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Today's Topics:
1. Re: Hairpin Matching Coil Questions - "Shunt"? (Jim GM)
2. 'Hairpin' matching (Tom Boucher)
3. Re: Hairpin Matching Coil Questions - "Shunt"? (Tom W8JI)
4. 'Hairpin' matching (Tom Boucher)
5. AutoEZ v2 with Optimizer (Dan Maguire)
6. Re: 'Hairpin' matching (Charlie Cunningham)
7. Re: Measuring Vertical input parameters while installing
radials (Eduardo Araujo)
8. Re: AutoEZ v2 with Optimizer (Charlie Cunningham)
9. Re: 'Hairpin' matching (John Chappell G3XRJ)
10. Re: Measuring Vertical input parameters while installing
radials (Charlie Cunningham)
11. Re: elevated radials (Mike Waters)
----------------------------------------------------------------------
Message: 1
Date: Thu, 19 Sep 2013 13:25:02 -0500
From: Jim GM <jim.gmforum@gmail.com>
To: topband <topband@contesting.com>
Subject: Re: Topband: Hairpin Matching Coil Questions - "Shunt"?
Message-ID:
<CAD+2Gyv-O=LHuK6fNhwmERocfAJKc+ZGXNSkWZvQ+yLaqPB4Zg@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
Thankyou Charlie.
I got those Q numbers from
http://www.m0ukd.com/Calculators/air_core_inductor_calculator/
Maybe a decimal point was left out.
Thanks Tom
--
Jim K9TF
------------------------------
Message: 2
Date: Thu, 19 Sep 2013 19:52:33 +0100
From: "Tom Boucher" <tom@telemetry.demon.co.uk>
To: "160 reflector" <topband@contesting.com>
Subject: Topband: 'Hairpin' matching
Message-ID: <B5E21A6FDAC14C5CB33D4039811252CC@Tom>
Content-Type: text/plain; charset="iso-8859-1"
Just to add a comment on this thread:
I do not use an inductor to match my inverted 'L', just a capacitor from
coax centre/bottom of wire to the radial point. Further I do not use big
wide space 'toast-rack' Cs, but tiny ceramic ones rated at 6.3KV which
will handle very decent amounts of power and are readily available over
here. They seem to handle the high currents at the bottom of the quarter
wave 'L' quite happily.
I measure the impedance at resonance of the antenna without any matching
network, then use
www.sandiego.edu/~ekim/e194rfs01/jwmatcher2.html
to calculate the L-network values needed. Fit the parallel capacitor then
lengthen the antenna slightly to bring it back to the required frequency.
This provides the inductance necessary for the L-network.
Needless to say, your MFJ, or Palstar ZM-30 in my case, antenna analyser
will probably give you the wrong sign for the reactive part of the
antenna's impedance. This had me going for a long time before I realised
the problem! Check this by moving the analyser frequency LF from resonance
and the impedance should show -jX (capacitive). Moving the analyser HF
from resonance should show inductive reactance (+jX).
My inverted 'L' needs 1600pF to give me 50 + j0.
I have also made switched L-networks to successfully resonate the same
antenna on some other bands.
73
Tom G3OLB
------------------------------
Message: 3
Date: Thu, 19 Sep 2013 16:22:57 -0400
From: "Tom W8JI" <w8ji@w8ji.com>
To: "Jim GM" <jim.gmforum@gmail.com>, "topband"
<topband@contesting.com>
Subject: Re: Topband: Hairpin Matching Coil Questions - "Shunt"?
Message-ID: <3F7B5C34343645EF9DDACB0DCBFC62E3@MAIN>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
Thankyou Charlie.
I got those Q numbers from
http://www.m0ukd.com/Calculators/air_core_inductor_calculator/
Maybe a decimal point was left out.
Jim,
I thought something was misleading you somewhere.
Be careful with online calculators. The one in the link uses pi out to 39
places (which might give the impression of accuracy), but omits many far
more critical, important, parameters. It is a very rough guess that might
be
a mile off, even though the publisher implies accuracy. They would be
better
off to just use "3.1" for Pi, and add in some more important things.
One way to evaluate an inductor calculator for design omissions is to see
if
it asks for:
1.) Insulation thickness and type
2.) Turns spacing
3.) Form material
4.) Conductor size
5.) Form length
6.) Form diameter
That one grossly fails. It doesn't ask for several important things.
To check the calculator for function, start taking a large coil up higher
in
frequency. If you get weird results like progressively increasing Q that
goes over 1000 for normal good conductors, extreme inductance values (like
values near whole Henries at HF and higher), the calculator is likely just
junk.
That one completely fails. It obviously does not consider turn-to-turn
capacitance, skin effect, materials, or internal resonances, because I can
"make" door bell wire inductors with Q's in the thousands and almost a
Henry
of inductance on 50 MHz!!
Since it doesn't ask for enough things and obviously ignores many
important
traits of inductors, it is unreliable. It might work in some cases by pure
luck, but who knows when it could be trusted!!
Things like that can send you down the wrong path, and cause you to start
giving out wrong numbers.
73 Tom
------------------------------
Message: 4
Date: Fri, 20 Sep 2013 07:25:18 +0100
From: "Tom Boucher" <tom@telemetry.demon.co.uk>
To: "160 reflector" <topband@contesting.com>
Subject: Topband: 'Hairpin' matching
Message-ID: <B2F6B0749DD74038A2250A2A0D97A705@Tom>
Content-Type: text/plain; charset="iso-8859-1"
The excellent web site for calculating matching network values should have
been:
http://home.sandiego.edu/~ekim/e194rfs01/jwmatcher/matcher2.html
not the one I posted yesterday.
73,
Tom G3OLB
------------------------------
Message: 5
Date: Fri, 20 Sep 2013 01:48:17 -0700 (PDT)
From: Dan Maguire <djm2150@yahoo.com>
To: topband@contesting.com
Subject: Topband: AutoEZ v2 with Optimizer
Message-ID:
<1379666897.77410.YahooMailBasic@web125405.mail.ne1.yahoo.com>
Content-Type: text/plain; charset=us-ascii
AutoEZ is an Excel application that lets you automate the use of EZNEC.
Version 2 is now available. Major changes are 1) an optimizer, 2) new
"Create" dialog windows to easily build common antenna configurations, and
3) faster calculation speeds.
The AutoEZ home page with revised documentation is here:
http://ac6la.com/autoez.html
For a complete list of all changes since v1 see:
http://ac6la.com/aenewforv2.html
A free demo version of AutoEZ is available for download. The demo
includes the optimizer feature.
Dan, AC6LA
------------------------------
Message: 6
Date: Fri, 20 Sep 2013 08:15:51 -0400
From: "Charlie Cunningham" <charlie-cunningham@nc.rr.com>
To: "'Tom Boucher'" <tom@telemetry.demon.co.uk>, "'160 reflector'"
<topband@contesting.com>
Subject: Re: Topband: 'Hairpin' matching
Message-ID:
<!&!AAAAAAAAAAAYAAAAAAAAAF0xXac1rOhFkn7GlcEWNIjCgAAAEAAAACgK5fVIF41BlN+usQG1Cv4BAAAAAA==@nc.rr.com>
Content-Type: text/plain; charset="us-ascii"
Very nice to have all of those collected into one place!
Thanks for sharing, Tom! Have a god day!
73,
Charlie, K4OTV
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of Tom
Boucher
Sent: Friday, September 20, 2013 2:25 AM
To: 160 reflector
Subject: Topband: 'Hairpin' matching
The excellent web site for calculating matching network values should have
been:
http://home.sandiego.edu/~ekim/e194rfs01/jwmatcher/matcher2.html
not the one I posted yesterday.
73,
Tom G3OLB
_________________
Topband Reflector
------------------------------
Message: 7
Date: Fri, 20 Sep 2013 05:31:47 -0700 (PDT)
From: Eduardo Araujo <er_araujo@yahoo.com>
To: Topband <topband@contesting.com>
Subject: Re: Topband: Measuring Vertical input parameters while
installing radials
Message-ID:
<1379680307.68664.YahooMailNeo@web160703.mail.bf1.yahoo.com>
Content-Type: text/plain; charset=iso-8859-1
Hi friends,
??????????????? I finished sending the measurements data to all that
requested it. In case somebody didn?t receive it yet, please let me know.
Even though I did not mention it before, I also have Field Strength
measurement synchronized in time with the AIM measurements.
As surely this was not a professional procedure, I will explain how I did
it and you may judge if it is useful for you or not.
- I installed 2 verticals antennas 3 mts long, at about 300-350 meters
from the tower base in two opposite directions. So measurement was done at
ground level.
- I did not tuned up the elements in any way, they were connected to the
FS instrument directly and as ground connection I used a 50 cm aluminum
pipe buried in the ground
- As a FS meter I used a DIGI - FIELD from IC- Engineering
- First 2 radials were installed more or less in the direction of the RX
verticals
- From there, they were installed consecutive in counter-clock wise. (look
from above)
- I used 20W at 1840 during daylight, and matched the antenna input for
every change in radial number. I used an MFJ-962B for this purpose.
- After all readings were done, I calibrate the readings against an
HP-8640B signal to visualize which was the change in db
Botton line - the measured change at ground level between 2 and 114
radials was between 5.2 in one direction and 5.8 db to the other.
I understand this is not a professional procedure nor professional
equipment and it was done having fun enjoying the hobby.
I will like to hear from you your thought about if this kind of
measurement done at ground level and at that distance from the antenna
base has a correlation to actual radiated Field at the maximum vertical
azimuth of the vertical whichever it is.
And, also, How the procedure or elements I used could be improved
....still within amateur measurement accuracy and not professional level.
'73 to all..... Eddie, LU2DKT
----------------------------------------------------------------------------------------------------------------
From: Eduardo Araujo <er_araujo@yahoo.com>
To: Topband <topband@contesting.com>
Sent: Thursday, September 12, 2013 9:28 AM
Subject: Measuring Vertical input parameters while installing radials
Hi everyone, I recently complete the installation of +100 1/4 radials for
the 1/4 vertical.
I measured input vertical parameters using AIM4170 from 1600 to 2000Kc
I assumed it is not something new for many of you, but I wonder if the
information I collected may be of interest for some of the group members.
I have available for sharing BMP or JPG images of each scan which were run
at 2, 4, 8, 16, 32, 60 and +110 radials. Also, I have the .scn files for
each scan which could be viewed using AIM4170 SW even though you don?t
have the unit.
The good thing looking at the files using the sw is that you can move the
cursor and have all the values at all fcies from 1600-2000 Kc
In case someone is interested, let me know and I will see the way to share
it.
?73 to everyone.... Eddie, LU2DKT
PS: By the way, what a nice toy the AIM !!!, Even though I bought it more
than one year ago, this is the first time I use it
------------------------------
Message: 8
Date: Fri, 20 Sep 2013 08:38:44 -0400
From: "Charlie Cunningham" <charlie-cunningham@nc.rr.com>
To: "'Dan Maguire'" <djm2150@yahoo.com>, <topband@contesting.com>
Subject: Re: Topband: AutoEZ v2 with Optimizer
Message-ID:
<!&!AAAAAAAAAAAYAAAAAAAAAF0xXac1rOhFkn7GlcEWNIjCgAAAEAAAADW4NUZikEVNrR4r+1pbfH4BAAAAAA==@nc.rr.com>
Content-Type: text/plain; charset="us-ascii"
Thanks for sharing, Dan! I've used EZNEC a LOT over the years, and I've
done
a lot of useful work with it, but I was unaware of AutoEZ. I'll look into
it
and maybe investigate the paid version as well.
Thanks, and have a good day!
73,
Charlie, K4OTV
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of Dan
Maguire
Sent: Friday, September 20, 2013 4:48 AM
To: topband@contesting.com
Subject: Topband: AutoEZ v2 with Optimizer
AutoEZ is an Excel application that lets you automate the use of EZNEC.
Version 2 is now available. Major changes are 1) an optimizer, 2) new
"Create" dialog windows to easily build common antenna configurations, and
3) faster calculation speeds.
The AutoEZ home page with revised documentation is here:
http://ac6la.com/autoez.html
For a complete list of all changes since v1 see:
http://ac6la.com/aenewforv2.html
A free demo version of AutoEZ is available for download. The demo
includes
the optimizer feature.
Dan, AC6LA
_________________
Topband Reflector
------------------------------
Message: 9
Date: Fri, 20 Sep 2013 15:05:25 +0100
From: John Chappell G3XRJ <john@g3xrj.com>
To: topband@contesting.com
Subject: Re: Topband: 'Hairpin' matching
Message-ID: <523C5625.7070905@g3xrj.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Just measured the 'hairpin' coil for my 160m 38 foot top loaded - coil
and 2 x 18 foot wires - antenna.
Feedpoint impedance without match is 12 ohms.
Placing shunt coil to ground of 1.7microH and tx sees 50 ohm 1:1.
Only problem with the vertical being so short the bandwidth is only 12
khz between 2:1 points.
John G3XRJ
The excellent web site for calculating matching network values should
have been:
http://home.sandiego.edu/~ekim/e194rfs01/jwmatcher/matcher2.html
not the one I posted yesterday.
73,
Tom G3OLB
_________________
Topband Reflector
------------------------------
Message: 10
Date: Fri, 20 Sep 2013 10:10:33 -0400
From: "Charlie Cunningham" <charlie-cunningham@nc.rr.com>
To: "'Eduardo Araujo'" <er_araujo@yahoo.com>, "'Topband'"
<topband@contesting.com>
Subject: Re: Topband: Measuring Vertical input parameters while
installing radials
Message-ID:
<!&!AAAAAAAAAAAYAAAAAAAAAF0xXac1rOhFkn7GlcEWNIjCgAAAEAAAAEGDM6c6gmhMhtQKwGvBo8IBAAAAAA==@nc.rr.com>
Content-Type: text/plain; charset="iso-8859-1"
Hi, Eddie
Nicely done! Looks reasonably professional to me! At the very least,
you've made a good effort to quantify your results in a meaningful and
repeatable way, with decent tools. No need to tune your sense antennas,
as
long as there is enough signal level and dynamic range for your FS
measurements.
Congrats on having mad some meaningful quantitative measurements! Thanks
for
sharing!
73,
Charlie, K4OTV
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of Eduardo
Araujo
Sent: Friday, September 20, 2013 8:32 AM
To: Topband
Subject: Re: Topband: Measuring Vertical input parameters while installing
radials
Hi friends,
??????????????? I finished sending the measurements data to all that
requested it. In case somebody didn?t receive it yet, please let me know.
Even though I did not mention it before, I also have Field Strength
measurement synchronized in time with the AIM measurements.
As surely this was not a professional procedure, I will explain how I did
it
and you may judge if it is useful for you or not.
- I installed 2 verticals antennas 3 mts long, at about 300-350 meters
from
the tower base in two opposite directions. So measurement was done at
ground
level.
- I did not tuned up the elements in any way, they were connected to the
FS
instrument directly and as ground connection I used a 50 cm aluminum pipe
buried in the ground
- As a FS meter I used a DIGI - FIELD from IC- Engineering
- First 2 radials were installed more or less in the direction of the RX
verticals
- From there, they were installed consecutive in counter-clock wise. (look
from above)
- I used 20W at 1840 during daylight, and matched the antenna input for
every change in radial number. I used an MFJ-962B for this purpose.
- After all readings were done, I calibrate the readings against an
HP-8640B
signal to visualize which was the change in db
Botton line - the measured change at ground level between 2 and 114
radials
was between 5.2 in one direction and 5.8 db to the other.
I understand this is not a professional procedure nor professional
equipment
and it was done having fun enjoying the hobby.
I will like to hear from you your thought about if this kind of
measurement
done at ground level and at that distance from the antenna base has a
correlation to actual radiated Field at the maximum vertical azimuth of
the
vertical whichever it is.
And, also, How the procedure or elements I used could be improved
....still
within amateur measurement accuracy and not professional level.
'73 to all..... Eddie, LU2DKT
----------------------------------------------------------------------------
------------------------------------
From: Eduardo Araujo <er_araujo@yahoo.com>
To: Topband <topband@contesting.com>
Sent: Thursday, September 12, 2013 9:28 AM
Subject: Measuring Vertical input parameters while installing radials
Hi everyone, I recently complete the installation of +100 1/4 radials for
the 1/4 vertical.
I measured input vertical parameters using AIM4170 from 1600 to 2000Kc
I assumed it is not something new for many of you, but I wonder if the
information I collected may be of interest for some of the group members.
I have available for sharing BMP or JPG images of each scan which were run
at 2, 4, 8, 16, 32, 60 and +110 radials. Also, I have the .scn files for
each scan which could be viewed using AIM4170 SW even though you don?t
have
the unit.
The good thing looking at the files using the sw is that you can move the
cursor and have all the values at all fcies from 1600-2000 Kc
In case someone is interested, let me know and I will see the way to share
it.
?73 to everyone.... Eddie, LU2DKT
PS: By the way, what a nice toy the AIM !!!, Even though I bought it more
than one year ago, this is the first time I use it
_________________
Topband Reflector
------------------------------
Message: 11
Date: Fri, 20 Sep 2013 10:42:16 -0500
From: Mike Waters <mikewate@gmail.com>
To: topband <topband@contesting.com>
Subject: Re: Topband: elevated radials
Message-ID:
<CA+FxYXgOdihGKak1B4CwNZj7nN93YXnX9OYyUfKVBa7q0kODiw@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
Hello Jim,
Thank you for this. I don't doubt for a second that my elevated 1/4 wave
radial currents may be unequal. I should throw together an RF current
meter
and check them sometime, and add more radials while I'm at it. After the
ticks and chiggers here die, though. :-)
I don't have any Communications Quarterly issues, but K5IU's article
sounds
interesting, if anyone has a copy.
73, Mike
www.w0btu.com
**
Hey Mike
Saw your post to TB reflector:
"I suppose if you made the elevated radials long, then you could adjust
the current balance with series variable capacitors. You could use a
simple
clamp-on meter like W8JI has on his site to measure the relative current,
perhaps.I didn't bother with that myself, I was just careful to keep the
radial lengths the same length and height."
My old friend K5IU had an article "Optimum Elevated Radial Vertical
Antennas" in Communication Quarterly, Spring 1997, pp 9 - 27. He showed
why 1/4 wave elevated radials are the worst length as it invariably
results
in radials having unequal currents (at least on the low bands where the
height is small in terms of lambda). He only concluded the pattern was
distorted, explicitly stating no opinion on efficiency. Dick is pretty
careful - he likes actual measurements. The fix was to use non-1/4 wave
radials with a single lumped reactance between the shield and the
junction
of all the radials to bring to resonance. Using separate reactors for
each
radial makes it too critical to adjust.
Since some of his measurements showed next to no current in some radials,
I figured right off the efficiency would almost always be higher with
equal
currents, even when using shorter radials of the same number. I never
needed to use elevated radials, so it was all merely academic for me.
I'll bet anything you have very unequal currents in your elevated radials
despite their being precisely the same physical length. Dick's article
shows how he measured the currents with a simple HB device. Don't know
if
it is simpler than W8JI's or not.
------------------------------
Subject: Digest Footer
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------------------------------
End of Topband Digest, Vol 129, Issue 29
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