How to fix a transmitter by Ian Gillis

Seeing the title "Anecdotes" related to the broadcasting wiki reminds me of one told a very long time ago by Basil Neil Maclarty.  At the time I was a member of the Chelmsford Amateur Radio Club and he was a guest lecturer.

The anecdote is one of those that could be padded out for an after-dinner speech, but the essence of it is as follows:

Marconi installation engineers were working on a transmitter for Vatican Radio and they just couldn't get it to perform correctly.  So a passing cardinal suggested that they sprinkled it with holy water and blessed it.  As this was the only thing they hadn't tried they gave it a go, and were amazed when the transmitter ran up perfectly.

The corollary to the story is that one of those engineers happened to be present when some American engineers were having a similar difficulty with one of their transmitters.  So he said that he had a fix which had worked before, at which they gathered round, all agog - but they didn't believe it when they heard it!

This may be apocryphal and it's over 50 years since I heard it - but maybe someone else could put more detail to the legend?  Ed. Any comments in box below please.

How to build a transmitter by George MacLean

Click here to see how it is done

Recollections of the Ikorodu, Nigeria Transmitter by George MacLean

Click here for details

The Foreman's Do - by Ewan Fenn and Martyn Clarke

The after effects after a long evening 'just chatting' can be seen here.

From George MacLean via email - 15th July 2013

I remember when I was asked to help out with the IBA (ITA then), 50 kW UHF transmitter.  I was sent down to the Midhurst transmitter site in Kent, as the site was due to come on air in a few days time, but the dealers in the Petersfield area could not pick up any signal.  So, on Ron Bradbrook's orders, I was sent out with another bod, with a portable TV set that would work off the car battery, a long cable and a TV aerial, to see if we could get any reception.  We travelled in a semi circle on the Petersfield  side of the transmitter, stopping the car, getting out and pointing the aerial toward the mast, at various intervals and as reported the signal died, as we reached Petersfield.  We later we found that the 'riggers' had connected the dipoles so that it was 'cardioid' instead of omnidirectional.  But the purpose of this anecdote is still to come.

That night we were all in the hotel bar, a pub, I think that it was, and a guy came in, asked if we were the Marconi people.  When we admitted to this, he proceeded to buy us drinks.  He was in fact the local post office chief, and as we has caused a stir, by people thinking that we were detector vans looking for unpaid TV licence dodgers, many people had come in to buy licences!

Happy days.....

From Neil Friday - September 2014

My reminiscences of designing, installing and running the Isle of Wight Radio Station using Marconi equipment can be viewed here.

Update - March 2016

Neil watched a TV programme (dated 2015 RTF production) about houses costing more than a million GBP in the UK.  One of them, he recognised on the Isle of Wight where he did an outside broadcast from when he was Engineering Manager at Isle of Wight Radio in the 1990´s.

See this article from the Australian Daily Mail suggesting Marconi made his first broadcasts from here.

From George MacLean - September 2014

I was at BBC Rampisham, in Dorset, commissioning two B6128 Short Wave transmitters.  On this particular day I was setting up for a wire test, that would test the 'Crowbar' circuitry that protected the Valve from being damaged by an internal flash over and the resulting arc.

The main part was an ignitron and circuitry that would determine the beginning of an arc, in the valve and this would cause the ignitron to fire, and short the HT across the valve anode ('plate' for American readers) to earth, before the arc was strong enough to damage the Valve.

The test comprised of a vacuum switch that was connected to a length (one inch  per kV of the HT, 35 inches in this case) of 40 gauge copper wire across the HT to earth and when the Vac switch would be remotely operated.  Then for the test to work, the ignitron must fire quickly enough (in nano seconds) to short out the HT before the wire would fuse and break.  The test, if working, would just be non alarming, and all that could be heard is the clunk of the vac switch operating, however if the test did not work then the description below will inform.

My contact at Rampisham was a friend and colleague from the BBC's headquarters at Warwick in England, Doug Frostick.  He and I had a good working relationship.  On this particular day, he had a party of school kids there, and was showing them around and asked me if I would demonstrate the test to them.  As the Customer is always right, I agreed.

Here I should point out that this test had to be conducted with the wire and a Vacuum switch outside the cabinet, as, should the test not work, then there would be remains of molten copper wire splattered all over the transmitter components.

This necessitated  'frigging' (bypassing) the door interlock so that the Transmitter could be powered with the modulator door open.  A 'No No' these days with 'Health and Safety at Work'.  Because of this danger I would conduct the test in between the two cabinets with safety barriers blocking access to about ten metres.

The kids assembled at this barrier, about a dozen or so, with Doug, and I explained what I was going to do, and I added, that not much was going to happen, and that there was not going to be much to see (the crowbar on this transmitter was very reliable and this test was about 99% successful).  So I operated the Vacuum switch and to my shock and disbelief there was an almighty bang and a flash of flame as the wire exploded.  I recovered myself quickly and turned around to explain to the children that this is what did happen when the test did not work, however there were no children there, as they had all done a bunk for the exit door, leaving Doug there by himself, smiling.  I said to Doug, (and I was still shaking as one does when the test does not work when one expects it to) 'Bloody Hell, what happened, I expected that to work'. 

'I didn't', he replied, with a much bigger smile, putting his hand into his pocket and fishing out the Ignitron exciter lead.  He had removed this at an earlier time, after I had checked the circuitry!!

I made him buy the beer that evening!  There was an extra pair of trousers in the laundry that week!