Review of MFJ -9232 QRP Mini Loop Tuner (AD#90)
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- Опубликовано: 28 авг 2024
- This week's video takes a close look at the MFJ-9232 QRP loop antenna. Given sizes of components and all, it is rated to handle no more than 25 watts. It can be used both indoors and out. This is a great little adjunct to those who want to play with (er...I mean "study") loop antennas.
I got the 9232 loop tuner as a gift and haven't used it yet but I will over the next couple of days.
I have the MFJ-935C loop tuner and have been very impressed with it, you will need to make different sized loops for different bands + it handles 150 watts SSB.
Just today using 2 meters of soft copper pipe on 20 Meters and 5 watts from Ireland I made contact to a Ham in Belarus, 2,223 Kms.
Using 4 meters of copper pipe I made contact to a Ham in Canada with 20 watts. 4 meters of pipe seems to be the most efficient for 20m but with 2 meters of copper there is no problem to make contacts on 20m.
These contacts were made with the loop tuner sitting on the patio table.
This was helpful. An awfully large box for a QRP tuner. While I’m a big fan of the largest non resonant wire a setup can handle, I need a small backup antenna for a hotel room for an upcoming trip to Slovenia.
Not sue I can justify such a large package for backup antenna.
Thanks for opening the case and showing all that wasted space inside.
I tried it with up to 50 watts during field day and it worked perfectly. NO BURNOUTS!
I had an unfortunate occurrence with 35 watts or so and saw smoke coming out and apparently the plastic wafers that make up the capacitors had melted enough to deform.
I made a 24 inch loop from a 1/2 inch x 6 ft. aluminum strip from Lowes ($9.95). Sitting beside my desk in my shack, I made several FT8 contacts on 20 meters. I adjusted the tuner with the aid of my MFJ antenna analyzer set on the desired frequency instead of trying to tune by ear / swr meter. Surface area is important with this type antenna, which is why I went for the aluminum strip instead of a wire, plus I wanted the loop to be more rigid.
Thanks for an honest review of MFJ -9232 QRP Mini Loop Tuner. Not quite the performance I was hoping for, but indeed something to tinker with.
Nice video Dave. Now, although you have a QRP rig displayed on your video table it is obvious from your other videos that you are not a QRP Operator. You question why QRP OPs prefer BNC over PL259. Several reasons: for the homebrewer the transmitter or transceiver that is constructed is typically small. Using BNC connectors for antenna keeps the kit small rather than using the large PL259. Image a transceiver built into an Altoids Tin using PL259; a) making them fit the tin is problematic but it they are fitted, then b) the oversized PL259 connectors distract from the neatness of the rig. A lot of us QRP OPs use our rigs portable and have the quick to connect BNC is preferable over the screw on PL259. Those of us that use balanced feedline typically use the binder post to BNC adaptor to connect to our QRP rig or ATU and rig.
True that it has been a long time since I've done serious QRP, but my QRP rigs came with SO-239s. I think the movement to BNC for QRP is relatively recent, say, in the last 15 years or so. My only objection to BNC connectors is that I don't know how to connect them to a piece of coax. I tried once and gave up in frustration.
@@davecasler I use crimp ends and they connect the same as a PL259, expose a length of center conductor and the correct lengths of insulator and braid, insert in the BNC end and slip over the cowling. Crimp and covert with tape or shrink tube.
i like watching vids about things i've wondered about but couldn't really afford to try.
Good analysis of the pros and cons of this product. Well done Dave as usual. As for connectors, I can see both sides of this discussion. If I am traveling in the outdoors with my QRP equipment, I would want to travel as light as poissible, therefore big bulky cables with SO connectors is not the way to go. If however I have a fixed base station, I would want the SO connectors. But, as we can all observe from the comments, it is ALWAYS a matter of PERSONAL choice, not right or wrong. "A rising tide floats ALL boats...LOL. Looking forward to your analysis of the function generator.
Richard, thanks for your comments and for the chance to review the product.
Thanks for the video Dave. I do disagree with you about the connectors though, I prefer BNC to a bulky SO239 any day. I build some pretty small radios and BNC's are a must have and sometimes have to be SMA. I have this tuner and use it with 3/8 copper tubing and it works very well.
:-) A couple comments down someone says just the opposite! People seem to be using BNC for QRP a lot these days.
Dave.
Another nice video. I've heard good reports about the tuner. 73 WB3BJU
I would experiment with copper tubing or pipe as the loop element, as the lower the resistance, the more efficient the antenna. On the higher bands, that wouldn't be too cumbersome, I think.
Bnc is used for quick connect and quick disconnect. Allowing for faster deployment of a qrp remote station
Saves a few seconds, I guess. BNCs are used a lot in instrumentation.
The problem is the short loops. Loops can be fairly easy to tune if they are the correct size. If one were to be in a truly "field" environment with a long hunk of just about any wire , 265 to 280 ft , you end up with a great 80 meter antenna (unfortunately this tuner won't tune there, ?? what were they thinking ? . Shorter for low heights and longer for up high. I'm then wondering what would happen if you fed the loop with open or at least 450 ohm flat line, and were able to tune right next to your rig. My system uses this configuration but without that tuner. One would think that perhaps the MFJ tuner is set up for low ohm loops. You would need have provided the measurements of your analyzer directly hooked to the loops for us to know what the tuner is dealing with. I've made loops with every material in the book and some that are not "in the book". Currently, my 285 ft loop is using steel guy wire. I've measured the resistance dc and its a few ohms. This surprised me. Its able to hear amazingly, works the entire country with JS8CALL qso's with florida on 40 and the Philippines and japan. Of course, some of that is because of the amazing low signal qualities of JS8CALL. Complete QSO conversations with Max 4F1BYN in the philipines are typical.
Thanks for the nice review and yes this little loop tuner is very fussy when it come to tuning but it does work. I usually use this for listening in the field sometimes
What is the model or value of the dielelectric film variable capacitors of MFJ-9232?
They do make a version now that has a SO-239 connector - MFJ-9234 abt $94.95
Love this review and have watched it at least 3 times :-) I'm not sure I'll buy this as I already have one of it's big brothers that will easily handle 100 watts. On the other hand it's really cool and maybe I need it for my bug out kit ;-)
Wow, a lot of discussion about which connector is better. All good points, but as all old school hams know, the 259 connector has much less signal loss then BNC. Of course this comes down to power and FREQ too. BNC has nice disconnect qualities. I think there is not a side I prefer, just depends on what I am doing at the time.
They could have brought out the loop connections on the rear of the box so there is no chance of accidentally touching them. I once operated a 6 Watt homebrew rig into a long wire when another amateur connected his counterpoise earth while I was transmitting and he got an R.F. shock. So yes, their warning should be heeded even at these low powers. I'd rather have a larger diameter wire for better efficiency, mine has 3/8 inch coax for the main loop and a smaller gauge wire for the coupling loop. I tune my h/b loop on receive and then adjust for minimum SWR on transmit. I agree with using a reduction drive. I use all BNC connectors on my gear because I use small diameter coax.. The beauty of a loop, as in my case for receiving, is it can be placed away from sources of QRM and I use my dipoles to transmit, but a loop could be useful in locations where large aerials can not be put up, or portable of course.
Bill, G4GHB.
Sorry, I wandered off into mag. loops, but do heed the warning about R.F. voltages on aerials.
Bill, G4GHB.
For the record I hate PL-259/SO-239 connectors. Despite being called "UHF" connectors they are only good up to 2m (and really should be limited to HF). BNC connectors are good to 4GHz. They are also slow to attach compared to BNC. I would be happier if all HF radios switched to BNC over "UHF". They are arcane.
The MFJ 9232 tuner I purchased had a faulth capacitor which I replaced with a small air variable. Overall I find working with loop antennas to be very frustrating with frequent tuning and not much operating.
Loops need lots of TLC while operating. Hard for me!
Did anybody have a problem with the screws connecting from the front panel to the housing?
Nice shirt! 👍
My wife found it for me.
With respects, Mr Calser, I believe very small antennas and other compromised QRP gadgets are crutches for desperate radio operators. GI-Joe would never go on a mission with these toys. But it's fun experimenting.
* Very sorry for the spelling of your name. + * compromise antenna
A full dipole can be difficult to erect above the tree line and carrying poles adds weight and size to a pack. I've had a little luck on certain mountains just stringing a dipole along the ground...if it's rock enough, the ground is so poor it's like free space. But otherwise, a very small loop is great.
@@TrevorClarke I agree: "it's a cool way to play with loops". Moreover, If I was a prisoner in North Korea and had only a tiny antenna of the kind to call for HELP, I would certainly use it without any shame.
Can we use the rig's internal tuner to tune the loop to get lowest SWR?
Don't use two tuners in tandem--they'll fight each other. In this case the 9232 is a tuner, so turn off the tuner inside the rig.
It is possible to "fine tune" using the radio's built-in tuner, but is not a good idea. By "find tuning" I mean a few kilohertz. The tiny capacitor is going to be almost impossible to get exactly on frequency and the bandwidth is extremely narrow. Actually, using 20 gauge wire the "Q" is going to be so low that tuning is not sharp and efficiency very low. The higher the efficiency the sharper this thing tunes. I never use the radio's tuner in conjunction with a mag loop antenna.
Would a larger loop antenna with a cap with more pf range, offer a wider ability to transmit or tune. And for more voltage for the capacitor, more power capability.
Perhaps. These loops operate differently from "magnetic loops."
David Casler , ok, you cut the loop for a band. Less in size than a dipole. But the tuner box makes it work. Still voltage equals watts or power handling abilities. The tuner box needs more isolation. maybe the terminals could be moved around to the top, not the front. for and from the user. Not for rf burns, but tuning accuracy. Burns or just exposure second.
These loops are small enough that there are large circulating currents, so you have I^^2*R losses. But full-size loops without all the reactive currents flowing can be very effective.
@@dalemyers5096 Check out the MFJ- 936B and 935B. Same principle put 100+ power capable.
@@davecasler "These loops operate differently from magnetic loops."
It is a mag loop. You seem to be thinking (and it is unfortunately common) that what makes it a magnetic loop is the little inductor loop that excites the bigger loop. That's just the feed mechanism. You can also have a gamma match or a capacitor match. All are still "magnetic loops" since what defines the magnetic loop is intercepting the magnetic lines of force in a radio signal rather than the electric field which is the case for a dipole or viertical quarter wave. The advantage of the MFJ style of capacitor matched loops is that you don't need a small loop at the far end, typically high in the air, and so you can make almost any home-made loop typically out of copper tubing and it works great. It can also match more perfectly since you can tune the match whereas with a little loop, there is no tuning of the match whatsoever; you can only bend the feed loop a and tweak it a bit. Good luck doing that with a physicaly large loop.
I wonder how this loop compares to a Wonder Wand?
Not as simple but just as inefficient. But you will be able to hear stations strong enough to make the propagation able trip.
What is the radiation pattern for this antenna?
In theory, it radiates in the plane of the loop, and has a null perpendicular to the plane of the loop.
Quite expensive for two air capacitors and a plastic box...