Fotos of DF0WD
|Old Longwave equipment for 136kHz.
Shown below is a photo of DL4YHF's old 20-watt longwave transmitter and antenna tuner. From left to right: Power supply (12 V, 10 A), transmitter (with top cover removed), and antenna tuner.
The tuner is a big coil on a PVC pipe with a parallel high-voltage capacitor. The tuner matches the 50-Ohm output of the transmitter to the 200m long wire antenna (only 1/2 of the feeder line is connected).
The impedance match can be optimized with an alligator clip on the primary coil, which consists of 5 turns with larger diameter (held by plexiglass strips on the outer side of the secondary coil). Looks a little bit like an old tesla-transformer...
At the top of the coil, you can see an ugly antenna current meter and a neon bulb that helps to tune the system.
The (old) transmitter