A few weeks ago, Chameleon Antenna sent me a pre-production model of their new wideband magnetic loop antenna called the Chameleon CHA RXL.
I’ve evaluated and reviewed a number of Chameleon’s ham radio antennas (primarily on QRPer.com). I find that the quality of their products are second to none. Price-wise, they tend to be at the top of the market, but keep in mind they machine and manufacture all of their antennas here in the US and they’re incredibly rugged; indeed, military-grade. And in the spirit of full disclosure, I’m proud Chameleon has been a sponsor the SWLing Post and QRPer.com since last year. My sponsors are by invite only and focus on companies I trust with our radio community’s business.
When Chameleon shipped the CHA RXL to me, it wasn’t from their factory, it was directly from the field: Fort Irwin, to be exact.
This CHA RXL sample had been used by NTC Operations Group Fort Irwin (who, incidentally, won QRPX this year–click here to read the PDF report).
I was told that the condition of the antenna could be very rough after the QRPX because it had essentially been sandblasted in the desert winds. I was also told that someone accidently transmitted 5 watts into it at some point but it didn’t seem to harm it (for the record, like all amplified receive-only loops, it’s not designed to take RF).
Tony (W0NTC), who was one of the Ft. Irwin radio ops, sent me this note as he dropped off the shipment at Fort Irwin’s FedEx:
“Had a blast with [the CHA RXL], and it was absolutely critical while I was operating in the Army HF Low Power Competition (think tons of high powered MARS stations piling up and drowning out the 20W or less competitors). It absolutely crushed some localized RFI from a huge building I operated behind, and the receive on it I can only describe as “layered” in that I could hear stations somewhat clearer than usual if they transmitted simultaneously. Receiver I used was the IC-705 with default Auto Notch and Noise Reduction.”
Tony volunteered all of this info–I never asked him how it performed.
A few days later, I wasn’t sure what to expect when I opened the box although I knew that my operating locations were nowhere near as cool as its position next to a Humvee at Fort Irwin in the photo above!
I pulled the CHA RXL out of the box and it looked cosmetically flawless to me.
Frankly, there’s not a lot to get damaged. The 36 inch diameter loop is made of rigid aluminum and has a Navy gray powder coating. The preamplifier unit is completely sealed and made of a high-impact plastic/PVC type material. The steel loop is attached to the preamplifier loop flanges with wing nut connectors.
The only potentially vulnerable part of the antenna system is the Bias-T box which would normally be located in your shack close to your receiver.
If I mounted the CHA RXL permanently outdoors, I would use Coax Seal around the BNC connection point, of course.
Although the CHA RXL has a supplied mounting bracket for permanent installations, I love the fact that the preamp box has a 1/4” x 20 threaded camera socket on the bottom. This makes for a brilliant portable loop because it can so easily be mounted on a standard heavier-weight tripod! All antenna manufacturers should give us tripod mount options when possible.
On the air
One of the reasons amplified receive loop antennas have become so incredibly popular over the past couple of decades is because they do an amazing job mitigating radio frequency interference (RFI) a.k.a. “QRM.” If you live in a neighborhood with significant radio interference, you really should consider some form of loop in your antenna arsenal.
Ironically, at home, I live in pretty much an RFI-free zone. I’m surrounded by tens of thousands of acres of national forest, so I’ve only used amplified loop antennas in the past for mediumwave DXing–mainly, when I wanted to take advantage of their amazing ability to null out unwanted signals.
Many years ago, I purchased a Pixel Loop Pro antenna (now under a different name via DX Engineering), mounted it outside where it lasted almost a year before a bear decided to pull it down and chew through the coaxial feedline. He/she did so with enough energy that it ripped down the loop and damaged the connector end of the Pixel’s pre-amp. This all happened when our family was travelling for two months in Canada. Why bear, why?!? But I digress…
The CHA RXL version I was shipped has one single rigid loop–the “EU” version’s loop comes in two pieces (for easier shipping/transport)–but I had no problem fitting the entire assembled loop in the back seat of my Subaru or my truck (as long as no one was sitting back there at the time). If you plan to travel with your loop a lot, consider the “EU” version!
I’ve taken the CHA RXL to my parent’s home a couple of times and enjoyed doing a little mediumwave and shortwave listening. Inside the house, the loop would attenuate RFI nicely, but when outside it would all but eliminate many sources of RFI.
At their house, I primarily used my Icom IC-705 for cruising the bands (being careful, of course, to disengage the transmit function).
Listening time in my hometown, though, was very limited. Since the CHA RXL is so portable, I decided to set it up at home on our porch for a few days, giving me an opportunity to test both the Sangean ATS-909X2 and Tecsun H-501x with an external antenna.
I’ve especially appreciated using the CHA RXL on mediumwave. Even from our screened-in porch, I can rotate the loop and use its excellent nulling properties to pick out multiple station IDs on crowded frequencies.
I’ve spent time on shortwave, too, and found that it certainly gave these two portables a signal boost.
In fact, it was by using the CHA RXL that I discovered the audio level difference between AM and SSB on my ATS-909X2 is very minimal when an external antenna is connected.
I’m sure you’ll hear the CHA RXL in action when I post audio clips and recordings in upcoming reviews.
If I owned a CHA RXL loop, one of the first things I’d do is build a power cord for it with an in-line fuse and terminated with an Anderson Powerpole connector. Since the operating voltage of the Bias-T is 12-14 VDC, it would pair perfectly with one of my Bioenno LiFePo4 batteries, offering a power source with longevity in the field–ideal for a group LW/MW/SWL DXpedition.
It’s difficult for me to truly comment on the loop’s performance because I don’t have another loop at present for comparison. I can say that it’s amazing on mediumwave, where I’ve spent much of my listening time this past week. I believe shortwave reception has been at least on par with my former Pixel Loop, if not better. It’s hard to say, in truth, because propagation conditions have been so poor lately. The CHA RXL loop does effectively mitigate noise!
I’m not sure if the CHA RXL is currently on backorder or not, but I would suggest you check out the product page on Chameleon’s website and possibly contact them if you’re interested. They’ve a number of options and accessories to consider.
Click here to check out the CHA RXL at Chameleon Antennas ($490 US).
One thing for sure: this must be one of the most rugged and durable RX loop antennas on the market. In addition, that Navy gray powder coating helps this rigid aluminum loop disappear against the sky. I believe you could strategically mount this loop and the friendly neighborhood association may never notice–it’s pretty stealthy. Speaking of which…
Josh’s CHA RXL install and demo video
Josh over at Ham Radio Crash Course recently installed a CHA RXL on his house and tested it on several bands, comparing it with a number of his external antennas:
I bought the CHA RXL from GigaParts.com, received it a week ago. I’ve bench tested it plus tested it outdoors. I have a bunch different loops and loopamps–Wellbrook, W6LVP, etc., have tested and compared them all. I’m primarily an LF NDB DXer (see my info on qrz.com for AA7U). The CHA RXL is mechanically extremely nice–built very stout, even the 36″ dia. loop is solid, not a hollow tube. Unfortunately for actual performance at least at LF, the thing is deaf compared to the Wellbrook ALA1530LN or the homebrew LZ1AQ loopamp. Bench testing shows the reason–the CHA RXL has a high input impedance at LF and is a severe mismatch to the loop’s inductive reactance at LF. Loop sensitivity is directly proportional to loop area and to frequency, so at LF the small loop area and the low frequency all make for a relatively insensitive loop–the loopamp has to be close to the loop reactance for optimum sensitivity. The CHA RXL is, as mentioned, a severe mismatch to the small loop. The loop measures 2.22 uH which at, say, 300 kHz, is 4.2 ohms reactance. The loopamp should be in the 2-10 ohm input impedance range for a decent match to the loop. But the CHA RXL measures (with a DG8SAQ VNWA and 1:1 input matching transformer) 340 ohms–a very severe mismatch! I have a daytime weak beacon at 185 miles I use for small loop sensitivity tests. The ALA1530LN and LZ1AQ both easily hear it with the CHA RXL 36″ dia. loop; the CHA RXL loopamp has no trace of it. I did other bench tests–strong-signal performance, IMD using my two-tone IMD test set. The ALA1530LN and LZ1AQ both measure third order intercepts in the mid 40 dBm OIP3. The CHA RXL measures +18.5 dBm OIP3! This is very very poor! A decent loopamp should at least be in the 30 dBm OIP3 range. The CHA RXL is a $500 antenna, similar to the Wellbrook and the DXE Pixel Pro loops which both have excellent performance. Something is seriously wrong with the new CHA RXL loop antenna’s loopamp!
I’m very interested in seeing how this performs compared to the popular inexpensive loops. It obviously has durability in its favor.
And the popular EXPENSIVE ones as well like Pixel / DXE, W6LVP, etc.
I just came across this article and this is the VERY FIRST time I’ve seen anyone write about an amplified loop that can successfully withstand “high” RF fields without splatter or worse; by “high” I mean, as an example here in Phoenix, Arizona, LOTS of high power AM MW stations nearby, especially during the day. Of course, this thing can take literal high near-RF fields seemingly with little damage: it even withstood the 705 TX into it? What’s the secret to this thing?!?
Point being I thought I was limited to a passive loop (Moebius, I have one of AirSpy’s) due to the high noise floor, but this seems to say otherwise. Thanks for the review!
Forgot to mention, one down side I see is the very narrow 12-14 volt range. You are incorrect on your LiFePO4 battery being good for it: perhaps after a surface discharge, but charging voltage will approach 15V!
On the other end, lead will drop to 11V or lower towards the end.
Someone needs to ask them about that to get the issue clarified. Again, a working example, the vast majority of radios will max out at 16V & are safe with 15 to 15.5V. This thing should be rated likewise if battery power is to be used.
Good call. Mike… especially since this loop makes the W6LVP seem price-friendly by comparison.
Looking for more reviews on this antenna on SW!
Sound very nice I’m in HOA WHERE I was able to get my R7 up but for long thats the the big? Maybe if I sell the R7 I can get some money to. Buy that nice video
Barry w9ndu 73’s
Two different Chameleon factory tours. One with masks, the older one without…
Maybe you can do a shootout compared to other small antennas?
Looking forward to your review of this antenna!