Feed point is one part - try trimming the antenna length Richard Bonica C: 281.935.7222 Email: [email protected] Freq: 147.000 - DMR - Digital Mobile Territory: NE Fort Bend CERT, CST, EST, WEB EOC, HSEEP, FEMA PD, Wilderness First Aid, CPR, Extra Ameture Radio
On Wed, Oct 15, 2025, 5:25 PM Daniel Poirot via BVARC <[email protected]> wrote: > ...aaaand, the best I can muster is this: > > [image: Screenshot 2025-10-15 at 5.19.18 PM.png] > > Very strange. > > I moved the feed point to get a lower impedance and trimmed the driven > element quite a bit, but can't get it to come down at 444.3 MH. > > At this rate, I am going to stick with 2 meters! > > Dan KJ5IZK > > > > > On Wed, Oct 15, 2025 at 4:20 PM Daniel Poirot <[email protected]> wrote: > >> TL;DR What does a 70cm VNA trace look like? >> >> >> Howdy y'all, >> >> The car is in the shop, so I had some time on my hands... >> >> I took a 16 cm section of 450 Ohm ladder line, shorted one end, soldered >> on a 32.5 cm length of wire and BOOM. I have another J Pole. >> >> I tacked on a short length of RG-8x, 1.6 cm from the end, and put a >> female BNC on the end. Closer still! >> >> I calibrated my NanoVNA for 420-450 MHz and made a trace of SWR and >> Resistance. I am looking to hit the 444.3 repeater. >> >> [image: Screenshot 2025-10-15 at 4.16.08 PM.png] >> >> This here is some messed up stuff. Do I have to tune to catch 50 Ohms as >> it goes by? >> >> The SWR minimum is to the left of 444.3, so my J Pole is long. I am about >> to nibble away. >> >> Should I expect a 25 MHz cycle like this? The middle of the cycle will be >> crazy SWR and terrible resistance, right? >> >> Comments welcome! >> >> 73 >> Dan KJ5IZK >> >> ________________________________________________ > 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]/ >
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