Month: April 2015

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Grinding quartz and holding a frequency during World War II

I’m a great fan of the Prelinger Archives which is home to so many items like this video I’ve heard about recently from various ham radio email lists.

I like how the components of the earliest electronics and wireless were so basic and ‘natural’. Think of hand made capacitors and resistors using traces of graphite on paper. Valves (or tubes) of course were another story but still capable of being ‘homemade‘.

I love the idea that an accurate, literally rock solid frequency could be achieved using a piece of a very common rock – admittedly a pure piece of quartz cut just so.

This video details the elaborate and meticulous manufacture of quartz crystals during World War 2 by Reeves Sound Laboratories in 1943.

The 41’24” video can also be viewed (free of youtube ads etc) and downloaded via the Prelinger Archives.

Most of the ‘radio quality’ quartz was mined in Brazil which ceased its neutrality in 1942 and joined the Allies.

The story of quartz crystals during WWII is told in ‘Crystal Clear‘ by Richard J. Thompson Jr. (Wiley) 2011.

The cover of the book "Crystal Clear - The Struggle for Reliable Communications Technology in World War II" by Richard J Thompson Jr.
“Crystal Clear – The Struggle for Reliable Communications Technology in World War II” by Richard J Thompson Jr.

“In Crystal Clear, Richard Thompson relates the story of the quartz crystal in World War II, from its early days as a curiosity for amateur radio enthusiasts, to its use by the United States Armed Forces. It follows the intrepid group of scientists and engineers from the Office of the Chief Signal Officer of the U.S. Army as they raced to create an effective quartz crystal unit. They had to find a reliable supply of radio-quality quartz; devise methods to reach, mine, and transport the quartz; find a way to manufacture quartz crystal oscillators rapidly; and then solve the puzzling “ageing problem” that plagued the early units. Ultimately, the development of quartz oscillators became the second largest scientific undertaking in World War II after the Manhattan Project.” (from the book’s blurb)

Illustrating the precise angles needed for the AT and BT cuts of a quartz crystal…
Illustrating the precise angles needed for the AT and BT cuts of a quartz crystal…
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Reading in your head – the long path to morse code bliss

I’m one of those people who learnt morse code completely the wrong way. Starting off in the seventies with no guide I simply tuned into nightly morse transmissions sent by local hams at a very slow rate. I think they started at 5 words a minute. The main risk there was nodding off between words or impatiently guessing the wrong word.

Contemporary wisdom is that you should start listening at a much faster rate, say 15 or 20 words per minute. This is to prevent you counting dots and dashes in your head, and to make it easier for you to recognise the letters, numbers and even words by their sound.

Learning 15 wpm after mastering say 8 wpm is almost like learning a new language. Students of morse talk of ‘a plateau’ at 10 which is a mighty barrier to progressing up to a more useful conversational speed.

My personal goal is to be able to copy and send at 25 wpm and be able to sustain it over a couple of hours, and to be able to read mostly ‘in my head’, only using pencil and paper for details like names and callsigns.

Now that morse code is no longer compulsory for any ham licenses, surprisingly it seems to be more popular than ever! Especially with those hams who like to use low power to make contacts, or to take the lightest possible transceiver to a remote mountain top as part of the global ‘Summits on the Air‘ activity. Morse gets more mileage than voice per watt, and often these tiny transmitters are only putting out a couple of watts power.
And there’s something delightful in having the skill to read the beeps.

But for me it’s a skill I have to keep working on. I think in my twenties I was quite at ease chattering away at about 12 wpm seemingly for hours on end. Four decades on with a large slab of radio silence in between, I’m quite rusty, even though I know the basics are still there like riding a bike.

I’m a bit wobbly at the paddles, having grown up with the old fashioned straight key (the type you’re likely to have seen in old westerns). But you can feel slow but definite progress from every bit of practice you put in.

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