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Reviews Categories | Antenna Tuners/Matching Networks | MFJ-935 Loop Tuner Help

Reviews Summary for MFJ-935 Loop Tuner
MFJ-935 Loop Tuner Reviews: 4 Average rating: 4.5/5 MSRP: $179
Description: The MFJ-935 is a specialised Loop Antenna ATU for portable/home station use. It has a built-in RF antenna current ammeter for tuning. It turns virtually any wire loop into a high efficiency transmitting loop antenna. Depending on its length, and this can be 5ft, 10ft or longer, it is possible to cover two or more amateur bands. You can operate up to 150W, no ground, radials or counterpoises required. The wire can even be simply draped around a bookcase. The MFJ-935 is smaller than the MFJ-936 and has a carry handle built into the side.There is a detachable PVC mount that bolts onto the top of the case. Into this can be placed a PVC frame cross (MFJ-57) for mounting a 20-15m or MFJ-58 for mounting a 17-10m antenna, alternatively you can use insulated wire such as PVC coated multristranded copper wire to form an antenna. You can tune any shape loop - circle, square rectangle, any odd shape. A quarter wavelength wire shaped as a circle is the most efficient though. A 10ft wire formed into a loop operates 20-15m, 5ft for 17-10m, 24ft for 30-40m.
Product is in production.
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K8AEC Rating: 5/5 Jun 25, 2014 20:31 Send this review to a friend
Amazing!!  Time owned: 0 to 3 months
Southern Ohio remote camping trip June 12-15, 2014. 10 foot piece of 10 ga. wire, FT-450D, hand mic, Optima D31M marine battery, power output between 50-100W, depending on my mood.

Worked coast to coast, Washington to Virginia.
DX- Azores, St.Petersburg Russia, Finland, Sweden, Belize (20m and 17m), Italy, Belgium and Honduras.

Observations; as others have stated, tuning is VERY tight. Will take some time to find a flat match, but worth the effort.

I would suggest specific lengths of wire for each band in use. Multiband operation is possible, but can be problematic finding a good match.

Overall, some of the best money I've ever spent. For under $300 US, you can't go wrong with the MFJ-936B tuner.
N3LCW Rating: 5/5 Dec 15, 2009 12:18 Send this review to a friend
Amazing, it really works!  Time owned: more than 12 months
I've owned the MFJ-936B version of this tuner for 2 years now. It really does work and it works very well, and if you can get it outside or near a window it will do great.

I tried it first on 20M with a 13ft length of wire formed into a loop. Tuned it up on 14.070 and was amazed to hear loud PSK signals. I copied DX signals from South America that I could not detect with my 20M attic dipole. I had excellent reports on transmit also. The loop is much quieter than an indoor dipole or wire antenna but it still will get noise if you operate in a noisy environment.

Use the largest loop as close to 1/4 wave as possible and the efficiency of the loop will be much better.

Also consider a two turn loop if you are restricted for space. Be sure to have a few inches space between the turns.

Another little secret: you can work 80M with a 32ft circumference wire loop as long as you add a high voltage capacitor (doorknob cap, or HV air variable) in parallel with the loop terminals on the tuner. Try a 150pf capacitor for starter. This extends the tuning capacity and you will be able to use the tuner lower in frequency than previously thought. A 1/8w loop at 80M is very effective especially if you can get the loop outside. Keep the loop vertical and you can operate with the tuner on a small table a few feet above the ground.

Using this tuner eventually gave me magnetic loop fever and I've built many and use them exclusively at this CCR restricted QTH.

I think this tuner is an MFJ winner and am surprised it hasn't caught on yet.

Andrew N3LCW
WB8VGE Rating: 4/5 Dec 30, 2006 14:57 Send this review to a friend
Oh so close!  Time owned: more than 12 months
Well.. humm... Yea right!
Work the work on ten feet of copper tubing...

Well that's just what I ended up doing with this MFJ-935 loop tuner.

I set up on the coffee table one MFJ-935, a FT-897 and a hunk of copper pipe. I worked all up and down both coasts and had several dozen qsos. So, the damn thing does work! Simply amazing!

That ten feet of copper 1/4 inch pipe formed into a circle seems to just a tad short for 20 meters, but it's right on the nose for 17 meters.

The tuning is very sharp, as it should be and if you move more than 5-7 khz from where you tuned up, you need to retune. However, tha'ts not a fault with the tuner, it's just the nature of the beast.

Now for the MFJ-935 itself. Well it's so close, yet MFJ holds true to it's history. The main tuning knob is offset so badly it wobbles when you turn it. It looks like someone heated up the shaft and then pushed it into the nylon insulator shaft.

The paint thin and scratches easily.

I am not sure the pcb material used for insulators will hold up to a lot of stress. Only time will tell.

Because the tuner does work as described, I would love to give it a "5" but the quality being typical MFJ, I'll have to go with a "4."

Love'em or hate'em MFJ makes some interesting stuff. If only they could get a handle on their quality, they would own the market.
GM0WDD Rating: 4/5 Apr 8, 2005 15:38 Send this review to a friend
Promising  Time owned: 0 to 3 months
I've had the MFJ-935 tuner for a couple of weeks now and I have some good results.

Firstly I didn't get the optional wire kit to make a loop. I used copper brake pipe and formed it into a circle.

I found tuning to be very sharp. I used an MFJ-259B antenna analyser when tuning which makes it really easy to see when you've got a low SWR. At first I didn't think I could get a low SWR but then realised that the tuning was so sharp that I'd tuned passed resonance!

The loop was setup on the top floor of my apartment block in my living room. Using 5 watts SSB from an FT817 I managed to work a station in Serbia on 20m. He was the loudest station on the band and he was working strings of people so I was quite chuffed to have made contact.

Overall a useful piece of kit but the tuning is very sharp and 5 watts doesn't seem enough to move the current meter.

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