28MHz Test Source GW4RWR

A low power test source can be useful for testing receivers and antennas. This is the simplest transmitter possible, a single bipolar device and a pair of third overtone crystals, allowing access to 28.138 or 28.197MHz. The former frequency is clear for low power beaconing on 10m. It produces a few mW.

The source has been useful for playing with 70MHz antennas, allowing me to take just the transverter and a 4Ah battery outside, rather than a heavy HF radio, its power supply and an extension mains lead.

There's plenty of drive available for the transverter, and although it's limited to two frequencies, the 70MHz signal is spectacularly clean. A suitable driver for the annual CW contest perhaps?

An idea not pursued was to have two outputs, such that I could have a beacon going on 10m and a simultaneous transverted beacon.