If you have built this circuit correctly, no tune up should be necessary. You should be able to use a nearby 80M receiver on 3686.4 KHz to hear the signal. If it doesn't start oscillating when you key the transmitter into a dummy load or matched (50-ohm) antenna system, check again to make sure that all components were installed correctly, that there are no solder bridges, and that there are no loose connections.

If it still doesn't work, ensure that there is a positive voltage difference between the collector and the emitter (about 6.3V with a 13V supply). If not, then either one or more components is not installed correctly (most likely Q1, R1 or L1) or there is a problem with your transistor. Replacement 2N2222A transistors are available at both Radio Shack and Tech America. At last resort, you can use a 2N3904 or 2N4401 transistor (however, expect less power output).

If you ave a good voltage difference between the collector and the emitter, then if you have an oscilloscope, check to see if you have a sine wave at either lead on C3. If you do, and you don't have one coming out from the RCA jack, then one or more of the components in the output filter (C1, C2, L2, RCA jack) is not connected correclty.

You will most likely see little, if any, deflection on a normal ham shack power meter, unless you have one designed for QRP. A good circuit for testing the power output of QRP rigs can be found in Solid State Design for the Radio Amateur by Wes Hayward, W7ZOI, and Doug DeMaw, W1FB. This is a workhorse, utility circuit that has multiple uses in the QRP station.

The possibilities for experimentation with this circuit are endless. Initially, try making contact with a nearby ham (within a couple of miles, if possible). You'll be surprised how well he can hear your QRPp signal. As you get more familiar with operating this rig, try making contacts further and further out-even try checking in the NOGA and/or Knightlights nets (Tuesday and Sunday nights, respectively, at 9:30 Eastern time on 3686.4 KHz).

This circuit can be the basis for many more complicated circuits-nearly every piece of radio transmission and reception equipment has at least one oscillator in it. Experiment with placing a variable capacitor (available at any ham fest) in series with the crystal (remove the grounded end of the crystal and attach to one end of the capacitor, and connect the other side of the capacitor to ground). The oscillator in this configuration is known as a VXO or variable crystal oscillator. VXO's are very stable, but at 80M you will probably only get about 1KHz or so of swing, using a 200 pF to 300 pF variable capacitor. You can also adjust the frequency (downward) by adding inductance (say 33 uH to 56 uH) in series between the crystal and the variable capacitor.

The number one object of QRP operations, home-brew, and home-construction is HAVE FUN! Talk to others. Ask questions. MELT SOLDER!

Back to NOGAnaut Page