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Re: primary calculations

To: teslaatgrendel.objincdotcom, KLINEDAatunivscvm.csd.scarolina.edu, Pyrofishataoldotcom, WMEYERatscientia.up.ac.za, bhaleyatshoredotnet, brad.alheimatthespadotcom, cocoatastromandotcom, frerichsatzfe.siemens.de, froulaatcig.motdotcom, habaatsnakemail.hut.fi

Subject: Re: primary calculations

From: Esondrmnataoldotcom

Date: Wed, 21 Feb 1996 17:16:37 0500

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In a message dated 960221 12:48:13 EST, teslaatgrendel.objincdotcom writes:
>>
>Ed,
> I just recalculated my new (#2) primary and came up with 92.4uH. I
>measured it at 124uH.
> OhOh, I just noticed I'm using diameters not radiauses. Retry: 143.4uH
>/ 124uH = 1.16 much better, given a 5% or 10% scope reading error. For 14
>turns I measured 101uH. No, let me rephrase that: for 14 turns, I measured a
>period of 7.4us using a 13.7nF cap. a function generator and a 10K series
>resistor between the generator and the LC. I varied the frequency of the
>drive signal to maximize the voltage across the tank circuit. I then
>measured the period of the signal with my Oscope. I calculated an inductance
>of 101uH from these numbers. Tomorrow night I'll check my Oscope against my
>short wave reciever to see if my scope has lost calibration. It's about 5
>years over due. I'll also check the numbers with the coil off the ground! It
>was about 2" from my damp concrete floor.
>
> the formula I'm using for a pancake coil is:
> 2 2
> L = a x n
> 
> 8 a + 11 w
>
>
> my coil measures:
>
> inside diameter: 11.75"
> outside diameter: 31"
>
> turns: 15.5
>
> 1/4" copper pipe on a 30 degree slope from horizontal.
>
>
> What are the diameters of you coil?
>
> jim
Jim,
I also calculate 143 uh for your primary. My primary is 8.0" inside
diameter, 14 turns of 3/8" tubing with 3/8" spacing. I think the outside
diameter is about 26.5". It is 6.0" tall.
Ed Sonderman