Ham Radio - The GOOZEEZOO(a.k.a. Hamgeek HG-20a) magnetic loop antenna
Вставка
- Опубліковано 10 лют 2025
- Trying it out, doesn't work very well.. Nice hardware though.
If you like my videos, please subscribe here:
www.youtube.com...
If you want me to keep making more videos like this, consider becoming my patron at Patreon: / kb9rlw
Discuss this and other videos on Facebook:
/ kb9rlw
If you want to give me a tip, patreon donate page is here:
www.paypal.com...
Hi Kevin, good to see you looking well. Thanks for the video.
Always love your preroll. Glad you're better.
Great to see to back! Thanks for the info about this antenna.
I appreciate you took the effort to draw a schematic. Now I can build and try such a control box myself.
Well this is probably not the best design. But you can get the schematic for the MFJ loop tuner, which is similar. They have a couple of inductors in line with The coupling capacitor, might make the difference.
Lookin better man. Happy days. 🙂
I have a very wide band antenna that handles 100 watts and matches 1:1 across HF, VHF and UHF bands. It sits on my shack desk. It is, of course, my dummy load. Great video.
Two thoughts.
Take a dremel tool and cut the back open. Shorten the wires and cover the hole with a piece of flat plastic and a dab of silicone.
Second is use the loop for AM radio station listening at night. I bet you can get so many stations out there they overlap. The loop might give you directional discretion.
BTW, you look great Kevin. Look like you old self. Glad to see you back and feeling better.
Best wishes for a full recovery Kevin! You are looking and sounding better every video! Sorry about the loop, we all have parts in our junk boxes from wished successes….
ham radio brat
Looking better, I hope you feel better as well. It's difficult to know for sure if this antenna is intentionally bad with intent to maximize profit or perhaps it is defective. If you had the time perhaps you could improve this antenna and do a video about it. Thank you for sharing.
Thanks for the video. Really gives insight to what to pass up. It looks cool but that's all.
Hope we have our "good old Kevin" back for good. Much missed.
good to see you on
Kevin. Nice to see you again. I hope you're ok in your recovery. Regards from Santiago of Chile. 73's CE3PSD
Thorough review and the results speak for themselves! Good job!
for the $88+ dollars I would package it up and return it! Amazon "free returns" won't cost you a penny
Once again you are saving me money. Thanks Kevin and I hope that your health continues to improve!
Thank you, Kevin! Take care of yourself and "Keep the Faith"! 🇺🇸 👍☕
Tnx Kevin. Nice parts though. Good Hardline for your other loop, nice box… Hmm just needs an inductor and you can make a manual T-match or even a Pi network out of it. Maybe even a pre-selector…? Plenty of opportunity to use your VNA with such projects.
Thank you for putting out objective, quantifiable reviews.
wow< I almost bought one of these. Almost. Thanks for the review.
👍Thanks for video Kevin. I think your idea to repurpose the parts is good.
Glad to see your alive and well!
Great your back doing videos. I've seen other reviews on these loops and none of them good. Fred in the shed had issues trying to tune 11m and I think he did a mod and it worked a little better ? All the best Andy M6APJ
Hi Kevin. This was a very good video and test of the GOOZEEZOO. Those tiny variable caps and thin wire interconnects can't possibly handle more than a few watts of RF because (as you know) all magnetic loops have very large currents and voltages on the loop. I would check the resistance of the loop with a bench supply and then read the mv drop with a DVM across the loop and compute via Ohms Law. it should be about 0.1 ohms or less. Let's also take apart that faulty balun and see why it adds loss and broadens the Q of the loop. Looking forward to the next video. Glad to see you're feeling stronger as time goes forward. 👍73 OM
I have experimented with 4 different loop vendors. What I learned was that diameter definitely has a relationship with band efficiency. The MFJ Loop tuners print a chart of most efficient diameters for each band or multi-band use. I also learned that all of them receive very quietly. One more thing I learned - tuning with an antenna analyzer connected is better than listening with your ear. If you could transmit on a beam or dipole, and receive with a loop, I believe you would have the best of both worlds, but the arrangement would not be cheap.
Don't give them ideas Kevin! Even with the controls on the bottom of the box, the "improved" performance will still be pretty awful! Nicely made main loop though... (and if you put that lossy thin coax feed line, the SWR will look even "better"!)
Great video, Kevin. You, no doubt, saved a lot of operators from buying junk.
Maybe it's OK for receive only, but so is a 50' length of wire! 😀
Nice looking dummy load. The loop coax is probably the only thing worth using.
It looks like it's good quality. Now I want to see Kevin rebuild it to work the way it should. Thanks again for the videos and I hope you're doing well. 73 de N9JOD
I was thinking about coupling it with a coupling loop and feeding it that way. But the small light duty capacitors they use would arc over like fireworks. I don't think there's any hope for the design. At least not with the hardware they included. I might turn the box into a zmatch antenna tuner for QRP. And use that nice coax loop on one of my home built loops.
Hello Kevin, Glad to see you up and about. I think I've seen better performance out of DUMMY Loads ! Mag loops are supposed to be "HI Q" antennas. As I recall, HI-Q means NARROW Bandwidth. So their claims of service from 40 Meters to 70 CM just validates it is also LOW Q... A HIGH DOLLAR DUMMY LOAD. That piece of Hardline loop looks impressive :-}
I think you forget that a magloop needs to be tuned to the operating frequency. So the coverage says little about the Q.
To Add, I bought a UBeesize CT-50 Tripod for about $15.00 additional for this junky loop. Thanks for your review and warning.
Good to see you 73
Thank you for the review!
Thanks for the review.
Thanks for this.
At that price, you could crank up the transmit power and do a "smoke test" 😂 73, K7KS
*Thanks for taking one for the team.* Need to stay away from this one for sure !
It does show that a bought aerial doesn't mean it outperforms a home made one.
I've made five attic dipoles 20m to 10m, an outdoor 60m inverted vee, two loops for h.f. and a copy of a thing which was around in the 1960's and 70's called a Joystick and 26 foot of wire which tunes 160m to 10m using a supposedly non-working MFJ 16010 tuner I was given. It worked for me. It did stop working after a trip to Wales and I found a wire not soldered and soldered it so I guess vibration moved the unsoldered wire.
G4GHB.
Excellent video and tests against the other antennas! Thanks. On the issue of why the efficiency is low, I think its got low-Q capacitors. They're AM radio receiver caps. At this antenna size (2m circumference on 20 meters), the theoretical Q of the resonant loop (X/R) is likely about 2500 and the resonating cap Q should be very high (maybe 5000+). But then tuning would be very sensitive and arcing would likely result on transmit. As is, its still maybe a good receive antenna though (background noise is usually at least 20 dB above theoretical limits - so an efficiency of 0.01 would be fine 🙂) I'm curious. What kind of caps do you have in your homebrew loop (and how sensitive is the tuning)? And is the diameter about the same?
The homebrew loop is fully covered in two videos. Look back about three videos in my channel and you'll see building the small magnetic loop. The description references the design video from last year with all the details.
Yes, I bought a similar Goozeezoo look like this and it doesn't work well too. It makes a good table top display
Hi Kevin,
Would be interested in how the coax loop works on your homebrew loop. Might not be a total waste of money. 🙂 Stay safe. 73 WJ3U
Indoors, I could hear a strong shortwave signal on 15.770, WRMI in Florida
This really takes the user for a loop
The downside to so-called "magnetic loop" antennas made in this way, using flimsy, polyvaricon, receiver-grade capacitors, is just that. One needs to remember that at resonance, even with QRP power levels, a considerable amount of RF current (upwards of 4 amps RF at just 1 Watt- if losses are low- on a 4ft dia loop with a 5/8-in. diameter loop conductor operating on 14mHz.) flows in the loop and through the loop tuning cap. On a polyvaricon-type capacitor in a tuning unit like your example, that current flows through a small, mechanical, wiper contact that connects to the cap. rotating plates on one side and the stator (stationary) plates of the cap. section on the other side. That wiper contact has considerable RF resistance and, thus, significant power loss. (Keep in mind that RF currents flow only on the surface of conductors.) Even more substantial capacitors, such as air-variable transmitting capacitors with a single section (or two sections in parallel- same thing) are to be avoided. Instead, a "split-stator" (dual-section) type of tuning capacitor is needed with loop connections made ONLY to the stator plates and NO connection to the mechanical contact of the rotor plates. That eliminates resistance losses in a wiper contact. The only other capacitor type superior to that is a vacuum variable transmitting capacitor. BTW- Our ham radio slang calls these antennas "magnetic" which may lead some to think they somehow use permanent magnets. Instead, they couple RF radio energy waves to the air via Electromagnetic induction means.
You couldn't pick a worse and less efficient capacitor for this application than the polyvaricons that the loop tuner is utilizing ! - VE3WMB
I would return it too.
It sounds like RG-174. Look it up 0.1 inch OD. 2.8 mm sounds about right.
Nothing ventured, nothing gained.
LoL I can see why you didn't include a link to purchase
Yep, this review turned out to be more of a warning. Ha
I never could make a contact with the stupid loop. I got better results on my own homebrew loop.
I imagine that coax being as lossy as it will be broadens the Q making it look wider than it is?
If you mean the main loop coax, I find that the best part of this antenna.
Much better than an RG-213 or other braided coax. The main loss is probably in the C1 capacitors.
5 W @ 14.1 MHz would produce 7.35 A in a good loop this size.
@@tomtwist1081no the feedline (2 mins 52 secs into video). But agreed using polyvaricon caps for the tuning is not really fit for purpose as well, considering the voltages generated at even modest power outputs is very high!
Only using the screen on the loop itself, one could use chicken wire. The coax "functionality" is not used in the loop. Thick cable is desired for mechanical stability.
I would rather like to see a measurement of the cable he didn't use....
@@migsvensurfing6310 Yes my mate has built one himself from aluminium strip. Worked 15000km Euro stations on 20w CW on his antenna ....in this video (DX will be in part 2 video :))
ua-cam.com/video/FmkMDeXaCOU/v-deo.html
@@TheArtofEngineering He is not using the RG-174 in his tests. It looks like RG-58. But the RG-174 only har 0.12 dB more loss than RG-174, and 0.21 dB at 28 MHz. Negiable compared to the other losses in this antenna.
You sure that's coax? That looks like a shower hose they used.
I didn't think it would work just based on the claimed specs.
If I spoke to the manufacturer I would give them some :cross talk.:
In absolute best case scenario,this loop will be about 4% efficient at 7Mhz So 5w in = 200mw out at best . Probably more like 0.5% eff due to resistance in coax connections ,switches,cap wipers. So maybe 25mw out. QRRRRRRRRppppp
Should be good for FT8 and FT65.
Hmm. How does the loop do as a rec only antenna? I need a RX only loop!
Poorly. I think I mentioned it briefly in the video that I only heard the strongest of stations.
Of all the stupid names for a company, this has to be in the top ten.
*Здравствуйте! Я купил такую антенну и она не работает на передачу! Скажите, что находится в дополнительной коробочке, куда подсоединяется кабель питания? Как заставить эту антенну работать? Спасибо!*
This antenna does not work well. It's poorly designed.
could you do better by changing the coax loop size ???
No the problem in this loop is the design and the inadequate capacitors.
On HF it doesn’t outperform a dummy load that much and on UHF/VHF every loop does better. So…no no no!
CW is ft8 for men
That looks like Heliax, a full copper shield, (basically thin copper pipe with ribs to allow some flex in order to bend it,) that they are using the shield of for their loop. This loop antenna appears to be made out of whatever assortment of junk parts they could find, and poorly 'designed' by someone who knows nothing about RF. Any homebrew $10 loop that is designed and built properly would far outperform this piece of junk. The short coax they provided looks close to RG-174, which might work for HF but is just an attenuator at VHF/UHF. This isn't designed to work. It's designed to take money from the unwary. BTW, with antenna lengths at VHF/UHF being what they are, and vertical antennas being so very cheap and simple, there is really no point in trying to build a much more complex and expensive tunable loop that offers almost no advantage beyond slight directivity to combat noise that likely doesn't exist at VHF/UHF wherever the user is located. Certain types of antennas are advantageous on certain bands, but are seldom optimal on other bands that are far removed.
The box and capacitors might be a basis for a QRP Z-match. And check the skinny feed line COAX with you VNA before you toss it. Yes, it will be very lossy on VHF/UHF, but might be acceptable on the lower HF bands, or for cutting up to make short jumpers.
Yeah I was thinking along the same lines with that box, a QRP antenna tuner.
Short jumpers is an interesting idea with that coax. In lieu of antenna switches at my desk, I've been thinking about making a small BNC patch panel. Bring the antenna tuner in and out, the SWR meter in and out, the antenna feeds, and the radio feeds all up to BNC connectors and then just using short patch connect cables to patch things the way I need at that point. Much more flexible than trying to do things with multiple antenna switches.
Looks like rg174?
With the included coax it would have worked even worse. Buyer beware.
Thanks for the review. Think I’ll pass 😊
No inductor loop means it's junk.
Not necessarily. There are other means of coupling, gamma match, ferrite transformer. However, the army made loops this way, and MFJ has a loop tuner that works this way that works quite well. The design idea is sound if properly implemented. This loop uses poor wiring and inadequate capacitors. The only thing good about it is the coaxial main loop.
Hey, Kevin. 🙂
UA-cam works terrible. They may stop it working here soon. Too much complaints for political misuse.
One time I tried to search for "trinity", but two of three first search results were political news.
FB OM
Это плохая антенна!
That was my conclusion in the video
Achtung!
looks awful
Great video, Kevin. Glad to see you gaining more strength each video. Keep kicking that Covid to the curb. Take care. de VE6HDH