I would think that the thick insulation on the THHN would throw a bit of a monkey wrench into the mix versus enameled magnet wire. In a self resonant situation I have only seen coils with magnet wire used ...but that is me....maybe others have seen differently. Rick W5RH
On Wed, Jun 29, 2022 at 5:14 PM john Parmalee via BVARC <[email protected]> wrote: > While we are talking about inductors, I have a question. I want to build > a trap for 40 meters. This trap will be on the top of my 20-meter vertical > leading to a top hat that will extend the vertical with another set of > radials to 40 meters. I know it in a coincidence of the inductive Xl and > the inter winding Xc that brings resonance. How do you test for it? When > I wound 28 turns of #14 THHN on a 1.5" pvc form thinking this would be a > trap somewhere and I could trim accordingly. I get these results: > > > > At 34 mHz I get a dip to Xs of 200 Ohms on my 269 analyzers in the main or > vswr / Xs mode. > > > > Using the inductance mode at 43 mHz I get a dip of almost no L. > > > > I tried the sniffer as a grid dipper and found no dip > > > > Reading the 529 manual I found the advanced mode, Page 16. Hold down the > mode and gate button and select advanced one and then step mode to > resonance. > > > > What I get is like a low pass filter with a shelf at 21 mHz. Not a > resonance > > > > My Measurements Lab (Millen) Grid Dipper shows a dip at 45 mHz or so. > > > > I think I will believe the Millen. The real find was the advanced > functions on the 529. Some pretty neat features. > > > > I think I need more turns. I think I will try maybe 50 turns of enamel > on a 2.5” form and trim it back. I also expect the Xl &Xc will affect > the antenna lengths. > > > > Any thoughts? > > > > Another Question, has anyone tried Flex Seal to waterproof a coax > connection? Maybe a layer of tape then spray. > > > John Parmalee > [email protected] > 281-380-3811 > K5VGM WI2XLJ > In a message dated 6/29/2022 12:51:38 PM Central Standard Time, > [email protected] writes: > > > Thanks for info! I ended up figuring out my issue (it was something else) > but it’s good to know this stuff. > > I have that handbook and I’ll take a look. > > 73, > > Mike Giannaccio > W5REZ > > On Jun 29, 2022, at 11:09 AM, Rick Hiller via BVARC <[email protected]> > wrote: > > The Radio Amateurs Handbook (aka The ARRL Handbook for Radio Amateurs) > gives an excellent explanation of coils, windings, interwire capacitance > etc. Pretty much any edition back to the beginning of ham time has it. > > However, for those living in the 21st century HI, in the 2000 edition i.e. > find complete explanations under AC Theory and Reactive Components, Real > World Component Data and in the Reference section. > > A little RF design knowledge for your entertainment this AM. > > 73...Rick -- W5RH > > On Wed, Jun 29, 2022 at 9:50 AM Gary Sitton via BVARC <[email protected]> > wrote: > > Yes, that's also another reason for the increased spacing. > Gary K5AMH > > On 6/29/2022 9:00 AM, Joseph Benoit via BVARC wrote: > > In addition to otherwise stated by K5AMH, as the frequency gets much > higher incrementally smaller inductance value is required (wider spacing, > turns-per-inch on a given coil diameter) and smaller incremental change is > needed to fine-tune if it were. > > On Sat, Jun 25, 2022 at 11:14 AM Michael Giannaccio via BVARC < > [email protected]> wrote: > > This is probably a basic question but I’ve come up empty in my search and > can’t seem to find the answer in the Antenna Book. > > Can someone explain to me or link me to some reading as to why some roller > inductors and screwdriver antennas like the ATAS have less turns per inch > on the ends of the coil and more towards the center? I do have the latest > edition of the antenna book so if it’s in there I can look it up. > > > > > > Thanks! > > 73, > > Mike Giannaccio > W5REZ________________________________________________ > Brazos Valley Amateur Radio Club > > BVARC mailing list > [email protected] > http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org > Publicly available archives are available here: > https://www.mail-archive.com/[email protected]/ > > > ________________________________________________ > Brazos Valley Amateur Radio Club > > BVARC mailing > [email protected]http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org > Publicly available archives are available here: > https://www.mail-archive.com/[email protected]/ > > > -- > Gary Sitton, K5AMH > [email protected] > SDR/DSP Consultant, > "Have FFTs, Will Travel." > ________________________________________________ > Brazos Valley Amateur Radio Club > > BVARC mailing list > [email protected] > http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org > Publicly available archives are available here: > https://www.mail-archive.com/[email protected]/ > > > > -- > Rick Hiller > *e-mail: [email protected] <[email protected]>* > *Cell: 832-474-3713* > *Physical: 9031 Troulon Drive* > * Houston, TX 77036* > ________________________________________________ > Brazos Valley Amateur Radio Club > > BVARC mailing list > [email protected] > http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org > Publicly available archives are available here: > https://www.mail-archive.com/[email protected]/ > > ________________________________________________ > Brazos Valley Amateur Radio Club > > BVARC mailing list > [email protected] > http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org > Publicly available archives are available here: > https://www.mail-archive.com/[email protected]/ > > > ________________________________________________ > Brazos Valley Amateur Radio Club > > BVARC mailing list > [email protected] > http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org > Publicly available archives are available here: > https://www.mail-archive.com/[email protected]/ > -- Rick Hiller *e-mail: [email protected] <[email protected]>* *Cell: 832-474-3713* *Physical: 9031 Troulon Drive* * Houston, TX 77036*
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