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Re: [softrock40] Softrock RXTX Ensemble with a Magnetic Loop Antenna

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  • Sid Boyce
    The bandwidth is around 2.7 KHz for the loop made of 22mm copper tube. 73 ... Sid. ... -- Sid Boyce ... Hamradio License G3VBV, Licensed Private Pilot Emeritus
    Message 1 of 10 , Apr 1, 2011
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      The bandwidth is around 2.7 KHz for the loop made of 22mm copper tube.
      73 ... Sid.

      On 01/04/11 20:43, Richard wrote:
      > On Fri, 2011-04-01 at 20:09 +0100, Sid Boyce wrote:
      >>
      >> They work quite well. I even heard one guy say that when his beam
      >> blew
      >> down he used one and was able to maintain his daily sked UK to ZL.
      >>
      >> One other positive is that they don't need the height. Tony (G4OGP)
      >> who
      >> first sold magnetic loops in the UK said that he had used one on top
      >> of
      >> Blackpool tower and at ground level with no difference in performance.
      >>
      >> Usually at the then Leicester show which was in a large steel hangar,
      >> all the vendors could only show you their gear and say that antennas
      >> couldn't work at that location, while Tony had one of his loops on
      >> the
      >> air, pulling in European stations at 59+ and making QSO's.
      >>
      >> It was much much later before MFJ produced their magnetic loop.
      >>
      >> They are a number of Windows and DOS calculator programs on the net,
      >> mloop, mloop31, etc. so you can play with different parameters ahead
      >> of
      >> ordering any hardware. Also if anyone is interested in playing with
      >> different sizes and shapes of magnetic loops, these programs give you
      >> a
      >> good idea. I start off with inputting different sizes of copper,
      >> tubing
      >> lengths and shapes and when I come up with something that I like, I
      >> buy
      >> the materials and put it together.
      >> I use a Gamma match for lowest SWR, usually close to 1:1 and fire it
      >> up.
      >>
      >> Though copper is best, Tony's loops were made from aluminium tube,
      >> his
      >> customers were not only hams but Embassies and other government
      >> agencies. I've seen some made of aluminium curtain track.
      >> 73 ... Sid.
      > You can also make them out of expensive heliax cable such as LDF4-50,
      > once water gets in it its pretty usless and gets thrown away.
      > But you only use the outside solid ( corrugated ), copper and its self
      > supporting within reason, AND its an interference fit to 15 mm Cu
      > tubing, 1/2" will be very close as well.
      > I've a 6 mtr diameter loop in the garden I use on 160& 80 Mtrs.
      > Two wood cross members and the whole thing is on a fibreglass pole.
      >
      > I'd be interested in how broadband your gamma match is Sid ?
      > I use a loop and its gone a bit higher than normal.
      >


      --
      Sid Boyce ... Hamradio License G3VBV, Licensed Private Pilot
      Emeritus IBM/Amdahl Mainframes and Sun/Fujitsu Servers Tech Support
      Specialist, Cricket Coach
      Microsoft Windows Free Zone - Linux used for all Computing Tasks
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