Tips from Mark W. Persons

Grounding for the Arrakis 1200-10S Audio Console


This Arrakis 1200-10S Console has been modified in the shop to have a convenient grounding strip (buss) across the rear.  The photo was taken with the front panel open exposing the three main circuit cards inside.  At the rear of each card is a row of white plug-in connectors.  The connectors do not have ground brought to them at each card because noise may be induced into the audio card if current flows in the ground conductor.  To get around the problem, we have installed a 1/8 x 3/4-inch aluminum buss along the rear of the console case.  There is a convenient 1/2-inch area to bolt the buss to the chassis.  Along the front of the buss are sixteen 6-32x1/2-inch machine screws.  To do that, we had to drill and tap thread each hole. 

The station ground should be firmly connected to this aluminum buss along with the shields of audio cables coming to and going from the console.  Actually, shields are connected or not connected depending the the individual situation for that audio run.  Making the right decisions will result in clean hum-free audio.


Here is an earlier attempt at providing grounding in the Arrakis 1200-10S Console.  This one has 6-32 machine screws tapped into the step at the rear of the console chassis.  Ground wires, for each of the audio connectors, have spade crimp-terminals that are grounded by the screw.  In this way, changes can be made with a minimum of time and effort. 

Coming toward the front is a bundle of 2-pair shielded cables to the multiple input switches on the console face.  See the next photo down.


The 2-pair shielded wires go to the switches.  These assemblies were wired on the bench and then installed in the console at the studio.  It is important to keep the wiring neat and organized.  All later wiring needs to be done in the same manner in order to prevent a tangled mess that is difficult to work on.

The stories go on and on.  Stop in again sometime.  I'll leave the soldering iron on for you. 
Mark W. Persons   ham W0MH      

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