About the MFJ 1026

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Quebec337

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Hi,

I just received my MFJ 1026.

Not knowing if it's "normal", I'm a little surprised by something : When the main antenna (long wire) is connected through the MFJ, before getting out to the receiver, I seem to loose 75% of the signal I receive. But au contraire, when the main antenna is connected directly to the receiver, the signal is way way stronger.

Is it the way it should be ? I did check everything was in order, connected everything properly, checked my wires, opened the MFJ to checker for the components.....everything seem to be ok.

Thanks,
Matt
 

Scan125

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When you use an aerial tuner then often the displayed signal strength will decrease. What the tuner is doing is to optimise wanted signal and throw away unwanted. It is in effect applying a "notch" filter to either side of the reception frequency thus pulling out the weaker required signal. By removing unwanted signal interference then the overall signal strength (wider band) will be reduced but the signal part you are looking for will actually be far better pulled in.

Suggest you have a play as follows.

1) Turn bypass on and find a station which is weak / noisy
2) Turn bypass off and play with the MFJ 1026 setting to maximise your wanted signal

I think you will find that the tuner is quite capable of pulling out those weaker noisier signals into clarity but for strong signals will deliver a disappointing result "in your eyes/ears".
 

Quebec337

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Very well explained...thanks a lot :)
Ok silly question now....what is "bypass" (can't see that on the 1026...) ?

Matt
 

Scan125

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Good question as the MFJ 1026 is not as such an aerial tuning unit but a noise canceller.

For your unit OFF may be the bypass but I would suggest looking at the MFJ documentation and circuit diagrams for a definitive answer.

Whilst my previous post was more specific to an ATU (aerial tuning unit) we are on similar but different ground with a noise cancelling unit.

With a noise cancelling unit like yours the unit picks up all the signals/noise around your listening frequency and SUBTRACTS those signals from the frequency area you are tuning to. Think of it as an ACTIVE band/notch filter where instead of tuning out/blocking unwanted signals it instead subtracts those signals hopefully just leaving what you are interested in. Like in an ATU there will be net total signal loss, thus lower signal meter reading, but hopefully what is left is what you want to listen too / focus on.

Summary.

An ATU tries to maximise aerial and receiver receptiveness to a given signal and reject anything else.

A noise canceller takes the main aerial feed signal and then tries to subtract noisy local signals from the incoming main aerial feed. This allows the receiver to better focus on the desired signal.

Bother result in an overall signal strength loss but the lost signal strength of "out of interest" signals allows the receiver circuits / AGC / etc to focus on wanted signal.

Needless to say ATUs and Noise Cancellers can be used together but how many knobs and dials does one want to platy with at one time.

Let your receiver do all the hard work and only then deploy the other boxes when you have reached the limit of performance without them.
 

a29zuk

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What do you have your main antenna gain set at? Usually on my setup if I have the main antenna setting at 7 or 8 it is equal to the main antenna in bypass. If it turned down to 0 you will have a very low signal or none at all.

Do you have a noise antenna connected, too? If you do rotate the phase control to see if the signal level changes. Remember as stated in the other post the signal for each antenna should be matched to the same level for the phase control to function best.

I don't have the users manual in front of me but I believe the noise antenna amp is set up for more gain than the main antenna amp.

Jim
 

Quebec337

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Hi Jim,

Thanks for your response, I do appreciate.
Yes, I do have a noise antenna. It's a longwire parallel to the main antenna, lower than the main one.

Well, there is a lot I can't figure out...

1 - Strictly on a "main antenna" point of view, is it normal to loose 25 % of the signal when the main antenna is connected in the MFJ (wether the MFJ is on or off, doesn't make any difference), versus when it is directly into the receiver ? If it is, fine......but even as a beginner, it seems odd to me. And it creates another problem : when I try to find signals, it suddenly makes the 1.5 to 30 Mhz much quieter than usual...

2 - Now, the thing that intrigue me the most is that here doens't seem to be much fluctuation of the "S" meter. It will be stable at "8" or "5", but barely move at all (and it's not because it's not responsive in other situations, it seem to work fine). Even if I follow flawlessly what the instructions say, in all the maneuvers I'm doing with the aux antenna, the main antenna, the clockwise and counter-clockwise, the "S" meter chooses a number, and stays there (which makes phasing totally useless : I don't even know where the "friction point" is, at the base... But hey : maybe it's my way of handling things, at this point......I'm scratching my head....

So basically, the signal is practically nulled when I put the MFJ power on (even if the main antenna is at 10, and the aux antenna at 0.

I did try to replace the noise antenna with a shorter wire that runs outside. Unfortunately for me, it doesn't seem to make any difference...

Thanks for reading me :)
Matt
 

Ubbe

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To be able to phase out interferencies you must have the aux antenna and main antenna at different places and not next to each other. Shortwave wavelenghts are very long so to use phase shift they need to be seperated by quite a distance, maybe even a 1/4 wavelenght. On 80 meter band it's 20 meters, 70 foot.

Can't you use the telescope antenna?

/Ubbe
 

Quebec337

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Hi,

Yes, I could put on the telescopic antenna included with the 1026, but I heard it was quite poorly made so, I want to use better options before I resign myself to use that option.

My main antenna (longwire) is approx.107 feet long. So basically, are you saying I should use....let's say....... a 20 feet longwire in the opposite direction for the noise antenna ?

Thanks for your time,
Matt
 

a29zuk

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It sounds like you may have a defective unit. When you turn off the 1026 it is putting it in bypass mode. You should have the same signal in bypass mode as you do when you are connected straight to your receiver without the 1026.

Check all of the solder joints where your antenna inputs connect to the circuit board or a crack in the board.

Currently I have one antenna going east & west(60') and my noise antenna runs north & south(25'). The noise antenna runs along my house. The feed points are only a few feet apart.

In the past I've had good luck with one vertical and one horizontal antenna.

Good Luck,
Jim
 

Mike_G_D

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Remember that the bulk of the noise you are trying to null out using this device is locally generated, very likely much of it might originate in the same room as the radio equipment especially if you have a lot of computer equipment nearby. In that case, using the simple telescopic whip might be the best choice. Also, most noise is more prominent in the vertical plane relative to the antenna so using the vertical antenna as the noise antenna would, again, be a better option.

I suspect that one reason the telescopic whip on this unit got a bad rap has more to do with using the unit as an active receiver antenna rather than as a noise cancelling device (it's capable of being used either way but is primarily designed for the latter function).

Experiment and try it out, can't lose anything by doing so.

-Mike
 

Quebec337

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Your right, thanks Mike.

I also just realized that for some reason, I forgot to put the pre-amp "on" since I received it....hish....
Maybe it could be part of the explanation. I'll know when I get home...

Thanks again,
Matt
 

a29zuk

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If you read the reviews on eham.net you will find out that the telescoping whip that is supplied with the 1026 is about useless. The 1025 is the same unit without the telescoping whip. That's why I went with the 1025 with no whip antenna. Your outside antenna is going to pick up noise from a lot of external sources. A 25' noise antenna is plenty as it will pick up all the neighborhood noise.

Like we've posted above you may have bad solder joint somewhere as the unit in bypass mode(off) should have the same signal as if the antenna is hooked straight to your receiver.

Jim
 
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Ubbe

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Remember that this uses a phase cancelling technique which means that the aux antenna must be able to receive the source of noise you would want to get rid of. If there are several sources comming from different directions you can only cancel out one of them, like a strong broadcast transmitter on an adajcent frequency.

It will not reduce the overall background noise. That requies another type of noise blanker. You have to fiddle with the adjustments if you change the monitoring frequency or if one interference is fading away and another one appears and gets stronger. If you have noise comming from your own house it will probably travel by the mains wiring and not from a single location and cannot be phased out.

/Ubbe
 
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