15 May 2014

Lefax Data Sheets - Radio Engineering (1950)

I do not often search around on Ebay, it tends to be bad for the health of your bank account!!

However, knowing my interest in old Filofax or Lefax radio documents a couple of our readers kindly messaged me pointing out the sale of Lefax Data Sheets by a seller in the USA.

I left it a couple of days to think about it a bit, and then purchased them on 'Buy It Now', the seller packed them very well and they arrived within a week.

The outer cover is made from card.

Opening it you see that the pages are punched with the familiar 6 holes, and the pages held in to place with metal paper fasteners. The familiar Lefax cover sheet which is the same as the 1928 Radio Log, on the reverse side of this sheet are calendars for 1950 and 1951.

Removing the fasteners and the pages this is the cover.

The pages are in fact a large selection of booklets, some single pages, others are multiple page format booklets.

Each one is on a different radio related topic. They have all been formatted in a similar way with the order number, the Dewey classification number at the top, the title and the source of the information and the date of the original publication.

This one is six page booklet that looks like this folded up.

And when opened, the third page opens out. The outer or right hand page is slightly narrower than the other two to allow for the rings of course.

Here is a more conventional four page layout, with printing on both sides and the rings in the middle. There are also some eight and twelve page booklets too in the series.

Here's a full list of the data sheets.
  • Oscillation constants of radio circuits
  • Inductance calculations
  • Radio Telegraphy
  • Chart for determining inductance
  • Conversion tables Electricity and Magnetism
  • Radio Distance Chart
  • Radio Telegraph Code
  • The A-B-C of Filter Design
  • Magnetic Circuit Design
  • Design of Attenuation Networks
  • Approximate Formulas for the Inductance of Solenoids and Astatic Coils
  • Calibration of Microphones
  • Noise Measurement
  • Electronic Formulae
  • Matching the Antenna for Two-band Operation
  • The Para-Talkie transceiver
  • Short Wave Receiver
  • Insulated Wire Diameter Weight, Turns per Inch
  • Detector Circuits
  • Simple Methods of Radio Tone Control
  • Tube Replacements
  • Analysis of Current Stabilizer Circuits
  • Receiver Input Circuits
  • Portable Marine Radio
  • AC Galvanometer
  • Point to Point Antenna 
  • Automatic Gain Control in Receiver Design
  • Color Codes for Radio Equipment
Now, I know the data sheets will be of limited interest to the majority of you, and please don't feel you missed out at school because you were not paying attention in the science lessons... I suffer from the same thing sometime. I would be a genius if I could even de-cipher the title of some of the scientific papers I see published by friends of mine! For instance:
'Heat transport in the XXZ spin chain: From ballistic to diffusive regimes and dephasing enhancement' in Journal of Statistical Mechanics: Theory and Experiment (2013)
It's written in English I know but I couldn't tell you what it is about... but I know some one who does know and his name is also Steve! 

Now, I am not sharing these data sheets with you because I want to turn you all in to radio engineers, although wouldn't that be quite an achievement! No, I'm sure by sharing these pages with you because I know you will appreciate something I hadn't thought about that much until today.... 

And it is this... So the data sheets might not have a lot of relevance in the modern world we live in. Although a lot of the formulas and information still holds true today, you can not alter physics after all. 

In 1950 the Internet hadn't been thought of, so anyone needing access to this sort of information on a regular basis either had to have a brilliant memory (and I haven't!) or they needed text books or notebooks to hand where they had extracted the information from other sources to keep handy on a day to day basis. 

So these data sheets in their time are almost like a very very small cross section of what we see on Wikipedia today, which as long as the Internet is not broken we can get to quite easily. 

So that places them in context of why they were produced... but now think about how they were produced? There was no Word, or In-design back then to just 'drop your text to' and the application looks after all the formatting and margins, especially those 6 page layouts where page 3 and 4 are narrower than the rest! No the typesetter was king in this pre-computer era at taking the text and laying it out and putting together the printing plates. 

I'm no printing expert... sure I've seen it on TV and at Filofax in Dalkeith in the modern era, but I suspect the skill of producing printed pages like this has long since died, but I think you will agree it was quite an achievement when we look at it now. 

So printers of the past we salute you! As well as the editors and the compliers of the information that went in to creating these wonderful data sheets that sixty years later are making me pause for thought about the role of a radio engineer back in an era before I was even born! 

I will eventually get around to scanning all of these in as it is easier for me to read them on a screen with my poor eyesight and if there is anyone else interested in seeing them or specific sheets please get in touch. 

Again thank you to the readers that shared the link to these with me. 


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  2. Steve, thanks for a fascinating look into how the older data sheets looked. You made a good point about the typesetting, it really makes you appreciate the skills they must have used in those days, especially when you look at the number of formulaic symbols they had to include for specialist sheets such as these. Although we generally have regular access to the internet now, the use case has not changed, for me at least, to have certain data always with me. When you think about it, even upto the early/mid 1990s, a lot of us (regular Filofax users) carried all our contacts in our organiser, along with the relevant parts from the Data Sheets set, plus things like Central London street maps, UK road and rail maps, world time zones, etc. Even now, I carry a lot of printed reference info in my binder. I frequently go to countries where internet access in the hotels is non-existent or so slow that its impossible to connect to webmail. So some info is essential to me -such as world time zones when looking at global conference calls which I still have to join; a price list for the various products I look after; contact details and organisation charts of certain departments which I know I will need on almost every trip. And the ability to insert or remove sheets as required, for different countries, or different business/personal purposes, is the main reason why I think there will always be a place for a ringed organiser. Not everywhere in the world has superfast broadband, and until it does, which is still a long time away, I will always need to have a fair amount of reference material on hand.

  3. Steve, thanks for sharing this snapshot of history – of interest, as you say, as much for the content as the way they were produced.

    Lovely to see old typesetting and print - a sight for sore eyes in this computerised age. I learned the craft of hot metal typesetting and printing at art school in pre-computer days. I went on to run a typesetting business using the then state of the art Linotronic CRT machines and then the Apple Mac Desktop Publishing (DTP).

    These pages, printed in 1948, are of historical interest as they produced before the advent of phototypesetting. I have several books of that era on polar exploration. Bookbinding is also a lost art!

    What a treat to see these LeFax pages; look forward to seeing more.

  4. What a great post! I really like seeing these vintage pages, and I hope you post more of them.

    The Lefax (and by extension Filofax) concept was a brilliant marketing idea: if you bought a binder, you were locked into their format, and unless you could jailbreak your iphone, sorry *binder*, with the Lefax punch, (expensive for many people), you couldn't file any of your own stuff, so had to update with their consumables, namely more pages as above.

  5. Good post again Steve.
    The ability of Lefax to produce printed sheets with a maximum amount of information was used as a selling point in the early decades. A page from 1914 suggested to readers "Our experience in digesting information enables us to get several times the data on a Lefax sheet that is usually printed on a sheet of the same size. If you send us your printed matter, we will show you what can be done with it."

  6. Outstanding, as usual :) I'd be very interested in seeing the scanned pages, being a licenced Radio Amateur, as while I vaguely recall books published by the Radio Society of Great Britain chock full of various radio-related theorems, physics, tables, and whatnot (I probably still have them knocking around here somewhere!), I do not recall ever seeing similar listings on filofax-sized inserts!

  7. I have a copy of the lefax engineering formulas 1956-1957. Amazing amount of detailed charts and information. The fold out charts and awesome technical drawings makes me feel like Indiana Jones searching for clues to some lost treasure or something equally exiting just leafing through the pages even with my limited knowledge on the subject. Though the little I do know is more than covered in this tome. Everything you could want. From the heirachy of materials to a psychometric chart for calculating air conditioning no idea how to implement it but if I did I'd be able to calculate the weight of water vapor in one pound of dry air measured in grains, WOW! And don't even get me started on how to choose a bolt material size weight thread pitch for a given application, seriously please don't I'll stroke out. The more I read the less I realize I'll never understand unless I take a PhD in mechanical engineering in order to decipher it's true worth.

  8. If you would like me to photograph any part of it or in its entirety please let me know and I will if you want to publish it in your blog. Re: lefax 1956-1957 engineering formulas set (full set if I had to guess)

    1. Yes I would love to see those if it's not too much trouble.