Maxwell WROTE the book.
73, Duane
On Thu, 19 Jan 2006 10:49:27 -0800 (PST) Randy Russe3ll
<lord_russell53@yahoo.com> writes:
> Sounds to me like Maxwell needs to go back and read
> the ARRL Antenna Handbook.
>
> --- JOHN <ku3g@yahoo.com> wrote:
>
> > Thank You Scott finbally somebody has it correct.
> > 73 john ku3g
> > ps interestinmg subject
> >
> > Scott Harwood <scotth@hsc.edu> wrote:
> >
> > Hey guys:
> >
> > In his book, ?Reflections?, Maxwell states that all
> > power fed into the transmission line (minus line
> > loss) is absorbed by the load, regardless of the
> > mismatch. Secondly, with open-wire tuned feed lines,
> > we can ignore this mismatch at the junction of the
> > feed line and the antenna, and all matching can be
> > done at the transmitter itself. Put another way, if
> > an antenna tuner can properly match the impedance of
> > the input of the feed line, using open wire line we
> > can transfer just about all power to the antenna.
> >
> > Thus, the case for open wire line and a tuner.
> >
> > Scott K4VWK
> >
> > ---------- Original Message
> > ----------------------------------
> > From: Randy Russe3ll
> > Reply-To: Discussion of Ten-Tec Equipment
> > Date: Wed, 18 Jan 2006 18:57:09 -0800 (PST)
> >
> > >Even if you have a finely tuned resonant dipole,
> > and
> > >it is actually 50 ohms at your feedpoint heighth,
> > >you're losing more db in 100 feet of coax than I am
> > on
> > >a mismatched 4:1 swr. If you put your loading coils
> > >on to "fool the transmitter" your using even more.
> > If
> > >you try to use your coax on any kind of mismatch,
> > your
> > >losses skyrocket. This includes feeding a 35 ohm or
> > >say 80 ohm feedpoint with 50 ohm coax. Those are
> > both
> > >Z's attained on dipoles between 20 feet in the air
> > and
> > >a full wave high. The purpose of coax is
> > convienence
> > >swapped for performance. A link coupled tuner is
> > more
> > >of an Antenna impedance transformer. You've already
> > >got a few of those in your rig anyway. I didn't see
> > >anything supporting your theory about transmission
> > >lines in the ARRL Antenna book. In fact, if you go
> > >back and read it, you will understand what I'm
> > saying
> > >about losses in coax, and the reasons for the
> > >superiority of balanced feedlines. In a multi band
> > >system, it's an absolute must. Oh, and resonance is
> > >NOT a requirement for radiation efficiency. 73s
> > >--- Roger Borowski wrote:
> > >
> > >> After more than 45 years of continual hamming on
> > all
> > >> bands and modes, I can
> > >> honestly say that I never have used an antenna
> > tuner
> > >> and never found any
> > >> system that will outperform a resonant antenna
> > fed
> > >> with coaxial cable, which
> > >> I've always used since the early 60's. If the
> > >> antenna isn't resonant on the
> > >> desired frequency of operation, many people think
> > an
> > >> antenna tuner is the
> > >> fix. While an antenna tuner will allow you to use
> > >> most anything metallic as
> > >> a radiator of RF, the most efficient power
> > transfer
> > >> is to a 50 ohm resonant
> > >> load via 50 ohm coaxial feedline. In all cases
> > where
> > >> an antenna tuner is
> > >> used with a coaxial fed antenna, all it does is
> > >> further complicate a system
> > >> with an added piece of equipment that only fools
> > the
> > >> transmitter into seeing
> > >> the match it is looking for, while creating
> > losses
> > >> in itself and further
> > >> losses in the coaxial feedline due to the
> > mismatch
> > >> that still remains
> > >> between the antenna tuner and the antenna.
> > >> Fortunately I've never been
> > >> forced to use anything other than resonant
> > antennas
> > >> fed with good quality 50
> > >> ohm coaxial cable. If you're bound and determined
> > to
> > >> use open wire feeders
> > >> to one of the many non-resonant antenna designs
> > of
> > >> yesteryear, that would
> > >> require an antenna tuner. Why anyone who
> > understands
> > >> antennas would want to
> > >> do that 50-60 years after coaxial cable became
> > >> common place is beyond my
> > >> comprehension. It's an easy chore to adjust
> > antenna
> > >> lengths for resonance
> > >> and where available space doesn't permit, it's
> > also
> > >> easy to use loading
> > >> coils or linear loading configurations on the
> > >> antenna. If you haven't a clue
> > >> as to what I'm saying, pick up a book on
> > antennas,
> > >> such as the ARRL Antenna
> > >> Book and read the entire section on the theory of
> > >> antennas. As a Ham, you
> > >> really need to know this. An antenna tuner is a
> > band
> > >> aid approach that
> > >> allows one to use an inefficient antenna,
> > whatever
> > >> it may actually be, with
> > >> some degree of success. You see 1:1 SWR on the
> > tuner
> > >> meter and you and your
> > >> rig are happy, but in actuality, put another SWR
> > >> meter after the antenna
> > >> tuner and you'll see the real mismatch, why you
> > are
> > >> generating RFI, and
> > >> experiencing far less performance, both
> > transmitting
> > >> and receiving, than you
> > >> could be.
> > >> 73, -=Rog-K9RB=-
> > >> FCC First Class Commercial License first attained
> > in
> > >> 1967, Ham Radio license
> > >> first attained 1961.
> > >> A-1 Operator Club, ARRL Life Member, DXCC #1
> > Honor
> > >> Roll (350) Mixed, Phone,
> > >> CW (since '92) and presently need 11 more on RTTY
> > >> for H.R. Need (4) more
> > >> zones on 160M. for all (9) HF band "Worked All
> > >> Zones". At present 160 Meter
> > >> DXCC - 211 + 36 zones. Former member NIDXA
> > No.Ill.DX
> > >> Assn., 9th area
> > >> incoming QSL bureau sorter for many years,
> > Charter
> > >> Member Metro DX Club,
> > >> Life member / former Trustee W9AA Hamfesters
> > ARC.,
> > >> CP-40 in 1963 at 14 years
> > >> of age, former ARRL OO, & NCS, active 160M
> > through
> > >> V.H.F. / U.H.F. for 45
> > >> years. 1st place CQWPX-CW 15M in 1981. 1st place
> > >> CQWW-CW 40M in both 1980 &
> > >> 1988. (Ancient history now!) Also KG4RB -GTMO
> > Cuba,
> > >> Bio and photos available
> > >> at www.qrz.com Reply direct to; K9RB@arrl.net
> > >>
> > >> ----- Original Message -----
> > >> From: "Richard Williams"
> > >> To: "Discussion of Ten-Tec Equipment"
> > >>
> > >> Sent: Wednesday, January 18, 2006 5:43 PM
> > >> Subject: Re: [TenTec] What makes the 238 good or
> > any
> > >> other tuner good?
> > >>
> > >>
> > >> Rich,
> > >>
> > >> Quite a number of answers I see on the board. My
> > >> personal opinion is the
> > >> best tuner out there is the XMatch tuner
> > >> manufactured by Paul Schrader
> > >> (N4XM). This is pretty well backed up by the ARRL
> > >> when they did a review
> > >> of this one and three others back in Mar of 97.
> > You
> > >> can read it by signing
> > >> on to the ARRL home page and search for XMatch
> > >> tuner.
> > >>
> > >> I don't think anything comes even close to it
> > specs
> > >> when operating on 160
> > >> Mtrs. I believe he still makes them as I see his
> > >> ads in EST..
> > >>
> >
> === message truncated ===
>
>
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>
Duane Calvin, AC5AA
Austin, Texas
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