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Hamwaves.com RF Inductance Calculator




 
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Author Topic: Hamwaves.com RF Inductance Calculator  (Read 4692 times)
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aa5wg
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« on: January 27, 2010, 08:47:20 PM »

Hi to all

At the bottom of the RF Inductance Calculator located at Hamwaves.com  ( http://www.hamwaves.com/antennas/inductance.html ) Self-Resonant Frequency is listed.  The calculator states 1/4 (parallel) self resonant frequency of n=0 sheath helix mode. 

If I build/design a coil using this calculator and the listed self-resonant frequency is in the ham bands or close to the ham bands is this bad?

73,
Chuck
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Opcom
Patrick J. / KD5OEI
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« Reply #1 on: January 27, 2010, 09:21:42 PM »


Wouldn't it be a good thing if it were self resonant at the operating frequency? That is a cool page.

What Z has the coil? In plinking, I'm not seeing near 50 ohms at a resonant frequency, but I don't know how to use the tool yet!


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aa5wg
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« Reply #2 on: January 27, 2010, 09:37:15 PM »

I am building a tank coil for the link antenna coupler. i.e. One coil will be used on several band, 160 - 30 meters.  If there is a self resonance close or inside one of the bands is this bad?

73,
Chuck
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Steve - WB3HUZ
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« Reply #3 on: January 27, 2010, 10:02:43 PM »

Not necessarily bad but may cause tricky or touchy tuning.
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Opcom
Patrick J. / KD5OEI
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« Reply #4 on: January 27, 2010, 11:55:16 PM »

I misunderstood what it was for.
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Steve - WB3HUZ
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« Reply #5 on: January 28, 2010, 09:35:10 AM »

In most cases you would short out some turns on the coil as you move higher in frequency, so the self-resonance would also change and move higher.


I am building a tank coil for the link antenna coupler. i.e. One coil will be used on several band, 160 - 30 meters.  If there is a self resonance close or inside one of the bands is this bad?

73,
Chuck
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aa5wg
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« Reply #6 on: January 28, 2010, 12:21:13 PM »

Is there a rule-of-thumb how far below self resonance I should operate the output tank coil.  This coil is for a link antenna coupler.
Both parallel and series feed will be used.
73,
Chuck
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aa5wg
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« Reply #7 on: January 29, 2010, 10:28:39 PM »

Opcom, WB3HUZ:
Thank you.
Chuck
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