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| MFJ-1979 & eBay whip |
In Lowband DXing, John ON4UN (SK) cites work done by many lowband DXers (confirmed by antenna modeling) that four elevated radials is equivalent to 120 on-the-ground radials in terms of antenna efficiency and in lowering the antenna's angle of radiation.
My own experience lacks the formality of anything that could be defined as research but I do have a logbook full of DX on multiple bands when using this antenna from parks, whether those parks are on the Florida coast or inland Colorado. Whether the rig is the FT-891 (100 watts) or a QRP rig.
The MFJ-1979 makes it easy to set up and take down this effective manifestation of a 1/4-wave vertical and is of heavy-duty-enough construction to have lasted me 5 years (and counting) in three different countries & numerous parks around the US.
There is only one problem (now solved):
Fully retracted, the MFJ-1979 will not fit into my motorcycle's side cases or top case. To take it on the bike to a park, it must be bungee-corded to the rear seat.
A look around the internet provided a possible solution in the form of the poorly named 5M/16.4FT QRP Antenna 14M-30MHz 300W HF Antenna 1/4 Wavelength For USDX Radio.
Too many words. Bad for us; good for the search engines.
I'm just gonna call it an eBay vertical.
It is simply another 10-20m 1/4-wave vertical along with a mounting spike and a coupler for attaching coaxial cable. It also includes a 10-conductor ribbon cable for use as ground radials.
Both the vertical and the ribbon cable are 5m/17 feet long - ie, 1/4 of a wavelength on 20m.
But retracted, it's only 20" (51cm) long and fits easily into my bike's top case whereas the retracted MFJ-1979 is 28" (71cm) and does not.
Both whips are 0.7" (17mm) in diameter at the thickest part. The MFJ-1979 has 10 sections; the eBay whip has 15.
The MFJ-1979 costs $70 and includes only the whip. The eBay antenna costs $55 and includes whip, ground stake, coupler and radials.
The eBay vertical is not as heavily constructed as the MFJ-1979. Time will tell how it stands up to repeated use.
RF-wise, they are the same antenna.
An motorcycle-POTA activation today was absolutely fantastic in two ways regarding the new antenna: 2 minutes to set up and take down, and lots of callers from California to the Czech Republic.
There were pile-ups on several bands with more simultaneous callers than either I or the FT-891 could easily discern, particularly on 20 meters but also on 17 and 15 meters. 10m was not open at the time I was on the air.
See for yourself - sharp-eyed viewers will notice something "wrong" at some point in the video (which I quickly corrected off-camera!):
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I swear by elevated radials. My POTA antenna for 2023 was a 20m GP on a 10m fiber pole, feedpoint 5m high with two sloping radials. I use those as guy wires, extended with some rope.
ReplyDeleteFor 2024, I'm planning on multibanding it. Stay errr 'tuned'.
I had hoped the FT-710 ATU would find a fix but it's next to useless. It can shift a CW antenna to SSB on one band, but certainly not tune a 20m GP to some other band. My TS-850SAT 20y ago would do this...
I use and have used elevated radials with success on ALL HF bands (160m <> 10m).
In the past I tuned 'm to frequency as a (low) dipole with the antenna analyzer. Then I connect both halves at the feedpoint. Then the vertical wire goes up. Now I just cut to calculated length and adjust the vertical part to get it close to 50ohms.
The video: yes I noticed you had your L and R sock reversed!
I envied the WX in that video. It's been lousy here since early October. Gray, VERY wet, often windy. Not really winterish. Not really POTA-proof.
BTW I also envy the pileups I see from a few US POTA guys. It was one of the things that made me try it. However it does not catch on in EU. RBN shows I was loud on 20m all over the world with that GP and 100W. But I mostly logged EAs who seem to be into the chase.
Happy holidays. 73
Franki ON5ZO
Hi Franki - I think WWFF is more popular in EU than POTA but there are still a lot of dedicated POTA ops there. I know I had a lot of European callers in the video...I should have just posted my operation to the WWFF site to start, then to the US-oriented POTA page after working the DX. Next time...I'm still a work in progress, learning (sometimes slowly!) as I go.
DeleteI do prefer elevated radials but they take more time and consideration to plan and install, and they need to be dedicated to the band in use, as you already know.
In the video, the ATU is connected input-to-output at first, totally bypassing the radio - I fixed that after a few minutes of trying to operate the tuner.
I've got you in Ham Alert so if you activate when I'm near a radio, I'll try to get you logged. See you later OM!
John