A Dedicated Interface … (/cont)

Left: I built the interface around a standard box from Maplin, mounted upside down as a chassis. The die-cast box serves to allow the mains transformer to be mounted below the top of the chassis. This was necessary since it would have extended beyond the upper edge of the front panel.

Right: The loudspeaker is from an ex-PMR installation. The audio output transformer is one of the two that were removed from the RA218. With reference to the photograph above, note how the transformer is ‘sunk’ into the box … much like the mains transformer in the RA218 actually.

Left: The Interface, finished in Light Admiralty Grey and installed … The switches are deliberately sited to complement those on the RA218. I even opted to make the mains switch operate in the up position. It should be noted that when using the interface and the RA218 with the RA17 or RA17L it is necessary to ‘swap’ the sidebands. This is because the RA218 was designed to complement the RA117 which is Quadruple-Conversion. The RA17 and RA17L are only Triple-Conversion receivers and thus the sidebands are reversed. I filled the space above the RA117 with a vented 3U panel, also finished in Light Admiralty Grey.