Davco DR-30s Speaker/Power Supply Reproduction

This clone of the Davco DR-30s speaker/power supply provides 12V DC, a small speaker, and a headphone jack. A small edge-view meter measures the output voltage.

Davco manufactured an optional speaker/power supply for the DR-30 receiver, known as the DR-30S, but these are even rarer than the receiver itself. Using a photo from the manual as a guide, I homebrewed a reproduction of this factory accessory for my DR-30.

Patience is a virtue when doing metalwork, and this project stretched my patience to the limit. To make the complicated rectangular cutouts in the front panel, I first roughed out the cutouts with a nibbling tool, and then filed the openings to the desired size, using a piece of bar stock as a guide.

The chassis and panels for the speaker/power supply were fabricated out of .043" alodized (gold-tinted) aluminum sheet. In order to match the original accessory, I fabricated a sub-panel to hide the mounting screws for the switch, meter, and speaker. I obtained the dimensions for the cutouts on the front panel by scaling measurements taken from the photograph.

This interior view shows the voltage regulator mounted on a small circuit board. The regulator is heat-sinked to the rear panel, although given the modest current demands of the receiver, heat-sinking isn't really necessary.

The interior of my reproduction speaker/power supply bears no resemblance to the factory original. I used a high-quality Radio Shack 3.5 inch speaker, a fleamarket edge-view s-meter (relabeled to indicate DC volts), and other parts out of my junque box. Whereas the original Davco power supply used a simple zener diode and one-transistor regulator, I used a 3-terminal integrated circuit which provides current-limiting and automatic shutdown. I also used a 3-wire line cord (for safety) and fused the transformer primary with a 250mA slow-blow fuse.

I am indebted to Rick WA6NCX for providing the nice wraparound aluminum cabinet. The paint for the cabinet and panel was mixed by a local body shop.