Hi Guys,

Some more on conventions in values.

Leafing through some of my library of old technical books, I have found the following regarding capacitor designations:

Practical Radio Communication, McGraw Hill, 1943, page 78, sec 2.10: “The unit of electrostatic capacity is called the farad.? A condenser which has a capacity of 1 farad would require 1 coulomb of electricity to bring its plates up to a potential difference of 1 volt.”

And further on in that paragraph: “In electrical- and radio-engineering practice the values of capacity are generally always expressed in micro-farads or microfarads. The micro-farad is 1/1,000,000 part of a farad, consequently a condenser having a capacity of 1 mf…..” So, the authors, Arthur R. Nilson and J. L. Hornung’s preference is for lower case. In the various circuits in this book, lower values of capacitance are indicated by the use of mmf for picofarad.

Electrical and Radio Notes for Wireless Operators, Air Publication 1762, October 1939: designates capacitors only in μf on the circuit diagrams. And mentions smaller value, but only in the text, as micro-microfarads.

Reference Data for Radio Engineers, an STC publication, (no publication date), but mentions STC’s supplying of 100 kW – 130 kW transmitters for the BBC’s Empire service. (The case of kW is as printed). Uses “microfarads” and “μ μF”.

CREED & CO., LTD’s instruction booklet No 20. The Morse Reperforator model No 7W/3. Uses “Capacitor ‘C’, 5uF” in the components list for fig 2, p6. But “CONDENSOR ‘C’ ?, 1 or 2MF” in fig 3.

The Ferguson service manual for their (405 line) TV, model’s 992 – 998, uses uF and pF.

Electricity and its uses, J. Munro. Published by The Religious Tract Society, 1890. Mentions condensers, but has no mention of values thereof.

The Radio Data Charts; second edition, third reprint by R. T. Beatty, pub by Iliffe & Sons. Talks of micro-microfarads and μμF.

The RSGB’s Radio Data Reference Book (1962) uses μF & pF.

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It brings to mind a Ralph Waldo Emerson quote. The first line being “A foolish consistency is the hobgoblin of little minds, adored by little statesmen and philosophers and divines”.?

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Regards

Rodger Bean

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