MFJ noise canceling question

KF0AWL

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Iowa
Finally had enuf of the noise floor blanking things out at night so I'm setting up a MFJ - 1026.
I'm going through the operation setup and on page 12 step 8 (advance the MAIN ANTENNA GAIN until you just see the s meter change).. Will it change up? Change Down? Or can it go either direction?

On a side note I'm running a IC 7300 and normally I'm running NB, NR, P.AMP1 I turned the nb and nr off to the noice cancel. Is that the correct thing to do?

Anyone that can give me info is appreciated!
 

Ubbe

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How it works are that it takes the signal from two antennas and then tweak the phase on one of them so that an interfering signal are in the opposite phase and the two signals are then mixed together cancelling out the interference.

It needs you to set the two signals to the same level. You have to adjust one signal so it will be 180 out of phase. You probably have to jump between the phase control and the level control several times.

It's easier to do if the antennas gives almost the same signal strength from the interfered signal and that the antennas are as far apart from each other as possible. It only works for reducing a clean signal from a broadcast station or similar and not like static noise from mains wiring or electrical fences and similar things that emit signals from a broad angle. It will also take out most signals you want to receive from the same angle as the interference. If you receive a direct signal and its reflection that bounce off an object and comes in at another angle you cannot do anything about that. It only handles one single source at a time.

/Ubbe
 

KF0AWL

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Ok, what I'm working with is at night I get a steady static noise floor and also a 🤔 best way i can describe it is a rhythmic (speed bump) if that makes sense? I'm trying to phase both but! The night static is my main concern, the speed bump is annoying but not as annoying.
I'm good with the setup till I get to that part about the S meter change. How do I know if I'm setting it right if I don't know what way it should move the meter?
Also should I leave the preamp NB and NR on, off or what?
Usually they do good with instructions but not this one.
 

AK9R

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What band? Since you are talking about nighttime operations, I'm going to assume 80m. If so, Preamp should definitely be off. It's only useful on the higher bands. Remember, preamps amplify the noise as well as the signal, so if you are on a noisy band, like 80m, the preamp just gives you more noise. NR should definitely be on if you are using SSB. It should be off for data modes. Adjust the NR level so that it knocks down the noise a bit without making the audio sound funny. NB only if needed for pulse type noise, like ignition noise. Turn your RF gain down (counter-clockwise). Then use the AF gain to bring the audio back up to listenable level.

Horizontal or vertical antenna? Horizontal will generally be quieter.
 

KF0AWL

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Iowa
20m if its there 40m and 80m mostly tho.
As far as antenna I'm running eagle one
a 10-80 vertical end fed wire for my main and a OCF MFJ 20 40 80 Dipole. As far as a match between the two they seem to be a very close match if you turn down the main gain and bring up the aux antenna gain.
If that helps.
 

AK9R

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Any difference in noise between the two antennas?

What do you mean by "aux antenna gain"?
 

KF0AWL

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Both antenna are a really close match in noise and reception.
The aux antenna gain is the gain of the secondary antenna that your using to phase out the noise.
Easy way to put it is main antenna is your RX TX antenna the aux antenna is used for listening to filter out the noise
 

Ubbe

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Ok, what I'm working with is at night I get a steady static noise floor
Also should I leave the preamp NB and NR on, off or what?
It's pretty much impossible to adjust the noise canceller if you have some noise reducing feature turned on in the receiver. Turn all that off while adjusting the 1026.

If you are lucky that steady noise floor comes from a LED light or similar device, probably from your own house or closest neighbor, and the direction are pretty narrow in angle.

If you keep in mind how that 1026 works, adjusting two signals to the same level and twist the phase on one of them, it should be a straight forward operation that doesn't need any written instructions. What it says about the S meter are probably that you will need a proper signal level that the S meter can work with and then adjust the phase to lowest possible S meter value, where the interference are attenuated the most when receiving at a frequency that have no transmitters active. It's probably more easy to listen to the noise while tweaking the controls.

Also remember that the 1026's design makes it frequency dependent so you will have to tweak the controls when you switch band. If you listen to a station you can also tweak the controls to make the two antennas be in the same phase, increasing reception from one angle and not attenuating the actual interference. You can do that if the noise floor are of a general noise pollution type and impossible to attenuate.

/Ubbe
 

WA8ZTZ

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Ideally, the main antenna and the aux (noise) antenna should be the same polarity.

Make sure your 1026 internal jumper is set up for external aux antenna max sensitivity for best results.

Try to alternately adjust the phase and aux gain controls when trying to null out the noise. Use the invert function if necessary.

It takes some practice manipulating the controls to get best results.
 

W8HDU

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Lima, Ohio
Ok, what I'm working with is at night I get a steady static noise floor and also a 🤔 best way i can describe it is a rhythmic (speed bump)...

Not to be flippant, but I think what I would do is locate the noise source.

Start by putting your radio on battery and confirm you hear the noise. Then start dumping breakers in your panel to see if the sound goes away.
If it doesn't go away, take a small transistor AM radio and dial to an empty channel where you hear your noise. Then start walking around outside in the neighborhood DF'ing the location and source of the noise.
 

majoco

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After duplicating the circuit of all the noise-cancelling devices I could find and removing all the unnecessary bits (I wanted a receive only version) I came up with this which works well but with too many problems in use. The noise signal has to be local - anything that has come via the ionosphere does not have a stable phase to cancel out. The noise has to be a single source - I found noise coming down the power lines was to broad a source. It wasn't a great disappointment, but it wasn't the holy grail either!
 

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