Looking Back
by Allan Ogden, G50D
After Brian took over as Editor of Wey Ahead, I thought that my days as an amateur journalist were well and truly over. Not a bit of it! Brian has asked me if I would write a short article… he emphasised “short”…on some aspect of Amateur Radio in an earlier era.
In a long and busy life it has not so much been difficult but impossible to keep up with all the many and wonderful changes that have taken place in the world of electronics, but looking back to the time when I was first licensed, perhaps one of the most significant changes has been in the frequency control of our transmitters.
In the early 1930s Variable Frequency Oscillators were just that,…their frequency varied…spontaneously! It varied with small changes in ambient temperature and with small changes in HT voltage. Yes, High Tension, as transistors had not then even been dreamt about. The oscillators were tamed by quartz crystals so, as a consequence, all our transmitters were “crystal controlled” as we called it. This meant that we each had our own frequency within any particular band and the spot frequency working that we have now was not possible. It also meant that two stations in contact could be, and often were, widely spaced within the frequency band.
After the advent of crystal control the transmissions were frequency stable, with virtually no drift and free from keying “chirp”, provided that the keying was done in the later stages.
Unfortunately, being unable to shift the frequency of our transmitters meant that we had to search the band for any answer to our calls and the replies had to be relatively lengthy.
Some bright spark invented our own Q code to deal with the situation. British stations, uniquely in the world at that time, were not allowed to call CQ; it was laid down in the licence that the call had to be “TEST”. As we ended a “test” call we used codes to show where in the band we would be listening for replies, QLM for tuning low end to middle, QMH for middle to high and so on!
Some of us had several crystals in different parts of a band. Such a system, together with the fact every contact occupied two frequency spots would not have coped with our modern crowded (sometimes!) bands, but then there were only about 2000 licensees in Britain compared with perhaps twenty times that number to-day. The difference that frequency stabilisation with the subsequent spot frequency working was to make to our operating conditions could hardly have been imagined at that time.
By the time of WW2 in 1939, frequency stabilisation had been much improved and my own experience over several years with the Marconi SWB8 and SWB11 transmitters was very revealing. These used the two valve Franklin oscillator which was mounted right at the bottom of the transmitter, on the floor, where temperature change was minimal. This was particularly important in one case where the SWB11, drawing over 22 Kw. ( 2 amps at 11,000 volts for the output stage), plus its driver stages, plus its high level Class C modulator (AM), plus its 22Kw oil cooled variac and three phase power supply were fitted into two (large!) articulated trailers. It could become quite warm!
To return, in 1946, to our 150 Watt rigs (then the permitted maximum power) was quite a comedown!
Allan, G5OD