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By Amanda Lynsdale on

Biscuits and secret messages: The intriguing history of WW2 BBC technology

Amanda Lynsdale discusses some of what she discovered while cataloguing the extensive BBC Collection, acquired in 2012.

I was volunteering at the Museum and working with the BBC broadcasting equipment in the museum’s archives. While in this BBC Collections volunteer role I became familiar with the equipment which has contributed to history of television, radio and broadcasting as we know it today.

Due to my interest in the Museum and the BBC, I wanted to highlight some of the interesting pieces I discovered while helping to catalogue the broadcasting equipment. The extent of the collection meant that choosing an angle for this post needed some careful thought. As 2015 marks 70 years since the Second World War ended, I wanted choose was an examine how BBC radio equipment was used during the time. These are some examples of the various microphones, amplifiers, and receivers that helped shape broadcasting technology we have today.


Microphones

One of the Standard Telephones and Cables 4017-C microphones in the BBC Collection, with its original box
One of the Standard Telephones and Cables 4017-C microphones in the BBC Collection, with its original box

One of the use of microphones during the Second World War was for outside broadcasts. An example of a microphone that was used in this way was the STC 4017-C microphone (1), which the BBC used up to 1953. This microphone was created as an improvement to the BBC’s STC 4017 microphone, of 1938(1), which had a design fault in the plug causing it to disconnect at random. With this more robust design it continued in regular use becoming a standard mic for the BBC at time. Neville Chamberlain even used something akin to the STC 4017-C microphone to make some of his public addresses.

A Marconi Type L ‘lip’ microphone from the BBC Collection, c. 1937
A Marconi Type L ‘lip’ microphone from the BBC Collection, c. 1937

Another make of microphone used for making broadcasts during the Second World War was the Marconi Type L ‘lip’ microphone. Designed in 1937 and used mainly for outside sports commentating (2), a lip microphone was famously used by Ed Murrow during the Second World War to broadcast the blitz from the roof of Broadcasting House. The design is little changed even to this day and you’ll still see sports commentators using this type of microphone.

First introduced in 1935, this later ‘F’ version of the classic STC 4021 ‘Apple and Biscuit’ microphone dates from about 1965 (BBC Collection)
First introduced in 1935, this later ‘F’ version of the classic STC 4021 ‘Apple and Biscuit’ microphone dates from about 1965 (BBC Collection)

Microphones could also be used specifically as studio talkback microphones, or to pick up the ambient noise for outdoor productions. The STC Moving coil type 4021 that the BBC also had at its disposal during the Second World War, nicknamed the “Apple & Biscuit” mic, was used for this purpose(2). The 4021 was designed with a disc, because it needed to capture and even out the reverb that it picked up from all angles(3). Both the 4017 and 4021 were used with the BBC-designed anti-vibration microphone mounts.


Amplifiers

Another important grouping of broadcast equipment items are amplifiers. They take the weak signals picked up by microphones and boosts them for transmission. Before the Second World War most audio-frequency amplifiers were single purpose in nature with many types being made for specific needs(4). The onset of the War reduced the resources available so the amplifiers that were made, were designed to have a general purpose function (4), an example was the BBC GPA/1 General Purpose Amplifier.

The OBA/8 Outside Broadcast amplifier – it formed the basis of a range of BBC equipment for broadcasting outside the studio
The OBA/8 Outside Broadcast amplifier formed the basis of a range of BBC equipment for broadcasting outside the studio

One ­­exception at the time was that standard microphone amplifier used by the BBC during the Second World War, the model 0BA/8 outside broadcast amplifier that introduced volume control at the OB point.

Microphones and amplifiers aren’t the be-all and end-all of the equipment needed for a successful broadcast. Indeed, those crucial Second World War broadcasts from the BBC would not have been possible were it not for other equipment such as the BBC OBA/8 4-channel passive mixer and the LSU/4A Studio loudspeaker.


Receivers

Then of course there were the receivers, which brought each war-time broadcast to the audiences’ living rooms.

This Civilian Radio Receiver (also known as the ‘Utility Set’) is part of the BBC Collection.
This Civilian Radio Receiver (also known as the ‘Utility Set’) is part of the BBC Collection.

To receive wartime speeches and other radio broadcasts at home, most of the public used British Wartime Civilian Radio Receivers. These receivers were cheap to buy, and so implicitly suitable for the period of Second World War rationing(5). Murphy Radio Ltd produced them to meet government demand for standardised low-cost radios.

The Civilian Radio Receiver was inspired by the previous Murphy AD94 radio receiver(6). The Murphy AD94 was the first of the Murphy receivers to use the Eden Minns designed Bakelite cabinet. The material was trade-named ‘Bakelite’ after its creator(7), a Belgian-American chemist named Leo Baekeland.


Also of note…

Quite apart from the parliamentary/government and civilian uses for the above broadcasting equipment during the Second World War, the military also found a purpose for such BBC broadcasting technology at this time. One thing the military did with this technology, was to use it as a tool for internal communications. The Throat Microphone is the piece of equipment most noted for this function.

RAF throat microphone No. 2, Mark II, ZA 19734. (Ex-War Department). Used by WW2 pilots for communications. ZA reference means it was for army use. (BBC Collection)
RAF throat microphone No. 2, Mark II, ZA 19734. (Ex-War Department). Used by WW2 pilots for communications. ZA reference means it was for army use. (BBC Collection)

The Throat Microphone is essentially a sensor worn against the larynx, which means words are audible in situations where there is a lot background noise(8). The sensor also allows whispers to be heard, for example people in sensitive military operations and are still used today.

To contact resistance fighters, the BBC would include ‘personal messages’ in its broadcasts of news and entertainment to occupied-Europe. Often they were coded messages(9), intended for resistance fighters. On a more basic level, the BBC acted as a method of improving morale.

MCR1 ‘Biscuit Tin’ radio (1943-44) with its multi-standard mains power supply and four plug-in coils (BBC Collection)
MCR1 ‘Biscuit Tin’ radio (1943-44) with its multi-standard mains power supply and four plug-in coils (BBC Collection)

The military positioned the MCR1 ‘Biscuit Tin’ radios, behind enemy lines, so that ’civil broadcasts’ such as political speeches and news could be received from Britain. The MCR1s were specifically designed to be used by the Army and Special Forces(9). They were developed by Philco in 1943(10) and in just two years around 30000 had been manufactured. The name “Biscuit Tin” came from the fact that this radio’s components: receiver, power supply, and coil packs, were in fact delivered to users within an actual biscuit tin (bare metal without any markings).

Each of the above pieces of radio broadcasting equipment that I have discussed is available for you to view, by appointment, in our archives here in Bradford.


References

  1. Retrieved from www.coutant.org/stc4017c/index.html
  2. Golden Age TV Recreations, Equipment for hire. Retrieved from www.golden-agetv.co.uk/equipment.php?ProducerID=40
  3. Retrieved from www.historyofpa.co.uk/pages/microphones.htm
  4. General Purpose Amplifier, GPA/1 (PDF). Retrieved from www.bbceng.info/ti/eqpt/GPA_1.pdf
  5. Radio Workshop, Civilian Wartime Utility Radio. Retrieved from www.radio-workshop.co.uk/civilian.shtml
  6. Classicwireless.co.uk, Murphy Radio Model AD94 From 1940. Retrieved from www.classicwireless.co.uk/Murphy_AD94.htm
  7. Science Museum, Murphy Bakelite radio AD94, 1940. Retrieved from www.makingthemodernworld.org.uk/everyday_life/home/1939-1968/TL.0215/
  8. Wikipedia, Throat microphone. Retrieved from www.wikipedia.org/wiki/Throat_microphone
  9. Crypto Museum, MCR-1. Retrieved from www.cryptomuseum.com/spy/mcr1/
  10. Radiomilitari.com, MCR1 type 36/I Biscuit Tin Spy Radio Receiver 1943. Retrieved from www.radiomilitari.com/mcr1.html

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