V55V's Rhombics - A Big Signal Out of Africa!

Discussion in 'Amateur Radio News' started by DK7PE, Mar 9, 2018.

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  1. NH7RO

    NH7RO Ham Member QRZ Page

    Thanks, Dennis; I'll check out that other link when I have more time---lots of good info on Tom's site, too.

    73,

    Jeff
     
  2. K7LZR

    K7LZR Ham Member QRZ Page

    Agreed and I'm glad that Tom's information doesn't detract from a person wanting to erect and use said antenna. Maybe I'm too jumpy these days because it seems like every time a good story comes along like this where somebody is proud of their antenna(s), then it gets attacked & picked apart before long......
     
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  3. W6RZ

    W6RZ Premium Subscriber QRZ Page

    I'm not going to argue about the science of rhombics, but I'll always remember ZS6DN's huge signal on 20 meters with his rhombic.
     
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  4. KR3DX

    KR3DX Subscriber QRZ Page

    Keep in mind that a terminated rhombic has 3db of loss in the terminating resistor, both on transmit AND receive. An unterminated rhombic doesn't have this loss, but it is a bi-directional antenna.
     
  5. KA2FIR

    KA2FIR Ham Member QRZ Page

    Is there a record of this?
     
  6. G6YZC

    G6YZC Ham Member QRZ Page

    ??? not sure what you mean?

    There were QSL cards and log books etc but never bothered looking to see if it was listed on the internet. Remember this was pre internet radio days. Maybe in Dave Butler's VHF column or you could look through the Italian records as an Italian staton about 30KM north of John tail ended the QSO and worked V51E to set the new 2m TEP record at the time. It was either the 1990 or 1991 TEP season if I recall correctly but I may be a year or 2 out either way.

    I remember John spent several years listening for the beacon through headphones whilst playing cards with his young daughter until he eventually heard V51E's 2m beacon. John telephoned directory enquiries in Namibia for V51E's telephone number and got him on the phone to ask him to go to 2m.

    3A2LU was using 150W into a 15 ele yagi and I remember V51E was using his 160m antenna as that was the antenna he used to run his 2m beacon on if I recall correctly. The QSO took place in CW.

    Paul N2EME
     
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  7. K7JOE

    K7JOE Ham Member QRZ Page

    Lets also keep in mind that a DX/Africa callsign has at least 20dB of incremental "cool factor" gain, at least in the N.America direction. And a likely real advantage of 10dB as far as ambient noise figures due to the low population density of the huge farmland.

    Wouldn't the antenna guru's like to op some day from an exotic location? Put the theories to the real test...

    I seem to recall that doc Seymour W6 Charlie Charlie Papa (SK) ran some monster rhombics, no ? I could hear him "beaming the long path to Asia and the Indian Ocean" from my Asia locations most early mornnings on a literal wet noodle.
     
    Last edited: Mar 12, 2018
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  8. DL6BCX

    DL6BCX Premium Subscriber QRZ Page

    I have been three times in Namibia, it is a colourful great country.
     
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  9. KZ4USA

    KZ4USA Ham Member QRZ Page

    Yes you are so right. The antenna works and that is what counts for him.
     
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  10. W0PV

    W0PV Ham Member QRZ Page

    If you like HF rhombic's, check out the story of the Desert Voices Project.

    http://www.mapability.com/ei8ic/rhombic/ncaec1.php

    Quickly erected with leadership by Hams at an abandoned Nike missile base in Minnesota during the first Gulf War to provide a HF link to Middle Eastern MARS stations in the field. Besides the big rhombic on wooden power poles, they had a conventional Yagi on ~100 ft tower. I recall operators saying the fixed azimuth wire consistently out performed the rotatable beam by a lot except of course for long path propagation.

    Also, rhombics have been utilized on VHF for decades, such the array set up by moonbounce pioneer VK3ATN (SK), who accomplished the first VK<>USA EME QSO in 1966.

    "The aerial chosen for use in the Birchip efforts consists of four rhombics with 342 feet on each leg. The individual beams are stacked roughly one wavelength apart with a mean height of 24.4 feet. Apex angle for 144.090 Mc is 11 degrees 28 minutes. Calculated gain is approximately 34 dB with a main-lobe radiation angle of 4 degrees. This is approximately the performance one might expect from a 150 foot diameter parabolic reflector. The half-power beamwidth is 3.5 degrees which allows about 8 to 10 minutes of moon time at full gain. (Minus 1 dB points.)"

    http://www.ok2kkw.com/eme1960/eme1965eng.htm

    73, John, WØPV
     
    Last edited: Mar 13, 2018
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