1.25 metres

From Amateur-radio-wiki
Jump to: navigation, search

Other VHF/UHF/Microwave wiki pages : 13 centimetres, 9 centimetres, 6 centimetres, 3 centimetres 1.25 centimetres and Bands above 24GHz.

Band: 1.25m
Bands
160m 80m 60m 40m 30m 20m 17m 15m 12m
10m 6m 4m 2m 1.25m 70cm 33cm 23cm 3cm
Band Privileges
US Extra 222.000-225.000
US Advanced 222.000-225.000
US General 222.000-225.000
US Technician 222.000-225.000
UK (all) Not used

222 MHz to 225 MHz is an amateur band only in Region 2. Countries where 222 MHz operation exists include the United States, Mexico, Central American nations, Caribbean nations, and Brazil. In the United States, 222 MHz is one of very few bands in which holders of the Novice license had been permitted to transmit voice.

Availability of 222 MHz repeaters varies widely from one US region to another, as the bulk of FM activity is on 2 metres and 70 centimetres with other bands most often used in congested areas where all suitable 2-metre repeater frequency pairs have already been allocated. In California, 222MHz has been used as a means to link multiple repeaters in and around the state.

A 220-222 MHz band segment has been reallocated to commercial narrowband land-mobile users in the US, but had been available in portions of Canada. This segment is not tunable on most new radios. A secondary allocation on 219-220 MHz exists in the US (fixed digital stations only, with stringent restrictions to prevent interference to automated marine services) but is rarely used.

Equipment selection tends to be more limited than on the 2 metre band: a cause for concern in the US radio amateur community as fewer choices for transceivers leads to fewer users on the band, increasing the risk that more of this valuable but underutilised VHF spectrum will be lost to reallocation to commercial land-mobile use.

Equipment

Because 222 MHz is only available to amateurs in Region 2, very little currently-manufactured equipment supports it. Examples include the Alinco DR-235T, the Kenwood TH-F6A and the U.S. versions of the Yaesu VX-7R and VX-6R HT. While the Alinco 235 is a reasonably-powerful single-band mobile transceiver, most of the current generation of 222MHz-capable transceivers are small handheld devices which operate at greatly-reduced power on this band. New multiband mobile or base equipment for 222MHz is not readily available commercially at this time.

Conversion of commercial land-mobile radio equipment for radio amateur use is more difficult on 222MHz as much of this equipment is designed for operation below 174 MHz, on bands near or adjacent to the 2 metre band. Adaptation of surplus commercial base station equipment (such as the Motorola Micor or GE Mastr II series) to repeater operation is possible but requires extensive RF modification as there is little or no commercial activity in this portion of the spectrum. Hamtronics does manufacture new single-channel receiver and transmitter boards which are suitable for the construction of radioamateur repeater systems on 222MHz.

Many amateurs, especially those who do weak-signal work, use transverters on this band.

Modulation

Like the 6 metre and 2 metre bands, operation is typically CW and SSB in the lower band and FM in the upper band.

Propagation

222 MHz propagation is primarily line of sight, although enhanced modes do exist. There is no F2 layer propagation on this band, but tropospheric ducting and aurora exist.

External link

Bands
HF and MF 160 metres * 80 metres* 60 metres * 40 metres * 30 metres * 20 metres * 17 metres * 15 metres * 12 metres * 10 metres
VHF 6 metres * 4 metres * 2 metres * 1.25 metres
UHF 70 centimetres * 33 centimetres * 23 centimetres * 13 centimetres
Microwave 9 centimetres * 6 centimetres * 3 centimetres * 1.25 centimetres * Bands above 24GHz
See also US bandplan