Popular Posts

Tuesday, November 29, 2011

Planet Hamradio Malaysia



Planet Hamradio Malaysia adalah satu website yang mengumpulkan banyak blog dan memaparkan semua updates dari blog-blog yang terdapat di dalam senarai langganan.

Tujuan Planet Hamradio Malaysia ini dibuat adalah untuk membina satu one stop center untuk radio amatur di Malaysia. dengan melawati website ini, anda akan dapat:-

  1. membaca semua kemas kini dari blog-blog rakan anda pada satu website.
  2. dapat mengetahui apa perkembangan terkini dalam scene radio amatur di Malaysia.
  3. memberi peluang kepada anda untuk menyertai sebarang aktiviti yang akan dibuat ataupun yang sedang berlaku.
  4. dapat mengenali radio amatur yang juga blogger lain.
  5. sebagai self-training resources. terdapat banyak artikel dalam planet hamradio malaysia yang berkaitan dengan homebrew aktiviti, sebagai contoh. antenna building, electronic circuits dan lain-lain.
  6. apabila anda melawati website planet.hamradio.my, anda juga dapat mengetahui perkara-perkara yang sering dilakukan dan juga menjadi rutin seseorang radio amatur di Malaysia.
  7. dan lain-lain
Planet Hamradio Malaysia juga mempunya Facebook pagenya sendiri iaitu https://www.facebook.com/hamradiomy. Jika anda click Like, anda akan melanggan kepada updates dari Planet Hamradio Malaysia dan dapat membaca kemaskinian setiap kali anda membuka Facebook.

Bagi mereka yang sukakan microblogging seperti Twitter, Planet Hamradio Malaysia juga ada menyediakan updates untuk para peminat Twitter.com. Sila follow @hamradiomy

Bagi mereka yang tidak sukakan social networks seperti Twitter atau Facebook, atau di rumah/pejabat anda terdapat halangan untuk social networking sites, mailinglist untuk Planet Hamradio Malaysia adalah yang terbaik jangan teragak-agak untuk join dan sumbangkan apa jua idea, pendapat, ketidakpuasan, kritik, komen dan lain lain yang anda rasakan perlu. http://groups.google.com/group/planet-hamradio-malaysia

Planet Hamradio Malaysia ini ditaja oleh:-

  1. Mypapit 9W2WTF dari Kirostudio - Sumbangan space dan bandwidth.
  2. Amir Haris dari Localhost - Sumbangan domain name beserta DNSSec.
  3. Piju 9M2PJU - logo designer, konfigurasi wordpress dan plugins.

Terima kasih kerana menyokong Planet Hamradio Malaysia.

Thursday, November 24, 2011

Delta Loop Antenna Untuk High Frequency



Delta loop adalah satu multiband antenna yang senang dibuat dan toleran terhadap objek yang berdekatan. Ia boleh dipasang dalam pelbagai konfigurasi, dari mono band kepada multiband. Suapan dari tengah bawah memberi polariti berbentuk tegak. Kelebihannya berbanding dipole adalah sebanyak 2db.

Formula yang digunakan untuk mengira antenna ini adalah 1005 / frekuensi (mhz), satu 4:1 balun diperlukan untuk menjadikannya multiband antenna atau pun satu kabel 75 ohm suku panjang gelombang dipasang pada 50 ohm kabel penyuap akan menjadikannya monoband antenna. 4:1 balun digunakan kerana nilai impedance antenna ini adalah lebih kurang 90 ke 112 ohm.


Keperluan:
  1. wayar cooper yang berinsulator ( wayar eletrik rumah )
  2. panjang wayat lebih kurang 141 kaki (40 meter band)
  3. 4:1 balun / kabel 75 ohm sebagai matching stub
  4. 50 ohm RG58 sebagai penyuap
transceiver akan menunjukkan nilai SWR sebanyak 2:1 jika tiada matching dipasang. delta loop versi monoband dibuat dengan matching section dipasang dengan satu quarter wave transformer menggunakan kabel 70 ataupun 75 ohm coaxial. dengan ini beban sebanyak 112 ohm tadi akan match dengan nilai impedance transceiver iaitu sebanyak 50 ohm membolehkan pengaliran kuasa dari radio ke antenna tanpa sebarang reflected power. Walau bagaimana pun tuner masih diperlukan untuk tune di beberapa band lain selain dari frekuensi resonan.

oleh kerana dimensinya yang lebih besar maka kadar radiation efficiency bertambah berbanding dengan satu dipole separuh gelombang. loop ini boleh dipasang dalam pelbagai kedudukan, tetapi perlu diingat. setiap kedudukan menghasilkan polariti, gain, pattern, take off angle yang berbeza. 

contoh kedudukan delta loop


kedudukan yang berbeza menghasilkan pattern radiasi yang berbeza. angle yang tinggi sesuai untuk local communication manakala low angle bagus untuk DX contact.

New Carolina Windom



New Carolina windom atau window antenna adalah sejenis off center feed dipole. Antenna jenis ini popular pada tahun sekitar 70 dan 80an dan terkenal oleh kerana sifatnya yang multiband tanpa memerlukan antenna tuning unit. Dicipta oleh Loren G. Windom, bercallsign W8GZ. Idea asal beliau adalah berbeza dengan new carolina windom, traditional carolina windom menggunakan 300 ohm ladder line atau twin lead cable sebagai penyuap manakala new carolina windom menggunakan RG58 50 ohm sebagai penyuap. Traditional windom juga dikatakan tidak bagus kerana tiada RF choke, menjadikan RF berkeliaran sehingga ke dalam shack.

New carolina windom untuk 40 meter band berukuran 20 meter panjang atau 66 kaki, separuh gelombang untuk 40 meter band, mempunyai satu titip penyuap yang terletak di 37.8% dari hujung salah satu sisi. Oleh kerana impedance antenna ini adalah sekitar 200 ohm, maka satu balun 4:1 perlu dipasang pada titip penyuap. RG58 sepanjang 10 kaki adalah kabel penyuap kepada wayar antenna juga bertindak sebagai vertical radiator. satu rf choke perlu dipasang selepas kabel RG58 10 kaki untuk menghalang transmission line dari menjadi separuh dari antenna.

New carolina windom dikatakan bagus kerana kurang loss dan juga banyak RF diradiasikan secara omnidirectional pada sudut yang rendah, menjadikannya pilihan untuk para DXer. Untuk mereka yang mempunyai ruang yang luas, full size 80 meter new carolina windom adalah yang terbaik. Bagi mereka yang kesempitan ruang, 40 meter separuh gelombang sudah memadai.

Cara membuat antenna new carolina windom untuk 40 meter band dan 80 meter band:

  1. potong wayar kuprum sepanjang separuh gelombang untuk frekuensi paling bawah yang akan digunakan, sebagai contoh 7.100mhz  (468 / 7.1mhz = 65.9 kaki), 3.9mhz (468 / 3.9mhz = 120 kaki)
  2. potong wayar tadi pada titik 37.8% dari sisi
  3. sambungkan kedua elemen wayar tadi kepada 4:1 balun
  4. suapkan balun dengan satu kabel RG58 50 ohm sepanjang 10 kaki, untuk 80 meter band adalah 20 kaki, nisbah 4:1.
  5. sambungkan hujung RG58 tadi kepada satu line isolator / RF choke
  6. pastikan bila anda memasang antenna ini, tentukan elemen wayar tergantung sekurangnya 24 kaki dari paras bumi secara horizontal dan RG58 sepanjang 10 kaki / 20 kaki perlu dalam keadaan tegak.

Far field plots untuk antenna new carolina windom pada ketinggian 7 meter. Perhatikan gain dan juga rupabentuk lobes yang terhasil.


Carta VSWR antenna New Carolina Windom.

Wednesday, November 23, 2011

Hamming it up on the air

Back in the dark ages of twentieth-century communications, or before the advent of the Internet, the general populace relied on two primary methods of instantaneous long-distance communication. One is tried and true telephone technology, which almost everyone depended upon, and which is relatively easy to master - simply pick up the receiver and dial the number you want. The other method is somewhat more esoteric, and cabalistic in the sense that only a select group of people are privy to its workings and secrets - ham radio.


Of course, with the arrival of the Internet and subsequently, lightning-speed broadband Web access, ham radio has become somewhat archaic, with the number of ham radio operators (or 'hams') dwindling with each passing year. However, as rare as hams are as a collective breed presently, a smattering of them still do exist. Not just existing, but ironically, also thriving and keeping their beloved pastime very much alive.


One of the few hams left on this planet is Bil Paul, 59, who makes a living as a public-relations officer for a biotech company when he is not on the air. Bil's interest in ham radio started when he was in high school in the 1950s, when he developed an interest in short-wave listening, receiving aural missives from shortwave stations on the other side of the planet like Radio Moscow. He also got his first ham licence when he was only 12 years old. Bil enlightens us, via email from San Mateo, California, USA on what exactly is it that ham radio operators do, and also talks about the fascination in talking to strangers a continent away.



Bil with his portable ham radio set

What exactly is ham radio, and how did it come about?
Ham radio, or amateur radio, is simply a way of global communication using relatively simple radio sets. It is a world-wide hobby that began at the same time radio was invented early in the nineteenth century. The first radio stations were set up by innovators such as Guglielmo Marconi, widely known as the Father of Radio. Several years later, commercial broadcast stations were set up, but non-commercial operators (hams) continued to experiment and establish personal radio stations.
After a time, in the U.S., the Federal Communications Commission was set up to regulate radio transmissions. It granted operating licences to commercial stations, and also to ham radio operators. In order to receive a licence, an aspiring ham radio operator has to pass a written test and a Morse code sending and receiving test.


How does ham radio differentiate from commercial radio?
Early commercial radio stations used low frequencies (the AM band of 600 to 1600 kilohertz) to broadcast, and their range was considerably short (several hundred miles) except at night. But radio hams discovered that the higher frequencies that they were allowed to operate on (called the shortwave frequencies - anything from 3 megahertz to 50 megahertz) often allowed them to broadcast world-wide with modest amounts of power, because their signals bounced off the ionosphere and back to earth (a process dubbed "the skip"). With several skips, American hams could talk to Europe, Asia, and so on.


What does being a ham radio operator mean to you? To me, the most important and enjoyable thing about being a ham radio operator is being able to send radio waves through the air (and even into space) with a great deal of freedom. I enjoy the challenge of using relatively low power to talk to people everywhere - whether they are the CEOs of companies or students in high school. It's a form of ultimate freedom for me. Being a ham also means that I can operate my radio from almost anywhere - at home, in cars, boats and ships, and even from airplanes. Radios can be so large as to occupy an entire desk, or small enough to fit into one's pocket. Hams most often buy their equipment ready-made, but some still build most of their equipment.


Are there any specific reasons why some people get into ham radio? It's a very good way to learn about electronics and radio operations. But more importantly, it's a terrific way to get over any shyness one might have, since hams will often be talking to total strangers, maybe even someone from another continent. It's also a fantastic way to learn about other countries and meet people from other countries. Ham radio operators form a fraternity of sorts, and there are ham clubs all around the world; in the US, the "umbrella" ham organisation is the Amateur Radio Relay League www.arrl.org. However, there is currently a worry that not enough young people are becoming hams. There is a general belief that the Internet has demystified some of the allure of talking to people in other parts of the world.


What is the appeal about ham radio, or to put it another way, what goes on on the air amongst the ham community? People always ask me what we hams talk about on the air! Well, we talk about anything, but most commonly about the kind of equipment we're using, the weather, our families, and our occupations. More often than not, the other hams we connect with are total strangers. And at other times, we keep to a schedule with another ham - maybe a relative or longtime friend - say every day, or once a week. There are also times when groups of hams who know each other will talk to one another at the same time. This is known as a "net" - something like an Internet chat room, I suppose!


What are some of the activities that a ham radio operator can pursue? There are many activities that hams can pursue. The thing is, you might come to ham radio with a certain activity in mind, but once you spend more time on the air, you'll find new things to do. Many hams like to participate in contests to see how many stations they can contact in a day or so. "Contesting" is actually one activity that has more participation than any other sport in the world! A skilled ham can reach literally hundreds and even thousands of stations in a given period of time.

Others may go on ham expeditions to remote places, often islands, and make long-distance contact with hams from around the world, from that location. These expeditions are called "DXpeditions", because in ham language, DX means "distance communication", or contacting countries beyond your own continent.

Some hams like to try to reach as many other countries they can. A common goal to to obtain DXCC - or to contact over 200 other countries. Hams are doing a lot of experimentation with extremely high radio frequencies these days.

Other hams collect old, vintage radios, and some may even enjoy designing and building their own equipment. This can be as simple as an antenna, or as complex as a transmitter.
But I have to say, the most common activity that a ham can do on the air is to just "chew the rag", or talk endlessly to their friends and contacts.


How does one go about being a ham radio operator, as in what sort of qualifications or licences do you need? Every country has a licensing system for their hams, and licence requirements differ from country to country. In the U.S., there is an "entry-level" licence called the Technician's licence, which is very easy to obtain. However, it doesn't allow access to all of the ham-radio frequencies. The most common licence is the General Class, which is the one I have. For both the Technician and General, one needs to pass a written test containing a series of questions on basic regulations, operating practices and electronic theory. Your knowledge of Morse code is also tested if you wish to obtain a General Class licence.

Then there are the more difficult classes, the Advanced and Extra Classes, which give one all the possible frequency privileges. Again, you need to pass a written test and a Morse code test. The speed of the Morse code increases with the more difficult tests.


What kind of equipment do ham radio operators use, and what forms of transmission are usually used? The average ham radio operator uses a combination receiver and transmitter (this is usually of Japanese manufacture, such as Yaesu/Standard or ICOM), running at around 100 watts output (some advanced users use transmitters running at 1,500 watts). The ham also uses an antenna tuner which "matches" the radio to the antenna. The average ham uses either a home-made wire antenna (of which there are many varieties), or a factory-built "Yagi" antenna made of aluminum, which is large, has drooping arms and sits at the top of a tower or on top of a mast on a rooftop.

The most common form of transmission is voice transmission, using a mode called single sideband. It provides the best voice signal at the lowest power. The next most common mode of transmission is Morse code. Even though Morse code is rather old, many people still use it and can send and receive it very fast (about 20 or 30 words per minute). As for me, I use an electronic device which can read Morse code, translate it automatically, and display the letters on a TV screen.


What is a call sign, and what is its importance to a ham radio operator? A call sign for a ham is like a licence plate on a car. It is unique to the ham and it identifies him or her, what part of the country he or she is in, and the Class of licence he or she holds. In my call, "KD6JUI", the "KD" represents the U.S. and my General Class licence, the "6" means that I live in the state of California, and the rest identifies me as an individual. When I was growing up in Wisconsin and operating from there, I had the call "W9KSJ".


What is the significance of a radio band to a ham radio operator? A radio band is a range of frequencies that a ham is allowed to operate on. For example, the 20 meter band (one of the most popular) stretches from 14.0 megahertz to 14.35 megahertz. Portions of that band (the lower portion) are devoted to Morse code only. Other portions are devoted to voice transmissions. Unlike commercial radio and TV stations, which can only operate on one frequency or channel, ham stations can change frequencies within a band. There are many bands that are available to use, from high frequency or shortwave, to VHF (very high frequency) to UHF (ultra high frequency). Hams are constantly lobbying politicians and governing bodies to protect their ham frequency allotments, since many other commercial users would like to have the ham bands to use.

There are also satellites circling the earth which hams can use to communicate with one another. Some hams have also built repeaters in areas which offer local communications; this works much like cellphone networks. On a regular basis, hams also communicate with each other by sending signals to the moon, which reflects them back to earth. This is called a "moonbounce".


Have you made many friends abroad with your ham radio pastime? I regret to say that I haven't made any ham radio friends abroad. Since I'm still working, I don't have the time to operate a great deal. Plus I am a father with three children, so family comes first! But in ham radio, it seems when you meet another ham on the air, you become instant friends. When I was a student in high school, I used to talk every morning before school to another ham my age in the next state. I actually met him one time at a national Boy Scout Jamboree.

What are the advantages of being a ham radio operator, and what do you enjoy most about being a ham radio operator? To the public, hams are often best known for being the only means of communication out of an area devastated by a natural disaster such as a typhoon, hurricane, tornado or earthquake. Hams also operate out of war zones, when communication lines are down or it's too dangerous to get a message out by conventional means.

My specialties in ham radio - the things I enjoy doing the most - are building and designing antennas and experimenting with them, building electronic equipment, and operating in natural surroundings (state parks, the forest, the mountains or on long bicycle trips), using very small radios with low power (5 watts or less). Sometimes, I use solar power to charge the batteries I use to power my radio. Someday, when I'm retired, I want to try bouncing signals off the moon (a "moonbounce") and creating and publishing my own book on antennas. When I am on long bicycle trips (lasting over a week) with my friends, the ham radio is rather handy to have along, just in case there should be a medical emergency and we need to call for help - when our cellphones are out of range. We actually had to do that one time, when a group of us was bicycling in the Sierra Nevada mountains in California, and a woman got sick. We managed to use our portable ham radios to get medical help for her.


Ham radio in Malaysia Malaysia also has its fair share of ham radio operators - in fact, there are several active ham radio clubs in this country, the most notable and largest one being the Malaysian Amateur Radio Transmitters Society. Ham radio as a hobby in Malaysia has been around since 1952, and there are about 1,000 licensed amateur radio operators here. Licences are issued by the Malaysian Communications Multimedia Commission, who also supervise the activities of ham radio operators here.

A prominent ham radio club in Malaysia is based in Penang, the YMCA Amateur Radio Club, which has its roots as a hobby and computer club way back in 1983. In 1994, the club became more involved in ham radio, and became one of the flagship societies promoting and organising ham radio activities in Malaysia. Aw Kean-Chin, Webmaster for the official YMCA ARC website, tells us more about the state of ham radio here in Malaysia.

Members of the Penang YMCA Amateur Radio Club.

What is the level of ham radio involvement in Malaysia?
I have to say that it's not very high, but ham radio is starting to gain some popularity. Since the demise of Jabatan Telekom Malaysia in 1999, no new licences have been issued. However, since the Malaysian Communications Multimedia Commission took over in 2001, there has been an increase in new licences issued, due to the interim inactivity. By the way, the Malaysian Communication and Multimedia Commission or MCMC is the governing body that supervises ham radio activities in Malaysia.

How does one go about obtaining a ham radio operating licence in Malaysia? You need to pass the Radio Amateur Examination conducted by the MCMC to secure a Class B licence (this licence allows you to operate on limited frequencies). If you want a full Class A licence, you must pass the RAE together with a Morse code test of 12 words per minute.
As mentioned earlier, the MCMC which supersedes the JTM, did not issue any new licences from 1999 to 2001, the reason being there was no examination conducted. The MCMC had to seek the help of MARTS to re-establish ham radio exam procedures, and the latter helped to draft the examination syllabus and questions.

What are the some of the activities pursued by ham radio operators in Malaysia? Like hams elsewhere, hams in Malaysia primarily make friends through their hobby. Radio contacts can be local, regional or worldwide. In addition, many hams are experimenting and designing new circuits, equipment and even antennas to evaluate how far and how well their signal can reach the other end. There are some who are more adventurous by communicating with satellites, international space stations,etc. There are also some who experiment with different digital transmission modes. Besides all that, ham radio operators are expected to provide emergency communication facilities during disaster.

What is the future of ham radio in Malaysia? The growth of ham radio in Malaysia is being hampered by the inability of the MCMC to conduct the RAE and Morse code tests. Since 2001, two RAEs have been conducted, but there has not been any Morse code test, which allows Class B licence holders to upgrade to a Class A licence. If this trend continues, the future of ham radio here will be jeopardised, as many hams have been waiting for many years to sit for the test. In Western countries, the RAE and Morse code test are conducted by volunteers, and can be done anytime upon request.

from: http://thestar.com.my/special/online/bilpaul/hamops.html

Tuesday, November 22, 2011

HALO Antenna

halo antenna adalah antenna yang mempunyai polariti mendatar, omnidirectional dan dipole separuh panjang gelombang. bentuknya lebihkurang small loop antenna, dan putus di bahagian yang setentang dengan titik suap atau feedpoint. antenna ini merupakan satu konduktor yang bersambung, disuap dengan satu kapasitor gamma match. antenna halo tidak sama dengan magnetic loop walaupun rupa bentuknya nampak lebih kurang sama.



kelebihan antenna halo

  1. apabila dipasang dengan betul, antenna ini akan menghasilkan matching yang bagus kepada 50 ohm coaxial cable dengan kadar SWR yang rendah.
  2. antenna ini memberikan take off angle yang rendah disamping pattern yang omnidirectional.
  3. diameternya yang kecil sesuai untuk penggunaan di kenderaan dan juga untuk frekuensi VHF ke atas.

Loop Antenna




Antena loop adalah satu antenna radio yang terdiri satu gelungan atau banyak elemen konduktor eletrik seperti wayar, rod ataupun tube di mana hujungnya bersambung dengan satu balanced transmission line. keadaannya berbeza sebagai contoh, gelungan kecil atau magnetic loop selalunya bersaiz kecil daripada panjang gelombang dan gelungan resonan mempunyai panjang lebih kurang sama dengan panjang gelombang.



loop kecil mempunyai kadar efficiency yang sangat lemah selalunya digunakan sebagai receiving antenna untuk frekuensi rendah.antenna ini juga kadangkala digunakan dalam aktiviti fox hunting ataupun amateur radio direction finding. secara teorinya, satu loop kecil ataupun magnetic loop mempunyai saiz lebih kurang 1/10 panjang gelombang ataupun kurang.



self resonant loop ataupun gelungan resonan adalah lebih besar, selalunya digunakan pada VHF dan UHF kerana saiznya tidak begitu ketara besar berbanding HF. kadangkala bentuknya sama dengan folded dipole, kadar radiasinya juga tinggi dan hampir sama dengan dipole.

walaupun antenna loop ini popular dalam bentuk bulat, kadar efficiencynya tidak berubah jika dibentukkan menjadi satu segiempat. sepertimana antenna quad, yang mempunyai satu resonan loop (gelungan yang hampir panjang dengan panjang gelombang) dan biasanya ditambah dengan satu parasitic element berbentuk segiempat bagi memudahkan elemen dipasang pada pemegang dan boom. frekuensi resonan pada satu resonant loop ditentukan oleh loop itu sendiri.



small loop antenna adalah lebih pendek dari saiz gelombang dan selalunya digunakan sebagai receiving antenna pada frekuensi yang rendah. small loop antenna juga dikenali sebagai magnetic loop kerana ia bertindak sebagai satu coil (inductor) dengan satu kadar rintangan radiasi. ianya juga immune kepada noise disekeliling. oleh kerana small loop antenna ini pada asasnya sebagai satu coil, kadar rintangan elektrikalnya juga bersifat inductive. untuk digunakan bersama radio, kadar inductive ini selalunya dihapuskan dengan satu nilai capacitance. sifat small loop antenna ini tidak sama dengan satu gelungan besar (resonant loop), pattern radiasinya juga berbeza. oleh kerana saiznya lebih pendek dari satu panjang gelombang, kadar efficiency antenna akan menurun kerana voltan yang melaluinya akan bersilang dan akan terhapus sesama sendiri disebabkan oleh kepanasan yang terhasil dari kadar rintangan yang rendah. bagi mengelakkan keadaan ini terjadi, maka panjang gelung harus ditambah bagi meningkatkan kadar rintangan radiasi.

small loop antenna juga digunakan sebagai transmitting antenna. harus diingat, perubahan panjang dan pendek elemen memberi kesan kepada pattern radiasinya. sebagai pelengkap, kadar efficiency harus ditingkatkan dengan menggunakan saiz konduktor yang lebih besar untuk mengurangkan loss.


bagi tentera, biasanya antenna loop ini digunakan pada kenderaan untuk frekuensi dari 3 ke 7mhz. antenna jenis ini boleh digunakan sebagai antenna NVIS iaitu near vertical incidence skywave. komunikasi yang tiada skip zone pada jarak 300 kilometer. tentera biasanya menggunakan elemen yang berdiameter 2 atau 3 inchi.


small loop antenna juga digunakan dalam fox hunting bagi jarak gelombang yang panjang untuk mencari triangulation.

Monday, November 21, 2011

Yagi Dan Quad



Yagi adalah satu antenna directional terdiri dari driven elemen yang selalunya satu dipole ataupun folded dipole di tambaha dengan parasitic element seperti reflector dan director. reflector adalah panjang dari driven elemen, selalunya 5% lebih panjang dan directornya adalah lebih pendek dari driven elemen. bentuk design yagi ini menjadikannya directional dengan gain yang lebih tinggi dari satu dipole ringkas.



Quad antenna adalah satu antenna yang mempunyai satu driven element dan juga parasitic element juga seperti yagi tetapi elemen-elemen ini berbentuk segiempat. jika satu elemen dan satu parasitic elemen, selalunya dipanggil qubical quad kerana ia berbentuk satu kiub.

Quad antenna dicipta oleh seorang jurutera bernama Clarence C. Moore dan bercallsign W9LZX.

Kelebihan antenna quad berbanding yagi,


  1. Gain yang lebih tinggi
  2. rintangan radiasi lebih kurang 50 ohm
  3. ketinggian boom yang rendah
  4. boom yang lebih pendek
  5. boleh dipasang dengan banyak menjadikan satu multiband array
  6. sudut radiasi yang lebih rendah dari antenna yagi
  7. bandwidth yang lebih besar berbanding yagi
  8. lebih immune kepada RF noise.

Antena Dipole Separuh Gelombang

Seperti yang kita sudah sedia maklum, dipole antenna adalah antenna ringkas yang boleh dibuat dari wayar dengan suapan tengah driven element. dipole antenna merupakan antenna dari 2 konduktor terdiri dari rod ataupun wayar dipasang secara parallel dengan satu ruang di tengahnya (insulator). voltan frekuensi radio diberi pada bahagian tengah di antara kedua konduktor. dipole sedia ada boleh digunakan ataupun boleh digunakan sebagai driven element untuk antenna lain seperti Yagi. dipole dicipta oleh ahli fizik Jerman, Heinrich Hertz pada sekitar tahun 1886 dalam eksperimen beliau dalam gelombang radio.


ini adalah skematik satu dipole antenna separuh gelombang bersambung dengan unbalanced coaxial cable. Amalan yang bagus adalah dengan menyambung balanced dipole kepada unbalanced transmission line dengan satu balun.





bahagian yang bewarna biru adalah medan eletrik dan bahagian bewarna merah adalah medan magnet yang diradiasikan oleh antenna dipole.


dipole yang lebih pendek dari panjang gelombang selalunya dipanggil sebagai Hertzian, short, shorten, atau pun infinitesimal dipole. dipole yang pendek ini mempunyai kadar rintangan radiasi yang rendah dan kadar regangan yang tinggi menjadikannya tidak efisyen tetapi selalunya antenna sebegini yang digunakan pada gelombang yang panjang. dipole yang mempunyai panjang hanya separuh gelombang selalunya dipanggil dipole separuh gelombang atau pun half wave dipole merupakan salah satu antenna yang efisyen. dalam term kejuruteraan radio, dipole selalunya dipanggil bagi dipole separuh gelombang.

sebaiknya, satu antenna dipole separuh gelombang mesti di suap dengan balanced line bagi mengimbangi impendance antenna sebanyak 73 ohm. satu folded dipole antenna selalunya digunakan dengan 300 ohm balanced feeder line.

ramai orang memilih untuk menyuap dipole secara terus dengan satu coaxial cable berbanding dengan satu ladder line. bagaimanapun, coaxial cable sebenarnya tidak symmetrical menjadikannya bukan satu penyuap yang seimbang.ini adalah kerana bahagian luar coaxial cable itu sendiri bersambung dengan pembumian. apabila satu balanced antenna seperti dipole bersuap dengan satu suapan yang tidak seimbang, arusnya akan menjadikan coaxial cable itu untuk radiate disamping elemen antenna itu sendiri, maka radiation pattern akan terganggu. keadaan ini boleh diselesaikan dengan menggunakan balun.

pelbagai jenis balun boleh digunakan bersama dipole, samada current balun, coax balun ataupun sleeve balun.

dipole adalah jauh lebih bagus dari whip antenna, yang selalunya quarter wave monopole. jumlah radiasi yang terhasil dari dipole jauh lebih kuat dari satu antenna suku panjang gelombang. Oleh itu whip antenna memerlukan ground plane yang sempurna untuk memastikannya bekerja dengan lebih efisyen pada keadaan half space seumpama dipole pada free space, jauh dari permukaan yang konduktif seperti permukaan bumi.

Sunday, November 20, 2011

G5RV Antenna: Inverted V Atau Flat ?

G5RV adalah satu jenis antenna dalam kategori multiband yang memerlukan tuner. Antenna ini menjadi pilihan mereka yang suka membuat contact dengan station yang jauh (DX) kerana mudah dibina, murah dan juga senang dibawa untuk portable operation.

Antenna ini dicipta oleh Louis Varney dengan callsign G5RV pada tahun 1946. Secara asasnya, antenna ini terdiri dari 102 kaki element wayar dan 34 kaki feeding stub. Interaksi di antara elemen wayar ini dan juga feeding stub menjadikan antenna ini senang di match kan untuk frekuensi dari 80 meter band sehingga 10 meter band.

Secara kasarnya, antenna ini juga sama dengan dipole separuh gelombang untuk 80 meter band dan juga gelombang penuh untuk 40 meter band. Pada 20 meter band, antenna ini memberikan 4 ke 6 low angle lobes dalam kesemua arah menjadikan antenna ini sesuai untuk membuat contact dengan station DX.


Bagaimana untuk memasang antenna G5RV ? adakah inverted v setup ataupun horizontal ? mari kita bincang.

setelah membuat simulasi dengan menggunakan software, saya mendapati antenna G5RV ini mesti dipasang secara horizontal untuk mendapatkan 4 ke 6 low angle lobes pada 20 meter band supaya bagus digunakan untuk DXing. Jika dipasang secara inverted V seperti monoband dipole, 4 ke 6 low angle lobes itu akan hilang, gain juga akan turun.

Lihat gambar di bawah,

G5RV dipasang secara flat, ataupun horizontal. 



bentuk lobes yang terjadi apabila antenna G5RV dipasang secara horizontal, ketinggian 7 meter dari paras bumi secara teorinya.




Gain sebanyak 8.44dbi terhasil pada frekuensi 14.200mhz. 


G5RV di pasang secara inverted V ataupun V terbalik.
lobes yang terhasil dari pemasangan secara inverted V, perhatikan dan banding dengan pemasangan secara flat. Terdapat beberapa lobes yang hilang.

Gain sebanyak 5.64dBi, perhatikan lobes mengecil dan tidak menonjol ke semua arah. manakala low take off angle lobes juga hilang.


Kesimpulan, secara teorinya antenna ini mesti dipasang secara flat untuk mendapatkan prestasi yang bagus pada 20 meter band. Bagi mereka yang suka membuat contact dengan station yang jauh semestinya anda memerlukan kesemua low angle lobes yang mampu dihasilkan oleh antenna ini. Untuk komunikasi tempatan atau local communication pada 40 meter band dan juga 80 meter band, pemasangan secara inverted V sudah memadai.Tentukan feeding stub, ladder lane, atau twin lead cable dalam keadaan tegak.


Types Of Microphone

Condenser Microphone


The condenser microphone is a very simple mechanical system, with almost no moving parts compared with other microphone designs. It is also one of the oldest microphone types, dating back to the early 1900's. It is simply a thin stretched conductive diaphragm held close to a metal disk called a backplate. This arrangement basically produces a capacitor, and is given its electric charge by an external voltage source. This source is often phantom power, but in many cases condenser mics have dedicated power supply units. When sound pressure acts on the diaphragm it vibrates slightly in response to the waveform. This causes the capacitance to vary in a like manner, which causes a variance in its output voltage. This voltage variation is the signal output of the microphone. There are many different types of condenser microphones, but they are all based on these basic principles. The condenser mic generally has a flatter frequency response than the dynamic one. That is why you should choose a condenser mic when high accuracy and clarity of the recording is needed. For example vocals of almost any type, the acoustic guitar or any other acoustic instrument will be most accurately recorded with a condenser mic. Because of its construction the condenser mic is more sensitive to sound and also more physically fragile than a dynamic one, so it should be handled with care. Too hard handling ( a drop to the floor), too high sound pressure (screaming into it close up) can cause this type of microphone to stop functioning.

IMPORTANT!! If you choose a condenser mic you will need a preamp or a mixer that will provide phantom power or "phantom feed" of usually 48 volts. This is because the condenser mic needs electricity to operate. Most of the new preamps and mixers provide this, but if you're going to use a condenser mic be sure to check just in case.


Dynamic Microphone


A dynamic mic is one in which audio signal is generated by the motion of a conductor within a magnetic field. In most dynamic mics, a very thin, light, diaphragm moves in response to sound pressure. The diaphragm's motion causes a voice coil that is suspended in a magnetic field to move, generating a small electric current. Generally less expensive than condenser mics (although very high quality dynamics can be quite expensive), dynamics feature quite robust construction, can often handle very high SPLs (Sound Pressure Levels), and do not require an external power source to operate. Because of the mechanical nature of their operation, dynamic mics are commonly less sensitive to transients, and may not reproduce quite the high frequency "detail" other types of mics can produce. Dynamic mics are very common in live applications. In the studio, dynamics are often used to record electric guitars, drums and more. One example of a highly popular dynamic microphone is Shure’s hand held SM58.

The dynamic mic is usually more rugged . It can handle more rough handling, moisture and high sound pressure levels than the condenser. This is why live performers on stage and outdoors preferably use dynamic mics. It can also be used in your recording studio, but it's not well suited for recording soft vocals or acoustic instruments since its frequency response is much narrower than the condenser's. For rough and loud vocals like heavy metal vocals though, a dynamic mic might even be the only way to go since a condenser would only distort under the high sound pressure. This type of mic does not need any phantom power.



Ribbon Microphone


A type of velocity microphone. A velocity microphone responds to the velocity of air molecules passing it rather than the Sound Pressure Level, which is what most other microphones respond to. In many cases this functional difference isn't important, but it can certainly be an issue on a windy day. Very old ribbon mics could be destroyed from the air velocity created just by carrying them across a room; today’s ribbon mics can handle the rigors of daily studio use. A ribbon mic works by loosely suspending a small element (usually a corrugated strip of metal) in a strong magnetic field. This "ribbon" is moved by the action of air molecules and when it moves it cuts across the magnetic lines of flux causing a signal to be generated. Naturally ribbon mics have a figure 8 pick up pattern. You can think of it like a window blind; it is easily moved by wind blowing at it, but usually doesn't move when wind blows across it from left to right. Ribbon mics were the first commercially successful directional microphones.


USB Microphone


Probably one of the hottest developments in recent microphone technology has been the USB mic. Yet it's actually a fairly simple item to describe. A USB mic contains all the elements of a traditional microphone: capsule, diaphragm, etc. Where it differs from other microphones is its inclusion of two additional circuits: an onboard preamp and an analog-to-digital (A/D) converter. The preamp makes it unnecessary for the USB mic to be connected to a mixer or external mic preamp. The A/D converter changes the mic's output from analog (voltage) to digital (data), so it can be plugged directly into a computer and read by recording software.

Electret Condenser Microphone



type of capacitor microphone invented at Bell laboratories in 1962 by Gerhard Sessler and Jim West. The externally applied charge described above under condenser microphones is replaced by a permanent charge in an electret material. An electret is a ferroelectric material that has been permanently electrically charged or polarized. The name comes from electrostatic and magnet; a static charge is embedded in an electret by alignment of the static charges in the material, much the way a magnet is made by aligning the magnetic domains in a piece of iron. Due to their good performance and ease of manufacture, hence low cost, the vast majority of microphones made today are electret microphones; a semiconductor manufacturer estimates annual production at over one billion units. Nearly all cell-phone, computer, PDA and headset microphones are electret types. They are used in many applications, from high-quality recording and lavalier use to built-in microphones in small sound recording devices and telephones.

Though electret microphones were once considered low quality, the best ones can now rival traditional condenser microphones in every respect and can even offer the long-term stability and ultra-flat response needed for a measurement microphone. Unlike other capacitor microphones, they require no polarizing voltage, but often contain an integrated preamplifier that does require power (often incorrectly called polarizing power or bias). This preamplifier is frequently phantom powered in sound reinforcement and studio applications. Monophonic microphones designed for personal computer (PC) use, sometimes called multimedia microphones, use a 3.5 mm plug as usually used, without power, for stereo; the ring, instead of carrying the signal for a second channel, carries power via a resistor from (normally) a 5 V supply in the computer. Stereophonic microphones use the same connector; there is no obvious way to determine which standard is used by equipment and microphones. Only the best electret microphones rival good DC-polarized units in terms of noise level and quality; electret microphones lend themselves to inexpensive mass-production, while inherently expensive non-electret condenser microphones are made to higher quality.

Linear VS Switching Power Supply

For amateur radio operators, linear and switching power supplies are the most common power supplies topologies used today. Linear power supplies have been in the market for many years, while switching power supplies are becoming more widely used because of its advantages — cheap, high efficiency, small size, and low heat generation. Linear power supplies are typically used in R&D environments and in production test systems. They provide high performance, low periodic and random deviation (PARD), that is, less voltage ripple and noise, excellent line and load regulation, and superior transient recovery time.

When compared with switching power supplies, linear power supplies are relatively inefficient. Due to their design, they tend to be cumbersome, bigger. Typically, linear power supplies provide the most effective solution in low-power applications. When choosing an instrumentation-grade power supply for bench-station testing, you must consider efficiency, size, transient time, and price, with the key factor being noise performance of the instrument. Generally, linear power supplies have less noise compared to switching power supplies. 

However over the years, the design of switching power supplies has improved and the noise performance for switching supplies is as good as it is for linear power supplies. However, low-noise switching power supplies are more costly. Normally, low-noise switching power supplies are mainly for high-power applications, while low-noise linear power supplies are suitable for low-power applications. In this article, you will learn and understand why do we need low-noise linear power supplies and how linear power supplies compare to low-end switching power supplies for the same price range.

Do we need low-noise power supplies? 

Low-noise power supplies are essential in certain low-power applications, and the key advantage of linear power supplies are low voltage ripple and noise. If you use low-end switching power supplies with high output noise, or if you want to remove unwanted noise, you must add electronic filters (capacitors), electromagnetic interference filters, or radio frequency (RF) shielding to low-end switching power supplies in low-noise applications. Unfortunately, the filters and shielding add complexity and cost to the applications. Obtaining a clean output signal when you are transmitting and receiving RF signals can be challenging. Low-end switching power supplies may contain many high frequency spectral components in their DC output, while linear power supplies normally do not have high frequency noise in their outputs and therefore will not cause interference in RF applications.

Powering active antennas, down-converters, or preamplifier requires very low-noise power supplies. Any noise superimposed on the DC power can enter the antenna or the antenna lead and interfere with the useful signal. Also, electromagnetic interference generated by the power supply can enter the receiver input and reduce the signal-to-noise ratio of the received signal. Figure 2 and Figure 3 show how a circuit powered by a power supply can affect an RF signal.



Operational amplifiers (op-amps) used in analog audio circuits and high-density ICs in digital systems are highly sensitive to noise from the power supply. When an op-amp has its input referenced to the supply, any high frequency noise that exists in the low-end switching power supply will be coupled with the output. For example, when you design a simple op-amp based headphone amplifier, noise and ripple from the power supply may affect the output measurement of the on-amp and its performance. Using bypass or decoupling elements will clean up the output, but it will increase the design complexity and product cost.

C O N C L U S I O N 

Both linear and switching power supplies have advantages and disadvantages. Low-end switching power supplies are commonly used in many areas because they are more efficient and cost less, but they are not optimal for noise reduction. If you are looking for performance and noise-free power, a linear power supply or a high-end switching power supply is your best choice.

Switching Mode Power Supply (SMPS) Interference


1. Why are Switched Mode Power Supplies (SMPS) associated with radio interference?

Switched mode power supplies (SMPS) employ high frequency switching and thus, are a source of radio interference, a recipient of radio interference and a conduit of radio interference. (Older linear type transformer based power supplies do not employ high frequency switching voltages and will be quieter as compared to switching type of supplies).


2. What are the typical sources of radio interference in a SMPS?

The primary emission sources originate in the switching devices due to their fast switching current transitions: harmonics of the switching frequency and broadband noise created by under-damped oscillations in the switching circuit. The secondary source is from the bridge rectifier, both rectifier noise and diode recovery. The AC input rectifier / capacitor in the front end of the switching power supplies (excepting those with power factor correction) are notorious for generating power supply harmonics due to the non linear input current waveform. The noise is both conducted and radiated through the input power cord and the DC output wiring to the radio.


3. How is a SMPS affected by received radio interference? How can the problem be solved?

Switching power supplies are also recipients of radio interference. The normal operation of the power supply can be disturbed due to RF noise getting coupled into the power supply. Thus, the power supply may generate excessive RF noise and lose output voltage regulation due to excessive transmitter energy being coupled through the AC / DC lines to the power supply’s regulator feedback path. This may be due to antenna being too close or due to the antenna or feed system not radiating properly. First check the antenna system SWR. Then, if necessary, relocate either the antenna or the power supply farther apart.


4. What is the source of the “buzzing” sound heard at the receiver? How can this be avoided?

The receiver may “hear” the power supply. A slowly moving, slightly buzzing carrier heard in the receiver may be caused by the antenna being too close. As with the transmitter related noise pick up, a loose coaxial connector or a broken or a missing ground may aggravate this problem. Normally these noises will be below the background or “band” noise. Increase the separation between the power supply and the receiving antenna. Use an outdoor antenna. This will reduce the amount of signal picked up from the power supply and also increase the amount of the desired signal.


5. What are the standards pertaining to RF noise in SMPS?

The conducted and radiated noises are limited as per the applicable national / international standards. In North America, the applicable standard is as per FCC Part 15(B) for Class “B” digital devices. The European standard is as per EN55022, Class “B” & EN610000-3-2, 3. Thus, the RF interference is limited but not entirely eliminated.


6. How can conducted RF noise be limited in a SMPS?

The conducted RF noise from these power supplies is limited to the maximum allowable levels by internal filtration. The filtered RF noise currents (normally < 5mA) are bypassed to the chassis of the power supply. The chassis is, in turn, connected to the earth ground pin of the AC input power cord (for Class 1 units). Thus, the filtered noise currents are intentionally leaked to the earth ground. This is termed as the “Earth Leakage Current”. For safety against electric shock, this earth leakage current is also required to be limited. It will be seen that these two requirements are conflicting.

NOTE: In some cases, to prevent electric shock hazard due to abnormal leakage current (like in marinas, spas, hot tubs, wet spaces etc.), the AC outlet circuits / receptacles in these areas are served through a GFCI (Ground Fault Circuit Interrupter). This GFCI is normally set to trip when it senses an earth leakage current > 5 mA. A single GFCI may be serving multiple AC outlet circuits / receptacles and therefore, will be sensing the sum of all the leakage currents of the devices connected to these. As the switching power supplies have intentional leakage current as explained above, it may trip a GFCI feeding multiple AC outlet circuits / receptacles. In such cases, disconnect devices connected to the other AC outlet circuits / receptacles served by this GFCI.


7. What additional steps can be taken to reduce the effects of RF noise?

Following additional guidelines may be followed to reduce the effects of RF noise:

  • a. Use additional appropriate AC radio frequency interference (RFI) power line filter immediately before the ac input of the power supply. These cord sets, with integral line interference filters, reduce common and differential mode interferences over a wide frequency range. Because they are shielded, they are also effective against radiated interferences. In addition to the built-in filter networks, the cable conductors are coated with an RF absorbing ferrite compound. This provides additional attenuation at high frequencies that is lacking in most regular LC filters. The RF absorption of the ferrite-coated cable avoids resonance’s at high frequencies, reducing the conducted and radiated RF noises even further


  • b. Use additional appropriate DC radio frequency interference (RFI) power line filter immediately after the DC output of the power supply.


  • c. Twist the positive and negative wires from the output of the power supply to the radio


  • d. The DC side positive and negative outputs of these power supplies are isolated from the chassis. As explained at paragraph 6 above, the noise currents are filtered to the chassis ground and the chassis ground is connected to the earth ground through the earth ground pin of the AC power outlet receptacle. Avoid connecting (referencing) the DC negative output terminal of the power supply to the earth ground


  • e. Connect a 1/4” wave length of wire on the negative terminal of the power supply. Connect one end of the wire to the negatvie terminal and leave the other end free. The wave length corresponds to the wave length of the interfering frequency. (May not be practical for long wave lengths)
[ Formula: Wave length (Meters) = 300 / frequency in MHz ]

Saturday, November 19, 2011

Provokasi Dan Propagasi


Tertarik kepada komen yang lepas, rujuk komen http://9m2pju.blogspot.com/2011/08/2-meter-audio-on-40-meter.html ingin saya tulis sedikit tentang perkara ini. mari kita berkongsi idea.

Apakah itu provokasi ? dari sumber pusat rujukan persuratan melayu dewan bahasa dan pustaka
  1. perbuatan atau kata-kata yg membangkitkan kemarahan: Saya mendiamkan diri dan tidak menyambut ~nya. memprovokasi membangkitkan kemarahan: Kamu dipukul mungkin kerana kamu ~nya.
  2.  perbuatan membangkitkan kema­rahan, minat, dsb: saya mendiamkan diri dan tidak menyambut ~nya; memprovokasi 1. membangkitkan kema­rahan: barangkali kamu dipukul kerana kamu ~nya; 2. membangkitkan, menimbul­kan, mencetuskan: biarlah saya mengadakan sedikit renungan terhadap ketiga-tiga unsur tersebut, sekurang-kurangnya utk ~ pemikiran. 
 Apakah itu propagasi radio ?
  1. propagasi radio adalah satu sifat gelombang radio apabila dipancarkan dari titik ke titik yang lain di muka bumi atau ke bahagian-bahagian dalam atmospera.
  2. sebagai radiasi eletromagnetik, gelombang radio juga dipengaruhi oleh fenomena seperti refleksi, pembiasan, pembelauan, penyerapan, polarisasi dan juga penyerakan akibat perubahan harian wap air di lapisan troposfera dan juga pengionan di bahagian atas atmosfera mengikut aktiviti matahari.
Soalan

  1. adakah provokasi cuaca boleh membuatkan audio dari 2 meter band masuk ke 40 meter band ?
  2. adakah propagasi radio boleh membuatkan audio dari 2 meter band masuk ke 40 meter band ?

Bagaimana Untuk Memancar Di 40 Meter Band


Saya tertarik kepada komen yang di berikan oleh pelawat blog saya ini. rujuk komen http://9m2pju.blogspot.com/2011/08/2-meter-audio-on-40-meter.html beliau menulis "Saya TIDAK tahu menahu pun bagaimana untuk memancar di 40 meter".

Apa yang boleh saya kongsikan adalah tentang 40 meter band adalah :

  1. 40 meter band atau 7 megahertz frekuensi untuk kegunaan radio amatur yang melingkungi dari 7.000 megahertz sehingga 7.200 megahertz untuk wilayah IARU pertama dan ke 3. Manakala untuk wilayah IARU ke 2, dari 7.000mhz sehingga 7.300mhz.
  2. 40 meter band telah diberi kepada operator radio amatur di Amerika Syarikat sejak 10 Oktober 1924 pada Persidangan Radio Kebangsaan Ketiga ( Third National Radio Conference ).
  3. Band ini telah diluluskan penggunaannya di peringkat dunia pada Persidangan Radiotelegraph Antarabangsa ( International Radiotelegraph Conference ) di Washinton pada 4 Oktober 1927.
  4. Pada mulanya, untuk wilayah IARU ke 3, 40 meter band hanya diberikan dari 7.000mhz sehingga 7.100mhz, di World Radio Conference pada tahun 2003, semua telah bersetuju untuk mengeluarkan broadcasting station dari 7.100mhz-7.200mhz. Selepas itu, penggunaan 7.000mhz - 7.200mhz diberikan kepada radio amatur.
  5. 40 meter band merupakan satu band yang bagus untuk local communication dan juga untuk DXing.
  6. Di kawasan asia tenggara, hampir lebihkurang 70 peratus band ini digunapakai oleh radio amatur dari Indonesia. manakala selebihnya digunakan oleh radio amatur Malaysia, Filipina, Jepun dan sebagainya.
Jadi bagaimana untuk memancar di 40 meter band ?
  1. di Malaysia, hanya kelas A radio amatur sahaja yang dibenarkan untuk memancar di 40 meter band. Pada waktu artikel ini ditulis, kelas B belum mendapat kebenaran untuk menggunakan frekuensi ini.
  2. had kuasa pancaran di frekuensi ini untuk radio amatur kelas A Malaysia adalah 400 watts sahaja.
  3. anda memerlukan HF transceiver untuk memancar di frekuensi ini beserta antenna. antenna dipole separuh gelombang sudah memadai. lain-lain antenna yang lebih bagus juga boleh digunakan sebagai contoh, yagi, delta loop, log periodic, quad dan lain-lain.
  4. pastikan frekuensi yang ditala pada radio transceiver anda dalam lingkungan 7.000mhz - 7.200mhz kerana ini adalah 40 meter band untuk radio amatur di wilayah IARU ke 3.
  5. pastikan antenna anda match dengan frekuensi yang dipilihan bagi mengelakkan reflected power. jika tidak, antenna tuning unit boleh digunakan untuk menala radio transceiver dengan antenna yang digunakan.
  6. untuk mengetahui tentang bandplan yang disarankan oleh IARU 3, sila download http://www.iaru-r3.org/r3bandplan.doc
Komen saya tentang komen dalam gambar di atas. Saya tidak mengatakan beliau bersalah dalam hal tersebut, rujuk http://9m2pju.blogspot.com/2011/08/2-meter-audio-on-40-meter.html. Posting itu hanya berniat untuk menulis tentang salah satu fenomena yang berlaku di dalam dunia radio amatur sahaja. Pesalah dalam hal ini bukan menjadi isu utama. sebab dan juga kenapa perkara ini berlaku adalah perkara yang perlu kita fikir dan selesaikan. bak kata pepatah, melentur buluh mestilah dari rebungnya.


Wednesday, November 16, 2011

Mencelah Perbualan Dengan Hanya Menyebut Suffix

Terdapat beberapa stesyen radio amatur di Malaysia yang suka mencelah masuk perbualan di repeater ataupun simplex operation dengan hanya menyebut callsign belakangnya (maksud: suffix). Callsign radio amatur Malaysia yang dikeluarkan oleh Suruhanjaya komunikasi dan multimedia. Setiap callsign yang dikeluarkan mempunyai suffix dan juga prefix.

9M2 - ini adalah prefix beserta dengan kod kawasan. 2 untuk semenanjung, 6 untuk sabah dan 8 untuk serawak.

PJU - ini adalah suffix, 3 huruf dibelakang sebagai suffix.

Prefix dan suffix menjadikan callsign. Jika menyebut hanya suffix untuk mencelah masuk perbualan di repeater ataupun simplex operation, itu tidak dikira sebagai callsign. Kita ambil contoh kod Q, QRZ yang bermaksud "who is calling me ?". adakah dikira Q code jika hanya disebut sebagai RZ ?

Rujuk manual dari IARU bertajuk 1-Eth-operating-IARU-ENGLISH-version3-2010, muka surat 9, para II.3.


Jika anda radio amatur yang memegang isyarat panggilan 9M2PJU, adakah orang lain tau akan kod kawasan anda, kelas anda dan juga negara anda jika anda hanya menyebut PJU untuk mencelah masuk di antara perbualan di frekuensi ?

Sesuatu callsign atau isyarat panggilan radio amatur yang dikeluarkan dalam sesebuah negara mempunyai prefix dan juga suffix. di Malaysia, 9M adalah untuk kelas A dan 9W untuk kelas B, manakala kod kawasan adalah 2, 8 dan 6. 3 huruf dibelakang adalah suffix. Kalau masuk mencelah di antara perbualan, dengan hanya menyebut suffix. Adakah itu callsign yang sah ?. Sesungguhnya umur, darjat, bangsa, dan lain-lain yang berkaitan tidak sesekali menghalalkan apa jua kesalahan. Yang betul seharusnya betul dan yang salah semestinya salah. Rujuk kepada tatacara dan SOP. Guidelines di keluarkan untuk dibaca. Tiada kompromi.

Tiada niat penulis untuk tunjuk lagak, tunjuk pandai ataupun tunjuk hebat. Jika anda lebih mengetahui dari diri penulis, perbetulkan jika penulis ini salah.


Tuesday, November 15, 2011

Yaesu FT857 All Band All Mode DSP Transceiver




The Yaesu FT-857D is a multimode amateur transceiver that transmits and receives communications on bands ranging from high frequency (HF) to very high frequency (VHF) to ultra high frequency (UHF). It has inputs for an HF/6M antenna and a 2M/440 MHz antenna, as well as a removable front panel. It is even remotable with a separately sold kit.

General Specifications

  • The Yaesu 857D weighs 4.6 lb and measures 6.1 inches by 2 inches by 9.2 inches. It operates in temperatures ranging from 14 degrees to 140 degrees Fahrenheit. It runs on 13.8 volts of negative ground direct current power, plus or minus 10 percent. Its frequency stability is plus or minus 4 parts per million (ppm) between temperatures of 14 and 122 degrees Fahrenheit. Its emission modes are as follows: A1 (continuous wave), A3 (amplitude modulation, or AM), A3J (lower and upper sidebands), F1 (9,600 bps packet), F2 (1,200 bps packet) and F3 (frequency modulation, or FM). Its minimum synthesizer steps are 10 Hz (continuous wave/single-sideband modulation) and 100 Hz (AM, FM and wideband FM).

Reception

  • The Yaesu 857D receives transmissions over frequencies that range from 0.1 to 56, 76 to 108, 118 to 164 and 420 to 470 MHz. When receiving, it consumes between 0.55 and 1 ampere (A). Its sensitivity on the SSB/CW modulation (considering 10 dB signal-to-noise ratio) ranges from -uV to 0.125 uV. On AM, it ranges from 32 uV to 1 uV. Considering a 12 dB signal-to-noise and distortion ratio for FM, the sensitivity ranges from 0.5 uV to 0.2 uV. Its first intermediate frequency is 68.33 MHz on SSB, CW, AM and FM, and 10.7 MHz on wideband FM. Its second intermediate frequency is 455 kHz. Its audio output is 2.5 watts into 4 ohms at 10 total harmonic distortion, with impedance that ranges from 4 ohms to 16 ohms.

Transmission

  • The 857D transmits over frequencies that include the range between 160 and 6 meters, 2 meters, 70 centimeters (only for amateur bands) and the Alaska emergency frequency at 5,167.5 kHz. It consumes about 22 A during transmission. Its power output is 100 watts when transmitting between 160 and 6 meters, 50 watts at 2 meters and 20 watts at 70 centimeters. It has balanced modulation over SSB, variable reactance over FM and early stage modulation over AM. Its maximum deviation on FM is 5 kHz. Its SSB frequency response ranges from 400 Hz to 2,600 Hz. Its microphone impedance ranges from 200 ohms to 10,000 ohms, with the supplied microphone offering an impedance of 2,000 ohms.

FT-857D Specifications
GENERAL
Frequency Range: Receive:
0.1-56, 76-108, 118-164 and 420-470 MHz
Transmit:
160 - 6 Meters including 60 Meters
0
2 Meters
0
70 Centimeters (Amateur bands only)
0
5167.5 kHz: Alaska Emergency Frequency
0
(U.S.A. version only)
Emission Modes:
A1 (CW), A3 (AM), A3J (LSB/USB),
0
F1 (9600 bps Packet), F2 (1200 bps Packet), F3 (FM)
Synthesizer Steps (Min.):
10 Hz (CW/SSB), 100 Hz (AM),
0
100 Hz (FM), 100 Hz (WFM)
Antenna Impedance:
50 Ohm, Unbalanced
Operating Temp. Range:
-10 °C to +60 °C (14 F to 140 F)
Frequency Stability:
Better than ±4 ppm (-10 °C to +50 °C)
0
 
Power Requirements:
DC 13.8V ±10 %, Negative Ground
Current Consumption:
Receive (Squelched): 0.55A,
0
Receive (Max. Audio): 1A
0
Transmit: 22A (@ 100W RF output)
Case Size:
6.1" (W) x 2.0" (H) x 9.2" (D) (155 x 52 x 233 mm)
Weight:
4.6 lb. (2.1 kg.)
0
TRANSMITTER
Power Output:
160 - 6m: 100 Watts (25 Watts AM carrier)
0
2m: 50 Watts (12.5 Watts AM carrier)
0
70cm: 20 Watts (5 Watts AM carrier)
Modulation Types: SSB:
Balanced Modulator
FM:
Variable Reactance
AM:
Early Stage (Low Level)
FM Maximum Deviation:
±5 kHz (±2.5 kHz on FM-N)
Spurious Radiation: Harmonics:
At least 50 dB down (1.8 - 29.7 MHz)
At least 60 dB down (50/144/430 MHz)
0
Non-harmonic:
At least 50 dB down (1.8 - 29.7 MHz)
0
At least 60 dB down (50/144/430 MHz)
Carrier Suppression:
At least 40 dB
Opp. Sideband Suppression:
At least 50 dB
SSB Frequency Response:
400 Hz - 2600 Hz (-6 dB)
Microphone Impedance:
200 - 10 k Ohm (Supplied microphone: 2 k Ohm)

RECEIVER
Sensitivity:
SSB/CW AM-N FM
100 kHz - 1.8 MHz (IPO off):
- uV 32 uV -
1.8 - 28 MHz:
0.25 uV 2 uV -
28 - 30 MHz:
0.2 uV 2 uV 0.50 uV
50 - 54 MHz:
0.125 uV 1 uV 0.2 uV
144/430 MHz:
0.125 uV - 0.2 uV
SSB/CW/AM-N figures are for 10 dB S/N, 12 dB SINAD on FM

Squelch Sensitivity: SSB/CW/AM FM
1.8 - 28 MHz: 2.5 uV -
28 - 30 MHz: 2.5 uV 0.32 uV
50 - 54 MHz: 1 uV 0.16 uV
144/430 MHz: 0.5 uV 0.16 uV

Intermediate Frequencies: 0
1st IF: 68.33 MHz (SSB/CW/FM/AM)
0 10.7 MHz (W-FM)
2nd IF: 455 kHz
Image Rejection: Better than 70 dB (1.8 - 30 MHz, 50 - 54 MHz)
00 Better than 60 dB (144 - 148 MHz, 430 - 450 MHz)
IF Rejection: Better than 60 dB
Selectivity (-6 / -60 dB): 0
SSB/CW: 2.2 kHz/4.5 kHz
CW: 500 Hz/2.0 kHz (Optional YF-122C installed)
CW-N : 300 Hz/1.0 kHz (OptionalYF-122CN installed)
AM: 6 kHz/20 kHz
FM: 15 kHz /30 kHz (-6 / -50 dB)
Audio Output: 2.5 W into 4 Ohm @ 10% THD
Audio Output Impedance: 4 Ohm - 16 Ohm
0
Specifications are subject to change without notice, and are guaranteed within amateur bands only.

Related Posts Plugin for WordPress, Blogger...