• [G3XBM] Low pass filter design

    From G3XBM via rec.radio.amateur.moderat@21:1/5 to All on Sun Mar 6 13:33:46 2022
    XPost: rec.radio.amateur.moderated, rec.radio.amateur.equipment, uk.radio.amateur
    XPost: free.uk.amateur-radio

    Roger G3XBM's (Mainly) Amateur Radio Blog

    Low pass filter design

    Posted: 06 Mar 2022 08:23 AM PST http://g3xbm-qrp.blogspot.com/2022/03/low-pass-filter-design.html

    With my upcoming permit to test on 8m, I may need to add external low pass filtering to ensure my TX is totally clean. There are several circuit calculators on the Internet. The one below is an example. It seems daft to
    buy one when a simple one can so easily be made.
    See https://rf-tools.com/lc-filter/ .

    Radio amateurs in Ukraine

    Posted: 06 Mar 2022 06:21 AM PST http://g3xbm-qrp.blogspot.com/2022/03/radio-amateurs-in-ukraine.html

    Since the recent troubles began, radio amateurs in Ukraine have been asked
    to keep off the air on TX. This has largely been observed.
    Whatever your views, innocent civilians are being killed or displaced. I
    hope a peaceful way can be found to stop the bloodshed.
    Even at the height of the Cold War, radio amateur chats with stations
    behind the Iron Curtain continued. In a small way, we all tried to break
    down barriers.
    See http://www.southgatearc.org/news/2022/march/ukraine-maintains-ham-radio-silence-in-state-of-emergency.htm#.YiTBi4rP3rc .


    Posted: 06 Mar 2022 05:10 AM PST http://g3xbm-qrp.blogspot.com/2022/03/elecraft.html

    Over the years I have owned a couple of Elecraft kits. One was the T1
    auto-ATU and one was the K1 QRP CW transceiver. The latter is now

    These days, they sell the KX2 and KX3 rigs as well as the K4 transceiver. Elecraft transceivers are usually very high specification products.
    Some years ago I did a webpage on the K1.
    See https://elecraft.com/ for the main Elecraft site.

    6m FT8 QRP (Sunday)

    Posted: 06 Mar 2022 08:07 AM PST http://g3xbm-qrp.blogspot.com/2022/03/6m-ft8-qrp-sunday.html

    At about 1030z, I turned on 6m FT8 with 2.5W and the V2000 vertical omni.
    After a brief period on TX (2 G spots) I am now RX only (just 2 G spots). UPDATE 1313z: 8 stations spotted with the furthermost CT2HXM (1422km) .
    UPDATE 1604z: 11 stations spotted on 6m FT8 RX today. The latest DX is
    IU3MDI (1137km). I am not sure of the propagation mode.

    DX crystal set

    Posted: 05 Mar 2022 11:26 PM PST http://g3xbm-qrp.blogspot.com/2022/03/dx-crystal-set.html

    This is a circuit I have never built. It was in QST some years ago and uses
    a zero bias MOSFET to give better sensitivity. You may want to have a go. Please read the ARRL article below.

    See http://www.arrl.org/files/file/Technology/tis/info/pdf/culter.pdf

    Sunspots - Sunday March 6th 2022

    Posted: 05 Mar 2022 11:25 PM PST http://g3xbm-qrp.blogspot.com/2022/03/sunspots-sunday-march-6th-2022.html

    Solar flux is 120 and the SSN 95. A=27 and K=3.

    2m FT8

    Posted: 05 Mar 2022 01:41 PM PST http://g3xbm-qrp.blogspot.com/2022/03/2m-ft8.html

    After a brief period on TX with 2.5W and the big-wheel omni antenna (2
    spots of me, but no QSOs), I am RX only. No spots yet on RX. This isn't
    too surprising with a contest on SSB/CW.
    FT8 is far more productive than calling the SSB contest stations who are probably running much higher power than me. With my poor voice I find
    calling other stations quite a struggle these days. I enjoy VHF contests,
    but they are hard work for me.
    UPDATE 2137z: 2 stations spotted on RX: G4NVB (96km) and ON4JES (228km).

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