6AQ5 CW Transmitter

How's this for no-frills hamming? This cute little 40 meter CW transmitter is nothing more than a 6AQ5 oscillator coupled to the antenna. Power output is on the order of 6 Watts with 275 VDC on the plate and a crystal with good activity. The maximum plate voltage rating for the 6AQ5 is 275 VDC. Do not exceed that limit for very long, or you'll wear out your tube. It will last you a lifetime if you run it at 250 VDC. Tuneup is simple: just hit the key and adjust the slug-tuned coil for maximum power output. Use your Wattmeter or receiver's S-meter to determine when you have reached "maximum smoke". The neon bulb will saturate before that, so it's merely there for show (you can omit it if you like). Yes, the rig does have a little chirp, just enough to give your signal some "character". Using a well-regulated power supply will minimize the chirp. You can also use a 6005W tube (the military equivalent of the 6AQ5).


I take no credit for this design. It's straight out of my favorite project sourcebook, "104 Ham Radio Projects for Novice and Technician" (TAB Books, 1968).