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  • [G3XBM] Loop antennas

    From G3XBM via rec.radio.amateur.moderat@21:1/5 to All on Tue Aug 24 01:11:20 2021
    XPost: rec.radio.amateur.moderated, rec.radio.amateur.space, uk.radio.amateur XPost: free.uk.amateur-radio

    Roger G3XBM's (Mainly) Amateur Radio Blog

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    Loop antennas

    Posted: 23 Aug 2021 07:28 AM PDT http://g3xbm-qrp.blogspot.com/2021/08/loop-antennas.html


    From my own results I think loops are (maybe) 6dB down on a dipole. This is far from accurate, but the losses are likely to be greater on lower
    frequencies and less on higher bands.

    This is 1 S point, so not too great. For some applications that do not
    require much frequency change they can be ideal. FT8, PSK31 and WSPR come
    to mind.
    When I had no external 10m antenna earlier in the year, I used an old Whizz Loop on 10m FT8. Although I may have missed some stations, I still spotted plenty. Mine was just on the shack windowsill indoors.
    If you have limited space and can cope with them being very sharp tuned, if efficient, they can be a decent compromise antenna. With QRP you will not
    need special capacitors. With QRO the voltages at the high impedance points
    can be very high so special capacitors will be needed.
    See https://sites.google.com/view/g3xbm4/home/antennas/loops .

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    10m FT8 QRP (Monday)

    Posted: 23 Aug 2021 08:44 AM PDT http://g3xbm-qrp.blogspot.com/2021/08/10m-ft8-qrp-monday.html


    Shortly, I shall go on 10m FT8. Usually I TX at 2.5W for a few minutes and then go RX only for much of the day. Even as the Es season is winding down,
    I am still copying many stations.
    10m FT8 is ideal as it works with weak, fleeting, signals. Even stations
    coming through for just 12-15 seconds can be spotted. Although I have not
    tried it, FT4, although less sensitive, needs just half the time.
    There must be several times when the MUF just peaks at far higher than
    average.
    UPDATE 1040z: After a very brief period on 2.5W TX (spotted by 4 in Europe
    and one "near miss" QSO) I am now 10m FT8 RX only. 22 stations spotted, all
    in Europe by what seems to be Es.
    UPDATE 1544z: 30 stations spotted today so far. All EU.

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    10FT8R

    Posted: 23 Aug 2021 01:18 AM PDT http://g3xbm-qrp.blogspot.com/2021/08/10ft8r.html


    This DSB 10m FT8 RX was in a recent RadCom and is on the g3xbm.co.uk
    website. It's a very simple circuit but works well and frees up the "big
    rig".

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