Dave's First Code Practice Oscillator

Hi CW freaks! I am back again with another code practice oscillator. At noon today, I had no idea what I was going to do. After a couple of e-mails about my previous oscillator, I decided to make another. The box was prepared and the panel was fit to the box, so all I had to do is cut the holes and wire it up. Truly an afternoon project.

The box was purchased a while ago at Bed Bath and Beyond. They have some cool boxes there and when the coupon shows up at my door, I'm down there. There are two strips of pine, a soft wood that hold the panel to the box. First I drill two holes for the wood screws in the side of each piece of wood. The wood screws bite into the side of the box. Be careful as the wood splits easily. If you can, drill a  pilot hole in the side. You can also drill from the outside and put the wood screws in that direction too. 

After mounting the two pieces, place the cut panel on top of the box, measure and drill the 4 mounting holes. I then take off the panel, and drill the freshly drilled holes one size larger so the T-Nut fits underneath. The screw then draws the points of the T-Nut into the soft wood. I used this method on some of my earlier crystal sets. 

The circuit is much the same as the code oscillator shown above, except this one uses a power supply and a indirectly heated tube (heater and cathode). The type is a #43, an old time audio output tube. The reason that I selected this tube is that it is old time, and has a 25 volt heater. These tubes are widely available and usually aren't too costly. 300 milliamps is required to operate this circuit. All Electronics is a good source for this transformer.

Only a SPST switch is really needed for the power, but the DPST has extra terminals for connecting the the wires needed.

Not too much more to tell. The output is enough to fill a medium size room with sweet cw sound.  As a side note, I found it interesting that even though the cw requirement to get an Amateur Radio license disappeared over two years ago, there are still prospective hams that learn the code. Good for them!

Update: To mellow out the sound, I placed a .05uF capacitor from the plate to the cathode. This took off some of the "edge" off the waveform.