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MFJ amplified receiving loop antenna testing

Discussion in 'Amateur Radio News' started by KJ4YZI, May 17, 2017.

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  1. KK5JY

    KK5JY Ham Member QRZ Page

    Understood. That's somewhat unfortunate, because I'd almost guarantee there's another 3dB of S/N to be had if the preamp could be bypassed, especially for higher bands where the loop is large enough to set the noise floor without it. A loop that size can easily set the noise floor in a modern receiver on 40m, and probably 80m. But they inherited that design from the people who originally marketed it, so I'm not entirely surprised. Their inline preamplifier uses relays to hold the preamp in-line while there is DC, but when the DC is removed, the normally-closed contacts bypass the preamplifier. It's a nice feature to easily compare preamp-on vs. preamp-off performance. It's also handy for disconnecting the preamplifier while transmitting on another antenna, to avoid deafening the preamp. :cool:
     
  2. K8HU

    K8HU Ham Member QRZ Page

  3. K0SBV

    K0SBV Ham Member QRZ Page

    Interesting to see its noise reduction capabilities on HF. Equally interesting would be to see an example of its co-channel interference nulling capabilities of other stations on the Standard Broadcast Band.
     
  4. AA4EZ

    AA4EZ XML Subscriber QRZ Page

    I did not notice any drop in interference when he switched from cobweb to loop. Seems like a lot of money for nothing. Get a better radio with good DSP or add a DSP unti to the radio seems like a better idea to me. I might also try to find someway to make that defective transformer "require" that they come out to fix it.
     
    AF6LJ likes this.
  5. AF6LJ

    AF6LJ Ham Member QRZ Page

    I could agree with this when the day comes that a DSP can drop man made noise levels from S-9 to S-5 or lower. $500.00 spent on a DXE receiving loop has more than paid for itself, and I can use it on most of my radios.
     
    WA8FOZ likes this.
  6. WS3C

    WS3C XML Subscriber QRZ Page

    Have you tried it on 160 Meters yet? It looks a little small for 160.
     
  7. N4OW

    N4OW Ham Member QRZ Page

    Good review but I would like to have seen how deep a null you could get on that Power Transformer Noise. Peak the noise and then the deepest Null. I am trying to reduce RFI from a neighbors grow lights, it is over S9 on 40 meters and the hash covers the band. Could you do that specific test for me and send me the results via email ? 73 de N4ow Port St Lucie FL
     
  8. WD9GNG

    WD9GNG Ham Member QRZ Page

    I am glad that you are enjoying your MFJ loop. I recently picked up a W6LVP Magnetic Loop a few weeks ago and put it up about 20 ft on a Channel Master rotator and use it as my receive antenna on my ham station while using a 132 ft Carolina Windom antenna for transmit. I really have found a tremendous difference in noise after going to a loop. I also have a Timewave ANC-4 Noise reducing device that works great in combination with either antenna when fighting noise that is not nulled out by the loop because I am using the loop at times to pick between stations in different locations on the ham bands and also BCB stations. I have a 12 ft noise dipole at 3 ft above the ground for the ANC-4 that I placed right under my electrical power line pole. The combination of a loop and the ANC-4 has allowed me to enjoy listening to Shortwave like back in the 50s and 60s before all of the electrical environment issues we face today.
    73s
    WD9GNG
     
  9. G5TM

    G5TM XML Subscriber QRZ Page

    How close to a TX antenna with say 100 watts can you have one of these?
     

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