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Reviews Categories | Antennas: HF: Vertical, Wire, Loop | EARCHI End-fed HF Matchbox Antenna Help


Reviews Summary for EARCHI End-fed HF Matchbox Antenna
EARCHI End-fed HF Matchbox Antenna Reviews: 3 Average rating: 5.0/5 MSRP: $52 or home brew
Description: Wire antenna, fed through a 9:1 UNUN. Works on 6-40m w/ 30' wire and a
tuner.
Product is in production.
More info: http://www.earchi.org/proj_homebrew.html
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KK5R Rating: 5/5 Oct 4, 2017 20:54 Send this review to a friend
Great Antenna replaced other antennas  Time owned: more than 12 months
This is the preferred antenna here. Last contact was with a guy in Slovenia on 20M...

KK5R ENDFED DIPOLE

I made a 9:1 UnUn using a couple of ferrite cores designed to go over RG-8. It uses 9turns of hookup wire following the pattern used in the EACHI design. The image shows the antenna layout. I can use it without a tuner from 160M to 6M but there is a big thing to keep in mind: You have to be careful how you dress the feedline.

At first, I dressed the feedline straight down from the UnUn. The SWR was not good and the lower two HF bands (160 & 80 Meters) were unusable. In fact, the feedline dressing is critical. Then I tried dressing the feedline down under the "counterpoise" by bisecting the vertical and the horizontal, hanging it down approximately 45-degress from the counterpoise. I also included a 1:1 Balun that uses ferrite beads and this was enough to make the antenna usable from 160M to 6M. While the SWR is less than 2:1 all across the bands, I still use the FT-450AT's internal tuner to finesse the system.

The wire used is #14 house wire for the 16-ft counterpoise and #14 copper clad steel wire for the 53-ft section. The 20-ft of feedline connected between the 1:1 Balun and the 9:1 UnUn is composed of an 18-ft length of RG-8X coax which is connected to a 2-ft RG-58 pigtail coming out of the UnUn. The feedline to the shack is RG-8.

One other consideration is that it is isolated from any surrounding metal objects. If this is not done, the SWR could well be affected.

Note that I also have experimented with wire wound trifilar wound coils on 1-1/4 inch sections of PVC pipe and while they worked, they were best between 80M and 12M, the other bands were not very good. While PVC wound UnUns work, UnUns wound on ferrite cores seem to be more desirable because they measure better at lower and higher amateur bands.

KK5R

You can see the antenna here:
https://forums.qrz.com/index.php?threads/build-your-own-9-1-unun-antenna-on-the-cheap.579701/page-3
 
W1GOV Rating: 5/5 Jul 5, 2016 11:33 Send this review to a friend
works great for me  Time owned: 0 to 3 months
I have had my license (General) for just over one year. I live in an HOA restricted community and have been forced to use an old wire dipole (originally used for SWLing) in my attic for HF. It worked OK on 40 meters and I was able to make almost 70 contacts over the past year in casual operation. However, there are only about 3 DX stations in that list. I thought I would try the EARCHI end-fed as it looked like it would not be noticeable in my back yard; especially since I have no neighbors to the rear. I was astounded with the improvement. Within minutes after completing the installation I made a contact in the Balearic Islands with a reported 59 signal. Before, where I heard mostly noise on the bands I am now hearing stations. Just this weekend I have contacted 11 of the 13 Colonies Special Event. My rig is an ICOM 7000 and I am tuning the antenna with the LDG-7000. This antenna is certainly worth the $56 donation.
 
SMAUG Rating: 5/5 Dec 14, 2014 06:03 Send this review to a friend
Works well on 10-40m  Time owned: 0 to 3 months
(EARCHI = Emergency Amateur Radio Club of Hawai)

I'm a new General, and this is my first HF antenna, so I can't compare it to other anntennas. But I CAN tell you how it works for me.

STATION:
- Kenwood TS-440S/AT
- MFJ-949E manual antenna tuner
- 100' of DX Engineering RG-213/U coaxial cable
- Copy of a Kenwood MC-43 microphone
- Radiator wire is 31' long, hung vertically in a tree, about a foot away from the trunk

I live in the Chicago area and have made lots of contacts on 10m with this so far, after only a couple weeks. (10m contest this weekend, as I type this) Alaska, California, Oregon, and Washington were no problem. The guys with the 1.5 kW and a yagi on a tower walk right over me, of course, but once they've worked the station and have moved on, I'm in like Flynn.

I'm using this as a semi-permanent installation from my ground floor apartment, hence the long run of co-ax. The installation had to look neat so it doesn't draw extra attention. I installed it during the night, ninja-style. ^_^

In my 31' length, my built-in tuner will tune it to less than 1.2:1 SWR on 40-10m. Haven't tried 6m. Using my external tuner, I can match it to 80 and 160m, but haven't made any contacts yet. I'm told it is because the antenna is very inefficient at this relatively short length on those bands. Even so, I feel like this was a great value.

Anyway, it is an effective and inexpensive multi-band HF antenna. All the old hands tell me how inefficient it is, but all their alternatives either take up a load more space (dipoles) or cost a lot more, but look to be the same thing.

I considered a magnetic loop antenna, as they're said to work great and don't even need a long radiator wire. However, they spendy ($400+), need constant tuning, and develop lots of voltage. Much more complex to build home-brew, too.

I think for apartment-dwellers and for field operations, this is maybe the idea antenna.

As for my rating, I gave it 5 stars because it represents such a good value. It is effective, inexpensive, and space-efficient, and that makes up for any lack of efficiency.
 


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