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Re: [softrock40] Re: 6.3RXTX

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  • M. Barry LaZar
    All, I think you have a little misconception what happens with antennas and radios. Having a resonant antenna may not make your radio any happier than having a
    Message 1 of 14 , Feb 10, 2010
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      All,
      I think you have a little misconception what happens with antennas
      and radios. Having a resonant antenna may not make your radio any
      happier than having a non-resonant antenna. Power can only be transfered
      into a resistive load and for maximum efficiency that resistance should
      be equal to the source.
      A resonant dipole in free space is 75 Ohms which means if you were
      feeding this antenna your radio would only be marginally happy. If the
      antenna were to be erected at a more reasonable height, the impedance
      could be anywhere. If the resultant SWR were greater than 2:,1 most
      modern radios would start to shut down; you will need a tuner. Yes, you
      will need a tuner even if the antenna was resonant.
      What does an antenna tuner do? It doesn't tune the antenna. An
      antenna tuner simply "tunes" out the reactive component of the impedance
      and transforms the resistive component tjat is reflected to something
      the radio likes.
      The question of where does the energy go arose in this thread. The
      answer is it gets radiated except for the losses in the tuner and
      transmission line. But, that's another thread.


      73,
      Barry
      K3NDM

      Bruce Tanner wrote:
      >
      >
      > Yes, Jim, I think you are right as well. You say it a lot more kindly
      > that 'Crusty Old Kurt' of "World Radio", days gone bye! :)
      >
      > What I have noticed, however, is that the Softrock does like to be
      > happy, no matter the eventual resonance. According to the meters I use,
      > I will see literally no RF Forward Power showing without the tuner in
      > play with my G5RV and in RX its receptivity to weaker signals in a given
      > band clearly improves as well. You have to open the gates to the ether
      > somehow. I have not had a properly resonant antenna since my Novice
      > years and for most of them I have used the G5RV, especially for the
      > lower bands. I do have an optimized 3-ele yagi for 17 meters which I
      > have never hooked up to the Softrock as I don't have TX capability on
      > that band at this point. Got to get that 6.3 put together one of these
      > days!
      >
      > Hope we are not getting too far off topic with this jabber.. but a
      > little comedy once in a while can't hurt! Thanks for the responses.
      >
      > Bruce
      > --------------
      > Jim Rossell wrote:
      > >
      > > Hi HI just trying to find "elegantly tuned antennas" on the web. I
      > > know what you mean is a resonant antenna for the frequency. It does
      > > make a difference. Tuners ,as far as I know, make the xmtr happy but
      > > do not mean all that power went to the antenna. The antenna is still
      > > not resonant. What radiates now? The happy matching device? Where did
      > > the power go ? A non resonant antenna is still non resonant unless you
      > > tune the radiator. A tuner does not change the wire length it only
      > > makes up for the non resonant characteristics.
      > >
      > > Perhaps I am incorrect but why do we use 468/MHz. ??
      > >
      > > Sorry to pontificate.
      > > Jim, K3QYR
      > >
      > > ----------------------------------------------------------
      > > *From:* Pete Goodmann <pete@...
      > <mailto:pete%40lazydogengineering.com>>
      > > *To:* "softrock40@yahoogroups.com
      > <mailto:softrock40%40yahoogroups.com>" <softrock40@yahoogroups.com
      > <mailto:softrock40%40yahoogroups.com>>
      > > *Sent:* Wed, February 10, 2010 4:00:30 PM
      > > *Subject:* Re: [softrock40] Re: 6.3RXTX
      > >
      > >
      > > Sounds like that scene on "A Christmas Story"...
      > >
      > > Sent from my iPhone
      > >
      > > On Feb 10, 2010, at 11:05 AM, aa9wqham@aol. com
      > > <mailto:aa9wqham@... <mailto:aa9wqham%40aol.com>> wrote:
      > >
      > >>
      > >>
      > >> I find it more comfortable to take my shoes and socks off and wet my
      > >> fingure and touch it. The tongue thing makes my face twitch to much
      > >>
      > >> Larry W9AMR
      > >>
      > >> In a message dated 2/10/2010 10:15:02 A.M. Eastern Standard Time,
      > >> bet110@comcast. net writes:
      > >>
      > >> Well, the 'Forward Power' is reading one watt on a WELZ SP-10X
      > >> SWR/WATT
      > >> meter. I suspect that is getting to the antenna. If I can reach
      > >> it I'll
      > >> go out and stick my tongue on it later and see what that calibration
      > >> says. :) (Got up too early this morning... but worked K1MLP in
      > >> Boston
      > >> with the little bugger with a 559 received report.)
      > >>
      > >> Bruce
      > >> -----------
      > >>
      > >> Jim Rossell wrote:
      > >> > Yes, but does the output get to the antenna or is the Xmit just
      > >> happy
      > >> > with the new load impedance ?
      > >> >
      > >> > ------------ --------- --------- --------- --------- ---------
      > >> --------- ------
      > >> > *From:* Bruce Tanner <bet110@comcast. net>
      > >> > *To:* softrock40@yahoogroups.com
      > <mailto:softrock40%40yahoogroups.com> <http://ups.com>
      > >> > *Sent:* Tue, February 9, 2010 3:26:45 PM
      > >> > *Subject:* Re: [softrock40] Re: 6.3RXTX
      > >> >
      > >> > I use a tuner between my antenna and the Softrock. It makes a
      > >> whale of a
      > >> > difference in output unless you have an elegantly tuned antenna
      > >> to begin
      > >> > with.
      > >> >
      > >> > bet
      > >> > -----------
      > >> >
      > >> > g8voip wrote:
      > >> > >
      > >> > > Hi Nels,
      > >> > >
      > >> > > At 1W the output is not very clean, 500mW is far more realistic a
      > >> > > level to aim at, otherwise its 'never mind the quality, feel
      > >> the width'!
      > >> > >
      > >> > > 73, Bob G8VOI
      > >> > >
      > >> > > --- In softrock40@yahoogro ups.com <mailto:softrock40@
      > >> yahoogroups. com>
      > >> > > <mailto:softrock40% 40yahoogroups. com>, "nels_58701"
      > >> <anelson@...> wrote:
      > >> > > >
      > >> > > > That was suppose to be 1 watt instead of 1 volt.
      > >> > > >
      > >> > > > 73
      > >> > > > Nels W0TUP
      > >> > > > nels@...
      > >> > > >
      > >> > >
      > >> > >
      > >> > >
      > >> > >
      > >> > > __________ Information from ESET Smart Security, version of virus
      > >> > > signature database 4852 (20100209) __________
      > >> > >
      > >> > > The message was checked by ESET Smart Security.
      > >> > >
      > >> > > http://www.eset com <http://www.eset com>
      > >> >
      > >> >
      > >> > ------------ --------- --------- ------
      > >> >
      > >> > Yahoo! Groups Links
      > >> >
      > >> >
      > >> > (Yahoo! ID required)
      > >> >
      > >> > softrock40-fullfeat ured@yahoogroups .com
      > >> > <mailto:softrock40- fullfeatured@ yahoogroups. com>
      > >> >
      > >> >
      > >> >
      > >> >
      > >> >
      > >> >
      > >> > __________ Information from ESET Smart Security, version of virus
      > >> > signature database 4854 (20100210) __________
      > >> >
      > >> > The message was checked by ESET Smart Security.
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      > >> > http://www.eset com
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      > >>
      > >> ------------ --------- --------- ------
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      > >> Yahoo! Groups Links
      > >>
      > >>
      > >>
      > >
      > >
      > >
      > >
      > > __________ Information from ESET Smart Security, version of virus
      > > signature database 4856 (20100210) __________
      > >
      > > The message was checked by ESET Smart Security.
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      >
      >
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