A valuable lesson about high voltages - Tony Cunnane's Autobiography

A Yorkshire Aviator's Autobiography
Tony Cunnane
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A valuable lesson about high voltages

By the end of 1953 I was already beginning to feel like an old hand in the RAF even though I was only halfway through my initial trade training. New Year's Day wasn't a holiday - not in the RAF anyway. We started lessons on aerial (antenna) erection that day and I noted in my new diary that there was a 54ft antenna just for classes to pull up and down. We were not required to climb it when it was standing erect: the RAF had a special trade group for aerial erectors. I found that work progressed at a faster pace now that we had lost the weaker members of our original course. I thrived on it and enjoyed virtually every lesson.

Soon we moved away from the theoretical stuff and started working on real equipment that we could expect to meet when we got to our first operational station. That equipment included the T1509 medium-powered short wave transmitter and its partner the receiver R1475. Later we moved onto the VHF transmitter T1131 and the VHF receiver R1392. We were told that most of us were likely to be posted to airfields where those VHF equipments were used for short-range communications between air traffic control and aircraft. Once we had learned the theory, we were individually presented with equipment that had faults deliberately embedded and it was our job to identify and rectify them. We were warned that the two transmitters had high voltages inside and so we were given lessons on resuscitation from electrical shock, which seemed rather dramatic.

One of the considerations with rectifying faults on the transmitters was that in order to diagnose certain faults quickly it was necessary to have the HT (high tension) switched on to avoid the often lengthy 'warm-up' period each time the equipment was switched on. The training manuals stated emphatically that no work should be undertaken inside the equipment when the power was on and there were built-in safety devices to prevent you doing that. To get at the insides of the T1509, for example, you had to open the six-foot high rear door of the transmitter, which automatically released a micro-switch at the base, which in turn switched off the HT. Our sergeant instructor demonstrated a technique to get around that which would probably not be acceptable to today's Health and Safety officers.

"Always stand on the cork insulating mat the transmitter is mounted on and keep one hand in a trouser pocket," the sergeant told us. "That's probably the only time in your RAF career that you'll be ordered to put a hand in your pocket whilst working. As you start to open the rear door, jam one foot on the micro switch at the base of the transmitter - that keeps the HT on. You can then work on the transmitter with your other hand without any danger because there'll be no path to earth across your body."

To prove his point, he touched the high voltage antenna terminal of the transmitter while it was fully functioning. We were very impressed. However, his teaching was not fool proof, as I was to discover some months later in Sri Lanka when I received a very severe electric shock from a T1509 transmitter. I was strictly adhering to the Locking sergeant's advice but unfortunately, while reaching into the depths of the transmitter to adjust a variable capacitor, the fingers and wrist of my 'working' hand (my left hand) managed to form a short circuit to ground (earth) between a 1,200 volt terminal and the metal chassis of the transmitter. There was a flash and I was hurled back against a wall. I slithered to the floor unconscious. The base micro-switch would have sprung open as I fell and automatically cut off the power to the transmitter. No-one saw what had happened because there was no-one else in the transmitter room at the time, and that would doubtless also be against the Health & Safety rules these days. After what I believe was probably just a few seconds, I regained consciousness, sat up, shook my head to clear my vision, and resumed work on the transmitter. I never mentioned that incident to anyone but to this day I have a blue scar, now faded but still discernible, on my left wrist as a memento of it.

The mechanics course final examinations were in the first week of March 1954. I did well with over 80% in all the written and practical tests and I had come second overall to Denis 'Sparky' Wale. Sparky had been a wireless operator in the Merchant Navy for several years before leaving to sign on as a regular in the RAF. Because of his extensive experience as both a wireless operator and mechanic at sea, Sparky was told that he would be going straight onto the 8-month long wireless fitters course starting one week later.

"Never volunteer for anything" was a general rule in the RAF but "If you don't ask, you won't get" seemed more important to me at that time. I went to see Flight Sergeant Bettell, who was in charge of our flight, and asked him if I could move straight onto the fitters  course with Sparky. He said he would speak to the Trade Testing Officer and later in the day, to my great pleasure, I was told that I would be on the next fitters  course.

Sparky and I were sent on immediate eight days leave. Before going on that unexpected leave, I proudly sewed the 'sparks' badge onto the sleeve of my uniform jacket. The sparks badge goes back to the very earliest days of the RAF when an airman was not allowed to speak directly to an officer. Perish the thought that a lowly airman should have the temerity to address an officer unbidden: only NCOs were permitted to do so. However, when wireless telegraphy had been introduced into the Service, it was realised that it was sometimes necessary for wireless operators to approach an officer with an important signal message. The sparks badge had been introduced as the visible sign that a wireless operator was authorised to go straight up to an officer and speak. It was later decreed that all airmen who had passed their wireless trade test should wear the sparks badge.

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