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Re: [GEO-Subscribers] Balun

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  • Patrik Tast
    Hi Barry, Good work! Yeah, also at my location 63N images from NOAA 15 got alot of interference but your N19 are good. Patrik ... From: Barry Smith
    Message 1 of 78 , Dec 1, 2009
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      Hi Barry,

      Good work!
      Yeah, also at my location 63N images from NOAA 15 got alot of interference
      but your N19 are good.

      Patrik


      ----- Original Message -----
      From: "Barry Smith" <baz@...>
      To: <GEO-Subscribers@yahoogroups.com>
      Sent: Saturday, November 28, 2009 19:37
      Subject: Re: [GEO-Subscribers] Balun


      > In message <83C78B7A8D624EA8864EEF9EA4617A76@hp>
      > "Patrik Tast" <patrik@...> wrote:
      >
      >> Yes,
      >
      >> You will need always a BalUn (balanced to unbalanced) even if your
      >> antenna
      >> match your target impedance.perfectly, 50-50 ohm in our case.
      >
      >> I will reffer to Walt Maxwell's documet about this
      >> http://w2du.com/r2ch21.pdf
      >
      >> We have tried the DCA without ferrite beads and the images were not that
      >> happy.
      >> We use what ever ferrites we can find, monitor cables, power cables, etc.
      >
      >> To buy ferrites that are between 100-300 MHz are not expensive.
      >
      >> Patrik
      >
      > When I change the way that my aerial is supported, it will be much
      > easier to make modifications. I will then experiment and let you know
      > the results. At the moment I have the 5 clamp-on ferrites. I can see
      > what difference it makes if I take them off.
      >
      > At the moment I am using the DCA without a preamp and on N19, where
      > there is not too much pager interference, the results are good.
      > http://www.g4iat.co.uk/wx/noaa/
      >
      > Barry
      > --
      >
      >
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    • Simon L
      That is correct Andy... The DCA as described uses ferrites on the coax to act as far as can see as both current transformer and to stop any current flow on the
      Message 78 of 78 , Dec 1, 2009
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        That is correct Andy...

        The DCA as described uses ferrites on the coax to act as far as can see as both current transformer and to stop any current flow on the outside braid of the coax.

        Having now built two DCA antennas with both identical performance, the use of them in the design does work and such needs nothing further added.

        If it was any other type of antenna such as folded dipoles etc then yes some kind of further impedance matching would be required.

        But ... simply adding a clip on ferrite at the dipole and then a couple of additional ferrites on the feeders inside the junction box works perfectly and gives noiseless pictures horz to horz if correctly built.

        I would also add that if built to the correct dimensions with the feeders as described in the articles this antenna does match it says it does ... and having done some polar plots I can confirm the work excellent Jerry has done on bringing this antenna to the attention of the APT world.

        rgds

        Simon







        --- In GEO-Subscribers@yahoogroups.com, Andy Eskelson <andyyahoo@...> wrote:
        >
        > The antenna may well be balanced, but coax is not, hence the need for a
        > balun.
        >
        > andy
        >
        >
        >
        > On Tue, 01 Dec 2009 06:18:18 -0000
        > "Simon L" <simon@...> wrote:
        >
        > > Any half wave dipole cut for the actual operating frequency and fed with 50r coax is already balanced!
        > >
        > > you do not need a balun with every antenna IF it is at 50 ohms or close enough to 50 ohms.
        > >
        > > And the DCA does NOT need any balun.
        > >
        > > Having built one and get horz to horz noise free pics so can confirm the design works as well as described.
        > >
        > > forget the balun.....
        > >
        > > rgds
        > >
        > > Simon
        > >
        > >
        > >
        > >
        > >
        > > --- In GEO-Subscribers@yahoogroups.com, "Patrik Tast" <patrik@> wrote:
        > > >
        > > > Yes,
        > > >
        > > > You will need always a BalUn (balanced to unbalanced) even if your antenna
        > > > match your target impedance.perfectly, 50-50 ohm in our case.
        > > >
        > > > I will reffer to Walt Maxwell's documet about this
        > > > http://w2du.com/r2ch21.pdf
        > > >
        > > > We have tried the DCA without ferrite beads and the images were not that
        > > > happy.
        > > > We use what ever ferrites we can find, monitor cables, power cables, etc.
        > > >
        > > > To buy ferrites that are between 100-300 MHz are not expensive.
        > > >
        > > > Patrik
        > > >
        > > >
        > > >
        > > > ----- Original Message -----
        > > > From: "Ruud Jansen" <ruud@>
        > > > To: <GEO-Subscribers@yahoogroups.com>
        > > > Sent: Saturday, November 28, 2009 11:53
        > > > Subject: [GEO-Subscribers] Balun
        > > >
        > > >
        > > > > Hi Barry,
        > > > > I forgot to write:
        > > > > The DCA-design needs AND has Balun's.
        > > > > 5 ferrite beads.
        > > > > See Geo Quarterly number 20, page 15 and 16
        > > > > 73's, ruud
        > > > >
        > > > > Ruud Jansen PA0ROJ
        > > > > Saeftinge 102
        > > > > 2036 GC Haarlem
        > > > > Nederland
        > > > >
        > > > > website ruud:
        > > > > http://www.jendela.nl
        > > > >
        > > > > website adri:
        > > > > http://www.kookadri.nl
        > > > >
        > > > >
        > > > >
        > > > >
        > > > > ------------------------------------
        > > > >
        > > > > Paypal - Paypal - Paypal - Paypal - Paypal
        > > > >
        > > > > GEO now accept Paypal for subscription renewal and shop purchases
        > > > >
        > > > > See the web site for details
        > > > >
        > > > > *** RENEWAL of SUBSCRIPTIONS REMINDER ***
        > > > >
        > > > > Check your status by looking at the label on your latest issue or contact
        > > > > members@ by email
        > > > >
        > > > > ** AUTOMATIC CREDIT CARD RENEWAL **
        > > > >
        > > > > GEO will be operating automatic credit card renewal to save you time and
        > > > > reduce our administration. If you wish to convert to automated renewal
        > > > > contact members@ by email. Also a tick box is provided on
        > > > > the application form to indicate your preference. The form can be found
        > > > > here :- http://www.geo-web.org.uk/join.pdf Your credit card details will
        > > > > be held securely.
        > > > >
        > > > > Contact details ### GEO is run by volunteers ###
        > > > >
        > > > > David Anderson members@ Membership enquiries
        > > > > Ray Godden webmaster@ GEO website
        > > > > Les Hamilton editor@ GEO Quarterly Editor
        > > > > John Tellick info@ General enquiries
        > > > > Peter Wakelin meteo@ Meteorological matters
        > > > > Francis Bell francis@ Public Relations and Education
        > > > > Clive Finnis shop@ *** GEO SHOP ***
        > > > > Yahoo! Groups Links
        > > > >
        > > > >
        > > > >
        > > >
        > >
        > >
        >
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