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What is Ham Radio?

Amateur Radio (Ham Radio) is a popular hobby and service in which licensed Amateur Radio operators (hams) operate communications equipment.

Although Amateur Radio operators get involved for many reasons, they all have in common a basic knowledge of radio technology and operating principles, and pass an examination for the license to operate on radio frequencies known as the “Amateur Bands.” These bands are radio frequencies reserved by the Wireless planning commission (WPC) for use by ham radio operators.

Why are Amateur Radio Operators also called “Hams”?

Ham: a poor operator; a ‘plug’ (G. M. Dodge; The Telegraph Instructor)The first wireless operators were landline telegraphers who left their offices to go to sea or to man the coastal stations. They brought with them their language and much of the tradition of their older profession. In those early days, every station occupied the whole spectrum with its broad spark signal. Government stations, ships, coastal stations and the increasingly numerous amateur operators all competed for time and signal supremacy in each other’s receivers. Many of the amateur stations were very powerful. Two amateurs, working each other across town, could effectively jam all the other operations in the area. Frustrated commercial operators would refer to the ham radio interference by calling them “hams.” Amateurs, possibly unfamiliar with the real meaning of the term, picked it up and applied it to themselves. As the years advanced, the original meaning has completely disappeared.

Who is the Typical Ham?

Amateur Radio operators come from all walks of life — doctors, students, kids, politicians, truck drivers, movie stars, missionaries and even your average neighbor next door. They are of all ages, sexes, income levels and nationalities. Whether through Morse Code on an old brass telegraph key, voice communication on a hand-held radio or computerized messages transmitted via satellite, all hams use radio to reach out to the world.

Find out what you can do with ham radio!

What’s the Appeal of Ham Radio?

You can communicate from the top of a mountain, your home or behind the wheel of your car. You can take radio wherever you go! In times of disaster, when regular communications channels fail, hams can swing into action assisting emergency communications efforts and working with public service agencies. For instance, the Amateur Radio Service kept New York City agencies in touch with each other after their command center was destroyed during the 9/11 tragedy. Ham Radio also came to the rescue during Hurricane Katrina, where all other communications failed.

You can use telegraphy, voice, digital and images in communication with other hams. You can even talk to Shuttle astronauts or bounce signals off the moon!

Some hams like to build and experiment with electronics. Computer hobbyists enjoy using Amateur Radio’s digital communications opportunities. Others compete in “DX contests,” where the object is to see how many hams in distant locations they can contact. Mostly we use ham radio to form friendships over the air or through participation in one of more than 2000 Amateur Radio clubs throughout the country.There are over 600,000 radio amateurs in the United States and over 2,000,000 worldwide.

South India Amateur Radio Society

South India Amateur Radio Society is a non-profit organisation at Chennai, they can help you in becoming a Ham or an amateur radio operator in India.

They can be reached at www.siars.org.in

Ham radio Tamilnadu

Would you like to be a ham?  SIARS will help you

South India Amateur Radio SocietyThe South India Amateur Radio Society is giving free training to Amateur Wireless licence (Ham Radio licence) aspirants at Chennai, Interested, can visit their webpage. The webpage contain details about the application and syllabus of the ham radio licence exam.

This webportal also contain an application form generator, for ASOC exam 

ASOC Application form

ASOC syllabus

NIAR,ARSI, Amateur Radio Society of India, National Institute of Amateur Radio (NIAR), MARS, Madras Amateur Radio Society
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JOTA 40m RX by VU2DEV

 

( literature by VU2DEV )

JOTA—40 RX. is a simple single conversion super HET receiver. OM VU2KGN is the motivator for this project. The general topology is based on 1985 ARRL handbook receiver. A 5—section xta| ladder filter at 12.0 MHz. IF [intermediate frequency] is used to select the band width based on senior HAMS inputs. Xtal filter is a little wider than necessary (about 4.5 kilohertz). The receiver circuit doesnot use any IC’s [Integrated circuits] for the sake of simplicity.

 

The receiver consists of Three single sided PCB assemblies, Namely RF Amp,RF Main board & V.F.O

BLOCK DIAGRAM

VFO

The VFO circuit is based on 1978 ARRL handbook Info. The VFO gives three outputs for receiver, transmmitter and a frequency counter,
To cover 40 mtr band ile. 7.0 MH2 to 741 MHz, the VF0 covers 5.0 MHz to 4.9 MH2. VF0 tuning is by ordinary zener diode’s. This idea is from OM Hans Summers G0UPL. TheVFO is buffered by a two stage amp with feedback. This circuit shown below is adapted from a Hungarian radio. The original circuit had three outputs, Two main outputs and one counter output. So it is ideally suited to our application.

As mentioned earlier the VFO is a two transistor circuit and runs with an unusual voltage regulator. As the radio works an battery, battery voltage can drop up to 11V [Eleven volts]. The regulator used requires at least 2.4v  input output differential to maintain regulation and of course reverse voltage protection is a must,Hence we can get a maximum regulated voltage of 11V — 2.4V — O.7V =7.9V and hence we have used a regulator 78LO5 with center pin [common] lifted above ground by 2,6V to get 7.6V .This is just to ensure ready available components with no adjustments.

RF AMPLIFIER
7.0 MHz signals received from Antenna are Input to this PCB Assy. The Antenna signals are passed through A 2—SECTION BAND PASS FILTER to reject unwanted signals coming from Antenna. The circuit idea is from on old SIEMENS Radio [West Germany]. The circuit gives good rejection to IF FREQ of 12.0 MHz and image Frequency of 17.0 MHz. The Band width is left intentionally high at 350 KHz hoping that very soon we would be able to operate 7.0MHz to 7.2 MHz whereas presently we are authorised to operate only 7.0MHz to 7.1 MHz. The filter is low loss design ond the Inductors (Coils) are would on ϕ10mm Teflon® former with 24 S.W.G enamelled copper wire.

The RF AMP is the general purpose Amplifier with multiple feed back as given in ARRL hond book, This is a highly field proved design and there is scope for improvement by suitable choice of device for low cost, General purpose Receiver BC 547 is effective but experienced SWLS / Radio Amateurs could replace with more exotic/expensive devices for better performance. e.g 2N3866
 

RF AMP

The receiver circuit is realized on a separate single sided board. As given in block diagram this is a single conversion, high IF [12.0MHz] and for simplicity no AGC ond no lC`s. The image frequency is at 17.0 MHz [12.0 + 5.0] whereas wanted frequency is 12.0 — 5.0 = 7.0 MHz. So only a single section filter is used ahead of DBM [Double balanced diode rnixer]. The tuned circuit is shown below. The
antenna coil is rnode with  10mm teflon former ond 24 SWG wire is used for coil winding for low loss & high Q.

Coming to DBM block it is realised using 2no of trifilar transformers and T—1O Ferite core and 4 no of 1N4148 switching diodes. The idea at circuit is from 1985 ARRL handbook. This being a receiver diodes are picked—up from the same reel [Same batch], No further matching is done. The circuit is given below.

 

The mixer output is amplified in a single stage IF—Preamp using BC547. This is a very simple omplifier with feedbock 0nd no adjustments are necessory. The transistor collector directly drives the 3—stage Xtal filter.


The output from Xtal filter is amplified and buffered and given to the product detector. In our receiver A diode D.B.M is used as a product detector. The IF POST AMP circuit is given below. As the output is an emitter follower; It is low impedance and happily connects to the product detector.

A single stage Xtal  oscillator with an emitter follower is used as a B.F.O. Now for some JARGON(please read this) 40 Mtr band is full of LSB stations only[kindly ignore other than HAM stations who use USB/ISB]. In our frequency mixing IF = RF + L.O that means the signals at 12.0 MHz IF are also L.S.B. please remember we are using a ladder filter with Xtals marked12.0 MHz. Ladder filter is fortunately a good L.S.B. Filter BUT ……..,…. But the center frequency of ladder filter is slightly below the marked frequency by 2 KHz or more.So to receive LSB signals the B.F.O shall be a WEE—BiT below 12.0 MHz.[may be ll,9985 or thereabout] for a simple receive—only application B.F.O. frequency is not very critical. As the filter is kept intentionally WIDE. The circuit of BFO is given below.

The product detector is driven by B.F.O and IF POST AMPLIFIER. The output is filtered OFF high frequency components by the so called diplexer and a big RF Choke. The resulting low level audio is amplified in a low—input impedance audio preamp to match the D.B.M. This circuit is from 1985 ARRL handbook. This common base amp output is further amplified in PNP Amplifier stage driving the volume control.

 

A simple push—pull amplifier is used to drive a speaker. Transistors are used instead of IC’s to make the availability of components easy. The output is more than 200 mw r.m.s good enough to operate JOTA activities in the midst of bubbling children. The output of amp can be connected to either 15 ohms or 8 ohms spkr. 15 ohms spkr will reduce the drain on battery whereas 8 ohms spkr would give more audio output.

 

A few receivers have been built using these circuits. As mentioned earlier,The VFO is on a separate pcb. Both the pcb’have built—in reverse polarity protection. Performance of receiver is quite satisfactory while using a dipole antenna cut to 40 M—Band for normal HAM shack volume setting the receiver  draws around 150 mA current on12V battery.Some HAMS have experimented using long wire antenna also. As this is meant to be a beginner’s receiver the pcb’s are slightly big to facilitate comfortable handling. There is no critical adjustments in the receiver. In fact antenna—coil trimmer was not mounted at all in a few receivers.

We would like to express our gratitude to OM NADARAJAN, VU2KGN for continuously encouraging us to take—up this project. |VU2DEV|

 (photo of VU2DEV-courtesy -VU2JQX)

 

Congress AKA corruption

“I would go to the length of giving the whole congress a decent burial, rather than put up with the corruption that is rampant.” — Mahatma Gandhi May 1939

 Over fifty years of congress rule has made the people so immune to corruption that they have learnt how to live with the system even though the cancerous growth of graft persisted…but its high time to ditch away the bastards out of rule and end  the nepotism, to serve the real taste of democratic rule to the poor man in India.  

ALL are invited!!!!!…..but with a valid amateur license…

Jota TRX is a simple ssb(lsb) only, single conversion,40 mtr TRX designed by VU2DEV, OM Ramaprabhu.

It works on 12Volts Battery and outputs a Minimum Power of 15Watts average (30 watts pep) at 13.8 Volts sufficient to contact Soth-India and a few operators have contacted as far as Germany, South Africa etc running only a good Dipole antenna!

The proposed workshop’s main aim is to promote Home Brewing! As such this project is NOT meant for beginners.

Brief Tech Description:

This TRX is a singleconversion ssb rig. (lsb only)
The Local Oscillator (VFO) is a standard 5MHz requirement and hence the IF (Intermediate Frequency) is 12 MHz. So 12-5 = 7 MHz. Hence VFO tunes backward! That means an exact 5 MHz VFO gives 7MHz output whereas 4.9MHz VFO gives 7.1MHz.
The rig is kept simple by having a separate RX and a separate TX with common VFO to give Transceive operation.
Switching is done by a Double pole Relay and frontpanel switch functions as a PTT. The rig is originally meant for Scouts/Guides JOTA (Jamboree on The Air) activity and hence they needed a Send-Receive switch rather than a normal pushbutton switch.

For more details contact
VU3HLX Nakesh R, at nakeshr(at)gmail.com LL- 09895654344

CU 73, de….. VU3PKQ-   LL- 9946-987-997

Christian & UDF brothers

Chinese goods are cheap and is worth for your money, For eg: You will get a cheap bluetooth dongle delivered at your home for just 85 Rs,If you have a Paypal account.

Go through the online Chinese gadget shop Dealextreme and browse for thousands of useful gadgets.They are offering good service and you will get the ordered items in 10-15 days.

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