1,25 метрлік жиілік диапазоны: тарихы мен қолданылуы

The 1.25 meter, 220 MHz or 222 MHz band is a portion of the VHF radio spectrum internationally allocated for amateur radio use on a primary basis in ITU Region 2, and it comprises frequencies from 220 MHz to 225 MHz.

In 1938, the FCC gave U. S. amateurs privileges in two VHF bands: 2.5 meters (112 MHz) and 1.25 meters (224 MHz). Both bands (as well as 70 centimeters) were natural harmonics of the 5 meter band. Amateur privileges in the 2.5 meter band were later moved to 144–148 MHz (becoming the modern day 2 meter band), and the old frequencies were reassigned to aircraft communication during World War II. At that time, the 1.25 meter band expanded to a 5 MHz bandwidth, spanning 220–225 MHz.

Amateur use of VHF and UHF allocations exploded in the late 1960s and early 1970s as repeaters started going on the air. Repeater use sparked a huge interest in the 2 meter and 70 centimeter (420–450 MHz) bands; however, this interest never fully found its way into the 1.25 meter band. Many amateurs attribute this to the abundance of commercial radio equipment designed for 136–174 MHz and 450–512 MHz that amateurs could easily modify for use on the 2 meter and 70 centimeter bands. There were no commercial frequency allocations near the 1.25 meter band, and little commercial radio equipment was available. This meant that amateurs who wanted to experiment with the 1.25 meter band had to build their own equipment or purchase one of the few radios available from specialized amateur radio equipment manufacturers. Many of the repeaters which have been constructed for 1.25 meter operation have been based on converted land mobile base station hardware, often extensively modifying equipment originally designed for other VHF bands.

By the 1980s, amateur use of 2 meter and 70 centimeter bands was at an all time high while activity on 1.25 meters remained stagnant. In an attempt to increase use on the band, many amateurs called for holders of Novice class licenses (the entry level class at that time) to be given voice privileges on the band. In 1987, the FCC modified the Novice license to allow voice privileges on portions of the 1.25 meter and 23 centimeter (1.24–1.30 GHz) bands. In response, some of the bigger amateur radio equipment manufacturers started producing equipment for 1.25 meters. However, it never sold well, and by the early 1990s, most manufacturers had stopped producing equipment for the band.

In 1973, the FCC considered Docket Number 19759, which was a proposal to establish a Class E Citizen's band service at 224 MHz. The proposal was opposed by the ARRL and after the explosive growth of 27 MHz Citizen's Band usage, the FCC dropped consideration of the docket in 1977. In the late 1980s, United Parcel Service (UPS) began lobbying the FCC to reallocate part of the 1.25 meter band to the Land Mobile Service. UPS had publicized plans to use the band to develop a narrow bandwidth wireless voice and data network using a mode called ACSSB (amplitude companded single sideband). UPS's main argument for the reallocation was that amateur use of the band was very sparse and that the public interest would be better served by reallocating part of the band to a service that would put it to good use. In 1988, over the objections of the amateur radio community, the FCC adopted the 220 MHz Allocation Order, which reallocated 220–222 MHz to private and federal government land mobile use while leaving 222–225 MHz exclusively for amateur use. The reallocation proceeding took so long, however, that UPS eventually pursued other means of meeting its communications needs. UPS entered into agreements with GTE, McCall, Southwestern Bell, and Pac Tel to use cellular telephone frequencies to build a wireless data network. With the 220–222 MHz band then left unused, the FCC issued parts of the band to other private commercial interests via a lottery in hopes that it would spark development of super narrowband technologies, which would help them gain acceptance in the marketplace. In the 1990s and into the 2000s paging companies made use of the 1.25 meter band. Most all such use ended by the mid 2000s, with the paging companies being purchased by others and services moved to newer systems, or having gone out of business.

An auxiliary station, most often used for repeater control or link purposes or to remotely control another station, is limited in the United States to operation on frequencies above 144.5 MHz excluding 144.0–144.5 MHz, 145.8–146.0 MHz, 219–220 MHz, 222.00–222.15 MHz, 431–433 MHz, and 435–438 MHz. Operation of such control links in the crowded 2 meter band is problematic and on many frequencies in that band expressly prohibited, leaving 1.25 meter band frequencies as the lowest available for remote control of repeaters and unattended stations.

Since the band is allocated mostly in ITU Region 2 (Somalia, in Region 1, being the only exception thus far), the major equipment manufacturers (Kenwood, Yaesu, and Icom) do not often offer transceiver models that cover the frequency range. (see ). This exacerbates the lack of usage of the 1.25 meter band, though manufacturers argue that what equipment they have produced has not sold well compared to other products. In late seventies Yaesu introduced the FT 127 single band 220 MHz base station, and the FT 109RH portable radio. In 1987 they introduced the FT 33, single band 220 MHz version of the popular FT 23 portable radio. In recent years, Kenwood and Yaesu have both included the 1.25 meter band in some of their multiband handheld transceivers. The Kenwood TH F6A and TH D74A; the Yaesu VX 6R, VX 7R and VX 8R (United States and Canada version) include coverage of the 1.25 meter band in addition to the more popular 2 meter and 70 centimeter bands. Wouxun now has the KG UVD1P in a 2 meter / 1.25 meter model, legal for use in the United States. In the 1980s, ICOM offered the IC 37A—a 220 MHz, 25 watt FM transceiver that can still be obtained as used equipment from various sources such as eBay and private collectors. In 2013, the BaoFeng UV 82X, an inexpensive 2 meter / 1.25 meter handheld, became available. During 2021, Baofeng then introduced its latest, and cheapest, UV 5r III handheld transceiver, which now includes the 1.25 meter band as standard. Several 1.25 meter base/mobile transceivers are available. Among these are the Alinco DR 235T, the Jetstream JT220M, BTech UV 2501 220, BTech UV 25X4 quadband, and the TYT TH 9000 monoband radio, which comes in a 1.25 meter model. The Chinese company Wouxun offers a 2 m and 1.25 m dual band HT, the KG UVD1P. These have received FCC approval in the United States; but are awaiting approval by Industry Canada. Elecraft offers an all mode (CW, FM, SSB) transverter for the band compatible with its K2 and K3 transceivers.