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Strange problem with coils

4/9/2003 2:50 PM
Albert Kreuzer
Strange problem with coils
Just built Art Harrison's 126 tube theremin http://home.att.net/~theremin1/126/126.htm using self-wound inductors (air core, 5/16" diameter, 3/4" long, 800 turns).  
They measure exactly 1mH on my L-meter, the same as the small cheap ferrite core inductors I used for testing.  
What I don't understand:  
With the ferrite coils, I get the desired frequencies, with the air-core ones only half of it!  
Theoretically, this would mean they have four times the inductivity of the ferrite coils, but why do they read the same on my meter?  
Any kind of info or help appreciated!  
 
Thanks  
Albert  
http://www.albertkreuzer.com

 
Replies:
Don Symes What frequency does your L-meter me... -- 4/10/2003 12:06 AM