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MFJ-1786 Magnetic Loop

Road Squawker

Sr. Member
Jan 19, 2011
1,954
1,497
173
I would tend to believe the meter on the controller, it is in the correct place (the feedpoint) and it sees only the antenna
 

Riverman

Old Member
Nov 12, 2013
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I would tend to believe the meter on the controller, it is in the correct place (the feedpoint) and it sees only the antenna

Those were my thoughts so I connected my analyzer to the antenna using an 18' RG8X jumper and got 2.4:1 when the controller was reading 1:1. Dadgumit.

It's even worse on 10 meters. Controller reads 1.2:1 and the radio and analyzer reads about 3.5:1. Yikes!
 

Riverman

Old Member
Nov 12, 2013
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Just received a reply from MFJ customer support:

The only communication needed is between the loop and the controller. you will not get a good reading directly at the antenna because the capacitor plates cannot be moved at that time.

That appears to back up what you are saying, RS.
Still, it seems to me that a reading taken directly at the antenna with an analyzer using a short jumper should give a comparable result. (n)o_O And that the reading on the radio's meter should be closer.
 
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Riverman

Old Member
Nov 12, 2013
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Here is another reply from customer support. (Must say they are pretty prompt. Wasn't expecting that.)

as stated you won't be able to get a good look at your antenna using those analyers, because directly to the antenna the controller is off and unable to tune it.

Okay, that makes sense to me now. But I still don't understand the high readings on the radio's meter since the controller is on and between it and the antenna. Have asked them that question. Awaiting reply.
 

Riverman

Old Member
Nov 12, 2013
2,682
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Reply to my last question.

because the radio is reading loss through the controller. the controller is direct with the loop. the loop controller is between the antenna and the radio.

I guess. Still is a little nerve wracking to be transmitting and look down and see an SWR of 3.5 on the radio knowing the analyzer would read the same. In all the reviews I've read, not a single person mentioned this discrepancy. (n) You would think there would be mention of it in their manual.

This thing is shaping up to be a little too quirky for me. And makes me wonder how long before something goes really wrong.

Let's see . . . wonder what DX Engineering's Return Policy is? Looking now . . .

Guess that makes me the King of the Offbeat Antennas. I've had 'em all. You probably won't see me around these parts for a while. :cool: No way could I begin to cope with all the "I told you so's." And they would be fair and deserved in coming.

 

Riverman

Old Member
Nov 12, 2013
2,682
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What would happen if it was tuned using a meter at the radio, would that screw up the tuning of the antenna?

Tried that with both a separate SWR meter and analyzer. Couldn't get below 2.2 at 14.250 MHz. Or 3.5 at 28.400. Both times the controller was showing a flat SWR. I believe MFJ's last reply was telling me to ignore those readings as they are inaccurate. They sure might be, but they are disconcerting to say the least.

I can't handle that, so I E-mailed DX Engineering and thirty minutes later I had a return lable and choice of refund, exchange or some other item. Chose refund. Packaged it back up and will ship it tomorrow. Great customer service from DX!

I know a great many of you are laughing and think I'm an idiot.
Can't blame you. And that hurts. But life is too short to fret about such things. And so . . .

Guess my wife is going to get a wire clothesline whether she needs one or not. :D

Merry Christmas, everbody!
 
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camaro1

Well-Known Member
Nov 2, 2012
1,077
456
93
wisconsin
I have the same mfj loop, whenever I use it i just tune it off my radio swr meter, I never trusted the mfj meter, just tune to lowest swr on the radio and transmit away!
 

Riverman

Old Member
Nov 12, 2013
2,682
2,677
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What would happen if it was tuned using a meter at the radio, would that screw up the tuning of the antenna?
I have the same mfj loop, whenever I use it i just tune it off my radio swr meter, I never trusted the mfj meter, just tune to lowest swr on the radio and transmit away!

I'd be good with that, Jay, but I can't get very low doing that. About 3.0-3.5 on 10 meters. Progressively gets a little better as frequency decreases to about 2.2 on 20 meters. And I know that's fine to use but doggone, it bugs me.
 

Riverman

Old Member
Nov 12, 2013
2,682
2,677
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Does the control max out, or do you actually find a peak?
I know there are a lot of qa/qc problems with those and work is commonly needed when new.

Easy to find a clearly defined peak of lowest SWR. Is that what you are asking? The two loose nuts in mine confirm the much talked about quality control problems.
 

Riverman

Old Member
Nov 12, 2013
2,682
2,677
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Now Riv: Can I ask a question?...That privacy fence along your place is that Your fence or joint effort by you and the neighbors ?
All the Best
Gary

I paid to have it replaced three years ago and only one neighbor split the cost of the section between us. However, no one is probably gonna care one way or the other what I do with it.

But it's not tall enough for diddly squat, is it? Not really interestd in NVIS. Was going to put up a couple of 16' painters poles and string up the 10-20-40 endfed I had in my attic a while back. It worked good there and should do better outdoors.

That said, what do you have in mind?
 
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BJ radionut

Supporting Member and 6m addict
May 9, 2008
4,165
4,718
373
35 miles East of Indianapolis
Well for some reason I thought you had a manual antenna tuner but now looking at your pictures I don't see one.
And personally that fence is plenty high enough....However my idea is no good without a manual tuner.
So forget the idea...but just for giggles think about this...You have plenty of length from what I see to configure something like an OCFD.
Feed with 2 parallel runs of say RG6 coax from that pole on your picture over to the fence(high enough where does not obstruct passage) then droop down to top of fence...Then small gauge wire stapled to top of fence...nice and neatly and you have an outside antenna tunable for ALL BANDS at full power.
Not interested in NVIS...let me put it this way...on 20m/40m/80m...unless you have structure to raise antennas on those bands at least 50+ ft. in the air...Guess what 90% of us are using on those bands. That does not mean you won't work DX, or make more contacts on a consistent basis. A remote tuner at the fence would be another consideration that might work also.
All the Best
Gary
 

Riverman

Old Member
Nov 12, 2013
2,682
2,677
273
Well for some reason I thought you had a manual antenna tuner but now looking at your pictures I don't see one.
And personally that fence is plenty high enough....However my idea is no good without a manual tuner.
So forget the idea...but just for giggles think about this...You have plenty of length from what I see to configure something like an OCFD.
Feed with 2 parallel runs of say RG6 coax from that pole on your picture over to the fence(high enough where does not obstruct passage) then droop down to top of fence...Then small gauge wire stapled to top of fence...nice and neatly and you have an outside antenna tunable for ALL BANDS at full power.
Not interested in NVIS...let me put it this way...on 20m/40m/80m...unless you have structure to raise antennas on those bands at least 50+ ft. in the air...Guess what 90% of us are using on those bands. That does not mean you won't work DX, or make more contacts on a consistent basis. A remote tuner at the fence would be another consideration that might work also.
All the Best
Gary

No tuner at present time, but mulling that over. Thanks!
 

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