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Author Topic: Timewave ANC-4 or MFJ-1025/26 Noise Cancellation  (Read 6339 times)
KB9WQJ
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Posts: 205




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« on: March 03, 2006, 09:10:52 AM »

  Folks,  I'm about to tear my hair out here...I've got some local noise at the QTH here that mostly shows up on 30 meters and up...really bad on 20 and 15.  Also appears as high as 6 meters.  I have yet to find where it's coming from but it's audibility falls off pretty quickly as I leave the neighborhood.  It seems to come from a north to northwesterly direction from me since I sometimes get it on 2m SSB and have a directional antenna for that so I can tell what directions it's coming from...bottom line is it's more like a single point source which I understand these units work better at.

  Until I can find and eliminate this noise, I thought one of the above mentioned units might be the thing to try.  I understand about taking time to work on the noise antenna since it must clearly hear the noise.

  I have read all of the reviews of the MFJ-1026 (there appear to be none for the 1025 or are mixed in) and the ANC-4 as well the operating manuals for these units.  My questions seem to boil down to two.  Since I am also interested in 6 meters does that llimit me to the Timewave ANC-4 since the MFJ units only go to 30MHz and the Timewave indicates that it goes to 80MHz?  The MFJ reviews seem to indicate that if you do not use the T/R switch and instead rely on RF sensing to take the unit from receive to transmit it is just a matter of time before it doesn't switch quickly enough and you blow the unit.  The Timewave ANC-4 doesn't even have a provision for such and instead only relies on RF sensing.  Is the ANC-4 just that much better at switching itself from receive to transmit or is Timewave fooling themselves?

  I truly believe that I would have 3Y0X in thelog if not for this damned noise around here and am desperate to rid myself of it.  Does the ANC-4 sound like a viable solution for my problem provided I am willing to take the time to experiment with noise antennas?

  Thanks in advance to everyone who responds and gives me some more info to ponder.

  73 de Mike  KB9WQJ
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KA5S
Member

Posts: 229




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« Reply #1 on: March 04, 2006, 08:03:02 PM »

I have both an MFJ-1026 and the JPS (pre-Timewave) ANC-4. I have NOT used them on 6 meters. That said... the MFJ in my opinion works better.   Both of them require that the noise signal be as strong as the desired one, or that you have amplified it to be.  The MFJ-1026 has a preamp built in.  

Think of these as putting a steerable null in your antenna pattern.  If you don't have enough noise signal to drive the unit, that null will be extremely poor.  If you are bothered by (say) noise from a light pole a mile away, a short wire or whip in the shack will not pick up enough noise to do you any good.  

However, using too large a noise antenna can put harmful levels of RF into the noise canceller; the MFJ has a grain-of-wheat light bulb on the external antenna connector to keep from blowing things out.

There is no great reason you could not add an external TX/RX control line to either of these. It would of course have to be well decoupled.

Have fun!

Cortland
KA5S
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VE3TMT
Member

Posts: 990




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« Reply #2 on: March 10, 2006, 04:01:35 AM »

Hi Mike,

I feel your pain. When I was living in an apartment I had the shack located in the basement. Due to restrictions the only antennas I could run were long wires hidden in the hedges or strung up to the balcony above my unit. The hedge dipole was a great cloud warmer and the vertical worked but the noise was unbelievable. The power feed for the entire building came underground to a transformer that was located in the basement beside my unit. It doesn't get any worse than that! I finally picked up an MFJ-1026 to try and it did help quite a lot. Although it didn't eliminate all the noise it at least got me on the air. Lots of tweaking and tuning but in my opinion it was worth it. I used the keying line for mine, I did NOT rely on RF to bypass it.

Hope you find a solution.

Max
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