[Top] [All Lists]

Re: [TenTec] What makes the 238 good or any other tuner good?

To: scotth@hsc.edu,Discussion of Ten-Tec Equipment <tentec@contesting.com>
Subject: Re: [TenTec] What makes the 238 good or any other tuner good?
From: JOHN <ku3g@yahoo.com>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Thu, 19 Jan 2006 07:57:36 -0800 (PST)
List-post: <mailto:tentec@contesting.com>
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..
>> Maybe someone else out there has the Match and will
>> put there "two cents"
>> worth in.
>> Dick KHZ
>> _______________________________________________
>> TenTec mailing list
>> TenTec@contesting.com
>> http://lists.contesting.com/mailman/listinfo/tentec
>> _______________________________________________
>> TenTec mailing list
>> TenTec@contesting.com
>> http://lists.contesting.com/mailman/listinfo/tentec
>Do You Yahoo!?
>Tired of spam? Yahoo! Mail has the best spam protection around 
>TenTec mailing list

TenTec mailing list

Yahoo! Photos
 Got holiday prints? See all the ways to get quality prints in your hands ASAP.
TenTec mailing list

<Prev in Thread] Current Thread [Next in Thread>