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Re: [TCML] dc tesla coil

Thanks Matt, I have some old mica broadcast caps that say .005 MFD on
them, and while I know they are .005 uF, I have always wondered why they
were labelled as such.


On 11/25/2012 11:56 AM, mddeming@xxxxxxx wrote:
> Hi Jay, All,
> In the early days of radio, amateur and professional, mf or (mfd) meant the same 
> thing as uf does today, microfarad. Mmfd meant the same as pf does
now.   This is
>because the early experimenters and operators were mostly not college
>people and did not use the Greek alphabet. However,  mHy meant
millihenry as it
>does today because millihenries and microfarads were the size units
most commonly
>used in communications which were almost exclusively below ~10MHz. They
saw no
>ambiguity in this. When the military was trying to convert farm boys
into radio operators
>in 90 days or less( ca 1941-1945), they decided to keep the notation as
simple as possible.
>and go with the established convention. It wasn't until high speed
solid state ICs in computer
>and communication equipment became commonplace in the 1970s that the
terms like giga,
> tera, nano & pico and their abbreviations started to enter mainstream
> Matt_D

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