AL 705 Mag loop

Discussion in 'QRP Corner' started by K9ROB, Feb 16, 2021.

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  1. K9ROB

    K9ROB Platinum Subscriber Platinum Subscriber QRZ Page

    I have the alpha antenna upgrade kit for this antenna and run it on my 705 with a z1000 autotuner and pick stations up great but the transmit just does not seem to push the signal well. Just curious if anybody out there is having any success with this loop? I have tried it with the upgrade kit and just out of the box, not sure if I can see a difference.

     
    KO4ESA likes this.
  2. W2DWS

    W2DWS XML Subscriber QRZ Page

    Do Not use the Z100 tuner with the Alpha Loop. It is not needed. I have used the alpha loop and talked from New York to Florida and Texas (USA) with 10 watts.
     
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  3. W7HV

    W7HV Ham Member QRZ Page

    Yeah. The loop itself must be tuned, and it's very sharp and narrow. If it's not properly tuned, it won't work. Once tuned, you don't need the Z1000. If you use the Z1000 to compensated for the loop not being properly tuned, it won't work.
     
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  4. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    Tune the loop itself. Not appropriate to use an external tuner/matchbox.

    Yes, the output is small. Think about the tiny percentage of a wavelength the antenna is compared to the band. Tiny antennas therefore have transmitting efficiencies often in the single digits or at best teens.

    Despite what many promoters of Small Transmitting Loops claim, "You can't cheat physics". Want a bigger signal? Get a bigger antenna. shrug.
     
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  5. K9ROB

    K9ROB Platinum Subscriber Platinum Subscriber QRZ Page

    Thank you for the replies, I have tried it without the tuner as well. Going to give it another go!
     
    KO4ESA likes this.
  6. N3PM

    N3PM Ham Member QRZ Page

    Small antennae can be frustrating to get going on the xmit side. I don't use a tuner with the Miracle Whip, Wonder Loop or an MFJ 935. Start with tuning the ant for max receive signal, and then fine tune with low power for min SWR. Sometimes you have to compensate for yourself being near the antenna. An analyzer like the MFJ259 or Rig Expert can help a lot.
    Mike N3PM
     
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  7. K8HIT

    K8HIT Premium Subscriber QRZ Page

    I had one and returned it. Just wasn't even close to satisfactory.

    Could not get acceptable VSWR. Bandwith is so narrow it makes the nice waterfall on the IC-705 almost useless.
     
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  8. KC9YGN

    KC9YGN Platinum Subscriber Platinum Subscriber QRZ Page

    I love my Alpha loop, but you have to adapt to its quirks and I can understand why some people wouldn't like this type of antenna. I've had mine for quite a while now. You shouldn't have to use an external tuner. The antenna's own tuner should be more than adequate. It is, however, 'twitchy' in that it can be difficult to get it spot on. IMO they should have put a reduction gear or something in there because turning the knob just a tiny bit can result in a huge change. I can pretty much tune it by ear by just peaking the noise level while listening.

    If you don't like it, that's fine. Sell it and use the funds to build or buy an antenna you may have better success with. Everyone has their own operating needs, preferences and techniques. What works for some people doesn't work for others.
     
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  9. KG7WGX

    KG7WGX XML Subscriber QRZ Page

    I got an Alex Loop last summer.

    The latest model comes with "Alex Tune" built in. This is an LED which lights at resonance.

    The instructions are not very well-written, but I had saved the article in the August 2020 QST which described how to tune it.

    I set my KX3 antenna tuner to "bypass". Next, I adjusted the capacitor to "peak" the background noise. I transmitted around 1.5 watts and adjusted the capacitor for brightest LED, then increased power to 10 watts and called CQ.

    The pictures typically show the loop set up on a tripod near a picnic table, and that's what works best. You want to be able to reach over and adjust the capacitor every time you QSY.
     
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  10. KC7JNJ

    KC7JNJ Ham Member QRZ Page

    I think the Alex loop is the one I would like to play with.
     
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