Radio, Someone Still Loves You…

I’d sit alone and watch your light
My only friend through teenage nights
And everything I had to know
I heard it on my radio

From “Radio Ga Ga”, Track 1, Side 1 of Queen’s “The Works” (EMI Capitol 1984).
Written by Roger Taylor.

I’ve been delighted by the response to the “Joy Of Radio“, and accompanying “Resonant Frequency” [1], video that Brady uploaded to Sixty Symbols a couple of weeks ago. In addition to the very many kind, supportive, and heart-warming messages left under the video — which have done a lot to almost restore my faith in the humanity of YT’s comment sections — I’ve received a number of affecting e-mails telling me how much the video brought back happy memories.

One of these came from Rocco Cuffaro, a third year Mathematical Physics student here at Nottingham. Rocco saw the video, immediately thought of his crystal-radio-loving granddad (who is eighty years young), and emailed him a link to the video. Rocco’s granddad’s wonderfully engaging response is below. Thank you both for sharing this with me (and for giving me permission to post it here). Over to you, Rocco’s granddad…

Where do I begin?

After you and I built the Meccano type of Rocket steam engine it was my intention for you and I to build a crystal set exactly as the simple circuit in Prof Moriarty’s book. For the coil we would have used the cardboard centre of a toilet roll as a former. For the crystal I would have used a crystal from a ex war time radar if I still had some or more likely buy a silicon diode from Maplins. I have or did have plenty of variable vane capacitors that we could have used. The box of capacitors that Prof Moriarty showed us included some wide vane capacitors that were probably I guess ex transmitter components.

I very much like his approach with the experiment set up live and using a corroded penny with a wire whisker very much as it was with crystals in the early days before my time. Just a hook up of components rather than a workshop prepared demonstration.The early sets used a crystal and a wire whisker and just as he said there were many swear words so it was when people tried to find the right spot on the crystal and were then afraid to jog the thing. 

I attended an exhibition at the IET’s home in Savoy place in London( I am still a member but thinking of cancelling as I am in information overload with so many and varied things to read) which I believe marked the anniversary of the broadcast station 2LO which was the forerunner of the BBC. Many crystal sets from way back were on display and included some with more complex circuits that I was not aware of until then.

Before we became the affluent society in the 1960s I knew the elderly lady that occupied the old observatory tower in Falmouth. There was not much money around in those days so I built her a crystal set in an old cigar box and used an ex service radar diode for the crystal. The aerial was one to envy in that situation. A vertical wire 50 feet down the side of the building. The lady came from London and was thrilled to hear Big Ben for the first time in years. That happened not very long after the war.

When Nan and I lived in Ware we had a reel to reel tape recorder. I do not recall how it came about but I discovered that if I put a wire in the microphone socket the recorder thought it was a radio and picket up a strong radio signal of one programme only from obviously Brookmans Park not a million miles away. This can easily happen if all the real and stray capacitances and inductances etc allow this to happen with some non-linearity in a component giving that rectifier action that Prof Moriarty was demonstrating. I was able to record a complete set of the Gilbert and Sullivan operettas in this way. 

The converse of this phenomena is modulation and also cross modulation. At Lands End Radio the receiving aerials were close to the building housing the receivers. The transmit aerials were not very far away by a couple of fields. A problem arose when unwanted radio stations were splashing across the entire spectrum of the receivers (around and either side of 2182khz) [Editor’s note — see footnote #2 below]. I traced this to a dustbin (!) in the grounds of the station. The lid was placed lightly over the bin. On removing and replacing the lid the problem cleared. This was in my view caused by rust around the edge acting like the penny and whisker in Prof Moriarty’s experiment in reverse. The bin would have been receiving a very strong signal from the transmitting aerials of course plus a multitude of other radio signals from all over the place. The bin was transmitting a cross modulation of the lot and dumping it on the receiver aerial system. 

I will wind up there except to mention that there were a number of interesting cases of interference including a grandfather clock with no electrical connection interfering with television and the static from a lady combing her hair interfering with television through a party wall.(not mine but a colleagues) The frequencies in use then were much more susceptible to interference than now.

[1] I only realised this after reading the comments, but, remarkably, when I hit the desk to “kick start” the crystal radio at the start of the Resonant Frequency video, the song that blasts out is…Queen’s Radio Ga Ga. I was entirely oblivious to this while making the video. (This is a good thing. I’m already as overly enthusiastic as a litter of labrador puppies in that video. (Those five coffees before Brady arrived probably didn’t help.) If I had realised at the time that we’d picked up a broadcast of Radio Ga Ga I may well have melted down with excitement…)

[2] I deliberately set up the simulation of the crystal radio described in this post to mimic this “bleeding” of signals across the frequency spectrum.

Author: Philip Moriarty

Physicist. Metal fan. Father of three. Step-dad to be. Substantially worse half to my fiancée Lori, whose patience with my Spinal Tap obsession goes to far beyond 11...

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