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PF1F > TECHNI 10.09.05 21:31l 39 Lines 1119 Bytes #999 (0) @ DL
BID : 630128PF1F
Read: GUEST DL1LCA OE7FMI
Subj: Re: Pile wound coil problem.
Path: DB0FHN<DB0MRW<OK0PPL<DB0RES<DB0EA<DB0ACC<DB0ACH<DB0PKE<PI8DAZ<PI8HWB<
PI8WFL
Sent: 050910/1920Z @:PI8WFL.#NH1.NLD.EU #:9949 [Enkhuizen] $:630128PF1F
From: PF1F@PI8WFL.#NH1.NLD.EU
To : TECHNI@DL
G0FTD wrote:-
>
> Incidently the single layer coils I make work out to be accurate - e.g.
> a 25uH single layer is correct but a 3 layer version measures on average
> about 200uH.
>
> Should I expect this magnitude of value or is my measurement technique invalid ?
I haven't wound one myself, but the magnitude relation seems about
correct.
Having three layers, each of which of itself would measure 25 uH, we would
expect the following contributions to the inductance value:
- self-inductance from each winding: 3x 25 = 75 uH
- mutual inductaces, six pairs
(1-2, 1-3, 2-1, 2-3, 3-1, 3-2) : 6x 25 = 150 uH
total 225 uH.
In general, n windings, all coupled with a k of (practically) 1, will give
you approximately n^2 times the inductance of one winding.
There are many inductance calculators on the net, not all of which are as
trustworthy as the other.
One that has held me in good stead so far is on:
http://www.moshier.net/coildoc.html
Ruud, PF1F @ PI8WFL
Heemskerk, JO22im
Message timed: 20:10 on 2005-Sep-10
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