Well, I agree with Walt on this, except there is also a (usually small)
loss in the tuner. If you run Dean Straw's (N6BV, ARRL Antenna Book
Editor) excellent TLW, one of the s/w packages that comes with the ARRL
Antenna Book, it will calculate the loss in the transmission line as
well as calculate the antenna tuner loss for different configurations of
tuner.
73, Joel
Joel R. Hallas, W1ZR
Randy Russe3ll wrote:
>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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