135 kHz - an old hat

When the message was spread in the Germany round message the fact that the release of the VLF area is approaching with 135 kHz in DL (1997) became in me memories awake. Because I drove my first QSO to 135 kHz. Quite officially - with permission by the German post office (the late German Democratic Republic), at that time the sovereign authority responsible for my residence. Only it did not know at the time yet that one drives a manufacturing of a radio link " QSO " calls. It must have been in the year 1970 or 1971, I believes I was in the sieved class. I got a elektronic and radio kit to Christmas given by my parents. It contained three transistors, two so-called AF and a so-called RF transistor, different of resistances and condensers, of two sofitten (little light bulbs), a germanium diode (GA100), half headphone (one ear), a variable condenser 50 to 500 pF, as well as a medium wave coil and a long wave coil. These components were fastened on plastic carriers and could be put on a mounting plate and with wires, which had simple clamps at both ends are connected. Thus it was to be structured possible many simple circuits: Multivibrators, AF amplifier, detector, audion and as culmination a whole long wave transmitter. This long wave transmitter was a simple oscillator over a microphone (the high impedance telephone earpiece half headphone served as microphone) in amplitude modulation operated. Whereby an unpleasant, volume-dependent effect occurred, which one, as I learned FMing later call. To structure in the building guidance one to it obligates this sender only with the long wave coil and pivot the variable capacitor completely. Thus the frequency was sufficiently exactly determined. Further the uncoupled RF should be attached directly with a short wire to the antenna input of a radio. On the last page of the guidance booklet the " special permission of the German post office " was printed for the frequency of 135 kHz.

My friend Bernd, had also so a kit. To the broadcast recording with our detectors we had already before we these component systems got a bell wire (4 wired) over the yard strained (approx. 20 m), by which everyone uses a vein as antenna. Now everyone took a wire as transmitting antenna and one as receiving antenna. So we could structure a radiotelephone communication. The quality was very bad, the long wire caught a quantity of disturbances, the signals was very quiet and the FM effect did its remaining. It was an unforgettable experience nevertheless. Likewise the discussions (can we dare it?), those the experiment with the medium wave coil, which was executed only briefly, preceded.

Later Bernd the call signal DM4NTG and I had three or four years was DM4MTG.

The selection of the frequency for this component system was not so stupidly selected at all. At the lower end the long-wave range of each radio receiver, was the experiment in almost any household to be executed and to disturbances of other radio services were there probably hardly - and of this little transmitter only quite not - to be expected.

Thus 135 kHz! On a new!