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Author Topic: Best MWDX antenna?  (Read 53624 times)

Offline RobRich

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Re: Best MWDX antenna?
« Reply #180 on: November 01, 2022, 0201 UTC »
I will take a look. Thanks.

Appears my 148' LoG is out, too. At least I assume it was the right feedline I reconnected in the dark outside. :D

I am down to my 31' vertical tonight. S5 noise floor with higher static crashes around ~7MHz, too. Sigh.
« Last Edit: November 01, 2022, 0204 UTC by RobRich »
Tampa, FL USA | US Map Grid EL88
Airspy HF+ Discovery | KiwiSDR 2 | 2x Msi2500 Msi001 | 2x RTL-SDR V3 + NE602 | 2x RTL-SDR V4
148' + 60' Loops-on-Ground | 31' Vertical | 18' End-Fed Vertical | PA0NHC MiniWhip

Offline Josh

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Re: Best MWDX antenna?
« Reply #181 on: November 02, 2022, 2141 UTC »
Dunno if I mentioned this before, but a loop of wire tacked under the eaves, fed by coax, can make for a fine multiband (with transmatch) rx antenna, with a few caveats. First is in-house noise sources picked up by said loop, but this is often under the control of the listener such as turning off noisemakers. These antennae are very hardy as your house will have to be destroyed to take it down unintentionally, more or less. A transmatch (aka antenna tuner) will help wring most rf from this or any other antenna. Might not want to use it as a hf tx ant but that has and does take place.
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Offline RobRich

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Re: Best MWDX antenna?
« Reply #182 on: November 11, 2022, 1811 UTC »
Gutters as well, assuming they are bonded decently and not grounded.

As to my ongoing antenna farm adventures, I might be moving some antennas, including my 31' vertical.

Last night I deployed a temporary ~12.5' vertical wire on a fiberglass rod and tripod. Used a 9:1 receiving balun, which was far from optimal, but it was small and in a spare parts bin. Only a single on-ground radial. An 1:1 choke is back near the house. Even factoring the subpar design and associated losses, RFI on HF seems to be comparatively quiet where I deployed it.
Tampa, FL USA | US Map Grid EL88
Airspy HF+ Discovery | KiwiSDR 2 | 2x Msi2500 Msi001 | 2x RTL-SDR V3 + NE602 | 2x RTL-SDR V4
148' + 60' Loops-on-Ground | 31' Vertical | 18' End-Fed Vertical | PA0NHC MiniWhip

Offline ~SIGINT~

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Re: Best MWDX antenna?
« Reply #183 on: November 12, 2022, 0033 UTC »
Beats the ice hanging off my antennae. Freezing rain for the past 24 hours. I have a 50 ft long guy wire off of one of the legs of the T2FD. It's sagging ... but so far hanging on.

Offline zero33

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Re: Best MWDX antenna?
« Reply #184 on: November 12, 2022, 2146 UTC »
I recently put up a 10-11 Meter Band 1/2 wave Vertical (non ground wave) works better on MW then 10-11. Very disappointed with it tbh.
Maybe not high enough at around 20' high though
Getting Back into it on 10-11 meters

Offline RobRich

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Re: Best MWDX antenna?
« Reply #185 on: November 13, 2022, 0250 UTC »
Winter weather and Florida do not mix well. IIRC, years ago like 1" of snow shutdown much of Tampa.

----------------

Zero33, curious, homebrew or commercial? Type of coax used?

My "18' end-fed vertical" is a Shakespeare 318-GBT. It is mounted above 6" above ground, along with 8x 9' on-ground radials*. Works great for DX. Admittedly, I do not care much about local comms. Anyway, much below 20m it requires an antenna tuner or a preamp for realistic reception. On MW the resistance is probably low enough to about look like a short to a receiver.

*Regarding ground radials, Kirchhoff's current law still applies to end-fed antennas, so in reality end-feds are more like extremely offset-fed dipoles. There is return coupling somewhere. Without radials the return coupling can be nearby objects, the mast if metallic, and/or oftentimes common-mode on the feedline. YMMV.

Anyway, if your ~18' end-fed vertical is working nicely on MW, it could be more like your feedline acting as the MW antenna due to common mode or similar. Experimenting with RF choking along the feedline might help.
« Last Edit: November 13, 2022, 0254 UTC by RobRich »
Tampa, FL USA | US Map Grid EL88
Airspy HF+ Discovery | KiwiSDR 2 | 2x Msi2500 Msi001 | 2x RTL-SDR V3 + NE602 | 2x RTL-SDR V4
148' + 60' Loops-on-Ground | 31' Vertical | 18' End-Fed Vertical | PA0NHC MiniWhip

Offline zero33

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Re: Best MWDX antenna?
« Reply #186 on: November 13, 2022, 0738 UTC »
Its a commercially made CB-10-11 meter antenna from a local Aus supplier, I"m using RG-213 and through to my IC-7300 also have an unlocked Lincoln II + for 11 meters.
I am in the process of making a home made centre fed dipole hoping for better results.
Getting Back into it on 10-11 meters

Offline RobRich

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Re: Best MWDX antenna?
« Reply #187 on: November 27, 2022, 0159 UTC »
My Youloop has been having issues. Popped it open, and looked like a broken transformer. Yeah, like I am repairing that *tiny* winding. I do good to barely solder through-hole parts anymore. Not worth trying to source a replacement from Coilcraft or wherever, either.

So I popped the transformer off the PCB. Wound an 1:1 on a mix 73 binocular core like often used use on homebrew mobius small loops, and mounted it outside the enclosure. "Whatever" to the aesthetics.

Waiting on the glue holding the ferrite to dry, then finish a couple of connections and (re-)pot the boards with hot glue. Suppose I need to go find my NanoVNA, too.
Tampa, FL USA | US Map Grid EL88
Airspy HF+ Discovery | KiwiSDR 2 | 2x Msi2500 Msi001 | 2x RTL-SDR V3 + NE602 | 2x RTL-SDR V4
148' + 60' Loops-on-Ground | 31' Vertical | 18' End-Fed Vertical | PA0NHC MiniWhip

Offline ~SIGINT~

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Re: Best MWDX antenna?
« Reply #188 on: November 27, 2022, 0217 UTC »
Why not just contact AirSpy and see what they have to say. You never know. You might be able to get a replacement.

Offline RobRich

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Re: Best MWDX antenna?
« Reply #189 on: November 27, 2022, 0331 UTC »
I potted it once upon a time, so I probably damaged it. ;)

The enclosures are back together. Replaced the also damaged RG-402 loop coax with RG-6. A quick VNA sweep looks approximately like my previous Youloop measurement. I think the resonant frequency shifted somewhat, but again, a whatever given it is not a low SWR antenna anywhere in the HF and lower bands. I did not check VHF.

It is hanging in a window in one of the nosiest RFI locations inside the house. An elevated noise floor as expected, but it is generally working. I have already skimmed signals on 80m SSB, 11m AM locals, and a local MW BCB station.

I have interesting somewhat intermittent RFI on ~273KHz and upward harmonics. It is present on my 31' vertical as well, but it is 10s of dBs down there. Given the frequency I am inclined to think a switching DC voltage regulator somewhere in the house. Fun. Suppose I should now find my TinySA analyzer, but maybe later this weekend.
Tampa, FL USA | US Map Grid EL88
Airspy HF+ Discovery | KiwiSDR 2 | 2x Msi2500 Msi001 | 2x RTL-SDR V3 + NE602 | 2x RTL-SDR V4
148' + 60' Loops-on-Ground | 31' Vertical | 18' End-Fed Vertical | PA0NHC MiniWhip

Offline RobRich

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Re: Best MWDX antenna?
« Reply #190 on: November 27, 2022, 0718 UTC »
Longwave reception tonight. Have a carrier on 153KHz, and actual modulation on 171KHz.

Noted around 0700z:

153KHz - carrier in waterfall | possibly Radio Antena Satelor
171KHz - Medi 1 at SINPO 15242 trending 15241 with moderate to frequent static crashing from regional storms

I might do better with Medi 1 assuming I understood the language. Anyway.

Interesting part (for me) is using my 31' vertical with 4:1 unun and moderate ground radial field. I usually have to use my 148' loop-on-ground for longwave BCB listening, and it is out of commission pending repair or replacement.

BTW, I pushed my luck with the vertical further down the spectrum. 24Khz NAA, 25.2Khz NML, and 40.7KHz NAU are present tonight. Not difficult catches, but nonetheless there.
Tampa, FL USA | US Map Grid EL88
Airspy HF+ Discovery | KiwiSDR 2 | 2x Msi2500 Msi001 | 2x RTL-SDR V3 + NE602 | 2x RTL-SDR V4
148' + 60' Loops-on-Ground | 31' Vertical | 18' End-Fed Vertical | PA0NHC MiniWhip

Offline RobRich

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Re: Best MWDX antenna?
« Reply #191 on: November 27, 2022, 1247 UTC »
Tossed the factory feedpoint PCB and enclosure. Salvaged the connectors, which I mounted in a cheap plastic enclosure. Changed the wiring to (potentially) improve isolation by removing the homebrew design's ground from the loop shield to feedline ground that AFAICT basically turns the balun into something more like an unun. YMMV.

Regional 80/75m activity looks decent this morning considering the loop is in roughly the same indoor RFI noisy location as last night, along with a LCD TV powered on about 10'-12' away.



Likewise decent noise floor on the 49m band.



Next up the 40m/41m bands.



20m SSB activity is starting to trickle into the waterfall.



Several CW ops working the 15m band.



Faint activity on 27025am including an op in Ireland working DX into NA. Not too bad for an indoor loop hanging in a window.



Some CW traffic on the 10m band.



VHF NOAA weather.



Local daytime MW is not worth screenshots. One or two locals, plus a few relatively faint regional stations. At least it is working for MW.
« Last Edit: November 27, 2022, 1523 UTC by RobRich »
Tampa, FL USA | US Map Grid EL88
Airspy HF+ Discovery | KiwiSDR 2 | 2x Msi2500 Msi001 | 2x RTL-SDR V3 + NE602 | 2x RTL-SDR V4
148' + 60' Loops-on-Ground | 31' Vertical | 18' End-Fed Vertical | PA0NHC MiniWhip

Offline ~SIGINT~

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Re: Best MWDX antenna?
« Reply #192 on: November 27, 2022, 1401 UTC »
That is actually pretty good VLF / LF reception. I currently have one of my mini-whips in the window but I think I might replace it with my YouLoop to test it out. I still have not re-installed the Wellbrook loop after the move. Just recently swapped my end-fed longwire for my T2FD and finally got the RG-58 replaced with RG-213 yesterday. Hope to at least get the Wellbrook up before winter sets in.

Offline RobRich

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Re: Best MWDX antenna?
« Reply #193 on: November 27, 2022, 1547 UTC »
Congrats on getting the T2FD back in service. :)

Poking around "new" ideas, modelling for the SULA terminated loop looks interesting.

https://swling.com/blog/2022/08/introducing-the-amazing-sula-an-affordable-unidirectional-dx-grade-loop-antenna-that-you-can-build/

As modeled it has a wide frontal horizontal lobe pattern, though with a ~20dB F/B ratio for much of HF and a considerable back null from MW to 40m. "Gain" is well into negative dBs, but to be fair, it is not much different than many beverage or loop-on-ground designs. A preamp is simple enough to add if needed.
Tampa, FL USA | US Map Grid EL88
Airspy HF+ Discovery | KiwiSDR 2 | 2x Msi2500 Msi001 | 2x RTL-SDR V3 + NE602 | 2x RTL-SDR V4
148' + 60' Loops-on-Ground | 31' Vertical | 18' End-Fed Vertical | PA0NHC MiniWhip

Offline RobRich

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Re: Best MWDX antenna?
« Reply #194 on: November 29, 2022, 0250 UTC »
Temps are cooling, so it is about time to actually take a serious look at the antenna farm.

Just ordered an 1000' spool of Belden PPC RG-11 direct bury coax. I probably will have to enlist some help, but I intend to hopefully bury most of my feedlines.

https://www.ppc-online.com/hubfs/2057289/Downloadable_docs/Spec_sheets/Coax_Cable/Series_11_Underground/P11ET77EFRF.pdf

It has a CCS center conductor, which could be a low frequency concern due to skin effect, but the current cheap RG-6 deployed on most of my antennas suffices okay for my receiving purposes down to longwave. I probably would have went with a solid copper center if transmitting on 160m or lower, but I am not, so whatever.

I am thinking about moving the 31' vertical from ground mounted to ~10'-20' elevated. Probably just a couple of elevated ground radials, or maybe even only one for a little directivity potential, since it is a receiving antenna.

https://www.qsl.net/kk4obi/Center-fed%20L-dipoles%20Vertical.html

I should just outright replace the old 148' loop-on-ground. I might move it as well, as the existing far side of the square loop parallels to close power lines.

The two failed active miniwhips are likely to be replaced with a generic eBay active miniwhip and a MLA-30+ amplified loop. Yeah, neither are great antennas, but I already have them.

I do not have much interest above HF, but I do have a cheap little discone collecting dust. Instead of dealing with yet another mast, I am considering crimping and/or soldering a loop connector to the vertical tip and hanging it via rope line from a tree branch. It is omni anyway, so it is not likely a little movement is going to affect it too much.

I might get all that done in a few weeks.... or hopefully at least by next spring. lol

----------------

Somewhere along the way I hope to have some type of small radio area. For quite awhile now I have been mostly using a notebook+SDR in the den and a Kenwood R-2000 on the bedroom nightstand. It could be much worse, but it might motivate me to obtain an amateur license if I had a dedicated radio space, if I have a dedicated radio space.

BTW, the R-2000 is still using that temporary 13' fiberglass fishing pole vertical mounted on a tripod I slapped together awhile back. Another it could be worse situation, as at least it is outdoor antenna.
« Last Edit: November 29, 2022, 0303 UTC by RobRich »
Tampa, FL USA | US Map Grid EL88
Airspy HF+ Discovery | KiwiSDR 2 | 2x Msi2500 Msi001 | 2x RTL-SDR V3 + NE602 | 2x RTL-SDR V4
148' + 60' Loops-on-Ground | 31' Vertical | 18' End-Fed Vertical | PA0NHC MiniWhip

 

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