The KA1AXY 40-9er

The enclosure is a recycled Ethernet transceiver enclosure. It's unmodified, except that I replaced the original front and rear panels with pieces of aluminum sheet, which I drilled for the controls and connectors. It weighs maybe a pound, has rounded edges, and slips neatly into my pack.

The circuit design is pretty much the original Forty-9er, with some of the QRP-L modifications, like the C6/RFC6 interchange, the modified PI output filter (470-2.2-470) and the 180 pf cap in the RX input filter. I didn't notice much difference, but they didn't cause any harm either. I plan to add the new TX offset change, too. I blew up the first NE602 with a rogue oscillation, so I have a nasty feeling there is a bit more I can do in the way of grounding and bypassing.

The one thing I did do was to mount C6, the tuning capacitor, a little differently. Instead of mounting it on the PCB, I mounted it at right angles to the PCB, using the ground etch that runs around the periphery of the board as a tie point for the rotor connection, and tying the stator to the flying lead of RFC6. This gave the cap a solid mounting, and allowed me to extend the shaft with a piece of hobby brass rod.

One end of the brass rod is filed to a screwdriver profile, and engaged in C6's slotted shaft. A piece of 1/8 inch Teflon spaghetti over the joint holds the two shafts together, allowing for a slight alignment mismatch. The 1/8 inch tuning knob attaches to the brass rod coming through the front panel.

The Forty-9er PCB is attached with four small bolts to a larger piece of copperclad PCB material cut to the size of the former inhabitant of the enclosure

I call this the "carrier" board. Since it is copperclad, I can solder the battery compartment divider and the front panel mounting strip to it. The front panel is attached to the carrier PCB with a piece of brass strip, bent at a right angle.

I drilled a hole in the brass strip and used the antenna BNC connector to clamp it to the aluminum front panel. The whole assembly slides into slots in the enclosure and two screws hold it together. The battery seems to last quite a while, so it shouldn't be necessary to disassemble the unit in the field, but I used slotted screws, just in case. There's enough room in the cast to tape a spare screw inside, should one get dropped.

I'm in the process of replacing that battery compartment divider with a tiny iambic keyer circuit, built around a PIC16C84 controller, and designed by Rick Miller, KB9OBN. The PIC available is a surface mount package and the keyer requires only about 4 milliamperes. It's not done yet, but I have tested a full size breadboard version.

I'm also going to replace that power switch at the back of the carrier board with a tiny microswitch from Cherry, that will be activated by the tip of the headphone plug as it's inserted into the jack. The bracket holding that switch slips onto one of the screws holding the Forty-9er board to the carrier board.

The front panel artwork was done using Micrografx Designer on a PC, then plotted onto a piece of Scotch Magic Tape and covered with a second piece of tape.

This technique was described on QRP-L. It works really well, and for artwork that's bigger than the tape width, overhead transparency material also works.