Title: Hamwaves.com RF Inductance Calculator Post by: aa5wg 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 Title: Re: Hamwaves.com RF Inductance Calculator Post by: Opcom 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! Title: Re: Hamwaves.com RF Inductance Calculator Post by: aa5wg 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 Title: Re: Hamwaves.com RF Inductance Calculator Post by: Steve - WB3HUZ on January 27, 2010, 10:02:43 PM Not necessarily bad but may cause tricky or touchy tuning.
Title: Re: Hamwaves.com RF Inductance Calculator Post by: Opcom on January 27, 2010, 11:55:16 PM I misunderstood what it was for.
Title: Re: Hamwaves.com RF Inductance Calculator Post by: Steve - WB3HUZ 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 Title: Re: Hamwaves.com RF Inductance Calculator Post by: aa5wg 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 Title: Re: Hamwaves.com RF Inductance Calculator Post by: aa5wg on January 29, 2010, 10:28:39 PM Opcom, WB3HUZ: AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
Thank you. Chuck |