Monday, July 23, 2012

Ham Radios in Space

NASA's Space Amateur Radio Experiment is connecting students and ham radio operators on Earth with astronauts in Earth orbit.
U.S. Astronaut Owen K. Garriott - W5LFL

For most amateur radio operators, it is the thrill of a lifetime to receive a "CQ", or general call, from an astronaut in space. But for some, like former astronaut Dr. Owen K. Garriott, call sign W5LFL, the thrill comes from receiving a response from "hams" down on Earth.

Garriott, who has been an amateur radio operator for over 40 years, was the first astronaut to take a ham radio into space, pioneering the way for an increasingly well developed amateur radio space program.
"It was my good fortune to take the first amateur radio into space on STS-9 in November 1983," Garriott said. "In my spare time only, I managed to hold up an antenna to the window and to talk to amateurs on Earth."

This contact was the first communication between astronauts and people on the ground outside of "official" channels, which are usually reserved for presidents and heads of state.

Owen Garriott pioneered the use of ham radio from Earth orbit during his "spare time" on shuttle flight STS-9. Now, the Space Shuttle frequently carries amateur radio equipment into space where astronauts communicate with students on Earth below.
Hams, as amateur radio operators are often called, use radio transmitters and receivers to talk to other hams all over the globe, as well as to those in space. There are more than 1.5 million licensed hams worldwide, including more than 400,000 Americans.

Every radio amateur must be licensed by the Federal Communications Commission (FCC). In order to obtain a license, a ham must pass an examination, which includes questions about radio theory, rules and regulations. There are three grades of licenses, each at progressively higher levels of proficiency: Technician, General and Amateur Extra. Any licensed ham can chat with the Shuttle.

Once the examination is passed, the FCC issues the amateur operator's call letters. The first letter indicates nationality. In the United States, the first letters are A, K, N, or W.

Garriott had originally proposed the idea of taking a ham radio into space on his first space mission, Skylab 3, but was unable to due to timing and other complications. Ultimately, though, he persisted and was able to obtain permission to fly a small hand-held transmitter/receiver aboard the Space Shuttle Columbia
This is U.S. Astronaut Owen K. Garriott - W5LFL - aboard the U
.S. Space Shuttle Columbia STS-9. He is holding a Motorola two meter FM ham radio.

"When in orbit over land, I could make a CQ, which is a general call, and see who responded," Garriott said. "I used a well-designed, hand-held antenna, known as a 'cavity antenna', which could be velcroed to the window. It was about 24 inches in diameter and looked somewhat like a large aluminum cake pan. The transceiver then connected to the antenna."
In addition to the general calls, Garriott had made a few plans to send out a call to specific Earth-bound hams at prearranged times and dates."I had specified particular times and frequencies beforehand," Garriott said. "Among others, I was able to speak with the Amateur Radio Club in my hometown of Enid, Oklahoma, with my mom, with Senator Goldwater, and with King Hussein, who was an avid ham."
Since that first voyage into space, NASA has continued to see the usefulness of bringing ham radios into space, and astronauts have been able to speak to hams on earth on dozens of shuttle flights, as well as on the space station MIR. "There has been substantial amateur radio activity in space since I first brought one up," Garriott said. "There is now a program called SAREX that is allowing for more and more activity."
The Space Amateur Radio Experiment (SAREX) is a long-running program to use amateur radio equipment on board the Space Shuttle to involve students in exchanging questions and answers with astronauts in orbit. Students in hundreds of different classrooms across the country are able to ask the astronauts questions about space flight and the experiments being conducted on the mission. It also allows for communication with amateur radio operators on the ground.
SAREX is sponsored jointly by the American Radio Relay League (ARRL), the Radio Amateur Satellite Corporation (AMSAT) and NASA. Students and amateur radio operators can attempt to contact astronauts flying on a SAREX mission through voice, packet (computer) radio, or television, depending on what equipment is flying on the shuttle and on what equipment is available on the ground.

In addition, in 1997, NASA approved plans to include amateur radio equipment as part of the payload of the International Space Station (Amateur Radio on the International Space Station or ARISS). Since astronauts will have more time in space while on the ISS, more opportunities for ham radio contacts will exist. "Shannon Lucid used a ham radio while on MIR," said Garriott. "NASA saw how using an amateur radio would be a good thing for astronauts to do in their spare time on the space station."
Onboard the Space Shuttle Endeavour, astronaut Linda M. Godwin (right) talks to students (left) via the Shuttle Amateur Radio Experiment (SAREX). The payload commander, as well as several other STS-59 crew members spent some off-duty time using the amateur radio equipment to communicate with "hams" and students on Earth.

And certainly hams on the ground are eager for contact with the astronauts. Specially designed shuttle "QSL" cards, which are postcards used by hams to confirm two-way contact or reception of a signal, are among the most prized in a ham's collection -- even to a king.

"(King) Hussein regarded his 1983 contact with Owen Garriott, W5LFL, on board Space Shuttle Columbia, as a high point in his amateur radio career," reported ARRL Executive Vice President David Sumner in a special bulletin following the death of Jordan's King Hussein, JY1. ("JY1" was King Hussein's call sign.)

Sunday, July 22, 2012


Hello friends this one is the simple and basic Fm transmitter circuit using one transistor specially for student  and Beginners who want to starts their the hobby of electronic.

 It is simple in construction and working . And all the circuit and component details are given in the above picture and the video will show you the working and the function the small range  fm transmitter . 


Please friend just take care about the CBE of the transistor as you may new in the electronic and dont get hopless when your circuit will not working in the first time try until you not get the success . because this circuit will required little hard work not much but little. so never leave it by just after soldering it ok .
And i upload a video for your reference so you can get some basic idea of the making of it. and if is not compulsory to make it on copper plate , you can make it on any type of PCB.
 If any one have query or problem in the making of the fm transmitter then you can contact me any time. 

Saturday, July 21, 2012

The Monoband HF Dipole Antenna

If you're looking for an easy antenna for your favorite HF band, you can't go wrong with a half-wavelength dipole! All you need are three insulators (one is used as your center connector) and some wire. Strong, multistranded copper wire will withstand the elements best. The only trick to making a dipole is cutting it to the right length. A dipole antenna is made of two equal lengths of wire with the total length adding up to a half wavelength at the desired frequency.
Here are the required dipole lengths for each of the Novice/Technician HF sub bands:

80 meters: 126' 6"
40 meters: 65' 7" 15 meters: 22' 1"
10 meters: 16' 6"
For example, if you're making a dipole for the 10-meter band, you'll need two lengths of wire 8' 3" long (8' 3" x 2 16' 6") plus enough extra so the wire can be looped through the insulator and secured tightly. Attach the wires to the insulators and center connector as shown in Fig 1. Attach your coax feed line at the center connector.

Solder the shield braid of the coax to one side of your dipole. Solder the center conductor of the coax to the other side. Be careful not to melt the coax while you're soldering it to the antenna. You can also purchase center connectors that feature built-in SO-239 jacks.
With a matching PL-259 plug on your feed line, you can easily disconnect your feed line from your antenna whenever necessary for portable operation, for example. What-ever way you connect the coax to the antenna, be sure to waterproof the connection if it will be outdoors. If water gets inside the cable its loss will increase in a hurry!

So, what type of coaxial cable should you use? If the distance from your transceiver to your dipole is less than 50 feet or so, RG-58 is fine. For longer runs, I'd strongly recommend a low-loss cable such as RG-8, RG-213 or Belden 8214. If you own an antenna tuner, you can try feeding your dipole with 450-Q ladder line. This type of open-wire feed line exhibits very low loss at HF.
Choose your antenna supports: trees, flagpoles, chimneys or whatever stirs your imagination. You can even install your dipole in an attic. If you decide to mount it outdoors, invest in enough high-strength rope or cord to do the job. You want to be sure your antenna will survive storms, ice loading and so on. Mount your dipole as high off the ground as possible. How high is "high?" Conventional wisdom states that your dipole should be mounted at least a quarter wavelength above the earth at the frequency you choose to operate.
Getting an 80-meter dipole 60 feet off the ground could present a challenge! If you can't raise your dipole to this altitude, don't worry about it! Your performance may suffer a bit, but the antenna will work. Watch out for nearby gutters, pipes, aluminum siding, window screens and other large pieces of metal. They'll detune your dipole and increase the SWR if they're too close. And, of course, never place your antenna near power lines!

If you've cut your dipole to the proper length, your SWR should be reasonably low (less than 2:1). Don't worry if the SWR seems to rise as you move in frequency toward the band edges—this is normal.
Of course, the dipole you've just designed is good for only one band, right? Well.  not necessarily! If you own an antenna tuner, try using it to load your transmitter on other  bands.

The SWR will be very high, but your tuner may be able to adjust it down to a flat 1:1 match. This won't do a thing for the actual SWR on the feed line, but if you've invested in low-loss cable or ladder line, it doesn't matter! Are you surprised to hear this? Many hams, even veterans, are slaves to the idea that only a 1:1 feed line SWR is acceptable. If your feed line is very "lossy," this is true.
If you invest in low-loss feed line, however, only a small portion of your signal is actually lost due to high SWR. The rest of it is radiated by your antenna. So if you've designed your antenna for, say, the 40- meter band, try it on other bands as well. You may find that your monoband dipole is really a multiband antenna!

Saturday, May 5, 2012


Hello friends,
We know that building of Fm transmitter for first time is quite hard and we get confused about the components, parts, design, pcb, transmission frequency, inductor value and making of inductor , polarity of the capacitor and many things.

Here i am going to explain you a building of simple fm transmitter using a two transistor . I will try to explain as possible as i can. lets starts with the components required.

Q1= BC547

C1 & C2 =4.7uF(electrolytic)
C3,C4 &C7 = 100nF( ceramic 104)
C6 = 4.7 pF (ceramic )
C5= 10-30 pF (Variable capacitor or also known as  TRIMMER )

R1= 47K
R2= 220K
R4 & R5 =10k
R6= 100 ohm

L1=  8 turns of 22 Gauge copper wire around a simple ball pen.( I will upload a photo of it for more idea)


Battery (Power Supply) = 12-9 V DC (Always use battery and avoid adepter so i will     
                                                                        reduce  noise in transmission )


The circuit is basically a radio frequency (RF) oscillator that operates around 100 MHz. Audio from audio jack is fed into the audio amplifier stage built around the first transistor. Output from the collector is fed into the base of the second transistor where it modulates the resonant frequency of the tank circuit (the 8 turn coil and the trimcap) by varying the junction capacitance of the transistor. Junction capacitance is a function of the potential difference applied to the base of the transistor. The tank circuit is connected in a Colpitts oscillator circuit. It works on the principal of COLPITTS Oscillator.


A impudence matching ANTENNA is must required in the circuit,without Antenna circuit will never works .Generally we uses a telescopic antenna . which through the waves in the atmosphere .


It is easy to make take an 22 Gauge enameled copper wire and wound it on the ball-pen and make 8 turns  on it tightly. i shown in photo below.

 FM CIRCUIT CALIBRATION  ( IMPORTANT PART  :-     PLZ KEEP PATIENCE MAY BE                                                                   OF CIRCUIT  )                    YOU NOT GET SUCCESS IN
                                                                                                   FIRST TRY OF

Place the transmitter about 2-10 feet from a FM radio. Set the radio to somewhere about 89 - 90 MHz. Walk back to the Fm Transmitter  and turn it on. Spread the winding of the coil apart by approximately 1mm from each other. No coil winding  should be touching another winding. Use a small screw driver to tune the trim cap. Remove the screwdriver from the trim screw after every adjustment so the LC circuit is not affected by stray capacitance. Or use a plastic screwdriver. If you have difficulty finding the transmitting frequency then have a second person tune up and down the FM dial after every adjustment. One full turn of the trim cap will cover its full range of capacitance from 10pF to 30pF. The normal FM band tunes in over about one tenth of the full range of the tuning cap. So it is best to adjust it in steps of 5 to 10 degrees at each turn. So tuning takes a little patience but is not difficult. The reason that there must be at least 2-10 ft. separation between the radio and the TRANSMITTER is that the  Transmitter emits harmonics; it does not only emit on one frequency but on several different frequencies close to each other.

 Don't leave a circuit by just trying sometime try and try until you get some distortion in the fm receiver. once you get some distortion in it. that means your fm circuit is working. and if not then try to check all components and the soldering of your circuits and power supply .if you getting confusing about the power supply put one 2 Volt LED in series with 1K resistor in parallel with battery so you can easily get the on-off you fm transmitter.

I personally maid this project with great success i got a 1 km perfect range with proper quality of the signal after that up to 1.5 km small distortion starts and after that quality factor go down and then lost it. you should have to maintain the circuit in the metal case to protect it form the electrical isolation .

The range and quality are inversely personal to each other. Both can be increased by increasing the input voltage upto certain limit.  


  I used the simple copper plate and glue the other copper parts to place it on it

A telescopic antennae of proper height. 

A inductor of the copper


                                                                     A SIDE PHOTO OF THE CIRCUIT

 Today after the request of my many friends i uploading the working video of the Fm transmitter , which describe that how to configure your fm transmitter for first time set up and is working ......... Sorry friends for my poor English.


If you have any problem and any question about it then you are always welcome.

From :
 ( )
mb: 8866792042

Tuesday, February 21, 2012

Servo Motor

What are Servo Motors?
Servo refers to an error sensing feedback control which is used to correct the performance of a system. Servo or RC Servo Motors are DC motors equipped with a servo mechanism for precise control of angular position. The RC servo motors usually have a rotation limit from 90° to 180°. Some servos also have rotation limit of 360° or more. But servos do not rotate continually. Their rotation is restricted in between the fixed angles.

Where are Servos used?
The Servos are used for precision positioning. They are used in robotic arms and legs, sensor scanners and in RC toys like RC helicopter, airplanes and cars.

Servo Motor manufacturers:
There are four major manufacturers of servo motors: Futaba, Hitec, Airtronics and JR radios. Futaba and Hitec servos have nowadays dominated the market. Their servos are same except some interfacing differences like the wire colors, connector type, spline etc.

Servo Motor wiring:
The Servo Motors come with three wires or leads. Two of these wires are to provide ground and positive supply to the servo DC motor. The third wire is for the control signal. These wires of a servo motor are color coded. The red wire is the DC supply lead and must be connected to a DC voltage supply in the range of 4.8 V to 6V. The black wire is to provide ground. The color for the third wire (to provide control signal) varies for different manufacturers. It can be yellow (in case of Hitec), white (in case of Futaba), brown etc

Servo Control
The servo motor can be moved to a desired angular position by sending PWM (pulse width modulated) signals on the control wire. The servo understands the language of pulse position modulation. A pulse of width varying from 1 millisecond to 2 milliseconds in a repeated time frame is sent to the servo for around 50 times in a second. The width of the pulse determines the angular position.
For example, a pulse of 1 millisecond moves the servo towards 0°, while a 2 milliseconds wide pulse would take it to 180°. The pulse width for in between angular positions can be interpolated accordingly. Thus a pulse of width 1.5 milliseconds will shift the servo to 90°.
It must be noted that these values are only the approximations. The actual behavior of the servos differs based on their manufacturer.
A sequence of such pulses (50 in one second) is required to be passed to the servo to sustain a particular angular position. When the servo receives a pulse, it can retain the corresponding angular position for next 20 milliseconds. So a pulse in every 20 millisecond time frame must be fed to the servo.

Power supply for Servo
The servo requires a DC supply of 4.8 V to 6 V. For a specific servo, its voltage rating is given as one of its specification by the manufacturer. The DC supply can be given through a battery or a regulator. The battery voltage must be closer to the operating voltage of the servo. This will reduce the wastage of power as thermal radiation. A switched regulator can be used as the supply for better power efficiency.

DX Fun Web Cluster

DX Fun Web Cluster is in essence a "chatroom" or node into which amateur radio DXers can post information about DX either worked or heard. Physically, it is a central computer that collects, stores and disseminates information that ham radio operators send to it. There are thousands of nodes around the world, connected together via the internet or radio. Connection to a cluster is by either telnet or packet radio. The networked nature of DX clusters is perhaps its most powerful feature as it gives amateurs almost instant access to information about rare and unusual DX conditions such as meteor scatter or VHF ducting.

Cluster users will use computer software (for example, many logging programs have this capability) that is capable of communicating with the cluster. On initial login, users will be asked to provide station information. This allows other ham radio operators to compare DX openings to their physical position. DX is one of the most fascinating aspects of the hobby.

Sunday, January 8, 2012

Hamradio Homebrew 2 Meter Square Dipole Plan

Here is a plan for homebrewing a 2 Meter Square Dipole plan. The advantage of this antenna is that it is unidirectional, and it takes less space than the regular 2 meter dipole. The calculation included on the diagram below is for building the antenna using copper tubing, you should use MMANA-GAL or other antenna simulation software to come up with new dimension for other materials (aluminium, wire, etc).
2 meter square dipole plan2 meter square dipole plan
Click on the diagram to enlarge it. Hopefully this will help you in brewing new antennas! Original plan taken from KOFF website

Antenna In Less Space – The Inverted Vee

Another space saving installation method is to mount the antenna in an inverted vee configuration. This type of installation has worked well for me over the years and I highly recommend it for those of which enjoy HF Radio and are in a limited space situation.

Unfortunately, there is no such thing as the perfect antenna. There are just too many variables for that to be possible. So the theoretically perfect antenna just doesn’t exist.  Ham Radio is all about trying out new things, and homemade antennas are no exception.

Experimenting with Ham Radio Antennas and using your creation to talk with other Amateurs all over the world is definitely one of the most accessible and enjoyable aspects of the Amateur Radio hobby.