document_title: Citizens band radio

question_text: what year did the cb radio come out

question_tokens: what year did the cb radio come out

text: Citizens band radio

text: History[edit]

text: United States[edit]

text: Origins[edit]

text: The citizens band radio service originated in the United States as one of several personal radio services regulated by the Federal Communications Commission (FCC). These services began in 1945 to permit citizens a radio band for personal communication (e.g., radio-controlled model airplanes and family and business communications). In 1948, the original CB radios were designed for operation on the 460–470 MHz UHF band.[3] There were two classes of CB radio: "A" and "B". Class B radios had simpler technical requirements, and were limited to a smaller frequency range. Al Gross established the Citizens Radio Corporation during the late 1940s to manufacture Class B handhelds for the general public.[4]

text: Ultra-high frequency (UHF) radios, at the time, were neither practical nor affordable for the average consumer. On September 11, 1958[5] the Class D CB service was created on 27 MHz, and this band became what is popularly known today as "Citizens Band". There were only 23 channels at the time; the first 22 were taken from the former amateur radio service 11-meter band, and channel 23 was shared with radio-controlled devices. Some hobbyists continue to use the designation "11 meters" to refer to the Citizens Band and adjoining frequencies. Part 95 of the Code of Federal Regulations regulates the Class D CB service, on the 27 MHz band, since the 1970s and continuing today.[6] Most of the 460–470 MHz band was reassigned for business and public-safety use; Class A CB is the forerunner of the General Mobile Radio Service (GMRS). Class B CB is a more distant ancestor of the Family Radio Service. The Multi-Use Radio Service is another two-way radio service in the VHF high band. An unsuccessful petition was filed in 1973 to create a Class E CB service at 220 MHz, which was opposed by amateur radio organizations[7] and others. There are several other classes of personal radio services for specialized purposes (such as remote control devices).

text: During the 1960s, the service was popular among small businesses (e.g., electricians, plumbers, carpenters), truck drivers and radio hobbyists. By the late 1960s advances in solid-state electronics allowed the weight, size, and cost of the radios to fall, giving the public access to a communications medium previously only available to specialists.[8] CB clubs were formed; a CB slang language evolved alongside 10-codes, similar to those used in emergency services.

text: 1970s popularity[edit]

text: After the 1973 oil crisis the U.S. government imposed a nationwide 55 mph speed limit, and fuel shortages and rationing were widespread. CB radio was used (especially by truckers) to locate service stations with better supplies of fuel, to notify other drivers of speed traps, and to organize blockades and convoys in a 1974 strike protesting the new speed limit and other trucking regulations. One leader was able to almost single-handedly coordinate an interstate highway blockade of hundreds of tractor-trailers in eastern Pennsylvania using the citizens band radio in his truck. His name was J.W. Edwards and his "handle" (on air nickname) was "River Rat". The blockade began on I-80 and quickly spread throughout the country, with River Rat's messages literally being relayed from one area of trucks to the next.[9] The radios were crucial for independent truckers; many were paid by the mile, which meant their productivity was impacted by the 55-mph speed limit.[8] The use of CB radios in 1970s films such as Smokey and the Bandit (1977), Breaker! Breaker! (1977) and Convoy (1978), popular novelty songs such as C.W. McCall's "Convoy" (1975),[10] providing inspiration for songs like Breaker-Breaker from the Outlaws (1976) and truckers legendary, and on television series such as Movin' On (debuted in 1974) and The Dukes of Hazzard (debuted 1979) established CB radio as a nationwide craze in the United States in the mid- to late 1970s.

text: Originally, CB required a purchased license ($20 in the early 1970s, reduced to $4 on March 1, 1975) and the use of a callsign; however, when the CB craze was at its peak many people ignored this requirement and invented their own nicknames (known as "handles"). Rules on authorized use of CB radio (along with lax enforcement) led to widespread disregard of the regulations (notably in antenna height, distance communications, licensing, call signs and transmitter power).

text: Betty Ford, the former First Lady of the United States, used the CB handle "First Mama".[11] Voice actor Mel Blanc was also an active CB operator, often using "Bugs" or "Daffy" as his handle and talking on the air in the Los Angeles area in one of his many voice characters. He appeared in an interview (with clips having fun talking to children on his home CB radio station) in the NBC Knowledge television episode about CB radio in 1978. Similar to internet chat rooms a quarter-century later, CB allowed people to get to know one another in a quasi-anonymous manner. As with the internet, CB radio usage allowed both the best and worst characteristics of anonymity.

text: Originally, there were 23 CB channels in the U.S.; the 40-channel band plan was implemented in 1977. Additionally, there were two more channels between 22 & 23, commonly referred to as 22A & 22B. Several people had 22A, but not many had 22B. In the early 1970s Radio Shack sold a "base station" CB radio that contained a crystal for each of the 23 channels, two extra slots existed, and you could order the 22A & 22B crystals for an easy plug-in. Channel 9 was officially reserved for emergency use by the FCC in 1969.[12] Channel 10 was originally often used for highway travel communications east of the Mississippi River, and channel 19 west of the Mississippi; channel 19 then became the preferred highway channel in most areas, as it did not have adjacent-channel interference problems with channel 9. Many CBers called channel 19 "the trucker's channel". Channel 11 was originally restricted by the FCC for use as the calling channel.

text: The original FCC output power limitation for CB radios was "5 watts DC input to the final amplifier stage", which was a reference to the earlier radios equipped with tubes. With solid state radios becoming more common in the 1970s, this specification was rewritten by the FCC at the same time the authorized channels were increased to 40. The current specification is simply "4 watts output (AM) or 12 watts output (SSB)" as measured at the antenna connector on the back of the radio. The old specification was often used in false advertising by some manufacturers who would claim their CB radios had "5 watts" long after the specification had changed to 4 watts output. The older 23-channel radios built under the old specifications typically had an output of around 3.5 to 3.8 watts output when measured at the antenna connector. The FCC simply rounded up the old "5 watts DC input to the final amplifier stage" specification to the new "4 watts output as measured at the antenna connector on the back of the radio", resulting in a far simpler and easier specification.

text: Initially, the FCC intended for CB to be the "poor man's business-band radio", and CB regulations were structured similarly to those regulating the business band radio service. Until 1975,[13] only channels 9-14 and 23[14] could be used for "interstation" calls (to other licensees). Channels 1-8 and 15-22 were reserved for "intrastation" communications (among units with the same license).[15] After the inter-station/intra-station rule was dropped, channel 11 was reserved as a calling frequency (for the purpose of establishing communications); however, this was withdrawn in 1977.[16] During this early period, many CB radios had "inter-station" channels colored on their dials, while the other channels were clear or normally colored (except channel 9, which was usually colored red). It was common for a town to adopt an inter-station channel as its "home" channel. This helped prevent overcrowding on Channel 11, enabling a CBer to monitor a town's home channel to contact another CBer from that town instead of a making a general call on Channel 11.

text: Boating and the U.S. Coast Guard[edit]

text: Since CB was coming down in price and VHF Marine Band was still expensive, many boaters put CB radios on their boats. Business caught on to this market, and introduced marine CBs containing a weather band (WX). There was a lot of controversy about whether or not the Coast Guard should monitor CB radio, but they did, using Motorola base stations installed at their search and rescue stations. The Coast Guard stopped this practice in the late 1980s and recommends VHF Marine Band radios for boaters.[17]

text: 21st-century use[edit]

text: CB has lost much of its original appeal due to development of mobile phones, the internet and the Family Radio Service. Changing radio propagation for long-distance communications due to the 11-year sunspot cycle is a factor at these frequencies. In addition, CB may have become a victim of its own popularity; with millions of users on a finite number of frequencies during the mid-to-late 1970s and early 1980s, channels often were noisy and communication difficult. This caused a waning of interest among hobbyists. Business users (such as tow-truck operators, plumbers and electricians) moved to the VHF and UHF business-band frequencies. The business band requires an FCC license, and usually results in an assignment to a single frequency. The advantages of fewer users sharing a frequency, greater authorized output power, clarity of FM transmission, lack of interference by distant stations due to "skip" propagation, and consistent communications made the VHF (Very High Frequency) radio an attractive alternative to the overcrowded CB channels.

text: Channel 9 is restricted by the FCC to only emergency communications and roadside assistance.[18] Most highway travelers monitor channel 19. CB radio is still used by truck drivers, and remains an effective means of obtaining information about road construction, accidents and police speed traps.

text: Australia[edit]

text: Before CB was authorized in Australia, there were hand-held 27 MHz "walkie-talkies" which used several frequencies between the present CB channels, such as 27.240 MHz.[19][20] By the mid-1970s, hobbyists were experimenting with handheld radios and unauthorized 23-channel American CB radios. At that time in Australia, the 11-meter band was still used by licensed ham operators and Emergency Services,[21] but not yet available for CB use. A number of CB clubs had formed by this time which assigned call signs to members, exchanged QSL cards, and lobbied for the legalisation of CB. In late 1977, having legalised Australian CB and allowed the import/sale of American and Japanese 23-channel sets, the Federal Government drafted new interim regulations for Australian 18-channel transceivers. The new RB249 regulations came in on January 1, 1978 and the last official registration date for 23-channel sets was January 31, 1978. After this date, use of unregistered 23-channel CB sets was deemed illegal and unlicensed sets were no longer be eligible to be licensed. The 18-channel band plan used 16 channels of the 23 channel CB radios plus 2 extra channels, namely 27.095 and 27.195, to make up the 18 channels. The original channels 1,2,3,4,10,21 and 23 were deleted from the 18-channel band plan. So channel 1 on an 18 channel was actually channel 5 on a 23-channel radio.[22] On January 1, 1982, the American 40-channel band plan was adopted.

text: From the outset, the government attempted to regulate CB radio with license fees and call signs, but eventually they abandoned this approach. Enthusiasts rushed for licences when the doors opened at post offices around Australia in mid-1977 and by the end of the first quarter of 1978 there had been an estimated 200,000 licences issued (Australia's Population in 1978 was 14.36 Million). The regulations called for one licence per CB radio. The price for a licence in 1977 was AU$25 Per Year (In mid 1977 the Australian Dollar exchange rate was AU 90 cents to US $1), a not insubstantial amount for the average Australian wage-earner. Australian CB radio uses AM, USB, and LSB modes (No FM) on 27MHz, allowed output power being 4 Watts AM and 12 Watts SSB. UHF is 477 MHz, with an output power of 5 Watts. When CB was first legalised the 27 MHz CB Band was intended to be closed to Australian CBers in 1982 and only the 477 MHz UHF band was to continue, but this did not eventuate. The first 477MHz CB radio in 1977 was designed and made in Australia by Philips and was a 40 channel CB called the FM320. 27 MHz CB Channel Allocation in Australia is Channel 8 (27.055 MHz) Truckies or Highway Channel, Channel 9 (27.065 MHz) Emergency, Channel 11 (27.085 MHz) AM Call Channel, Channel 16 (27.155 MHz) LSB SSB Call Channel, 35 (27.355 MHz) LSB 2nd SSB Call Channel. UHF CB Channel Allocation is Channel 5 Emergency, Channel 11 Call Channel, Channel 40 Truckies or Highway. (NOTE: Australians refer to heavy transport drivers as "Truckies", a local variation of the American term "Truckers". Aussie "Truckies" generally shied away from using the much-cliched American CB language and codes, glamorised in movies and popular US folk lore.)

text: The first CB club in Australia was the Charlie Brown Touring Car Club (CBTCC)[citation needed], which formed in Morwell, Victoria in 1967 and consisted mainly of four-wheel drive enthusiasts. The club used the prefix "GL" (for Gippsland), since "CB" could not be used. After July 1, 1977, the club changed its name to Citizens Band Two Way Communication Club (CBTCC).[citation needed] Other early clubs were "LV" (Latrobe Valley) and "WB" (named after Wayne Britain). Members of these clubs are still active, and have also become amateur radio operators. Other regional Australian cities which became CB radio "hotspots" were cities such as Seymour, Benalla, Holbrook and Gundagai, all located on the busy Hume Highway between Melbourne and Sydney. Other regional cities such as Bendigo, Mildura, Mount Gambier and Port Augusta, developed lively, colourful CB radio communities.

text: With the introduction of UHF CB radios in 1977, many operators used both UHF and HF radios and formed groups to own and operate local FM repeaters. Members of the CBTCC formed what became known as Australian Citizens Radio Movement (ACRM) in the early 1970s; this organization became the voice for legalization of CB radio throughout Australia. After peaking in the 1970s and early 1980s, the use of 27 MHz CB in Australia has fallen dramatically due to the introduction of 477 MHz UHF CB (with FM and repeaters) and the proliferation of cheap, compact handheld UHF transceivers. Technology such as mobile telephones and the internet have provided people with other choices for communications. The Australian government has changed the allocation of channels available for UHF CB Radio from 40 to 80, and doubled the number of repeater channels from 8 to 16. This was done by taking the existing channels that had a spacing of 25 kHz between (Known as wide band) them and placing new channels in between the old 40 channels. So now the channels have 12.5 kHz spacing between them (now called narrow band). But the original 40 channels are still on the original frequencies.[23]

text: Australia also has Marine Radio Using 27 MHz. There are several frequencies allocated to 27 MHz Marine Radio in Australia. The frequencies range from 27.6800 MHz to 27.9800 MHz. Mode:AM Power:4W Maximum. These Frequencies and Allocation are:

text: 27.6800 Ch 68 - Commercial calling and working 27.7200 Ch 72 - Professional fishing calling and working (ship-shore/ship-ship) 27.8200 Ch 82 - Professional fishing calling and working (ship-shore/ship-ship) 27.8600 Ch 86 - Supplementary distress, safety and calling 27.8800 Ch 88 - Distress, safety and calling 27.9000 Ch 90 - Non-commercial calling and working (ship-shore) 27.9100 Ch 91 - Non-commercial calling and working (ship-shore) 27.9400 Ch 94 - Non-commercial club calling and working (ship-ship/ship-shore) 27.9600 Ch 96 - Non-commercial calling and working (ship-ship) 27.9800 Ch 98 - Rescue calling and working (ship-ship/ship-shore)

text: Canada[edit]

text: In Canada, the General Radio Service uses the identical frequencies and modes as the United States citizens band, and no special provisions are required for either Canadians or Americans using CB gear while traveling across the border. The General Radio Service was authorized in 1962. Initially, CB channels 1 through 3 remained allocated to amateur radio and channel 23 was used by paging services. American CB licensees were initially required to apply for a temporary license to operate in Canada.[24] In April 1977, the service was expanded to the same 40 channels as the American service.[25]

text: Indonesia[edit]

text: In Indonesia, CB radios were first introduced about 1977 when some transceivers were imported illegally from Australia, Japan and the United States. The dates are hard to confirm accurately, but early use was known around large cities such as Jakarta, Bandung, Yogyakarta, Surabaya and Medan. The Indonesian government legalized CB on 6 October 1980 with a decision by the Minister of Communications, the "Ministerial Decree on the Licensing for the Operation of Inter-Citizens Radio Communication". Because many people were already using 40-channel radios prior to legalization, the American band plan (with AM and SSB) was adopted; a VHF band was added in 1994, along with allowing use of the Australian UHF CB channel plan at 476-477 MHz On November 10, 1980, the Indonesian Directorate General of Posts and Telecommunications issued another decree establishing RAPI (Radio Antar Penduduk Indonesia) as the official citizens band radio organization in Indonesia.[26]

text: Malaysia[edit]

text: In Malaysia, citizens band radios became legal when the "Notification of Issuance Of Class Assignments" by Communication and Multimedia Malaysia was published on 1 April 2000. Under this class assignment, a CB radio is classified as a "Personal Radio Service device". The frequency band is HF, 26.9650 MHz to 27.4050 MHz (40 channels), power output is 4 watts for AM and FM and 12 watts PEP for SSB. Channel 9 is reserved for emergencies, and channel 11 is a calling channel. On UHF 477 MHz, citizens band PRS radio devices are allowed 5 watts power output on FM on 39 assigned channels spaced at 12.5-kHz intervals between 477.0125 MHz and 477.4875 MHz. Channel 9 is reserved for emergencies, and channel 11 for calling. A short-range simplex radio communications service for recreational use is from 477.5250–477.9875 MHz FM mode with 38 channels and a power output of 500 mW. A CB radio or Personal Radio Service Device under Class Assignment does not need an individual license to operate in Malaysia if it adheres to the rules of the Warta Kerajaan Malaysia, Communication and Multimedia Act 1998 (Act 588), Notification of Issuance Of Class Assignment, P.U.(B)416 Jil. 48, No. 22(e) Personal Radio Service Device, 1 November 2004.[27]

text: On April 1, 2010 the MCMC (Malaysian Communications and Multimedia Commission) released a new Notification of Issuance of Class Assignments, the Communications and Multimedia Act 1998 Class Assignments No. 1 of 2010[28] and later on 2017[29]. This includes a new UHF PMR 446 MHz allocation: an eight-channel analog Personal Mobile Radio 446 MHz (Analog PMR446) with frequencies from 446.00625–446.09375 MHz (12.5 kHz spacing) FM with 0.5 watt power output, and 16 channels for Digital Personal Mobile Radio 446 MHz (Digital PMR 446). Frequencies for Digital PMR 446 are from 446.103125–446.196875 MHz with 6.25 kHz channel spacing in 4FSK mode and a power output of 0.5 watt. An unofficial citizens band radio club in Malaysia is the "Malaysia Boleh Citizen Radio Group", known as "Mike Bravo" (Malaysia Boleh).[30]

text: United Kingdom[edit]

text: In the UK, small but growing numbers of people were illegally using American CB radios during the late 1970s and early 1980s. The prominence of CB radio grew in Britain partly due to the popularity of novelty songs like CW McCall's "Convoy" and Laurie Lingo & The Dipsticks' "Convoy GB" in 1976 (both of which were Top 5 hits)[10] and the movie Convoy in 1978. CB radio use was even featured on one part of the popular television programme Are You Being Served?. By 1980, CB radio was becoming a popular pastime in Britain; as late as the summer of 1981 the British government was still saying that CB would never be legalized on 27 MHz, proposing a UHF service around 860 MHz called "Open Channel" instead. However, in November 1981 (after high-profile public demonstrations) 40 frequencies unique to the UK, known as the 27/81 Bandplan using FM were allocated at 27 MHz plus 20 channels on 934 MHz (934.0125 to 934.9625 MHz with 50-kHz-spacing). CB's inventor, Al Gross, made the ceremonial first legal British CB call from Trafalgar Square in London.

text: The maximum power allowable on the MPT 1320 27/81 system was 4 watts (in common with the American system), although initially radios were equipped to reduce output power by 10 dB (to 0.4 watts) if the antenna was mounted more than 7 meters above ground level. The power-reduction switch is also useful in reducing TV interference. MPT 1320 also restricted antennas to a maximum length of 1.5 meters, with base loading being the only type permitted for 27 MHz operation. Over the next several years antenna regulations were relaxed, with antenna length increasing to 1.65 meters and centre- or top-loading of the main radiating element permitted. On September 1, 1987 the UK added the usual 40 frequencies (26.965–27.405 MHz) used worldwide, for a total of 80 channels at 27 MHz; antenna regulations were further relaxed, and the 934 MHz band was withdrawn in 1998.

text: CB radio in the UK was deregulated in December 2006 by the regulatory body Ofcom, and CB radio in the UK is now licence-free. The old MPT 1320 27/81 band will continue to be available for the foreseeable future. On 27 June 2014, changes were made by Ofcom to allow the use of AM & SSB modes on CB in the UK legally for the first time. The rules regarding non-approved radios and power levels above 4 watts on AM/FM and 12 W on SSB still apply, despite deregulation. Persons using illegal equipment or accessories still risk prosecution, fines or confiscation of equipment, although this is rarely enforced. AM and SSB on the freeband and amplifier use are common among enthusiasts. Packet radio is legal in the UK, although not widely used. Internet gateway stations are also beginning to appear; although illegal on 27 MHz, these units are connected to other CB stations around the world.

text: Although the use of CB radios in the UK is limited they are still popular, especially with the farming community, truckers and mini-cab services.[31] The widely used channel for the Young Farmers' Club is channel 11. The normal calling and truckers' channel is channel 19, although many truck organisations and groups use other channels to avoid abuse.

text: Frequency allocations[edit]

text: CB radio is not a worldwide, standardized radio service. Each country decides if it wants to authorize such a radio service from its domestic frequency authorizations, and what its standards will be; however, similar radio services exist in many countries. Frequencies, power levels and modes (such as frequency modulation (FM), amplitude modulation (AM), and single-sideband modulation (SSB), often vary from country to country; use of foreign equipment may be illegal. However, many countries have adopted the American channels and their associated frequencies, which is generally in AM mode except some higher channels which are sometimes in SSB mode.[32]

text: Standard Channels[edit]

text: The standard channel numbering is harmonized through FCC (America) and CEPT (Europe) (The channels 23: 27.235 MHz, 24: 27.245 MHz, 25: 27.255 MHz are not on the same radio frequencies in the standard CEPT).[33]

text: See also channel assignments for CB usage in the United States.

text:
CB Radio Channels (FCC)[34]

Channel
 Frequency
Channel
 Frequency
Channel
 Frequency
Channel
 Frequency

1
26.965 MHz
11
27.085 MHz
21
27.215 MHz
31
27.315 MHz

2
26.975 MHz
12
27.105 MHz
22
27.225 MHz
32
27.325 MHz

3
26.985 MHz
13
27.115 MHz
23
27.255 MHz
33
27.335 MHz

4
27.005 MHz
14
27.125 MHz
24
27.235 MHz
34
27.345 MHz

5
27.015 MHz
15
27.135 MHz
25
27.245 MHz
35
27.355 MHz

6
27.025 MHz
16
27.155 MHz
26
27.265 MHz
36
27.365 MHz

7
27.035 MHz
17
27.165 MHz
27
27.275 MHz
37
27.375 MHz

8
27.055 MHz
18
27.175 MHz
28
27.285 MHz
38
27.385 MHz

9
27.065 MHz
19
27.185 MHz
29
27.295 MHz
39
27.395 MHz

10
27.075 MHz
20
27.205 MHz
30
27.305 MHz
40
27.405 MHz

tag: table

text: Intermediate channels[edit]

text: When looking at the FCC/CEPT channel list there are some channels with an offset of 20 kHz instead of the regular 10 kHz step. These intermediate frequencies are reserved for the Radio Control Radio Service (RCRS) (formerly known as the Class C Citizens Radio Service until the 1976 changes). The RCRS service is commonly used for remote control of model aircraft and boats. It is an unofficial practice to name these channels by their next lower standard channel number along with an "A". Specifically channel 11A is used to power Eurobalises.

text:
Channel
Frequency
Channel
Frequency
Channel
Frequency

3A
26.995 MHz
7A
27.045 MHz
19A
27.195 MHz

11A
27.095 MHz
15A
27.145 MHz

text: SSB usage[edit]

text: This section does not cite any sources. Please help improve this section by adding citations to reliable sources. Unsourced material may be challenged and removed. (October 2015) (Learn how and when to remove this template message)

text: Single-sideband (SSB) operation involves the selection of either the Lower Side Band (LSB) or the Upper Side Band (USB) mode for transmit and receive. SSB radios also have the standard AM mode for communicating with standard CB radio models. With the original 23 CB channels SSB stations commonly used channel 16, to avoid interference to those using AM (SSB stations are authorized to use 12 watts, as opposed to 4 watts for AM stations) and to more easily locate other SSB stations. With the FCC authorization of 40 channels, SSB operation shifted to channels 36–40. Channel 36 or 38 (LSB) became the unofficial SSB "calling channels" for stations seeking contacts, with the subsequent conversation moving to channels 37–40. CBers with AM-only radios are asked to not use channels 36 through 40. In return, SSB stations stay off the remaining 35 channels so they could be used by AM stations. This agreement provides interference-free operation for all operators by separating the far more powerful SSB stations from the AM stations. This solution also resolves the chaos created by the false advertising that SSB radios have 120 channels compared to only 40 for AM radios.

text: While a SSB radio has three possible "modes" (AM, LSB, USB) it can operate in, operation is still limited to the same 40 channels. Some manufacturers tried to sell more radios by claiming that with three different modes possible for each channel, it was the equivalent to 120 channels. Reality is far different. In general, each channel can only support one conversation at a time, whether it be in the AM, LSB or USB mode; however, a single channel can support separate LSB and USB conversations at the same time if there is no AM conversation in progress. For a particular conversation, everyone must be tuned to the same channel and same mode in order to talk with each other. Attempting an SSB conversation while an AM conversation is in progress results in jammed communications for everyone.

text: Country-specific variations[edit]

text: The European Conference of Postal and Telecommunications Administrations (CEPT) adopted the North American channel assignments, except channel nº 23, frequency 27.235 MHz; channel nº 24, frequency 27.245 MHz; channel nº 25, frequency 27.255 MHz.[33] However, legal CB equipment sold in Europe does follow the North American channel designation. Some member countries permit additional modes and frequencies; for example, Germany has 40 additional channels at 26 MHz for a total of 80. The United Kingdom has an additional 40 channels between 27.60125 and 27.99125 MHz, also making 80 in total. Before CEPT, most member countries used a subset of the 40 US channels.

text: In Russia and Poland the channels are shifted 5 kHz down; for example, channel 30 is 27.300 MHz.[citation needed] Many operators add a switch to change between the "zeroes" (the Russian/Polish channel assignment) and the "fives" (the international/European assignment). Most contemporary radios for that markets can do "fives" as well as "zeroes" out of the box. Since roughly 2005–2006, Russia and Poland have adopted use of the standard US channel offset as well as the older channel plan, for two overlapping "grids" of channels.

text: Russia uses an alphanumeric designation for their CB channel plans, due the fact that several "grids" or "bands" of 40 channels each are used, along with both AM and FM mode. Russian CB allocations follow the CB band 26.965 – 27.405 MHz (designated as band C), as well as 26.515 – 26.955 MHz (designated as band B) and 27.415 – 27.855 MHz (designated as band D). Some radios refer to the "mid band" (standard CB band) as "band D" which shifts the letters up one (making 26.515 to 26.955 MHz "band C" and 27.415 – 27.855 MHz "band E".

text: For the convenience of users of the grid were marked by letters. Classic is considered the marking when the main range is designated "C" letter. The most common description of the channel is considered to be similar to the following: (C9FM or C9EFM or C9EF or 9EF).

text: In it:

text:
the first letter ( "C") is indicated by a grid that contains a set of 40 channels. If the first letter is not specified, it is considered that it is ( "C"). For example, (C9EF, 9EF)
hereinafter ( "9") – the channel number. Sometimes less than 10 channels are designated 2 digits. For example, (C9EF, C09EF)
behind it – an optional designation ( «E») for "European" or mandatory ( «R») for "Russian" size frequency nets. For example, (C9EF, C9F, C9RF)
end – the used modulation ( «FM») or ( «F»), ( « AM») or ( «A»). e.g. (C9EFM, C9EF, C9EAM, C9EA )

tag: ul

text: An example of correct designations: C9EF, C9EA, C9RF, C9RA

text: The 25 – 30 MHz band (including the CB allocations and frequencies above and below the 26.5 – 27.860 MHz band) is heavily used for taxi cab and other mobile two-way communications systems in Russia, Ukraine and other former USSR country states.

text: New Zealand and Japan have unique allocations that do not correspond to those of any other country. New Zealand authorizes use of their New Zealand specific 40-channel 26.330 – 26.770 MHz frequency plan in addition to the "standard" 40-channel 26.965 – 27.405 MHz frequency plan for a total of 80 HF CB channels. New Zealand has also adopted the Australian UHF CB System as well.[35]

text: Japan's CB allocation consists of 8 voice and 2 R/C channels with a maximum power output of 500 mW. AM mode is the only mode permitted and antennas must be non-removable and less than 199 cm (78 inches) long. In Japan, the 26 – 28 MHz range is allocated to fishery radio services and these frequencies are heavily used for marine communications. Japan's "double side band fishery radio" or "DSB Fishery Radio Service" covers 26.760 MHz-26.944 MHz, 27.016 MHz, and 27.524-27.988 MHz. However, frequencies such as 27.005 MHz AM are widely pirated in Japan with very high power transmitters. This causes interference to the authorized low-power 1 W DSB (1 watt AM) fishery radio service. Instead of 26 – 27 MHz, Japan has authorized several UHF-FM CB-type personal radio services in the 348 MHz, 420 – 422 MHz and 903 – 904 MHz bands.

text:
26.968 MHz – Japanese CB Channel 1
26.976 MHz – Japanese CB Channel 2
27.040 MHz – Japanese CB Channel 3
27.080 MHz – Japanese CB Channel 4
27.088 MHz – Japanese CB Channel 5
27.112 MHz – Japanese CB Channel 6
27.120 MHz – Japanese CB Channel 7
27.144 MHz – Japanese CB Channel 8 – Calling Channel

tag: ol

text:
27.048 MHz – Japanese Remote Control R/C Frequency
27.136 MHz – Japanese Remote Control R/C Frequency
27.152 MHz – Japanese Remote Control R/C Frequency

text: Indonesia has the usual 40 channels at 27 MHz, plus a unique 60-channel allocation from 142.050 MHz – 143.525 MHz.[36]

text: In Brazil, CB operators can use up to 80 channels (from 26.965 MHz to 27.805 MHz).

text: South Africa, like New Zealand and the UK, permits the use of two HF CB bands. South Africa has a 23-channel AM/SSB 29 MHz CB allocation (called "29 Megs" or "29 MHz CB") from 29.710 MHz to 29.985 MHz in 12.5 kHz steps. South Africa also permits use of standard CB channels 19 through 27 (27.185 to 27.275 MHz) with AM/SSB permitted. Many radios sold in South Africa feature both the 27 MHz and 29 MHz bands.

text: Hungary allows use of the "low channels" for a total of 80 channels (26.515 MHz to 27.405 MHz).

text: Germany authorizes a similar allocation, with 40 channels from 26.965 to 27.405 MHz and another 40 channels from 26.565 to 26.955 MHz in straight 10 kHz steps.

text: The Czech Republic authorizes 80 channels as well (same as the German 80 channel plan). As in Germany, digital modes are allowed on certain frequencies (channel 24 – 27.235 MHz, channel 25 – 27.245 MHz, channel 52 – 26.675 MHz, channel 53 – 26.685 MHz, channel 76 – 26.915 MHz, and channel 77 – 26.925 MHz). Internet gateways and radio repeaters are allowed on channels 18 (27.175 MHz) and 23 (27.255 MHz). Paging is permitted on channel 1 (26.965 MHz) and channel 80 (26.955 MHz) is the recommended call channel for Czech CB radio operators.

text: Using radios outside their intended market can be dangerous, as well as illegal, as frequencies used by Citizen's Band radios from other countries may operate on frequencies close to, or used by, emergency services (for example, the Indonesian service around 142 MHz operates on frequencies allocated to a public safety network shared with police, fire and EMS services in Ontario, Canada).

text: In the Philippines, up to present time, the use of 27 MHz CB is still banned since the Marcos regime banned it in 1980s. A few operators still illegally utilize the 40 CB channels. There are active CB groups that are now asking Senator Bongbong Marcos, the son of the late president Ferdinand Marcos, to lift the ban and make the use of CB radios legal again.

text: Current use[edit]

text: CB was the only practical two‑way radio system for the individual consumer, and served several subsets of users such as truck drivers, radio hobbyists, and those in need of short‑range radio communications, such as electricians, plumbers, and carpenters, who needed to communicate between job site and main office. While some users have moved on to other radio services, CB is still a popular hobby in many countries. The 27 MHz frequencies used by CB, which require a relatively long aerial and tend to propagate poorly indoors, discourage the use of handheld radios. Many users of handheld radios (families, hunters and hikers) have moved on to 49 MHz and the UHF Family Radio Service; those needing a simple radio for professional use (e.g., tradesmen) have moved on to "dot-color" Business Band radios and the VHF Multi-Use Radio Service.

text: CB is still popular among long-haul truck drivers to communicate directions, traffic problems and other relevant matters.[37] The unofficial "travelers channel" in most of the world is channel 19; in Australia it is channel 8 (27.055 MHz) and UHF channel 40 (477.400 MHz). In Russia it is channel 15 (in addition to traditional "emergency" 9 and "truckers" 19 channels) and in Greece it is channel 13, all AM. These frequencies may have evolved because tuned circuits (particularly antennas) work best in the middle of the band; the frequency for channel 19 (not channel 20) is the center of the 40-channel US band and other things being equal, signals will be transmitted and heard the farthest. Since less standardization exists in Europe, CB there is more associated with hobbyists than with truckers.

text: Legal (short‑range) use of CB radio is sometimes impeded by users of illegal high‑power transmitters, which can be heard hundreds of miles away. The other problem with short‑range CB use is propagation; during long‑range "skip" conditions local signals are inaudible due to reception of multiple distant signals.

text: In the United States, the number of users and law enforcement financing by the Federal Communications Commission mean that only the worst offenders are sanctioned, which makes legitimate operation on the citizens band unreliable. Most offenders are not caught for interfering with other CB users; often, their self‑modified equipment generates harmonics and spurs which cause interference to services outside the citizens band and to consumer equipment.

text: The maximum legal CB power output level in the U.S. is 4 watts for AM (un-modulated carrier; modulation can be four times the carrier power, or 16 watts PEP) and 12 watts PEP for SSB, as measured at the transmitter antenna connection. However, external linear amplifiers are often used illegally.

text: During the 1970s the FCC banned the sale of linear amplifiers capable of operation from 24 to 35 MHz to discourage their use on the CB band, although the use of high‑power amplifiers continued. Late in 2006, the FCC amended the regulation to exclude only 26 to 28 MHz to facilitate amateur 10-meter operation.[38] Lax enforcement enables manufacturers of illegal linear amplifiers to openly advertise their products; many CB dealers include these amplifiers in their catalogs. Due to their rampant, unchecked use of linear amplifiers, American CB Radio operators are often referred to as "Alligators", by operators in other countries. (Suggesting American operators are "All Mouth and No Ears".) Attempts by law-abiding CB users to increase regulatory oversight have been ineffective.

text: Technology[edit]

text: At the beginning of the CB radio service, transmitters and receivers used vacuum tubes; solid-state transmitters were not widely available until 1965, after the introduction of RF-power transistors.[39] Walkie-talkie hand-held units became affordable with the use of transistors. Early receivers did not cover all the channels of the service; channels were controlled by plug-in quartz crystals, with one of several operating frequencies selected by a panel control in more expensive units. Superheterodyne receivers (using one or two conversion stages) were the norm in good-quality equipment, although low-cost toy-type units used super-regenerative receivers. With the earliest sets two quartz crystals were needed for transmitting and receiving on each channel, which was costly. By the mid-1960s "mixer" circuits made frequency-synthesized radios possible, which reduced cost and allowed full coverage of all 23 channels with a smaller number of crystals (typically 14). The next improvement came during the mid-1970s; crystal synthesis was replaced by PLL technology using ICs, enabling 40-channel sets with only one crystal (10.240 MHz). Almost all were AM-only, although there were a few single sideband sets.

text: Most CB radios sold in the United States have the following features:

text:
Automatic noise limiter or noise blanker: Reduces background noise (such as spark ignition)
CB/WX switch: Selects weather-radio receiver
Automatic level control (ALC): Limits the transmitter modulation level to reduce distortion
PA: Some transceivers can drive an external speaker and act as a low-power public address system, or "bullhorn".
RF gain: Adjusts the RF amplifier gain of the receiver; used to reduce received background noise, and to reduce "clipping" due to over-amplification of already-strong signals (for example, when the receiver is near the transmitter)
NOR/9/19: Quickly tunes preset channels for calling or emergency use
SWR: Meter used to monitor reflected power caused by mismatched antennas and antenna cables
Volume control

text: Microphone choices include:

text:
Dynamic microphone: Uses magnetic coil and permanent magnet
Ceramic mic: Uses a piezoelectric element; rugged, low-cost but high-impedance
Echo mic: Deliberately introduces distortion and echo into transmitted audio
Electret microphone: Uses an electrostatic method to convert sound to electrical signals
Noise-canceling microphone: Uses two elements to reduce background noise
Power mic: An amplified microphone[40]

text: Antennas[edit]

text: 27 MHz is a relatively long wavelength for mobile communications, and the choice of antenna has a considerable impact on the performance of a CB radio. A common mobile antenna is a quarter-wave vertical whip. This is roughly nine feet (2.7 m) tall; it is mounted low on the vehicle body, and often has a spring-and-ball mount to enhance its flexibility when scraping or striking overhead objects. Where a nine-foot whip is undesirable, shorter antennas include loading coils to make the antenna impedance the same as a physically longer antenna. The loading coil may be on the bottom, middle, or top of the antenna, while some antennas are wound in a continuously-loaded helix.

text: Many truckers use two co-phased antennas, mounted on their outside mirrors. Such an array is intended to enhance performance to the front and back, while reducing it to the sides (a desirable pattern for long-haul truckers). However, the efficiency of such an arrangement is only an improvement over a single antenna when the co-phased antennas are separated by approximately eight feet or more, restricting this design to use mainly on tractor-trailers and some full-size pickups and SUVs. Some operators will use only one of the two antennas; this removes both the complexity and benefit of a true co-phased array, but gives a symmetrical cosmetic appearance preferred by some truck drivers.

text: Another mobile antenna is the continuously-loaded half-wave antenna. These do not require a ground plane to present a near-50-ohm load to the radio, and are often used on fiberglass vehicles such as snowmobiles or boats. They are also useful in base stations where circumstances preclude the use of a ground-plane antenna. Handheld CBs may use either a telescoping center-loaded whip or a continuously-loaded "rubber ducky" antenna.

text: Base CB antennas may be vertical for omnidirectional coverage, or directional "beam" antennas may be used to direct communications to a particular region. Ground-plane kits exist as mounting bases for mobile whips, and have several wire terminals or hardwired ground radials attached. These kits are designed to have a mobile whip screwed on top (a full-length, quarter-wave steel whip is preferred) and mounted on a mast. The ground radials replace the vehicle body (which is the counterpoise for a mobile whip in a typical vehicle installation).

text: Working skip[edit]

text: All frequencies in the HF spectrum (3–30 MHz) can be refracted by charged ions in the ionosphere. Refracting signals off the ionosphere is called skywave propagation, and the operator is said to be "shooting skip". CB operators have communicated across thousands of miles and sometimes around the world. Even low-power 27 MHz signals can sometimes propagate over long distances.

text: The ability of the ionosphere to bounce signals back to earth is caused by solar radiation[citation needed], and the amount of ionization possible is related to the 11-year sunspot cycle. In times of high sunspot activity, the band can remain open to much of the world for long periods of time. During low sunspot activity it may be impossible to use skywave at all, except during periods of Sporadic-E propagation (from late spring through mid-summer). Skip contributes to noise on CB frequencies. In the United States, it is illegal to engage in (or attempt to engage in) CB communications with any station more than 250 km (160 mi) from an operator's location.[41] This restriction exists to keep CB as a local (line-of-sight) radio service; however, in the United States the restriction is widely ignored. The legality of shooting skip is not an issue in most other countries . A recent FCC decision now allows the shooting of skip in the United States.[42]

text: Freebanding and export radios[edit]

text: Operation on frequencies above or below the citizens band (on the "uppers" or "lowers") is called "freebanding" or "outbanding".[43] While frequencies just below the CB segment (or between the CB segment and the amateur radio 10-meter band) seem quiet and under-utilized, they are allocated to other radio services (including government agencies) and unauthorized operation on them is illegal. Furthermore, illegal transmitters and amplifiers may not meet good engineering practice for harmonic distortion or "splatter", which may disrupt other communications and make the unapproved equipment obvious to regulators. Freebanding is done with modified CB or amateur equipment, foreign CB radios which may offer different channels, or with radios intended for export. Legal operation in one country may be illegal in another; for example, in the UK until June 2014 only 80 FM channels were legal.

text: Unlike amateur radios with continuous frequency tuning, CBs manufactured for export are channelized. Frequency selection resembles that of modified American CBs more than any foreign frequency plan. They typically have a knob and display that reads up to channel 40, but include an extra band selector that shifts all 40 channels above or below the band and a "+10 kHz" button to reach the model control "A" channels. These radios may have 6 or even 12 bands, establishing a set of quasi-CB channels on many unauthorized frequencies. The bands are typically lettered A through F, with the normal citizens band as D.

text: For example, a freebander with an export radio who wants to use 27.635 MHz would choose channel 19 (27.185 MHz) and then shift the radio up one band (+450 kHz). It requires arithmetic on the part of the operator to determine the actual frequency, although more expensive radios include a frequency counter or a frequency display—two different components, providing an identical result. Illegal operations may unintentionally end up on frequencies very much in use. For instance, channel 19 shifted two bands up is 28.085 MHz, which is in a Morse code/data-only part of the 10-meter ham band. Voice transmissions in a Morse code-only segment are easily detectable by authorities. Amateur Radio Service operators record, locate, and report frequency trespassing and intrusions of their government or ITU allocations by pirate transmissions or illegal operators to the FCC for enforcement action.[44]

text: Many freeband operators use amateur radios modified to transmit out of band, which is illegal in some countries. Older amateur radios may require component changes; for instance, the 1970s Yaesu FT-101 was modified for CB by replacing a set of crystals used to tune portions of the 10-meter band, although some variants of the FT-101 were sold with the US FCC channels standard and were capable of transmitting above and below the legal 40 channels by another 10 or more channels.[45] On some newer radios, the modification may be as simple as disconnecting a jumper wire or a diode. Many types of amateur transceivers may be found on CB and freeband, ranging from full-coverage HF transceivers to simpler 10-meter mobile radios. In the United States, the FCC bans the importation and marketing of radios it deems easily modifiable for CB;[46] it is illegal to transmit on CB frequencies with a ham radio except in emergencies where no other method of communication is available.

text: A gray market trade in imported CB gear exists in many countries. In some instances, the sale or ownership of foreign-specification CB gear is not illegal but its use is. With the FCC's minimal enforcement of its CB rules, enthusiasts in the US use "export radios" or European frequency modulation (FM) CB gear to escape the crowded AM channels. American AM gear has also been exported to Europe.

text: "Export radios" are sold in the United States as 10-meter Amateur Radio transceivers. Marketing, import and sale of such radios is illegal if they are distributed as anything other than Amateur Radio transceivers. It is also illegal to use these radios outside of the Amateur Radio bands by anyone in the US, since they are not type-certified for other radio services and usually exceed authorized power limits. The use of these radios within the Amateur Radio Service by a licensed Amateur Radio operator within his/her license privileges is legal, as long as all FCC regulations for Amateur Radio are followed. The term "export radio" is a misnomer, since it implies that they cannot be used in the country in which they are sold and hints that the radio is legal in another country. However, the typical "export radio" has a combination of features, frequency coverage and output power which make it illegal worldwide; in reality, there is no country to which these radios may be legally exported.

text: Callbook[edit]

text: A callbook is a directory of radio station call signs. Originally a bound book that resembled a telephone directory, it contains the name and addresses of radio stations in a given jurisdiction (country). Modern Electrics published the first callbook in the United States in 1909. Today, the primary purpose of a callbook is to allow radio operators to send a confirmation post card, called a QSL card to an operator with whom they have communicated via radio. Callbooks have evolved to include on-line databases that are accessible via the Internet to instantly obtain the address of another amateur radio operator and their QSL Managers. The most well known and used on-line QSL database for the 11-meter/freebander community is QRZ11.COM, designed after its "big brother" QRZ.COM for Amateur Radio.[47][48][49][50][51][52]

text: Media[edit]

text: During the 1970s and 1980s heyday of CB radio, many citizens band-themed magazines appeared on newsstands. Two magazines that dominated the time period were S9 CB Radio and CB Radio Magazine. S9's successor was Popular Communications, which had the same editor under a different publisher beginning in 1982. It covered hobby radio as well as CB. The same publisher produced a magazine called RADIO! for RadioShack stores in the mid-1990s. In Australia, CB Action Magazine was produced monthly from mid-1977 and continuing publication through until the early 1990s. CB Action spawned several other popular publications, including a communications and scanning magazine and the hugely popular Amateur Radio Action magazine, produced over several decades and running to some 18 volumes.

text: In the early 2000s, National Communications Magazine added CB radio coverage to its coverage of scanner radios and to this day remains the only magazine covering CB radio in North America.


document_title: Period 7 element

question_text: what is the largest metalloid on the periodic table

root

text: Period 7 element

text: Properties[edit]

text: All elements of period 7 are radioactive. This period contains the actinides, which contains the heaviest naturally occurring element, plutonium; subsequent elements must be synthesized artificially. Whilst the first five of these are now available in macroscopic quantities, most are extremely rare, having only been prepared in microgram amounts or less. The later, transactinide elements have only been identified in laboratories in batches of a few atoms at a time.

tag: p

text: Although the rarity of many of these elements means that experimental results are not very extensive, their periodic and group trends are less well defined than other periods. Whilst francium and radium do show typical properties of their respective groups, actinides display a much greater variety of behaviour and oxidation states than the lanthanides. These peculiarities are due to a variety of factors, including a large degree of spin-orbit coupling and relativistic effects, ultimately caused by the very high positive electrical charge from their massive atomic nuclei.

text: Elements[edit]

text:
Chemical element
Chemical series
Electron configuration
Occurrence

87
Fr
Francium
Alkali metal
[Rn] 7s1
From decay

88
Ra
Radium
Alkaline earth metal
[Rn] 7s2
From decay

89
Ac
Actinium
Actinide
[Rn] 6d1 7s2
From decay

90
Th
Thorium
Actinide
[Rn] 6d2 7s2 (*)
Primordial

91
Pa
Protactinium
Actinide
[Rn] 5f2 6d1 7s2
From decay

92
U
Uranium
Actinide
[Rn] 5f3 6d1 7s2
Primordial

93
Np
Neptunium
Actinide
[Rn] 5f4 6d1 7s2
From decay

94
Pu
Plutonium
Actinide
[Rn] 5f6 7s2 (*)
From decay

95
Am
Americium
Actinide
[Rn] 5f7 7s2 (*)
Synthetic

96
Cm
Curium
Actinide
[Rn] 5f7 6d1 7s2
Synthetic

97
Bk
Berkelium
Actinide
[Rn] 5f9 7s2 (*)
Synthetic

98
Cf
Californium
Actinide
[Rn] 5f10 7s2 (*)
Synthetic

99
Es
Einsteinium
Actinide
[Rn] 5f11 7s2 (*)
Synthetic

100
Fm
Fermium
Actinide
[Rn] 5f12 7s2 (*)
Synthetic

101
Md
Mendelevium
Actinide
[Rn] 5f13 7s2 (*)
Synthetic

102
No
Nobelium
Actinide
[Rn] 5f14 7s2 (*)
Synthetic

103
Lr
Lawrencium
Actinide
[Rn] 5f14 7s2 7p1 (*)
Synthetic

104
Rf
Rutherfordium
Transition metal
[Rn] 5f14 6d2 7s2
Synthetic

105
Db
Dubnium
Transition metal
[Rn] 5f14 6d3 7s2
Synthetic

106
Sg
Seaborgium
Transition metal
[Rn] 5f14 6d4 7s2
Synthetic

107
Bh
Bohrium
Transition metal
[Rn] 5f14 6d5 7s2
Synthetic

108
Hs
Hassium
Transition metal
[Rn] 5f14 6d6 7s2
Synthetic

109
Mt
Meitnerium
Transition metal (?)
[Rn] 5f14 6d7 7s2 (?)
Synthetic

110
Ds
Darmstadtium
Transition metal (?)
[Rn] 5f14 6d8 7s2 (?)
Synthetic

111
Rg
Roentgenium
Transition metal (?)
[Rn] 5f14 6d9 7s2 (?)
Synthetic

112
Cn
Copernicium
Post-transition metal
[Rn] 5f14 6d10 7s2 (?)
Synthetic

113
Nh
Nihonium
Post-transition metal (?)
[Rn] 5f14 6d10 7s2 7p1 (?)
Synthetic

114
Fl
Flerovium
Post-transition metal (?)
[Rn] 5f14 6d10 7s2 7p2 (?)
Synthetic

115
Mc
Moscovium
Post-transition metal (?)
[Rn] 5f14 6d10 7s2 7p3 (?)
Synthetic

116
Lv
Livermorium
Post-transition metal (?)
[Rn] 5f14 6d10 7s2 7p4 (?)
Synthetic

117
Ts
Tennessine
Post-transition metal (?)
[Rn] 5f14 6d10 7s2 7p5 (?)
Synthetic

118
Og
Oganesson
Noble gas (?)
[Rn] 5f14 6d10 7s2 7p6 (?)
Synthetic

text: (?) Prediction

text: (*) Exception to the Madelung rule.

text: Francium and radium[edit]

text: Francium and radium make up the s-block elements of the 7th period.

text: Francium (/ˈfrænsiəm/ FRAN-see-əm) is a chemical element with symbol Fr and atomic number 87. It was formerly known as eka-caesium and actinium K.[note 1] It is one of the two least electronegative elements, the other being caesium. Francium is a highly radioactive metal that decays into astatine, radium, and radon. As an alkali metal, it has one valence electron. Francium was discovered by Marguerite Perey in France (from which the element takes its name) in 1939. It was the last element discovered in nature, rather than by synthesis.[note 2] Outside the laboratory, francium is extremely rare, with trace amounts found in uranium and thorium ores, where the isotope francium-223 continually forms and decays. As little as 20–30 g (one ounce) exists at any given time throughout the Earth's crust; the other isotopes are entirely synthetic. The largest amount produced in the laboratory was a cluster of more than 300,000 atoms.[1]

text: Radium (/ˈreɪdiəm/ RAY-dee-əm) is a chemical element with atomic number 88, represented by the symbol Ra. Radium is an almost pure-white alkaline earth metal, but it readily oxidizes on exposure to air, becoming black in color. All isotopes of radium are highly radioactive, with the most stable isotope being radium-226, which has a half-life of 1601 years and decays into radon gas. Because of such instability, radium is luminescent, glowing a faint blue. Radium, in the form of radium chloride, was discovered by Marie Skłodowska-Curie and Pierre Curie in 1898. They extracted the radium compound from uraninite and published the discovery at the French Academy of Sciences five days later. Radium was isolated in its metallic state by Marie Curie and André-Louis Debierne through the electrolysis of radium chloride in 1910. Since its discovery, it has given names likeradium A and radium C2 to several isotopes of other elements that are decay products of radium-226. In nature, radium is found in uranium ores in trace amounts as small as a seventh of a gram per ton of uraninite. Radium is not necessary for living organisms, and adverse health effects are likely when it is incorporated into biochemical processes because of its radioactivity and chemical reactivity.

text: Actinides[edit]

text: The actinide or actinoid (IUPAC nomenclature) series encompasses the 15 metallic chemical elements with atomic numbers from 89 to 103, actinium through lawrencium.[3][4][5][6]

text: The actinide series derives its name from the group 3 element actinium. All but one of the actinides are f-block elements, corresponding to the filling of the 5f electron shell; actinium, a d-block element, is also generally considered an actinide. In comparison with the lanthanides, also mostly f-block elements, the actinides show much more variable valence.

text: Of the actinides, thorium and uranium occur naturally in substantial, primordial, quantities. The radioactive decay of uranium produces transient amounts of actinium, protactinium and plutonium, and atoms of neptunium are occasionally produced from transmutation reactions in uranium ores. The other actinides are purely synthetic elements, although the first six actinides after plutonium would have been produced during the Oklo phenomenon (and long since decayed away), and curium almost certainly previously existed in nature as an extinct radionuclide.[3][7] Nuclear weapons tests have released at least six actinides heavier than plutonium into the environment; analysis of debris from a 1952 hydrogen bomb explosion showed the presence of americium, curium, berkelium, californium, einsteinium and fermium.[8]

text: All actinides are radioactive and release energy upon radioactive decay; naturally occurring uranium and thorium, and synthetically produced plutonium are the most abundant actinides on Earth. These are used in nuclear reactors and nuclear weapons. Uranium and thorium also have diverse current or historical uses, and americium is used in the ionization chambers of most modern smoke detectors.

text: In presentations of the periodic table, the lanthanides and the actinides are customarily shown as two additional rows below the main body of the table,[3] with placeholders or else a selected single element of each series (either lanthanum or lutetium, and either actinium or lawrencium, respectively) shown in a single cell of the main table, between barium and hafnium, and radium and rutherfordium, respectively. This convention is entirely a matter of aesthetics and formatting practicality; a rarely used wide-formatted periodic table (32 columns) shows the lanthanide and actinide series in their proper columns, as parts of the table's sixth and seventh rows (periods).

text: Transactinides[edit]

text: Transactinide elements (also, transactinides, or super-heavy elements) are the chemical elements with atomic numbers greater than those of the actinides, the heaviest of which is lawrencium (103).[9][10] All transactinides of period 7 have been discovered, up to oganesson (element 118).

text: Transactinide elements are also transuranic elements, that is, have an atomic number greater than that of uranium (92), an actinide. The further distinction of having an atomic number greater than the actinides is significant in several ways:

text:
The transactinide elements all have electrons in the 6d subshell in their ground state (and thus are placed in the d-block).
Except for the first two transactinides, rutherfordium and dubnium, even the longest-lasting isotopes of transactinide elements have extremely short half-lives, measured in seconds, or smaller units.
The element naming controversy involved the first five or six transactinide elements. These elements thus used three-letter systematic names for many years after their discovery had been confirmed. (Usually the three-letter symbols are replaced with two-letter symbols relatively shortly after a discovery has been confirmed.)

text: Transactinides are radioactive and have only been obtained synthetically in laboratories. None of these elements has ever been collected in a macroscopic sample. Transactinide elements are all named after nuclear physicists and chemists or important locations involved in the synthesis of the elements.

text: Chemistry Nobel Prize winner Glenn T. Seaborg who first proposed the actinide concept which led to the acceptance of the actinide series also proposed the existence of a transactinide series ranging from element 104 to 121 and a superactinide series approximately spanning elements 122 to 153. The transactinide seaborgium is named in his honor.

text: IUPAC defines an element to exist if its lifetime is longer than 10−14 seconds, the time needed for the nucleus to form an electronic cloud.[11]

text: Notes[edit]

text:
Jump up ^ Actually the least unstable isotope, francium-223
Jump up ^ Some synthetic elements, like technetium, have later been found in nature.


document_title: The Last One (Friends)

question_text: when was the last episode of friends shot

text: The Last One (Friends)

text: Plot[edit]

text: Part 1[edit]

text: Phoebe Buffay (Lisa Kudrow) and Joey Tribbiani (Matt LeBlanc) pack the belongings of Monica and Chandler, who have accompanied Erica (Anna Faris) to the hospital. Rachel leaves Ross' bedroom after their apparent reunion in the previous episode. Erica gives birth to twins, much to the surprise of Monica and Chandler, who were expecting only one child. At his apartment, Joey shows Phoebe his house-warming gift for Monica and Chandler: a chick and duckling to replace the ones that died. Ross arrives and confesses to the pair that he slept with Rachel. Rachel emerges from her bedroom and, to his disappointment, tells Ross that their night together was "the perfect way to say goodbye".

text: Later at the Central Perk café, Phoebe convinces Ross to tell Rachel how he feels about her before she leaves for her new job in Paris. As he is about to tell her, Central Perk manager Gunther (James Michael Tyler) confesses his love for Rachel. Back at Monica and Chandler's apartment, Ross decides not to tell Rachel, for fear of rejection. She prepares to leave to catch her flight, but waits long enough for Monica and Chandler to return with the twins, named Erica (after their biological mother) and Jack (after Monica's father). After Rachel leaves, Ross has a change of heart, and Phoebe takes him in her taxi to follow Rachel to the airport.

text: Part 2[edit]

text: Joey returns to his apartment to fetch the chick and the duck he was hiding, but finds they have become trapped in the foosball table. Chandler and Joey decide to break it open when they cannot find any other way of getting the birds out. Phoebe's reckless driving gets her and Ross to JFK Airport and, after buying a ticket to get past security, they search the information boards for Rachel's flight number. When they cannot locate her flight on any of the information boards, Ross calls and checks the number with Monica but discovers they are at the wrong airport; Ross and Phoebe drove to JFK, while Rachel was flying out of nearby Newark Airport. Phoebe phones Rachel, who has already boarded her flight, to stall her for time. When a passenger (Jim Rash) overhears Phoebe saying there is a problem with the fictitious "left phalange" of the plane, he gets off the plane, prompting everyone else to leave. Chandler and Joey, who are emotionally attached to the foosball table, find they are unable to bear breaking it open, so Monica nonchalantly offers to do it for them. After they retrieve the birds, Chandler suggests Joey keeps them.

text: Phoebe and Ross arrive at the airport as Rachel boards the plane again. Ross tells her he loves her, but she is unable to deal with his confession and gets on the plane anyway. Ross returns home, dejected, and finds a message from Rachel on the phone. She explains her actions and decides to get off the plane, but the message cuts off. Ross panickingly tries fixing the answering machine, wondering to himself out loud if she got off the plane. From behind him, Rachel says she did. They kiss and get back together for good, both agreeing that this is where they want to be. The following morning, the friends gather in Monica and Chandler's empty apartment. With some time remaining before Monica and Chandler leave for their new house, the six all leave their keys to the apartment on the kitchen counter and decide to go for one last cup of coffee together, to which Chandler sarcastically quips, "Where?". The final scene is a shot of the apartment, panning round slowly from the living space to the front door.

text: Production[edit]

text: Writing and music[edit]

text: The series' creators completed the first draft of the hour-long finale in January 2004, four months prior to its airing on May 6. Before writing the episode, David Crane, Marta Kauffman and Kevin S. Bright decided to watch the series finales of other sitcoms, paying attention to what worked and what did not. Kauffman found that they liked the ones which stayed true to the series, and they found the finale of The Mary Tyler Moore Show to be the gold standard. The writers had difficulty writing the finale, and spent several days thinking about the final scene without being able to write a word. Crane said that they did not want to do "something high concept, or take the show out of the show".[4]

text: The music playing as the camera pans across the empty apartment at the end of the episode is "Embryonic Journey" by Jefferson Airplane. The song "Yellow Ledbetter" by the band Pearl Jam is also featured in the episode—after Rachel boards the plane for the first time—making it the first Pearl Jam song to be licensed for a television show. A spokesperson for the group said it was, "simply a matter of the show's producers asking permission".[5]

text: Filming[edit]

text: The episode was filmed in Los Angeles, California on Stage 24 at Warner Bros. Studios, where Friends had been filmed since its second season.[6] The first part was taped on January 16,[7] and the second on January 23, 2004.[8][9] After the series finale, Stage 24 was renamed "The Friends Stage".[10]

text: A month before the filming of the final episode, Aniston said that with each episode it got "harder just to read the lines." She explained that the cast was "all just nerves and raw emotions [...] No one knows how to feel. We may need to be sedated on the last night."[11] The producers promised a tearful ending, and the cast admitted their crying was not faked when they filmed their scenes.[8] LeBlanc revealed it had been too much for him and the rest of the cast; he said Kudrow started crying first, and when he looked at Aniston and Cox they also appeared emotional.[12] Schwimmer, who LeBlanc thought was the "consummate professional", was also upset, so LeBlanc "just lost it."[12] Maggie Wheeler, who was Chandler's "on and off" girlfriend Janice, told People, "the entire cast had to go back and have their makeup redone before starting," and that Perry broke the tension by saying, "Somebody is gonna get fired."[9] Perry told the New York Daily News that he did not cry, "but I felt like I was about to for like seven hours."[13]

text: Although it was planned that some key scenes of the episode would be filmed without an audience in order to avoid leaks of plot spoilers,[14][15] the producers decided not to worry about the issue and filmed it all in front of the live studio audience.[16] The producers also instigated the rumor that multiple endings would be filmed; in fact, only one was planned and shot.[16]

text: At the start of each Friends episode filming, the cast would ordinarily be introduced to the studio audience one at a time, but this time the cast headed out for their pre-curtain bow together.[14] "That made me cry," said Diane Newman, who was the script supervisor of the show.[14] Among the specially invited audience of the taping were Hank Azaria, who played Phoebe's scientist boyfriend in several episodes over the years; David Arquette, who filmed his then-wife Cox and the others backstage with a video camera; and Wheeler. Missing was Brad Pitt, Aniston's then-husband; Pitt told the producers he wanted to be surprised when the finale aired on television.[9] Although some guests were invited, around 75% of the studio audience were 'ordinary' members of the public so that their reactions would be congruous with the rest of the series.[16] However, friends, family and colleagues of the cast and crew served as extras throughout the episode.[16]

text: Reception[edit]

text: Promotion, ratings and awards[edit]

text:
"It may have been impossible for any one episode to live up to the hype and expectations built up around the Friends finale, but this hour probably came as close as fans could have reasonably hoped. Ultimately, the two-hour package did exactly what it was supposed to do. It wrapped up the story while reminding us why we liked the show and will miss it."

—Robert Bianco of USA Today on the series finale.[17]

text: NBC heavily promoted the series finale, which was preceded by weeks of hype.[18] The top price for a 30-second commercial during the U.S. broadcast was approximately $1 million USD.[19] Viewing parties were organized by local NBC affiliates around the United States, including an event at Universal CityWalk featuring a special broadcast of the finale on an outdoor Astrovision screen.[20] It was shown in New York City, where over 3,000 people watched it on big screens in parks.[21] The finale was the subject of two episodes of Dateline NBC, one of which ran for two hours. Prior to the airing of the episode, a one-hour retrospective of clips from previous episodes was shown. Following the finale, The Tonight Show with Jay Leno was filmed on the set of the Friends' Central Perk cafe, which featured the series' cast as guests.[22][23] The advertising rates for the finale averaged $2 million for 30 seconds of commercial time. This currently remains as the largest advertising rate ever for a sitcom, breaking the previous record held by the Seinfeld finale at $1.7 million.[20][21]

text: The finale was watched by 52.5 million American viewers[24] making it the most watched entertainment telecast in six years, and the most watched episode of the decade 2000s on U.S. television.The Friends finale was the fourth most watched overall series finale in U.S. television history, behind the finales of M*A*S*H, Cheers and Seinfeld, which were watched by 105.9, 84.4 and 76.3 million viewers, respectively. The retrospective episode was watched by under 36 million viewers, and the finale was the second most-watched television show of the year, behind the Super Bowl.[22]

text: The episode was nominated for two Primetime Emmy Awards at the 56th Primetime Emmy Awards for Outstanding Multi-Camera Sound Mixing for a Series or Special and Outstanding Multi-Camera Picture Editing for a Series, but lost to the final season of Frasier in both categories.[25][26][27]

text: Critical reviews[edit]

text: Robert Bianco of USA Today described the finale as entertaining and satisfying, and praised it for deftly mixing emotion and humor while showcasing each of the stars.[17] Sarah Rodman of the Boston Herald praised Aniston and Schwimmer for their acting, but felt that their characters' reunion "felt a bit too neat, even if it was what most of the show's legions of fans wanted."[28] Newsday's Noel Holston called the episode "sweet and dumb and satisfying,"[29] while Roger Catlin of The Hartford Courant felt that newcomers to the series would be "surprised at how laughless the affair could be, and how nearly every strained gag depends on the sheer stupidity of its characters."[30]

text: An editorial in USA Today highlighted the view of many critics who found problem with the aging cast, commenting, "Friends was getting creaky even as it remained popular."[31] Heather Havrilesky of Salon.com said that despite the "nauseating hype and the disappointing season and the lackluster finale, it's important to remember what a great show this was for such a very long time."[32] Ken Parish Perkins of the Fort Worth Star-Telegram gave the finale a B grade, calling it "more touching than comical, more satisfying in terms of closure than knee-slappingly funny."[33]

text: Response from the staff[edit]

text: The cast members reportedly got together in Los Angeles to watch the finale.[21] It was well received by the main cast, who were confident that the fans would have the same reaction. David Schwimmer said, "It's exactly what I had hoped. We all end up with a sense of a new beginning and the audience has a sense that it's a new chapter in the lives of all these characters."[4] At the taping of the episode, the cast and crew passed around yearbooks, custom-made by the production staff, and signed them for each other. The cast gave the producers inscribed Cartier SA watches, while the producers gave the cast Neil Lane jewelry.[9] As the sets were broken down, the cast and crew each got a chunk of the street outside Central Perk in a glass box as a keepsake.[8]

text: There were 3 separate wrap parties - a dinner at the Aniston-Pitt residence on January 19, 2004, a sit down at cast hangout Il Sole in West Hollywood on January 22, and a big party for 1,000 guests on January 24 at Los Angeles' Park Plaza Hotel.[9] At the party at the Park Plaza Hotel, The Rembrandts performed the theme song of Friends, "I'll Be There for You", and the cast gave a re-enactment of the pilot episode's first they all got lit scene.[9]