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Thread: Which Antenna

  1. #1

    Join Date
    Mar 2019
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    Elkridge, MD
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    Default Which Antenna

    Hello,

    I am waiting on testing to begin again so I can get my General. I have been using my Baofeng handheld on a local repeater so far. I am trying to get my Ham Shack setup and need some antenna advice. I just want to get my Kenwood TS440S on the air. I have the radio and the power supply as well as an external speaker and a room in my single family house (no attic access) with two old lab tables and a computer with internet to use as my shack, that's it. My dilemma is the antenna part of the setup. I am willing to spend a little just to make sure I successfully get on the air. I THINK I have it down to two antennas that seem the easiest and most likely to end with success. This is based only on my reading and ultra limited understanding. The first is the Alpha 6-80 meter J-Pole (34 feet in length). The second is the Alpha 10-40 meter Outdoor 100 watt base Magnetic Loop https://alphaantenna.com/product/hf-...alpha-antenna/. I am thinking Alpha Antenna simply because of the great reviews but that is not set in stone. Yes they are NOT cheap, but at this point I need ease of setup and best chance for success (I have limited mobility after a broken back so high climbs and roof work are out).

    For the J-Pole, I was thinking I would run it from a PVC or other mast attached to my raised deck post (the deck is 10 feet up and the mast would be another 10 or so feet) to a downward slope secured to a tree about 6 feet off of the ground. I assume I will also need to run an 8' ground rod at the base of the deck for that antenna? Do I tie the ground in to the shielding of the cable or some other place on the antenna (I had planned on using premade coax so the shielding will not be exposed unless I need it for grounding). I also assume I need a lightning arrester in line and probably a choke before it goes into the house?

    For the Magnetic Loop I was thinking I would run it on the same yet to be purchased mast on my deck. Will I need the same ground rod setup? I assume I still need the lightning arrestor but don't need the choke on the coax.

    Which setup will give me the best performance? My goal is TX/RX as far as I can possibly can go. This is only a first setup, as I gain more knowledge and experience I hope to build my own antennas, but for now I just need to get on the air....

    I APPRECIATE any thoughts or input.

    THANKS!

  2. #2
    Super Moderator 5B4AJB's Avatar
    Join Date
    Mar 2008
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    Meneou, Cyprus
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    2,288

    Default

    $700 seems a bit inflated for a magnetic loop to be honest. Maybe if the controller had memories/presets, which would be useful.
    Have a go at building one, they really are simple things. The only pricey part is the variable capacitor (if you want high power handling), the rest you should have in the junk box.
    Magnetic loops should be mounted on an insulated mast and can be near ground level. A PVC mast/riser with wood inside should last for decades.

    I, personally would invest that kind of money (for V/UHF) in some Heliax (or similar) and a nice big vertical, maybe a small beam & rotator.

    Grounding a mast is always a good idea, however, if your stack does get hit directly by lightning, nothing will completely protect the gear & shack...

  3. #3

    Join Date
    Nov 2019
    Location
    Ash Fork, Arizona
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    88

    Default

    KC3MXI,

    I hope this isolation/distancing stuff gets over soon, so you can go for your test. As I always do, I suggest investing some time into studying for the Extra Exam.

    I also think that the Loop antenna you linked to is kind of pricey. I found the web site to be a bit confusing. The initial picture and description shows the loop with a manual tuning knob. But the details further down describe a Remote Tuner. If you download the user manual, it only discusses the manual tuning unit. I would be wondering what I was going to receive.

    If you are still thinking about a Small Loop antenna, you might want to check out this page on Small Transmitting Loop Antennas. As Steve Yates, AA5TB, points out, Small Loop antennas are very efficient but they have small bandwidth. That's not that big of a problem, as long as you have a good antenna tuner. Your TS440S may have a built in tuner, but built in tuners tend to have limited range and might not be sufficient. The rest of that page provides lots of information on Small Loop antennas. Including, how to build your own, for a lot less money.

    The other antenna, the J-Pole, is really just a End-Fed antenna. They mention that in their advertisement. End Fed antennas provide good bandwidth, but are not very efficient. The antenna wire is only 34 feet long, which is the minimum length that you can use, and still get 40 through 10 meter coverage. It can be used on 80 meters, but you will need a good tuner. Personally, I never use 80 Meters, so it wouldn't bother me. A good document on End Fed designs can be had on using 4:1 and 9:1 Baluns for a End Fed Antenna. If you look around a bit, you will find that you can make your own End Fed antenna for a lot less than the one on the Alpha site.

    As far as protection from lightening, you might want to check into the ARRL's book on station grounding. That will give you all the information you need. You seem to have lots of high trees on your property. They are probably higher than you are going to secure your antenna. The high trees will probably help protect you from a direct strike. However, a nearby strike can be just a devastating, so lightening arrestors may be in order.

    I have personally experienced a lightening strike. But the landscape in my area, high desert, is very different than yours. We have trees (Juniper), but they are pretty short. Near my barn (ham shack), there isn't any. I had a Hustler 5BTV mounted on top of a 18 foot section of 2 inch iron pipe. That put the top at about 42 feet. The antenna and mast were secured to a fence corner, also made from 2 inch iron pipe. But it was 100 feet from the barn and there wasn't anything else in the vicinity. One night, several years ago a active storm moved in. About 9:00 PM I heard an explosion. The explosion was the 80 Meter resonator exploding into thousands of little tiny pieces. The energy came down the coax and bored a hole in my tuner. It also welded all of the capacitor plates together. The tuner was a total loss, but nothing else was damaged. Even the antenna still works on 40 through 10 Meters.

    Good luck with your testing.
    Martin, K7MEM
    http://www.k7mem.com
    Ash Fork, AZ - 60 miles from the Grand Canyon on Rt-66. Elevation 5,300 ft.

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