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Rule-of-thumb coil-former size? |
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W0PBV 
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 Topic: Rule-of-thumb coil-former size?Posted: 10-Mar-09 at 22:43 |
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Harry often mentions an air-coil "rule of thumb" of "coil wavelength (in meters) = number of turns".
One could wind coils on biros or soccer balls (in the U.S. I would have said "ballpoint pens" or "oatmeal boxes", but I don't know who might be reading this), and the resulting inductance values would be vastly different, so what size coil-former does SM0VPO use when applying his "rule of thumb"? --W0PBV@ARRL.net |
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DragonForce
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Joined: 09-Oct-11 Location: Bristol, SW UK Online Status: Offline Posts: 32 |
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Posted: 10-Mar-10 at 01:27 |
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Taken from Harry's original article: QUOTE: These formers are 5mm dia. and fitted with an adjustable ferrite core. If I do not require a ferrite slug then I do not waste the former, I then use a bit of wooden dowel the same diameter. These formers agree with my usual formula for turns / capacitance for a given frequency:-
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I smell smoke...........
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sm0vpo
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Joined: 08-Nov-02 Location: Lunda, Sweden Online Status: Offline Posts: 340 |
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Posted: 10-Mar-15 at 12:31 |
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You took the words right out of my mouth
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