IW5EDI Simone - Ham-Radio

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20 meters QRP Dipole

Posted: 29 Apr 2020 03:03 PM PDT
http://www.iw5edi.com/ham-radio/4242...ers-qrp-dipole



This is a portable dipole I built for 20 meters. It works great.








The SWR is really low. I would not recommend this for permanent use just
because it is not build like a rock. It will do just fine for portable in
the field operation. It is a great backpacking antenna. I only used 3 item
to build this dipole.

Parts:




1. Film Canister
2. 36 feet of AGW 22 stranded wire. Cut it to 18ft for each leg.
3. However much of RG-58 you need with a BNC or PL-259.




Tools:




1. Soldering Iron with solder
2. Drill
3. Wire Strippers
4. Wire cutters




Directions:




I know how hard it is to read directions with no pictures. I have tried. I
have made these directions very easy. It is fool proof. I have also
included some pictures on the directions that are hard to picture in your
mind.

1. Drill a hole through the bottom of the film canister to accommodate the
RG-58; so it is SNUG. Make sure the hole is center.




2. Drill two holes on each side of the film canister. This is were the legs
of the dipole will be inserted at. The holes should be no bigger than what
is needed to fit the 22 gauge wire through.

3. Strip the coax. DO NOT cut off the braid. Untangle it and twist it so it
looks like a wire. Make sure there is 1 inch of wire shield sticking out.
Cut the dielectric down so there is about a 1/2 an inch. Then strip a VERY
small potion of the dielectric so there is a very small amount of center
conductor sticking out. Feed the coax through the film canister. Feed it
from the bottom to the top. So the end of the coax is coming out the top.




4. Next, strip about 5 inches of the 18 ft long 22 AGW wire. Feed the end
through the bottom hole; of the to holes on the side. Pull it through the
top. Next find the middle of the bare section of the wire. Solder the
shield to it. Just wrap the shield around the center once and solder. Cut
off the access SHEILD not the 22 gauge wire.




5. Next, do the exact same thing as you did in step 4 but with the other
dipole leg. And solder it to the center conductor not the shield hi hi.




6. Ok, now do exactly as I say. I dont care where you start but pick one of
the access wires one of the 22 gauge wires). There now should be two
sticking out the top of the canister. In the middle of each stripped
section there should be either a shield or center conductor soldered to
them. Next this is kind of tricky. Take the bare end of the 22 gauge wire
(the one that has the center conductor on it. Feed it through the hole
above were to put it in. It is kind of hard cause the solder has made it
stiff. Just try to feed it through so that out of one end there are 2
wires. One, the actually length of the leg. The other is the 2 inches of
stripped wire. Make sure that both of those wires have some stripped
sections that are closest to the canister. Look at the pic below.




7. Solder the small piece to the big piece. Look at the pic above you can
figure out what I mean.




8. Do the same to the other side.




9. Now every thing should be inside the canister. Out the bottom of the
canister there should be coax. Out the two sides there should be one wire
on each side. Remember we soldered the two wires together on each side.
Look at the pic below.




10. Now all thats left is cover the exposed bare, yet soldered wire on each
side with electrical tape. Then for water proof ness you MUST fill the
entire canister with Hot Glue or some kind of epoxy. I found that hot glue
worked very well. Fill the canister almost to the top. Just so no more coax
or wires are visible inside the canister.




11. String it up and cut it so length according to SWR. I found that
trimming of about a middle fingers length at a time works. (About 4
inches). Just keep on trimming until the SWR becomes very low. I had to
trim about 10 inches on each side to get perfect SWR.




Thats it. Enjoy your new 20 meter dipole.




copyright by W7TDC w7tdc.com

The post 20 meters QRP Dipole appeared first on IW5EDI Simone - Ham-Radio.


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2 meter band halo antenna

Posted: 29 Apr 2020 03:01 PM PDT
http://www.iw5edi.com/ham-radio/4237...d-halo-antenna








The post 2 meter band halo antenna appeared first on IW5EDI Simone -
Ham-Radio.


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Petlowany Antennas by K6NO

Posted: 29 Apr 2020 02:59 PM PDT
http://www.iw5edi.com/ham-radio/4231...tennas-by-k6no



If you have any interest in antennas at all, fasten your seat belts and
hang on to your hats, because what you are about to read here is going to
blow you away. Conventional wisdom concerning antenna matching and
resonating is about to be shattered and the principles revealed here might
just be the start of a new chapter in the field of antenna design.







The heavy 40-meter gift




The path leading to my discovery started with the four-element 40-meter
antenna given to me by K6SG in 1995 after it had been damaged in a severe
storm. I loaded the pieces into the back of my Chevy pickup, drove two
houses down our street and, with GeorgeÃ*s help, unloaded them onto some
saw-horses in my side yard.




During the next few months IÃ*d occasionally go out and look at the huge
pile of aluminum and wonder if my Rohn 25 tower would tolerate the
additional weight of such an antenna if I were somehow able to put it
together again. I think I realized subconsciously that adding that much
more weight to my tower was not a good idea.




On one such occasion, as I looked at the linear loading on one of the
elements, I was struck by the complexity of it all and how much weight was
added to the antenna as a result. I clearly remember thinking at that
moment, There must be a better way to do this. It wasnÃ*t until several
weeks later, however, that I was able to work on the problem of simplifying
the antenna.



Experiments with 2M antennas




At that time I borrowed an MFJ-259 SWR analyzer from K6SG and started to
build some test antennas on 2 Meters. I fashioned the antennas from
eight-gauge aluminum wire and proceeded to test the methods most commonly
used to resonate them when they were too short to be self-resonant.




I experimented with inductors placed at various places along the elements,
end-loading capacitors, wires hanging from the ends of the elements,
folded-back elements and, yes, linear loading too, but I didnÃ*t feel that I
had made any progress toward a better way to do this. In frustration, I
returned the SWR analyzer to K6SG.




After a few weeks of not giving the idea much more thought, I borrowed
GeorgeÃ*s analyzer again because I had the uneasy feeling that I had missed
something in my earlier experiments. As I reviewed the results of the
various things that I had tried, I noted that hanging wires from the ends
of the elements had proved to be not only simple, but effective as well.




In an attempt to make the hanging wires more compact I wound them into
coils and re-attached them to the ends of the elements. The coils of wire
then had little effect on the resonant frequency of the short antenna. In
theory, it would take infinitely large inductances placed at the ends of
the short dipole elements to tune the antenna to resonance, so the results
were not at all surprising.



Resurrected from the junk-box




At this point in my experimenting I thought about my late father-in-law,
W8TS. He was into Amateur Radio before 1920 ó so early, in fact, that he
didnÃ*t need a license to operate. I recalled that in the past he had built
antenna tuners using some very unusual coils.




Like many other Hams, I never throw anything away, so I still had one of
his home-made coils in my junk box. I had looked at the coil many times and
had no real use for it, but for sentimental reasons I just couldnÃ*t throw
the coil away. I decided to try winding coils similar to his by using the
lengths of the hanging wires.




I wound the coils in a spiral fashion by starting a turn with a very small
diameter and winding each successive turn with a slightly larger diameter
until the wire lengths were used up. The completed coils then had a pancake
shape with all of the turns in the same plane.




I did not expect these coils to react any differently than the previous
ones. Much to my surprise, when I attached them to the ends of the short
dipole the resonant frequency was lowered somewhat, although not nearly as
much as the hanging wires themselves.



The Petlowany Principle




The unexpected results of this test prompted me to many more experiments
with spiral-wound coils and caused me to formulate what I like to call (due
to my overly-modest nature, no doubt) The Petlowany Principle.




It states that if a length of wire is wound into a spiral-shaped coil and
excited by a radio frequency current connected to the innermost portion of
the coil, it will then, and only then, exhibit RF characteristics that
closely approximate those of a resonant linear wire of the same length.




The shortest self-resonant linear length of wire is not the half-wave
dipole as one might mistakenly assume, but instead, a wire one quarter of a
wavelength long. Vertical antennas of that length are commonly used by many
amateurs. I used wires 1/4 wavelength long in each of the spiral coils that
I tested in an effort to keep the size and weight of the coils to a
minimum. However, spiral coils wound with wires with resonant lengths
greater than 1/4 wave-length also exhibit RF characteristics similar to the
linear lengths used.




To further test the spiral coils, I built a full size half-wave dipole and
also a 1/4 wave dipole for 2 Meters. I tuned the short antenna to resonance
on 2 Meters with two spiral coils. Each coil was made from a length of wire
about 1/4 wavelength long. They were then connected to each end of the
short dipole. I trimmed off equal lengths of wire from both coils to tune
the short antenna to the same frequency as the half-wave dipole.




On-the-air tests on 2 Meters with KI6O indicated that the transmitted
signal strengths of the short dipole were equal to or better than the full
half-wave antenna. Because the on-the-air tests were crude at best, I donÃ*t
make the claim that the short antenna had any gain, but in any case, it was
no worse than the full-size antenna.



Moving on to 20 & 40M




To test the spiral coils on an antenna for use in the HF Ham bands, I then
constructed a full-size 20-meter dipole from aluminum tubing and by
adjusting the lengths of the elements resonated it to 14 MHz. I then took
two lengths of wire, each slightly longer than 1/4 wavelength on 40 Meters,
wound them into spiral coils and attached them to the ends of the antenna.




By trimming off equal lengths of wire from the outside turns of each coil I
was able to resonate the antenna to 7040 kHz. Amazingly, the antenna was
also still tuned to the 20-meter band, although the resonant frequency was
lowered somewhat by the capacitive end loading that resulted from attaching
the coils.
As amazing as the resonating capabilities of spiral coils appeared to be, I
found its matching abilities even more remarkable. When the 20-meter dipole
was tuned to 14 MHz, it presented a fairly good match to the 50-ohm line
feeding it. The SWR was somewhat greater than 1 to 1. On 40 Meters,
however, the match was much better than on 20 Meters and was about 1 to 1.




The 1/4 wavelength 40-meter dipole antenna would normally have a radiation
resistance of about 14 Ohms. The radiation resistance of the short 40-meter
dipole was increased to 50 Ohms by the use of the spiral coils and resulted
in a much better match to the 50-ohm transmission line. The RF current on
the antenna sees the spiral coils as simply more linear wire and the
additional radiation resistance presented by that wire contributes to the
overall radiation resistance of the system.




In the process of checking the SWR on 7040 kHz, I had reduced my power
output to about 10 Watts so as not to cause any unnecessary interference.
When I sent my call to identify, a station in southern California called
and we had a short QSO. He surprised me by giving me a 569 signal report.
At the height of the antenna (about 30 feet), the power level, and the time
of day (mid-afternoon), I was not expecting to be heard at all. Apparently,
in spite of its unconventional method of tuning, the short 40-meter dipole
could also radiate quite well.




The bandwidth of the 40-meter antenna over a 2-to-1 SWR range was about 80
kHz. The coils were wound with bare aluminum wire that measured .061 inches
in diameter and were built with a spacing between turns of about one wire
diameter. Subsequent tests with other wire diameters and spacings indicate
that the bandwidth can be improved significantly by using larger wire
diameters and greater spacing between turns. It is also important to wind
the coils with the diameter for the innermost starting turn to be as small
as possible if the maximum bandwidth is to be realized.



Testing out the coils




I have not made any tests to measure the improvement in efficiency to be
gained by using the spiral coils, but since they are not connected in
series with the high current portions of the antenna, their use can help to
reduce the losses normally associated with matching networks, loading coils
and linear loading schemes.




During my testing of the spiral coils, I found that their resonant
frequency was little affected by the length of the linear portion of the
short dipole. The antenna length can literally be from inches long to just
short of full half-wave resonant size with only small adjustments to the
wire lengths in the coils necessary to achieve resonance. I also found that
the radiation resistance was always very nearly 50 Ohms, regardless of the
length of the linear portion of the antenna.




I have given much thought to the spiral coils and their behavior in an
attempt to better understand how they function. I have concluded that, due
to the unique physical and electrical characteristics of the coils, they
act as low impedance series-resonant circuits connected to the ends of the
antenna. The linear portions of the dipole are simply extensions of the
transmission line which is delivering current to the coils. Due to the low
impedance nature of the coils the linear portions of the antenna are
carrying large RF currents. If the linear portions are long enough in terms
of the wavelength of the applied RF current, an appreciable amount of
radiation takes place resulting in an efficient antenna.



What does it mean?




How can the amateur take advantage of the spiral coils with their unique
characteristics to improve his antenna systems?




He will now be able to resonate a short antenna using an inductor placed at
the ends of the elements which, according to conventional wisdom, would not
have been possible with anything other than an infinitely large inductor.
It is now possible to build very short resonant antennas using coils that
do not introduce major losses and that are not impossible to build.




Short dipoles or short monopoles resonated in this way are resonant at two
frequencies. One frequency is essentially that of the linear portion of the
radiator, the other is that set by the end resonating coils.




Multiband antennas are possible by using multiple coils to resonate the
short linear portion of the antenna at the desired frequencies provided
that sufficient spacing between coils is allowed to prevent detuning of the
individual coils. The desired frequencies need not be harmonically related.




Broadbanding of an antenna for a particular frequency range is possible by
the use of multiple coils that are all tuned within the desired range of
frequencies. Again, to prevent detuning, adequate spacing between coils
must be provided.
The driven element of a parasitic array can be resonated and matched to the
transmission line simply by the use of such coils. In fact, the parasitic
elements of such an array can also be tuned as directors and reflectors in
this manner.




Short vertical antennas (such as a short tower one might wish to use as a
radiator on 160 Meters) can be resonated to the desired frequency simply by
adding the appropriate spiral coil consisting of a wire length of
approximately 1/4 wave attached to the uppermost portion of the tower or
its mast. Doing so will increase the radiation resistance at the base of
the tower resulting in improved efficiency.



How well does it work?




I have included photographs of a 12-foot-long 40-meter dipole built with
spiral coils for use in my upstairs hamshack. The height above ground of
the antenna was approximately 12 feet and, using only exciter level power
(100 Watts ) I was able to work stations in the U.S. and Canada as well as
Japan and Fiji.



Whats next?




I believe that there is much more to be learned about spiral coils and
their RF characteristics and I hope that my work with the coils has proved
to be thought-provoking. If only a few of you have been inspired to further
experiment with the concept, writing this article will have been worthwhile.




Oh, I almost forgot! You might be wondering what became of the 40-meter
antenna which precipitated all of the experiments with the spiral coils.
Well, the antenna is still patiently waiting for me, but these spiral coils
have proved to be such a fascinating distraction that I must further
explore some or all of the possibilities I have suggested before I can get
back to modifying it.




I would like to acknowledge the help and encouragement of the following
radio amateurs: My late father-in-law Fritz, W8TS, George, K6SG, Jay, W6GO,
Peter, W6QEU, Derek, K7FF and my wife Carolyn, K8TFR.



Article By Bill Petlowany, K6NO




(This article ran in Worldradio, March 1998.)




originally available at this url
http://www.wr6wr.com/newSite/article...withtwist.html

The post Petlowany Antennas by K6NO appeared first on IW5EDI Simone -
Ham-Radio.


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7 elements Yagi-Uda Antenna for 144 MHz

Posted: 29 Apr 2020 02:56 PM PDT
http://www.iw5edi.com/ham-radio/4227...na-for-144-mhz



An original project by I0QM of a 7 element yagi anetnna in a PDF File.




The QM7 antenna is a simple 7 elements Yagi with 3.7 m boom length for the
lower 144 MHz
SSB/MGM band




forward gain is 1.35 dBd; i.e. 13.5 dB forward gain over the isotropic
radiator, while the F/R is about 12.5 dB



QM7144MHzDownload






The post 7 elements Yagi-Uda Antenna for 144 MHz appeared first on IW5EDI
Simone - Ham-Radio.


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Rhombic Antenna

Posted: 29 Apr 2020 02:53 PM PDT
http://www.iw5edi.com/ham-radio/4222/rhombic-antenna



Rhombic Antenna dimensions and plan for HF and VHF bands by N6JSX







Rhombic-MathDownload

The post Rhombic Antenna appeared first on IW5EDI Simone - Ham-Radio.


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Cobracom - Waveguide

Posted: 29 Apr 2020 02:50 PM PDT
http://www.iw5edi.com/ham-radio/4218/cobracom-waveguide



Oscilloscope, Realtime spectrum analyzer, Impedance meter, RLC bridge and
signal generator for Windows. Is a Windows application that converts your
PC into a powerful dual-trace signal analyzer (oscilloscope, FFT etc) .
Uses your PC sound card as an Analog-to-Digital a Converter to digitize any
input waveform and as Digital-to-analog Converter for the signal generator.
True 24 bit adc/dac 48K/96k/192k sampes/sec.













Download Wavetools.zip 4.42 Mb

The post Cobracom Waveguide appeared first on IW5EDI Simone - Ham-Radio.


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Boomless Quad

Posted: 29 Apr 2020 02:46 PM PDT
http://www.iw5edi.com/ham-radio/4213/boomless-quad



A Quad antenna is a full wavelength conductor in the form of a square (or
circle or diamond). It is actually two half wave dipoles spaced half wave
length apart, bent at right angles at l/8th wavelength points and joined
together.




If the Quad is fed at either sides it is vertically polarÂ*ized and if fed
at bottom or top it is horizontally polarÂ*ized. The radiation will be
perpendicular to the plane of the Quad. In this design a single feeder is
used for all the bands, viz., 28 MHz, 21 MHz and 14 MHz.








The dimensions are the ones suggested in the JanuÂ*ary 1982 issue of QST,
but the centre section design is altered to enable the quad to be rotated
on the vertical as well as horizontal axis, so that the whole installaÂ*tion
may be carried out easily.




A telescoping mast is suggested so that the complete installation may be
done with the centre section at about ten feet level. This will clear the
spreader touchÂ*ing the ground, while it is rotated on the horizontal axis
during installation.




Eight 14 feet long good, strong and straight bamboos have to be selected
and given two coats of waterproof varnish. The tie points of the elements
on each bamÂ*boo will be marked as shown in the sketch. One perÂ*son standing
on the ground can hold the bamboo to the angles with suitable hose clamps
or any other clamps that may be available. I have used old motor cycle
chains for this purpose and find it most efficient since it clamps the
bamboo quite tight and does not allow it to slip down. The centre section
is rotated on the horizontal axis and all the bamboo spreaders are clamped
in a similar manner.




Now nylon guys are fixed between the spreaders (raÂ*diators and reflectors)
as shown. A hook may be fixed at the centre of each guy. This will be
unhooked while rotating the Quad horizontally to clear the mast and hooked
back again. After fixing all guys as shown in the sketch, the copper wire
could be strung.




Copper wire, preferably 14 swg or stranded insulated wire may be used.




The elements have to be cut to the full length as shown, plus 3 inches for
each egg insulaÂ*tor and termination points (i.e., 6 points about 18
inches). This is passed through the egg insulator up to the appropriate
point, given a twist and soldered at the twist. Nylon string, about 18
inches long is strung through the other end of each insulator to bo tied to
the appropriate points on the bamboo already marked.




All reflector elements terminate on a 4 inch insulator (if this is not
available, two egg insulators may be used 4 inches apart). Stubs, about 9
inches long are soldered on either end of these insulators for tuning
purposes.




All radiator elements terminate on either end of a 4 inch insulator at the
centre of the 21 MHz element- so this 21 MHz element may be fixed first and
the other two 28 MHz and 14 MHz elements may be fixed later, terminate at
the same 21 MHz parts.




Tie the radiator elements to the bamboo spreaders standing on the ground,
by rotating them on the horiÂ*zontal axis so that all the spreaders can be
reached, one after another. The horizontal axis is locked after this
process is over.




With the centre section raised to about 10 feet, the botÂ*tom wire of the 14
MHz radiator will be about 1-2 feet from ground level. Each radiator may be
tuned indiÂ*vidually for best front to back ratio. Finally the comÂ*plete
quad may be raised to optimum height.




Copyrights VU2GX Girimajij

The post Boomless Quad appeared first on IW5EDI Simone - Ham-Radio.


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A 1:1 Coaxial Balun

Posted: 29 Apr 2020 02:41 PM PDT
http://www.iw5edi.com/ham-radio/4207/a-11-coaxial-balun



This balun documented by I0QM use a ¼ wavelength and the ¾ wavelength
adapting sections with the 50-Ohm coaxial cable,Â* or a coax line with the
impedance you need.







I0QM_BALUNDownload

The post A 1:1 Coaxial Balun appeared first on IW5EDI Simone - Ham-Radio.


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6 Element Log Periodic Yagi for 6 meters

Posted: 29 Apr 2020 02:38 PM PDT
http://www.iw5edi.com/ham-radio/4199...i-for-6-meters



G3SYC began designing and using a LPY on 6 metres in 1991. Since then he
has refined the design and has worked some superb dx from his qth in IO93.
The design featured here evolved in 1996, and is the mk2 version.




This yagi antenna has a very clean polar pattern and a good front to back
ratio.




Here below you can find spacing and element lenght that you will find
usefull in case you want to homebrew your own log periodic beam.



SPACINGInchesELEMENTLENGTH (Inches) Radiator 1114.6Rad.1 Rad.
213.6Radiator 2111.2Rad 2 Rad 313.2Radiator 3108.0Rad 3 Rad 412.8Radiator
4104.0Rad 4 Dir 135.5Director 1107.0Dir 1 Dir 350.0Director 2104.0Boom
Length121.1








Some notes and assembling instructions



The elements are made from 0.5 inch (13mm) aluminum tubingThe boom is 1
inch (25mm) square section aluminum tubeAttach the feeder to radiator 4All
of the elements are mounted on plastic dipole insulators commonly found at
radio ralliesA shorting strip is connected across the terminals in the
dipole insulator on D1 & D2The phasing strips are made from 1/8 inch (3mm)
x 1/2 inch (13mm) aluminum stripAll element lengths given are tip to tipThe
phasing strips are attached with the dipole insulator element securing bolts

The post 6 Element Log Periodic Yagi for 6 meters appeared first on IW5EDI
Simone - Ham-Radio.


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eSoftAnywhere DSP & More

Posted: 29 Apr 2020 02:32 PM PDT
http://www.iw5edi.com/ham-radio/4196...where-dsp-more



This freeware software performs DSP (Digital Signal Processing) on audio
signals received from an input line on your computer’s sound card. It is
specifically intended for processing audio signals from short wave, amateur
(ham) radios, or any other radio to “clean up� or improve the listening
quality of radio signals. It can also improve radio signal quality before
the signal is sent to a radio modem or TNC (Terminal Node Controller)








Offer audio recording functionalities.




A logbook feature is incorporated so that radio contacts and transmissions
may be recorded (something practically mandatory for ham radio operators
and often practiced by short wave listeners as well). There are a great
many other features available, just browse through the help file.

To properly use eSoftAnywhere DSP & More you will generally need to run an
audio cable from your radio audio output jack to the microphone or other
input jack on your computer’s sound card. The Audio Wizard can then
fine-tune your sound card audio levels for use by the audio processing
features of the software.

By Konrad Byers VE1EXE (sk)




Download eSoftwAnywhere DSP & More (3.8 Mb)

The post eSoftAnywhere DSP More appeared first on IW5EDI Simone -
Ham-Radio.