Saturday, October 19, 2019



As I've mentioned a time or two, my chance at an outdoor antenna has been zilch, or maybe negative zilch. I tried a simple indoor dipole with terrible results, then last year I tried using the MP1 "Super" antenna indoors with no luck whatsoever, and ended up selling it at a local Hamfest this past Spring. 

Enter stage right - Chameleon's P-Loop 2.0 Magnetic Loop Antenna (MLA). 

Combining several specials (10% off first order and a 30% OFF sale from Chameleon) I was able to order this model for just a little over $250. I had toyed around with constructing my own MLA (and still do) but I knew that I'd probably keep putting off buying what I needed to build one and end up six months later with nothing. So I took the plunge.

So what was in the box that arrived? The coax that is used to form the loop, the capacitive ring that is velcro'd approximately at the mid way point of the coaxial loop, the "magic" sealed box where the capacitor lives, tripod, 15' of rg58 coax to connect the loop to a transceiver, and a nice canvas back to stuff everything into when being stored away.

I had viewed numerous YouTube videos detailing how to put together and use one, but when I pulled everything out from the shipping box I was still trepidacious about getting things just right. In one video I watched it was stressed that you should get the smaller loop exactly in the middle of the big one, and once that was done it was recommended to mark that spot with some tape so that when assembled it would always have that sweet spot. In another video it was mentioned that the tuning knob was so touchy that just by placing your hand on or near it the loop could de-tune. Other videos said that it was best used when at ground level, yet others suggested it would be better to have it well off the ground. I was ready, and then again I was not.

The instruction sheet was just "okay". Several sheets of regular weight paper that appeared to be printed off your typical home laser jet. There isn't a lot of detail that has to be written about setting one up, yet the MFJ-style instructions seemed a bit homemade.

Looking back, it's really stupid at how intent I was to get this right. I actually played-paused-played a YouTube video as I began assembly, but don't be alarmed, it's really "Easy Peasy". The main thing is to stay loose and don't get too stressed while putting your loop together.

I setup the tripod and extended it high enough so when the thicker coax was screwed into the SO-239 connectors on the tuning box it would form a half-assed circular loop. It was held in place whenever the smaller loop was attached via velcro (approximately midway to the thick coaxial loop I just formed). Now let me explain "Half assed". The coax is scrunched into the box for shipping so when it's pulled out, being stiff coax, it doesn't allow for perfect smoothing, so YES it's roughly the shape of a loop, but it looks like I put it together while hung over - which I wasn't.

Moving on....

Once set up and affixed to the tripod it was time to figure out MLA tuning. One end of the variable capacitor stops at the top of the 10 meter band while many-many (many) turns later it end-stops in 40 meters. I wanted to try 20 meters so a-tuning-I-did-go. Like you've heard and/or been told many times turn the capacitor, while listening for the loudest noise to come out of your receiver. Once your in the ball park you can tune it more slowly until the SWR is at it's lowest.

The way I did it (and currently still do it) was to have the 15' foot coax come into a 2 position switch box. One position sent the signal to my radio while the other one was connected to my Comet SWR display. I slowly tuned it down to under 1.5:1, switched over to my radio and BAM--->my FT-817's receiver came alive with actual activity on 14.300. This was the most I'd heard out of it since the last time I ran portable, and never inside the QTH.

Sitting in my "shack" on the second floor of the house I was actually able to get in on one of the morning nets that are running on 14.300. Let me stress that this was the first time I'd ever been able to hear a net, much less talk on one, from an indoor antenna and I was elated. Eventually I put the 817 back in storage and have used my TS-2000 ever since. The maximum supported wattage is 25 and I normally keep my rig set to 20 watts just to play it safe. I've checked in on various nets, and participated in several ARRL contests where I've discovered that if I hear them, they'll hear me as well. Many times I have given out a 5-7 signal report and received a 5-9 report back from the other station.

Let's get down to brass tacks about my take on this antenna -

  • PRICE - At $400 this is fairly expensive. At the price I bought it for the P-Loop was affordable 😁
  • You don't need to make a perfect circle. I.E. - feel free to half-ass it.
  • It has never made a difference on the precise location of the smaller loop. I eyeballed it when I set it up, but have moved it a little each way to see if there was a noticeable difference and there wasn't.
  • Once you get used to it, setting the loop up should take you all of a minute or two.
  • I never found that I could distort the tuning by merely touching the black tuning knob.
  • Tuning is really easy. If you have 29 mHz at one end and 7 at the other why tune slowly? If I'm on 10m and want to get to 20 I know it's roughly at the mid tuning point and take huge turns of the capacitor to get in the ball park quicker.
  • Location: I've tried this downstairs at garage level and then upstairs in the shack and have not found either location to be better or worse than the other.
  • Being vertical there should be quite a bit of directivity to the loop. Sometimes I've noticed it and have moved the loop's direction to get a better signal, while other times it doesn't seem to matter much. Perhaps this has to do with the type of propagation I'm getting. If anything is certain, I know that by turning the loop in one direction or the other allows me to tune out much of the electrical noise I pick up from our structure.
  • Bandwidth. Yes, the bandwidth gets wider as you tune upwards towards 10 meters but even on 7 meters I haven't found that having to re-tune is an issue. After a  month or two I discovered that it had become second nature.
  • 25 watts maximum SSB. Yes, that is quite a drop from 100 watts, but seriously, the loop has a butt load of electricity on it and because it's right there in the room with me I wouldn't be comfortable with it any higher.
  • Yep... It works fine on 11 meters too!

To wrap up: Before the loop I was strictly a listener indoors, only able to work stations while mobile or in the field. Now I'm able to sit in the shack and make contacts. I am no longer bound by the constraints of not being able to have an outdoor antenna.

One day, when I have some extra cash floating around I plan to make my own magnetic loop. Also, since using this one, I've been kinda chomping at the bit to see what using the F-Loop can do for me, via coax or the solid aluminum loop, but that would fall into the category marked "Luxury"

A magnetic loop is not the ultimate antenna, however, I'll leave you with these words: "The best antenna you have is the one you can actually use"..(Nuff Said)



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