Popular Posts

Wednesday, October 21, 2015

List Of Best Audio Processing Software For Ham Radio

ableton live


pro tools

ozone advanced

 sonar x3




acid pro




logic pro

Tuesday, September 29, 2015

Automatic TX/RX Antenna Switch

Sometimes it is necessary to use separate antennas for receive and transmit. For example you want to use an efficient vertical on 80m for transmit, but a directional beverage antenna for receive. The MFJ-1707 automatic antenna switch serves exactly this purpose. Just connect your transceiver, receive and transmit antenna as well as power - and off you go! The built-in HF sensor (HF vox) immediately switches from receive to transmit antenna. Instead of the HF vox a cable can be used for PTT keying. After releasig the PTT the switch reverts to the receive antenna after an adjustable delay time (hold time). This delay protects for example a very sensitive receive amplifier. An additional switching contact signals the state of the switch, useful for blocking other devices or. The MFJ-1707 automatic antenna switch can be used with any mode. Max. power is 200W SSB PEP. A 12V DC supply is required, you can use the normal power supply from your transceiver. Size of the switch: 101 × 66 × 38mm.

Tuesday, August 25, 2015

SkyJack - autonomous drone hacking w/Raspberry Pi, aircrack & Javascript

How To Run Google Chrome On Kali Linux Sana

First you need to download and install it. Then follow steps below

  1. dpkg -i googlechrome.deb
  2. install deps, apt-get -f install
  3. edit /opt/google/chrome/google-chrome and add --user-data-dir before fi
  4. run google chrome from terminal with --no-sandbox
  5. make a desktop shortcut for easier launch

Wednesday, May 20, 2015

Episode 405: Sniffing GSM with rtl-sdr and gnuradio

Part 2: RTL-SDR 160-10 Meter Receiver on the Cheap! w/ Homebrew UpConver...

Part 1: RTL-SDR (Software Defined Radio) 160-10 Meters w/ Homebrew HF Up...

Going Deeper Into GNURadio Companion, Hak5 1601

Spectrum, Frequencies, Wavelengths And Boycotting The RSA Conference, Ha...

Carrier Waves, Amplitude and Frequency, Hak5 1604

How To Build An ADS-B Antenna, Hak5 1606

The Earth is ROUND! All about Radio Horizon, Hak5 1608

Getting Started With The HackRF, Hak5 1707

HackRF + Android + Open Source Spectrum Analyzer!

Tracking Aircraft over 300 miles away! Mountain + Drone + SDR

Using A RTL-SDR To Learn About The GSM Network Around You

Monday, May 11, 2015

Where Does 468 Come From - half wave dipole

We’ve all seen this number over and over again – the “magic number” that gives us the length of a half-wavelength dipole in feet from the dipole’s resonant frequency: L = 468/f. In free-space the wavelength in feet is 492/f, but a practical half-wavelength antenna is shorter so the constant is smaller. The number 468 is on the license exams and in the literature. It’s been there ever since I started reading about ham radio in the mid-1960s. It’s a pillar of amateur antenna theory. Every ham is expected to memorize it. And it’s wrong. 
It would be more accurate to say that it’s rarely correct. There are certain instances where it’s close, but using it often leads to wasted wire. The usual instructions to a new ham are, “Calculate how much wire you need using 468/f and then add a couple of feet.” What that really means is the value 468 is too small and we compensate for the error by “adding a couple of feet”. If 468 isn’t right, why do we use it? Answering that question requires a trip along the paths of history. 
Recently, I had the opportunity to spend a few days at ARRL Headquarters to plan upcoming writing and editing projects. The ARRL has a great Technical Library with every edition of ARRL publications and technical publications going back decades. (If you ever get close to Connecticut, it’s well worth dropping in on the ARRL for a tour!) I had some time one afternoon and decided to find out when and how the number 468 first appeared in the ham literature. 
My first stop was the ARRL Antenna Book’s initial edition in 1939. Sure enough, on page 13 in the chapter on “Antenna Properties”, the familiar formula 468/f appears. The Antenna Book states that the “end effect” due to the attachment of insulators at the ends of the antenna results in the approximately 5% reduction in length from the free-space 492/f to 468/f. The text goes on to state that the percentage “varies slightly with different installations”, but doesn’t say how, nor is a citation provided to identify how the value of 468 was obtained. 
Since it is unlikely that the value of 468 appeared in the Antenna Book without any “prior art”, I next turned to the ARRL Handbook’s first edition in 1926. That turned out to be a dry hole – no formula for antenna length and nothing in 1927 or 1928 either. Then, in the 1929 edition’s “Antennas” chapter on page 128, I hit pay dirt! The text defines natural wavelength as the highest wavelength (the lowest frequency) at which the Hertz antenna (a half-wavelength dipole) will resonate. It is stated that “The natural wavelength of the wire…will be its length in meters multiplied by 2.1” Hmmm…2.1 is 5% longer than would be the free-space value of 2. (Remember, the text is discussing wavelength, not frequency.) Farther down the page I saw, “Speaking in terms of feet, the natural wavelength of the antenna will be its length in feet divided by 1.56.” That equation translates to L = (300 x 1.56)/f and 300 x 1.56 is 468! Here were the headwaters of the mighty River 468! 
Still, no background for the correction was given. Where does the use of a correction factor originate? Back to the stacks! Did I really want to go through all of the QST magazines until I found my answer? Well, not really, but inspiration struck in the form of the online QST archives. I logged into the ARRL Web site, brought up the QST archive search page, and…hit another roadblock. I couldn’t very well search for “468” because it was unlikely to be a keyword. “Dipole” would return hundreds of hits. Then I realized that in the early days, a half-wavelength dipole would have been referred to as a “Hertz antenna” or “Hertzian antenna”. I entered the former and scrolled down to the very earliest entries. 
Heinrich HertzThe oldest article on Hertz antennas was in the July 1925 issue by 9BXQ and titled “The Hertz Antenna at 20 and 40 Meters” but it didn’t discuss a formula for length. The next oldest article, October 1926’s “The Length of the Hertz Antenna” by G. William Lang, turned out to be what I was looking for. In the article, Lang (who was apparently not a ham, but worked in the Dept of Radio Operations for Radio Station WBZ in Boston) set up some Hertz antennas at amateur station 1KA and also measured antennas at station 1CK and 1KF. He used an oscillator and a wavemeter to determine the frequency at which the antenna resonated then measured the entire antenna - tip-to-tip, including the counterpoise. A table of correction values was derived, with the free-space wavelength in meters multiplied by an average value of 1.46 to get the antenna’s resonant wavelength in feet. This corresponds to an equation of L = 438/f. This is the first suggestion that the actual resonant length of a practical amateur antenna can be predicted by using a correction factor to a free-space wavelength. 
The early experiments of 1925 and 1926 took place on or near 40 meters. In those days, CW operation on what we now call the “low bands” of 80 and 40 meters was the norm. At these wavelengths, a half-wavelength dipole was of a reasonable length. It could be made of ordinary copper wire, probably #8 to #14 AWG, and installed in the back yard at heights of 20 to 40 feet. For these antennas, 1/8th to 1/4th wavelengths above ground, a value of 468 is about right, resulting in the equation printed in the ARRL Handbook in 1929. 
In truth, many variables affect the resonant frequency of a half-wavelength dipole, the two primary factors being the length-to-diameter ratio of the antenna conductor and most strongly, the antenna’s height above ground. These can combine to change the actual correction factor quite a bit! (Insulation can also affect an antenna’s electrical length.) In my November 2009 QST column, “Hands-On Radio: Antenna Height”, I modeled a typical 20 meter dipole made of #12 AWG un-insulated wire at heights from 1/8th to 2 wavelengths over realistic ground and calculated the correction factor at each height. It varied from 466 to 481 over that range! Clearly, using 468/f would lead to an antenna being too short most of the time.
If 468 is too small and rarely correct, what should you do? Realistically, you should expect to trim your dipole to get the resonant frequency you want. Instead of being frustrated that the calculations aren’t exact, learn to adjust the antenna’s length efficiently by using an instrument such as an antenna analyzer. Start with an estimated value based on a more realistic formula such as 490/f that results in a small amount of extra wire for attaching insulators. During tuning, twist the wire connections together or use clamps, then raise the antenna into position and measure. When it’s right, only then solder and weatherproof the connections. Recognize that every antenna’s circumstances are slightly different – height, ground conductivity, thickness of wire, nearby conductors, and so forth. 
Another lesson to learn from this exploration is to realize that “magic numbers” in formulas have often been determined through experimentation under specific circumstances. As such, they likely depend on a variety of factors that you may not be able to replicate. They will only approximate what you actually encounter. If the assumptions behind the value are given – you can use that information by comparing it to your situation. If the assumptions are not known – you should allow for variations or try to find a more accurate model representative of your own circumstances. 
I hope you’ve enjoyed reading about this journey as much as I enjoyed taking it, opening the covers of books nearly 80 years old and mapping the stream of knowledge back to its sources - finding there the footprints of wireless pioneers that set ham radio on the course we travel today.

Voice of America Museum Special Tour

FreeDV, JT65 & Pi

Ardunio Antenna Switcher

TNC Pi, Wattmeters & Python

Pi-Supply & Tape-Tenna

Ameritron Amplifier Factory Tour

Softrock Software Defined Radio

batteries experiment with lemons, copper, and zinc

Locating Power Line Noise

Digital Amateur Radio


ARDF (Fox Hunting)

DVB-T Digital Video

DSP Using GNU Radio Companion

The CW Geek on HamRadioNow

Earth Moon Earth Communication

RazPi + Xastir = APRS Mobile

High Speed Networks on UHF and Microwave

Sunday, April 26, 2015

High strength stack

Ham radio must have items

Self amalgamating tape

High voltage. Weatherproof. 

Anti static brush.

Clean your circuit boards. 

Multipurpose velcro strap.

Suitable for cable management tool. Multipurpose. 

Epoxy putty

As permanent sealant for antenna connections, cables and connectors. 

Element shape vs resonant frequency

Thursday, April 23, 2015

YL 33: The First Female Ham Radio Operators, and their Awesome Legacy

Historically, literacy—in its many forms—has given the marginalized a way to speak and participate in a system that previously prevented them from doing so. And while the printing press revolutionized the way writing was exchanged and shared with the world, the invention of radio as entertainment, emergency, and communication technology had a similar effect on oral storytelling. From this, ham radio, also known as amateur radio, was born as a subset of commercial radio. The appeal of communicating independently to others across the globe struck a chord with many people in the early 20th century—including women looking for ways to participate in war efforts, and connect with other women around the world.
Although enthusiasm for ham radio as the medium of choice for hobbyists, veterans, and emergency responders hasn’t waned much over the last fifty or so years, the hobby is making a strong resurgence as aspiring makers acknowledge radio’s contribution to the movement. Many hams consider amateur radio to be the original maker skill, requiring knowledge of electricity, geography and communication.
And it’s one of many mediums that gave women the chance to have a global voice—and they took it.
Calm the ham
For those unfamiliar with the subculture of ham radio, the title “ham” was originally used as a negative name associated with amateur operators who, without proper training, would disrupt professionals. Eventually, though, the name lost its negative stigma and is now used interchangeably with “amateur.” Regardless of someone’s amateur status, all operators must be licensed and complete a training program, through FCC regulations.
Female hams are called “YLs,” which is short for “Young Lady,” regardless of the operator’s age. While that seems simultaneously antiquated, cute, and patronizing, keep in mind that the ham radio subset of men is referred to as “OMs,” or “Old Man.” The largest organization for YL ham operators in the world is the Young Ladies’ Radio League, Inc. (YLRL), founded in 1939, which exists to encourage and assist YLs throughout the world to become licensed amateur radio operators.
Although amateur and commercial radio was heavily male-dominated, the response to the influx of women operators was—and still is—largely positive. In “The Feminine Wireless Amateur,” a 1916 article in The Electrical Experimenter, the writer says:
JUST because a man, Signor Guglielmo Marconi by name, invented commercial wireless telegraphy does not mean for a moment that the fair sex cannot master its mysteries. […]
Women seem to progress excellently in the engineering branches. Primarily this is so because her brain is quick of action, and moreover she usually will be found to have extremely well-balanced ideas as to proportions, so essential in designing. A wonderful imagination coupled to a number of other worthy faculties help to make a really fine combination, so that we find a steadily growing number of women architects, mechanical and electrical experts, radio operators, civil engineers, ad lib. What we need is more of them in the higher positions, where the square root and binomial theorem are everyday quantities.
That’s quite a positive—and progressive—perspective on women in science and engineering – especially for 1919. A 1931 article in the New York Times also remarked on this trend, saying that
The list of women obtaining licenses as amateur radio operators is increasing rapidly, the Department of Commerce said today, although there were only eight registered women commercial operators in the country. […] There are eighty-six women amateurs, compared with about 18,000 men operators.
This number has changed drastically since the 1930. And while there are now thousands of women worldwide with call signs, several notable women during the early 20th century set the stage for the new generations of girls finding a voice on the airwaves.
Gladys Kathleen Parkin
At just fifteen years old, Gladys Kathleen Parkin (1901-1990) received her professional ham radio license. Basically, this makes her a total badass, considering that she’d had her amateur radio license since age nine. She was featured on the cover of The Electrical Experimenter, and at the time was the “youngest successful female applicant for a radio license ever examined by the Government at that time,” according to a 1916 article in the San Francisco Chronicle. Parkin began her hobby at age five with her brother, and was the first woman in California to pass the first-class radio license.
Parkin’s call sign is 6S0, and she spent her life in the radio industry, developing a reputation for building her own equipment. Here she is, quoted in The Electrical Experimenter:
With reference to my ideas about the wireless profession as a vocation or worthwhile hobby for women, I think wireless telegraphy is a most fascinating study, and one which could very easily be taken up by girls, as it is a great deal more interesting than the telephone and telegraph work, in which so many girls are now employed. I am only fifteen. … But the interest in wireless does not end in the knowledge of the code. You can gradually learn to make all your own instruments, as I have done with my ¼ kilowatt set. There is always more ahead of you, as wireless telegraphy is still in its infancy.
Graynella Packer
At twenty-two, Graynella Packer of Florida became the youngest woman to become a wireless operator “on board an ocean-going steamship,” reads a 1914 article in the King Country Chronicle. Her experiences at sea gave her many stories that she later recounted to her friends and family. Although she technically wasn’t an amateur, her passion began as a hobby, and Packer had long been interested in the way electricity and communication worked on the open seas. She served on the steamship Mohawk from 1910 to 1911.
Olive Carroll
Canadian-born Olive J. Carroll had a passion for travel and exploration while growing up during the 1930s and 40s – and radio was her gateway to the world. Carroll’s interest in amateur radio began in high school, but she eventually turned it into her career and attended the Sprott Shaw School of Radio, where she earned her second class radio certificate in 1944. She was hired by the Canadian Department of Transport as an interceptor operator, and a few years later, when an opportunity opened on the Norwegian passenger freighter M/S Siranger, she accepted the position—having never before traveled farther than 500 miles from her home. Like Packer, Carroll was driven by a desire to explore the world by operating from the ocean.
In 1994, she authored a book about her experiences called Deep Sea ‘Sparks’: A Canadian Girl in the Norwegian Merchant Navy. The San Francisco Maritime Museum has recreated a ship’s radio room with the same equipment Carroll used during her time on the M/S Siranger.
Clara Reger
It’s impossible to talk about notable female hams without acknowledging the work of Clara Reger, who received her call sign in 1933 at age thirty-five. Reger had a long career as an operator, and managed disaster communications after WWII. Known for her exceptional Morse code skills, Reger spent much of her life teaching others how to become operators. She also received the Edison Award for teaching a fourteen-year-old boy without arms to send Morse code with his feet.
But Reger is also known for her signature salutation, which she created especially for women communicating with other women—the salutation ’33,’ which meant love sealed with friendship. Reger knew that to hear another girl’s voice on the other end was rare and special. What a gift, to find kinship with women, through the radio, across the ocean, across the globe!
YL 33 is considered sacred by female hams, and there’s a poem dedicated to Reger’s accomplishments and passion for radio communications. You can read it in full on the Young Ladies Radio League’s website, but here’s a passage:
There’s no real definition
But its meaning is known well.
It’s how a YL says good evening
To another friend YL.
Although these are just a few of the many women who used radio as their medium of choice, their stories as operators are fascinating and inspiring. These women are united in their mutual passion for exploration, technology and adventure, and that still holds true today for many female ham operators. If you’re interested in becoming a ham radio operator, consider joining YLRLthe Sisterhood of Amateur Radio, or the ARRL.
Ashley Hennefer, M.A., is a writer and researcher based in Reno, Nevada. She’s the founder and editor of The New Artemis, and is passionate about technology, travel, and the humanities

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