HFU HF Underground
Loggings => 10/11 meters => Topic started by: ChrisSmolinski on November 13, 2021, 1631 UTC
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1631 UTC Italy on 38L.
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Hearing Italy also on 27.385 LSB. No luck getting back. Hearing several AZ stations also
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Hearing Italy also on 27.385 LSB. No luck getting back.
I remember you talking about getting family feedback regarding your antenna farm, but have you considering deploying say a stealth half-wave dipole or even an end-fed vertical cut for 11m? The reason is your 80m OCF likely has multiple significant lobes as frequency increases. If a contact falls outside one of the large lobes, your signal could be many dB down on upper-HF bands.
Take a look at the 10m pattern here:
https://www.onallbands.com/off-center-fed-ocf-antenna-multitalented-or-misunderstood%EF%BB%BF/
Unless one wants to spend money on a retail antenna, a homebrew EFHW vertical can be built for a few dollars. Wind or obtain a basic 49:1 or 64:1 transformer placed near ground level, then add 18' of wire for the vertical along with four or so ~9' radials on the ground. Now with the OCF and vertical antennas you would have both horizontal and vertical polarization options available.
Feed it with inexpensive RG-58 or RG-8x if within 50' of the radio IMO, though even RG-6* is workable; again IMO. Not that I would recommend QRO power and any actual loses aside, I have seen even cheap big-box-store RG-6 readily handle 100w with horrid mismatches.
BTW, want a portable 11m solution? Build the same EFHW, but skip the ground radials instead winding the coax feedline as a 1:1 choke on a mix 43 toroid around 1.8' feet from the transformer. It could be deployed as a vertical, horizontal, sloper, etc. I suspect even an integrated autotuner should tune such an antenna for 12m and 10m, too.
*RG-6, RG-59, and most other non-50-ohm coaxes cut as a multiple of 1/2 wavelength times the coax velocity factor will ideally present approximately the same input and output impedance, which makes for a neat low-cost coax hack for 50-ohm systems. Preferably you want coax with a listed VF spec, but RG-6 VF tends to be around .78 to .83, so one can ballpark the length then add or trim after measuring SWR, impedance, etc. Initial length also could be computed with NanoVNA readings and an online velocity factor calc.
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I actually have pretty good luck on HF. Worked a good amount of EU/UK AZ/CA/OR/MT stations on 10/11 since the recent band openings. There just weren't big signals today. Since learning how to use my NanoVNA for easy SWR reading's, I've figured out that the SWR is pretty good between 27/28 Mhz. 15/30M, not so much.