K2 s/n 4276 Output Power Instability

[Robert 'RC' Conley]

Okay Dave thanks
I saved all your information and it looks like I found something I can
work on this winter. Just about anything can be used to build the open
wire feeders and If your using the KAT2 a tuner would not be needed
but without a KAT2 a manual tuning "Z" match would do the job. It
looks like it will be fun to work with..
RC kc5wa


On Nov 16, 2007 4:05 PM, Dave Van Wallaghen <[hidden email]> wrote:

> >
> > The only question left is What is "Plastic Dip". Tthis is something
> > I've never heard of.
> > I have a lot of in formation on the "Z" match. A kit is available from
> > <http://www.qrpkits.com/norcal_blt.htm> Doug Kendricks
> >
>
> I got it at Home Depot as well. The can I have is called "Plasti Dip" it is
> made by a company called Perfomix.
>
> It is a multi-purpose rubber coating. I've seen it used in the past to put
> new rubber handles on tools as they became worn off. It is pretty flammable
> and vaporous. It sets up in about 30 minutes - allow 4 hours until use. It
> comes in a few different colors also.
>
> I don't see a price on the can I have - I want to say it was 4 or 5 bucks
> for a 15oz can. I did over 50 feet of feedline with around a half a can.
>
> 73,
> Dave W8FGU
>
>

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[David Woolley (E.L)]

Ron D'Eau Claire wrote:
> needed to produce a balanced "feed" is a length of transmission line (1/4
> wave or so) and a balanced load. If you have those things, it doesn't matter

Note that this is "approximately", not "at least".  Ignoring losses, a
half wave would be ineffective.

> whether the output from the rig is "single ended" or "balanced", the
> currents at the balanced load, such as the center of a dipole, will be
> balanced.
>
> All a "balun" does is wind up that feed line in a smaller, tidier package so

A [1:1 current] balun does rather more than that.  Firstly, the coiling
increases the inductance, so ignoring mutual capacitance changes and
that the inductance is behaving in a lumped way, L/C will increase and
therefore the common mode characteristic impedance will be much more
than the 620 or so ohms of a single wire feeder in free space.

Secondly, the radiation resistance will be much less than the 35 or so
ohms of a quarter wave of feeder in common mode, so it won't be
distorting the radiation pattern or picking up local noise.

The core material may be lossy, which also means that the common mode
signal will be dissipated as heat, which would only really happen for
the cable length if it were buried in the ground.

> The un-importance of balance is shown in popular antennas like the G5RV,

The G5RV *is* balanced at the radio side input to the ladder line.

> One important issue to remember is that a passive device is *not* a lossless
> device. Passive devices, like baluns, all have losses.

They also have finite inductance, etc., so it is true that the real
world is more complicated than an ideal balun.

--
David Woolley
Emails are not formal business letters, whatever businesses may want.
RFC1855 says there should be an address here, but, in a world of spam,
that is no longer good advice, as archive address hiding may not work.
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[Dave Van Wallaghen]

No problem RC. You're right, you can probably use just about anything
non-conductive for the ladder line spacing. I've been toying with the idea
of using polycarbonate tubing for something really durable. I use Lexan, a
polycarbonate, to build enclosures for some of the Elecraft mini-modules.
(In fact, I've been prototyping an enclosure for my HexKey all afternoon). I
get the Lexan from Home Depot, but all the other plastic supplies from a
place called Tap Plastics ( http://www.tapplastics.com/ ). They sell
polycarbonate tubing which I think would make great spacers for open wire
feedline.

I would like to build a long doublet with open wire feedline from insulated
14 of 12g wire. I think that using this polycarbonate tubing with a spacing
of around 6" would be ideal and very durable (and certainly usable for more
than QRP purposes). I just haven't yet figured out how to secure the wire to
the tubing yet. The plasti dip would probably be ok, but I need to explore
some other methods I think.

Good luck & 73,
Dave W8FGU

> -----Original Message-----
> From: Robert 'RC' Conley [mailto:[hidden email]]
> Sent: Friday, November 16, 2007 5:23 PM
> To: Dave Van Wallaghen
> Cc: [hidden email]
> Subject: Re: [Elecraft] Re: KAT100 with Ladder Line
>
> Okay Dave thanks
> I saved all your information and it looks like I found something I can
> work on this winter. Just about anything can be used to build the open
> wire feeders and If your using the KAT2 a tuner would not be needed
> but without a KAT2 a manual tuning "Z" match would do the job. It
> looks like it will be fun to work with..
> RC kc5wa
>
>
> On Nov 16, 2007 4:05 PM, Dave Van Wallaghen <[hidden email]> wrote:
> > >
> > > The only question left is What is "Plastic Dip". Tthis is something
> > > I've never heard of.
> > > I have a lot of in formation on the "Z" match. A kit is available from
> > > <http://www.qrpkits.com/norcal_blt.htm> Doug Kendricks
> > >
> >
> > I got it at Home Depot as well. The can I have is called "Plasti Dip" it
> is
> > made by a company called Perfomix.
> >
> > It is a multi-purpose rubber coating. I've seen it used in the past to
> put
> > new rubber handles on tools as they became worn off. It is pretty
> flammable
> > and vaporous. It sets up in about 30 minutes - allow 4 hours until use.
> It
> > comes in a few different colors also.
> >
> > I don't see a price on the can I have - I want to say it was 4 or 5
> bucks
> > for a 15oz can. I did over 50 feet of feedline with around a half a can.
> >
> > 73,
> > Dave W8FGU
> >
> >

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[Don Wilhelm-4]

Peter,

Antenna and transmission line behavior is a strange 'animal' that does
not mesh with our normal thoughts of electron flow in wires.   It is
indeed a complex subject that must be considered in 4 dimensions to be
fully analyzed, and our brains think in only 3 dimensions.  How an
electromagnetic wave is launched from an antenna is at the heart of the
full answer to your question.  The attempt to get the RF to the antenna
is the task of the transmission line.  A transmission line (hopefully)
keeps the RF contained until it reaches the antenna by maintaining a
balanced condition (equal and opposite RF currents) all along its length.

I like to think that the major thing that determines the balance of an
antenna system more than any other factor is the ends of the antenna -
there the current must be zero and the voltage must be high - the laws
of physics demand that.  With a center fed antenna, balance is carried
on the antenna wires to the center feedpoint if the antenna has symmetry
with its environmental surroundings.
If you connect a balanced feedline at the antenna feedpoint, that
balance should be preserved throughout the system until you get to the
balanced transmission line end.

Note that even coax is a 'balanced line' - if one considers only the
center conductor and the *inside* of the shield - the RF currents inside
a coax line are equal and opposite which is the definition of balanced.  
It is only the outside of the coax that makes it 'unbalanced' - in other
words, the outside of the coax shield can be an extraneous conductor in
space and if steps are not taken to prevent the RF current from getting
onto the outside of the shield, it too will act as part of the antenna -
this is the main function of a feedpoint balun used on a coax fed antenna.

If you follow those thoughts, you can see that balanced RF current *can*
and does flow out of the output of the tuner SO239 jack - so connecting
ladder line directly to that jack *is* a workable situation.  You may
have to experiment with the line length a bit to assure that you are not
feeding the line at a point of high RF voltage where leakage may be
significant, but that is all that may be required.  Most folks do not
want to go to the trouble of refining the transmission line length to
create the proper conditions, and for those situations, the balun is an
easy way out.

In other words - I believe that RF balance is a condition of the
physical and electrical nature in the antenna system, no matter what the
driving source (transceiver and ATU) might be.

Consider also that a ground wire to mother earth may not be a very good
RF Ground and the situation becomes more complex - in other words, RF
voltage can 'float' on a DC ground with no problem.  Connecting a ground
wire to the tuner may not change the amount of RF in the shack
significantly unless that ground wire is also an RF ground.  The
function of a balun at the point where the balanced line is attached is
similar to the function of a balun used at the antenna end of the coax
feed - it is there to keep the RF voltage from flowing back onto the DC
grounded part of the driving system, but if the RF voltage at the
attachment point is already zero (or very low), the balun will not have
much to accomplish and could even be eliminated.

So if you do not have RF in the shack (due to RF voltage floating on the
DC Ground), you have an installation where the balun at the tuner can be
eliminated.  You may or may not be able to achieve all the right
conditions in a multiband antenna/feedline setup, but you can make an
attempt.

I would suggest that you measure the RF current in each leg of your
feedline to determine if the direct connection to the KAT2 changes the
line balance situation.  If it changes the line balance significantly,
then use a balun or alter the feedline length to reduce the RF voltage
at the shack end.

Using a balun at a point where the reactance is high can cause losses,
but where the reactance is low, inserting a good balun will not create
significant loss.

Many 'old wives tales' and myths come from using baluns arbitrarily and
trying to make it a 'cure-all' for all antenna system ills.

73,
Don W3FPR

Peter Wollan wrote:

> Please, I'd like some more discussion of this question.  I've seen
> before that baluns on ladder line can be lossy, but I'm not about to
> get a balanced tuner, so it doesn't really help.  What happens if you
> connect the balanced line directly to the KAT100?  Or, in my case, to
> the KAT2?  I haven't had any problems so far -- maybe low power makes
> a big difference, or maybe I've just had antennas which were
> reasonable in some way.  I gather it's possible to get unpleasant
> currents on the case, mic, or paddle.  Is that exactly the condition
> in which the balun will be lossy?  Does connecting the ground screw on
> the KAT2 (or the one on the balun?) alleviate the common mode current
> problems?
>
>

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[Darrell Bellerive-2]

On Friday 16 November 2007 09:39, Ron D'Eau Claire wrote:
> On-air tests are meaningless to evaluate the effect
> since a few milliwatts can make it around the world at times and result in
> a nice signal report on almost any frequency in the HF spectrum. It's easy
> to throw away 50%, 75% or even more of the transmitter's power in losses
> and be completely unable to detect it by evaluating how easy or hard it is
> to make on-air contacts.

Shhh... Don't tell those QRO stations that they are really running QRP. :-)

--
Darrell Bellerive
Amateur Radio Stations VA7TO and VE7CLA
Grand Forks, British Columbia, Canada
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[AC7AC]

CONTENTS DELETED

The author has deleted this message.

[Darrell Bellerive-2]

On Friday 16 November 2007 08:37, Solosko, Robert B (Bob) wrote:
> Since at 100w, a
> significant mismatch could cause the balun to heat, I made my own
> current balun using a pair of FT43-240 cores which has a much higher
> capacity than the small core used in the BL2

A larger heat sink will make the heat less apparent as it is better
distributed and dispersed, but the efficiency would still be the same. A
smaller object heated by the same amount of energy will be hotter.

The larger core would be more resistant to saturation, but if you are near the
point of saturation, then you really have other problems that need to be
dealt with.

--
Darrell Bellerive
Amateur Radio Stations VA7TO and VE7CLA
Grand Forks, British Columbia, Canada
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[Darrell Bellerive-2]

On Friday 16 November 2007 14:22, Robert 'RC' Conley wrote:
> Okay Dave thanks
> I saved all your information and it looks like I found something I can
> work on this winter. Just about anything can be used to build the open
> wire feeders and If your using the KAT2 a tuner would not be needed
> but without a KAT2 a manual tuning "Z" match would do the job. It
> looks like it will be fun to work with..
> RC kc5wa

There are trade offs and compromises with each type of antenna system tuner.

Here are some factors to be considered in an antenna system tuner:
Frequency range,
Matching range,
Efficiency,
Common mode current suppression,
Isolation,
Harmonic and/or spurious emission suppression or out of band rejection,
Ease of operation,
Physical size,
Price,
Number and type of feedline terminations,
Balance in the case of balanced tuners,
and more that don't immediately come to mind.

There is no one best tuner.

Unfortunely most tuners on the market today are sold on the basis of ease of
operation, flexibility, and price.

Reviews of tuners generally follow suit. It was good to see the ARRL publish
efficiencies in their test of balanced tuners a while back. It was a step in
the right direction. Even that though was only for pure resistive loads. A
comprehensive test of a tuner would be quite a process.

The big problem as I see it is that those who buy the tuners don't realize the
tradeoffs they have gotten. After all it tunes to a 1:1 SWR and contacts can
be made, so it must be working well. The reality could be quite different.


--
Darrell Bellerive
Amateur Radio Stations VA7TO and VE7CLA
Grand Forks, British Columbia, Canada
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[Gregg W6IZT]

K3 s/n 47 arrived in Marietta GA on 11/15.


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[Brett Gazdzinski]

I use #12 insulated wire (scrap from work) and plastic spreaders made from
cut cable supports for wires/cables to be wire tied to in telco racks, (also
scrap)
and to hold the wire to the spreaders I just use plastic wire ties (also
scrap).

You dont need many, one every foot or more is fine, everything is insulated
as its plastic covered wire.

My current setup has been up about a year and looks new so far.

My cost was totaly zero for vurtualy zero loss on the feedline.

I use a G5RV type setup as I have not made a balanced tuner yet, and have
about 15 feet of RG214 modified (UV proof) between the tuner and the open
wire
line. It seems to work 80 to 10 meters ok, at least it tunes up ok and even
with full bore AM I have no problems on 80 or 40, I have not tried it
on other bands on AM.

The AM crowd seems to prefer open wire line, balanced tuners, and
as much wire in the air, and as high up as they can get it.

Brett
N2DTS



----- Original Message -----
From: "Dave Van Wallaghen" <[hidden email]>
To: "'Robert 'RC' Conley'" <[hidden email]>
Cc: <[hidden email]>
Sent: Friday, November 16, 2007 5:41 PM
Subject: RE: [Elecraft] Re: KAT100 with Ladder Line


> No problem RC. You're right, you can probably use just about anything
> non-conductive for the ladder line spacing. I've been toying with the idea
> of using polycarbonate tubing for something really durable. I use Lexan, a
> polycarbonate, to build enclosures for some of the Elecraft mini-modules.
> (In fact, I've been prototyping an enclosure for my HexKey all afternoon).
I
> get the Lexan from Home Depot, but all the other plastic supplies from a
> place called Tap Plastics ( http://www.tapplastics.com/ ). They sell
> polycarbonate tubing which I think would make great spacers for open wire
> feedline.
>
> I would like to build a long doublet with open wire feedline from
insulated
> 14 of 12g wire. I think that using this polycarbonate tubing with a
spacing
> of around 6" would be ideal and very durable (and certainly usable for
more
> than QRP purposes). I just haven't yet figured out how to secure the wire
to
> the tubing yet. The plasti dip would probably be ok, but I need to explore
> some other methods I think.
>
> Good luck & 73,
> Dave W8FGU

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[AC7AC]

CONTENTS DELETED

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[Don Wilhelm-4]

Yes, I fear that many hams do not realize how much loss is being
introduced by their tuners.  It has been stated that MFJ makes good
tuners, but my experience with their MFJ-963D and the MFJ-971 tuners say
otherwise - the inductor is mounted too close to the enclosure which
reduces the inductor Q and thereby reduces the efficiency.  BTW, there
is no real need to have the tuner inside an RF proof enclosure, a tuner
will not introduce harmonics or other spurious responses that have been
adequately suppressed by the transceiver - a tuner built on a plain
wooden board will work just great.
The fact that there are tuners and then there are tuners is true
indeed.  The easy to manufacture T network tuners can have multiple
setting combinations that produce a low SWR at the input, but many of
those combinations will have a high loss factor due to RF currents
circulating through the inductor.  This is a recognized problem with the
easy to implement T section tuners.  The PI section and L network tuners
do not have that ambiguity, but the only PI section tuner that I know of
is the old Collins tuner - it is almost as efficient as the classic link
coupled tuners, but due to the range of practical variable capacitors,
its matching range is limited - the L network tuners similar to the
Elecraft design are much more flexible and have a wide matching range.

Every tuner design has its limitations.  The T section, L network, and
PI network tuner designs are nothing more than a transmission line
section implemented with lumped components - the limits are defined by
the range of adjustment for each of the components, and bandswitching
with these designs is not difficult although the Pi network tuner does
have limitations due to practical capacitor values.  Iin bandswitching
tuners, the L network is the most efficient - the Elecraft tuners all
use the L network configuration.

The link coupled tuner is usually the most efficient, but does not lend
itself easily to bandswitching (the Johnson Matchbox is one link coupled
bandswitching design that works well, but even it has a limited matching
range).  When the going gets tough, I fall back onto the classic link
coupled tuners - they are the most efficient by far, but the use of
plug-in coils for bandswitching is a drawback to many hams.  With
renewed interest in low loss tuners, it may be time to accept the
reality that efficiency must be sacrificed for the convenience of
bandswitching designs.   Unfortunately, there is no one correct answer,
each situation must accept its own consequences.  I myself use the
KPA100 in the shack for fine tuning of my coax fed resonant antennas at
power levels up to 100 watts and an MFJ-962 tuner for times that I add
the linear.  It is a compromise, but it does work well for me. Since I
cannot have open wire line coming into the hamshack, any link coupled
tuners must be fixed tuned and located remotely (relay switched).  That
is not fully implemented yet, but is in the planning stages.

73,
Don W3FPR

Darrell Bellerive wrote:
> The big problem as I see it is that those who buy the tuners don't realize the
> tradeoffs they have gotten. After all it tunes to a 1:1 SWR and contacts can
> be made, so it must be working well. The reality could be quite different.
>
>  
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[Joe-aa4nn]

The tedious part of making your own ladder line is to keep the
spacing uniform.  Spacing is very critical for closely spaced wires
like for 450 ohm or so; whereas, wider spacing like 6 inches
for 600 ohm using #12 wire is quite a bit more forgiving.  Some
good information about open wire is at:

http://www.cebik.com/trans/par.html 
http://www.cebik.com/gup/gup31.html 

For spacers, consider using lexan strips 1 inch wide by 6.5
inches long.  Place the wire on center at one end and heat
it with a soldering gun until the wire melts 1/4 inch into the
lexan.  Messy but maybe quicker than drilling 1000 holes.

de Joe, aa4nn


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[wolfmanjack]

Wonder which call letters I should be keeping an ear out for in Sweepstakes...

If your K3 will be active, please let us know...

Thanks!

John K7FD
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[Craig Rairdin]

NZ0R #25

Craig

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of
[hidden email]
Sent: Saturday, November 17, 2007 9:28 AM
To: [hidden email]
Subject: [Elecraft] Who will be running a K3 in SS today/tomorrow?



Wonder which call letters I should be keeping an ear out for in
Sweepstakes...

If your K3 will be active, please let us know...

Thanks!

John K7FD
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[Matt Zilmer]

K3 s/n 24
WA6EGJ

matt


On Sat, 17 Nov 2007 07:27:44 -0800, you wrote:

>
>Wonder which call letters I should be keeping an ear out for in Sweepstakes...
>
>If your K3 will be active, please let us know...
>
>Thanks!
>
>John K7FD
>_______________________________________________
>Elecraft mailing list
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>
>Help: http://mailman.qth.net/subscribers.htm
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[Joe-aa4nn]

It can be quite tedious to build one's own ladder line.  Wire size and
spacing between wires is a critical factor in determining the resulting
impedance of the line.  Maintaining consistent spacing between wires
is difficult.  For closely spaced wires (eg. 1.5 to 2.0 inch for 450 ohm)
slight variations in spacing is very critical to maintaining consistent
impedance; whereas for 6 inch spacing there is less effect on impedance
with slight variations in spacing.  Eg. 6  inch spacing using #12 wire will
give approximately 600 ohm open wire feeders.  More info at:

http://www.cebik.com/trans/par.html
http://www.cebik.com/gup/gup31.html

I find lexan difficult to cut due to the low melting point and clogged
saw teeth.  Plexiglass is a little bit better.  I would opt for the smallest
PVC pipe, cut into 6.5 inch lengths.  Cut a 1/4 inch depth notch in
either end wide enough to accept #12 wire.  Use a band saw, scroll
saw or hand held saber saw.  After inserting the wire in the PVC,
put a dab of Marine Glue and Sealant on there, or other quick drying
adhesive.
de Joe, aa4nn

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[Jeff Stai]

WK6I #27, all audio reports good and bad are welcome - I'll be trying different stuff - j
--
Jeff Stai               [hidden email]
Twisted Oak Winery      http://www.twistedoak.com/
Winery Blog             http://www.elbloggotorcido.com/
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[Craig Smith]

<> It can be quite tedious to build one's own ladder line.  Wire size and
<> spacing between wires is a critical factor in determining the resulting
<> impedance of the line.  Maintaining consistent spacing between wires
<> is difficult.  

All of this is quite true.  But let me play devil's advocate.  I maintain
that keeping a constant impedance (and hence spacing) is not at all
important.  The impedance of the line could vary over a wide range (200 to
600 ohms, to pick some numbers) along the length of the line and the most
important characteristics would still be conserved.  1) The line would still
be low loss.  2)  At any given point along the line current balance would
still be maintained, even if the spacing was different than at another
point.

Most of us do NOT depend on the characteristic impedance of the ladder line
to do an exact impedance transformation from the antenna to the rig.
Rather, we use a tuning network at the transmitter end of the ladder line to
do the needed impedance transformation.  All a variable spacing on the
ladder line means, in pragmatic terms, is a slightly different setting of
the antenna tuner.

I've built only one ladder line recently and the construction technique
resulted in perhaps a +/- 20% variance in the spacing along the line.  It
works just fine.

        73
               ... Craig  AC0DS




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[Don Wilhelm-4]

I have not seen it mentioned yet, but the best installation of open wire
line will tension the conductors between 2 supports.  That means fewer
spacers are required because the tensioned wires do not sway as much in
the wind.

For my part, PVC spacers are easy to construct and inexpensive.

73,
Don W3FPR

Joe-aa4nn wrote:

> It can be quite tedious to build one's own ladder line.  Wire size and
> spacing between wires is a critical factor in determining the resulting
> impedance of the line.  Maintaining consistent spacing between wires
> is difficult.  For closely spaced wires (eg. 1.5 to 2.0 inch for 450 ohm)
> slight variations in spacing is very critical to maintaining consistent
> impedance; whereas for 6 inch spacing there is less effect on impedance
> with slight variations in spacing.  Eg. 6  inch spacing using #12 wire
> will
> give approximately 600 ohm open wire feeders.  More info at:
>
> http://www.cebik.com/trans/par.html
> http://www.cebik.com/gup/gup31.html
>
> I find lexan difficult to cut due to the low melting point and clogged
> saw teeth.  Plexiglass is a little bit better.  I would opt for the
> smallest
> PVC pipe, cut into 6.5 inch lengths.  Cut a 1/4 inch depth notch in
> either end wide enough to accept #12 wire.  Use a band saw, scroll
> saw or hand held saber saw.  After inserting the wire in the PVC,
> put a dab of Marine Glue and Sealant on there, or other quick drying
> adhesive.
> de Joe, aa4nn
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