THE LONE WOLF 6L6SE
STEP-BY-STEP FREE HARP AMP PROJECT

CHASSIS



CHASSIS PREPARATION
First determine where you want the components that will be mounted to your chassis to be located. Some considerations are the size of the cutout on the cab for your controls, power transformer location, output transformer location, length and routing of input signal wires as well as the Pt wires and heater wiring. The design shown takes all of these factors into consideration. The wiring is kept as short and direct as possible, the input signal wires are not routed along power wires, the transformers are mounted at 90° angles, the Pt is horizontally mounted, and the OT is vertically mounted.

The controls are spaced for at least an 8 1/2 x 2" cab opening; if you are using a cab with a smaller opening, you will have to make the needed changes to the control component spacing. When using faceplates, secure the faceplate to the chassis and drill pilot holes through both the faceplate and the chassis so that everything will line up properly.

Tools needed include a drill, a unibit, and a jigsaw to cut out the hole for the power transformer.








THE TURRET BOARD
I chose a turret setup for the circuit board, as opposed to eyelets or point-to-point, for ease of modifying and troubleshooting. Although I do not do much modding anymore, I know that many others do and it is very easy to change parts and wiring on a turret board. The other board types mentioned are excellent, and the choice is really up to the builder. One method is not any more prone to noise than the other as long as your design is good, wires are run properly, and transformers are orientated 180° out of phase and are spaced far apart.

I made a staking tool by drilling a hole into a bolt to place the turret in and grinding a screw to a wide angle point. The turret is placed in the hole in the bolt, and the pointed screw is inserted into a drill press. When pressed down onto the turret, it will spread the turret skirt and secure it into the circuit board. Staking tools can be purchased from Mouser if you do not want to make your own, and a hammer can be used to tap the screw and spread the turret skirt in lieu of a drill press. It is recommended to tape an image of your layout onto the circuit board as a guide for drilling the holes.




TRANSFORMER INSTALLATION
Care should be taken while installing the power transformer and the output transformer. They should be mounted as far apart as practical and they should be mounted 180° out of phase, one horizontal and one verticle to minimize coupling between them. Chassis strength is another consideration when mounting transformers; I used plate washers on the output transformers to spread the stress on the aluminum chassis. The turret board is then mounted on 1/2" spacers.





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