New list member/T1 tuner questions

[qrp_1]

Hello to the group !
  I'm Rick - KC8AON, in Southern Ohio.  Just joined the Elecraft group
because I am thinking of buying a T1 tuner kit to go with my Yaesu
FT-817.  I have been reading some of the reviews of the T1 on the web and
most seem to be good reviews except for the enclosure they put the T1 in.
 I guess they use plastic to save on weight and expense ?  Anyway, was
wondering if anyone has mounted their T1 in a more robust enclosure to
offer more protection in the field and if so did a metal enclosure effect
the tuning properties of the tuner ?  I have a nice small modem case that
would make a very nice rugged enclosue for the T1 that has an extruded
aluminum chassis and a slide on vinyl covered steel top.  But again, will
a metal enclosure effect the tuning properties of the T1 ?  I would
rather go ahead and build it into the more rugged enclosure as I build it
than I would to put it in the plastic box that comes with it if it will
work ok in the metal enclosure.

  Also, does the T1 work well with endfed wire antennas ?  I'm thinking
maybe non resonant lengths with counterpoise wires to eliminate the high
Z of half wave length wires so the tuner will not be trying to tune a
very high impedance and to move the feedpoint to much lower voltage point
on the antenna.  So, if the T1 will work with end fed wires, what are
some good lengths that have been proven to work well with the T1 for 10
thru 40 meters, 10 thru 80, and 10 thru 160 ?  Most of my portable
operations are 10 thru 40 meters, but I do like to work 60 & 80 meters on
occasion, and even 160 on scarce occasions.

  Now, when using the T1 with the FT-817, is the special control cable
absolutely needed ?  If so, how long is the cable and can it be easily
lengthened ?  My planned purpose for the tuner is to put it at the
feedpoint of the endfed wire when operating portable to eliminate coax
feedline loss between the antenna and the radio, so if the T1 will work
fine without the control cable, that would be much better.  If not, the
cable would need to be at least 8 or 10 feet long to reach the feedpoint
of the antenna where the tuner will be.

Thanks for the bandwidth !

73 - Rick McKee, KC8AON
Southern Ohio - EM88sn
www.angelfire.com/electronic2/qrp
With God all things are possible ~ ><(('> ~
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[Don Wilhelm-4]

Rick,

The question and discussion has mentioned end fed half wave antennas,
and has also mentioned that the half wavelength end fed types have a
high impedance feedpoint that must be dealt with.  There is an
alternative that is resonant and also end fed.

If you are looking for something end fed that is lightweight and easy to
put up for the upper bands, consider the classic "Zepp" antenna.  I know
that the term has been construed in ham usage, and most any dipole has
been referred to as a zepp antenna.
BUT what I am talking about is "The Classic Zepp" - a half wave dipole
and a quarter wave piece of parallel transmission line.
YES, if you look at a J-Pole antenna, you can see what I am referring to
- a J-Pole is nothing more than the classic Zepp antenna that was used
to trail behind zepplins - lighter than air craft, it does not have to
be vertical to work well.
You can use that antenna in a straight line, or you can bend it at the
point where the transmission line ends and the halfwave antenna section
begins, either configuration works.
It can be easily built from 300 ohm parallel transmission line - either
solid dielectric or window line, or it can be made of 450 ohm ladder
line, or even your own constructed parallel transmission line.
Measure out a 3/4 wavelength of the 300 ohm line (do not cut yet, just
mark it) using your antenna analyzer to determine the electrical length
or if you really know the velocity factor of the line, you can 'do the
math' and use a measuring tape.  Divide that length into thirds - the
length from the end to the first third should be 1/4 wavelength, so cut
one side of the parallel line there - this is the 1/4 wave transmission
line.
Now from that cut point, measure a full half wave dipole length (the
velocity factor of the transmission line does not count for this half
wave piece, but the insulation will have some effect on the length
required) - this piece could be regular wire or it can be an extension
of the transmission line with only one conductor used, take your pick.
You can either feed the open end of the directly from a tuner (the
impedance will be low), or you can do as is normally done with a J-Pole,
short the end and tap up on the conductors a bit to achieve a 50 ohm
match and feed it there with coax.

A J-pole is not only for UHF, they are handy for portable operation too
- but they are single band antennas, so plan to build and carry one for
each band you intend to operate.  The size is practical for 20 meters
and up and depending on the tree situation, 30 or even 40 meters is not
difficult.

73,
Don W3FPR

[hidden email] wrote:

> Hello to the group !
>   I'm Rick - KC8AON, in Southern Ohio.  Just joined the Elecraft group
> because I am thinking of buying a T1 tuner kit to go with my Yaesu
> FT-817.  I have been reading some of the reviews of the T1 on the web and
> most seem to be good reviews except for the enclosure they put the T1 in.
>  I guess they use plastic to save on weight and expense ?  Anyway, was
> wondering if anyone has mounted their T1 in a more robust enclosure to
> offer more protection in the field and if so did a metal enclosure effect
> the tuning properties of the tuner ?  I have a nice small modem case that
> would make a very nice rugged enclosue for the T1 that has an extruded
> aluminum chassis and a slide on vinyl covered steel top.  But again, will
> a metal enclosure effect the tuning properties of the T1 ?  I would
> rather go ahead and build it into the more rugged enclosure as I build it
> than I would to put it in the plastic box that comes with it if it will
> work ok in the metal enclosure.
>
>   Also, does the T1 work well with endfed wire antennas ?  I'm thinking
> maybe non resonant lengths with counterpoise wires to eliminate the high
> Z of half wave length wires so the tuner will not be trying to tune a
> very high impedance and to move the feedpoint to much lower voltage point
> on the antenna.  So, if the T1 will work with end fed wires, what are
> some good lengths that have been proven to work well with the T1 for 10
> thru 40 meters, 10 thru 80, and 10 thru 160 ?  Most of my portable
> operations are 10 thru 40 meters, but I do like to work 60 & 80 meters on
> occasion, and even 160 on scarce occasions.
>  
>

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[qrp_1]

Gang,
  Let me make myself clear on what it is I expect from the T1 and what my
plans are for it.  First, I do not want resonant antennas for each band -
takes too much time to setup and take down when changing bands.  The T1
will mainly be used for portable radio adventures which I do not get a
lot of time to do and changing antennas each time I change bands is just
too time consuming.  I know all the ins and outs of 1/2 wave end fed
wires and how they are less dependant on ground connections and I do like
them very well for single band operation with my little Small Wonder Labs
single band rigs.  But my FT-817 as you all know is an all band rig and
my plan is to utilize a small autotuner at the feedpoint of a single
endfed wire for all band operation.  I don't mind using radials or
couterpoise wires - thats not a big deal.  But the need to change bands
without changing antennas is the most important aspect to me, and a tuner
that will provide a match automatically is also very important.
Basically, I want more operating time and less time fiddling with knobs
and putting up and taking down antennas.  Maybe the T1 is not the tuner
for me, I don't know but I do like the size of it which will fit in my
Jump Kit very easily.  I could just switch to my Icom 703 with built in
tuner, but then its a non plus model with no 2,6, or 70cm bands and is
somewhat bigger.  My idea is to have a small packable station that will
do it all in one package and do it very quickly.  I was hoping that the
T1 coupled with my FT-817 would fill the need ?

So, what magic wire lengths work well on all bands with the T1 ?

Do I need to use a balun with the endfed wire to make it work or just
feed it direct to the T1 ?

Somewhare I read about some certain length wires used with the T1 - as I
recall, one was 32.8 feet long and would work 6 thru 80 meters with the
T1 but it did not specify the use of a balun or not.  It also listed 2
other lengths but I don't recall those but do recall that one was for 6
thru 80 meter operation and the other was 6 thru 160 meters.  The one
that went down to 160 meters may have been near 88 feet long - not sure ?
 Anyone know where this info is from my description ?  I thought I had
bookmarked it but cannot find it now.

Also, I now find that the T1 requires the push of a button before
starting to transmit, so is there no full autotune mode that cause it to
tune whenever the swr goes above a certain level ?  When changing bands ?
 If not, kind of messes wit hthe idea of having an utotuner in the first
place !  Hmmm ?

73 - Rick McKee, KC8AON
Southern Ohio - EM88sn
www.angelfire.com/electronic2/qrp
With God all things are possible ~ ><(('> ~
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[daleputnam]

Hi Rick,

  The length that I used for 80 - 10 was 88 feet.. 85 - 92 will be workable.. it isn't critical. Then I had window line from the center down to the T1, the length feedline is 44 or half the antenna length, the T1 was then connected to the radio by a hand length of coax... and that length of coax was very critical.. it had to reach from the T1 to the radio. The T1 is light enough to hang from the window line.... if the antenna is high enough. I used it on 80 - 20... with fine results on all bands... once the antenna was up.. didn't touch it til it came down.. I carried a balun... so could have used it if I needed... didn't.

  The shorter length you refer to... is for 40 - 10.

Good luck,

--... ...-- Dale - WC7S in Wy


 

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[qrp_1]

While I currently do not own the Elecraft T1 tuner, I do use a long wire
antenna with my radio.  The HF antenna is hung as an inverted Vee with
both sides cut
for the 40 meter band.  [[snip]]

Jim,
  I do not understand this statement.  How can a "long wire antenna" have
2 sides ?  A long wire is fed from one end only, so are you speaking of
an endfed wire with an equal length counterpoise laying on the ground or
are you speaking of a doublet antenna fed in the center with a feedline ?
 I do have manual tuners but want something much simpler like and end fed
wire with an auto tuner for quick band changes in the field - don't want
to pack something the size of a MFJ-941 tuner into the woods !

73 - Rick McKee, KC8AON
Southern Ohio - EM88sn
www.angelfire.com/electronic2/qrp
With God all things are possible ~ ><(('> ~
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[Geoffrey Mackenzie-Kennedy]

Rick,

A "long wire antenna" can be fed at any point along its length, not only at
one end, but at any given frequency the antenna's pattern will change as
will the antenna's feedpoint impedance as the position of the feedpoint is
changed. Some schemes such as the Off Centre Fed wire place the feedpoint at
a position where the feedpoint impedance is lowish and similar on several
bands, allowing the use of a coax feeder, but radiation from the coax feeder
can be a problem if not prevented.

When I was a young ham, a "long wire" had to be at least three or four
wavelengths in length. They have shrunk in recent years :-)

73,
Geoff
GM4ESD


----- Original Message -----
From: <[hidden email]>
To: <[hidden email]>
Sent: Sunday, July 12, 2009 7:54 PM
Subject: Re: [Elecraft] New list member/T1 tuner questions


>  I do not understand this statement.  How can a "long wire antenna" have
> 2 sides ?  A long wire is fed from one end only, so are you speaking of
> an endfed wire with an equal length counterpoise laying on the ground or
> are you speaking of a doublet antenna fed in the center with a feedline ?
> I do have manual tuners but want something much simpler like and end fed
> wire with an auto tuner for quick band changes in the field - don't want
> to pack something the size of a MFJ-941 tuner into the woods !

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[qrp_1]

A "long wire antenna" can be fed at any point along its length, not only
at
one end, [[snip]]

Well, if its fed anywhere except from the end, I would call it something
like a dipole, doublet, center fed zepp, off center fed dipole etc.  But
the true definition of a long wire is a wire that is at least one
wavelength long or multiples of a wavelength at the lowest frequency.
One that is cut for 40 meters on each half is either a doublet or a
dipole.  Technically speaking of course ! ;-)

73 - Rick McKee, KC8AON
Southern Ohio - EM88sn
www.angelfire.com/electronic2/qrp
With God all things are possible ~ ><(('> ~
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[qrp_1]

Hmmm... isn't a definition of a "long wire" one in which alternate half
wave
sections are out of phase? [[snip]]

In all the books I've read it says that a long wire is a wire that is one
wavelength or multiples of one wavelength at the lowest frequency and
radiation of a long wire is basically off the ends of such wire.  It has
nothing to do with phase....

73 - Rick McKee, KC8AON
Southern Ohio - EM88sn
www.angelfire.com/electronic2/qrp
With God all things are possible ~ ><(('> ~
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[Don Wilhelm-4]

Rick,

I beg your pardon - the radiation of an antenna has everything to do
with the relative phase.
That is what creates gain and cancellation in the radiation pattern.
The phase addition or cancellation on a long wire or any other antenna
for that matter is what gives rise to the radiation pattern.

A half wavelength antenna will have radiation perpendicular to the wire,
a full wavelength wire will have 4 lobes each at 45 degrees angle to the
wire, a 3 wavelength wire will have 6 lobes spaced at 60 degrees (30
degrees from the wire to the first lobes), a 4 wavelength wire will have
8 lobes 45 degrees apart, and so forth.  A "V" antenna or a rhombic
derives its gain in a bi-directional lobe by depending on the
cancellation and additive effects of two wires and is manipulated by the
angle between the wires.  I know of no case where the maximum radiation
is parallel with the wire (off the ends).

73,
Don W3FPR

[hidden email] wrote:

> Hmmm... isn't a definition of a "long wire" one in which alternate half
> wave
> sections are out of phase? [[snip]]
>
> In all the books I've read it says that a long wire is a wire that is one
> wavelength or multiples of one wavelength at the lowest frequency and
> radiation of a long wire is basically off the ends of such wire.  It has
> nothing to do with phase....
>  
>

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[qrp_1]

The specifics on the antenna are that it is center fed.  The actual
length of each leg is something that I personally do not know because the
ham friend that helped me with it has a special tape of tape measure that
is calibrated to measure antenna lengths.  His is the only one of that
kind that I have ever seen.  The feed line is 300 ohm television twin
lead. [[snip]]

Hello Jim,
  I saw two of those tape measures once and they were actually part of a
military dipole antenna system.  The original antenna had 2 of them and
you just pulled them ou to the coresponding frequency measurements on
each side and you had a resonant dipole for that frequency.  So if your
friend used that to measue the wire with, then its most likely somewhere
around 33 feet on each side.  Being fed with 300 ohm balanced feedline
makes your antenna a doublet - and a doublet is a very good all band
antenna !  I use a doublet here that is 178 feet long - 89 feet per side
and fed with 450 ohm feedline and it works 10 thru 160 meters via the
tuner.

73 - Rick McKee, KC8AON
Southern Ohio - EM88sn
www.angelfire.com/electronic2/qrp
With God all things are possible ~ ><(('> ~
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