大象传媒

THE CRYSTALS OF ABU ZAABAL

Abu Zaabal was a scruffy Egyptian village some 20 miles NE of Cairo. It is also the site or Radio Cairo, which in the forty鈥檚 was an enormous beast of several hundred kilowatts, Marconi Vintage. At that time there was also a civilian radio terminal which our forces used for unimportant traffic. It is probably still there.

One day I was told to go to the radio terminal, and see what spares they really did need from us, and to cut down their rather optimistic shopping list. This being completed the chief man led me to see their now dug-out (paid for by British tax payers), of which he was extremely proud. Well he might be. It was obviously the bottom story of a high building to be, complete with large holes in the 2ff thick roof for stair cases, pipes etc All dug out probably unique in military history.

The scene was of course somewhat dominated by the masts and Aerials of Radio Cairo, Which operated at about 550m. It was one of those prestige stations and was an object of great National Pride, with a potential coverage of all the neighbouring Arabic speaking lands. It broadcast in roughly equal times of French and Arabic plus a little English news for the troops.

However, the enormous aerial had a funny little, extension at an angle at one end, and according to my mate this had been added to try and increase the coverage in Saudi Arabia whore the Koran readings were very popular. It seems that the Russians had quite illegally used Cairo鈥檚 wavelength with some station down by Samarkand, which produced a lovely heterodyne, washing out the Saudis. Moreover the extension did not work. I asked my mentor why they didn鈥檛 change frequency and he said 鈥渨hy not go over the way and ask them?鈥�

This we did and indeed I knew a few of the lads there. They said that the station had a crystal oscillating on its fundamental frequency which was a cubic, and such crystals did not abound. I had 4 look at it whore it sat in a sort of cats cradle of silk threads within an oven. In a weak moment I offered to make them another one, some 15 2Hz down, where there was a nice gap in the radio spectrum in those parts. It seems that the Russians had refused to move and also did not even answer their letters. The Bear changes little over the years.

We had intact made a few cubics amongst our thousand crystals per month, and technically it would be easy. But, politically it was not. A fine old hornet鈥檚 nest was raised. It was suggested at one extreme that the British wanted to sabotage the station, and at the other they couldn鈥檛 make crystals anyway! In the end the head of ESB came round and saw our crystals duly made and was converted Also those rather nice old gentlemen who know the Koran by heart, and more often blind, agreed that if Allah had put the idea into the heads of the infidels it would probably work out O.K., for were they not also People of the Book?

My own people were not very pleased. I was told that if it did not work out, heads would roll, so I had better be careful.

A nice piece of quartz was selected with prominent edges, for fixing the axis free from optical twinning so far as we could make out. Then a slab at right angles to the main axis was cut and then taken up to the neighbouring hospital (military) with our x ray gun and a short squirt of their machine on the top gain setting, produced an excellent scatter spectrum resulting in a small correction of the axis assessment by about 20.

A number of oversize crystals were then cut off from a corrected slab, etched for twinning, etched for deeper flaws and finally a couple were finished to the correct frequency and tried out in a mock up of: the Marconi unit. As all checked with .known data as to thickness/frequency, temperature drift etc. the new crystal was slipped into position one midnight. A few controls were tweaked here and there round the station. An agent in the Saudi Capital had been alerted and he reported a miraculous improvement! No thanks were received or expected. The thanks arc to God who put the idea into the hearts of the Givers.

Some times after my return from Egypt I would listen late at night and check that the frequency was where we had left it. Suez however altered all that. Our lot bombed the radio station and it was off the air for some time. Perhaps the crystals escaped destruction - they deserved to, for I doubt if any other pair received such careful treatment and caused such bother!

Written by the late Eric Vast Submitted by kind permission of his family. Published in the Vital Spark the magazine of the Hastings Electronics and Radio Club in August 1986

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