The 70cm UHF band within the UK is 10MHz wide commencing at 430MHz and extending through to 440MHz. The band is allocated to the Amateur Service with Secondary status and includes additional restrictions in parts of the band.<\/p>\n
Additionally the 3MHz sub-band between 435-438MHz is allocated to the Amateur Satellite Service for both up and down links to\/from orbiting satellites.<\/p>\n
The UK 432MHz band has considerably more spectrum than all the amateur radio bands between 136kHz to 28MHz, 50MHz, 70MHz and 144MHz put together. In principle with 10MHz over the range from 430\u2013 440MHz there\u2019s plenty of room for everyone. However there are particular problems associated with band planning within this area of the spectrum.<\/p>\n
Although it is based on the International Amateur Radio Union (IARU) Region-1 band plan, many European countries have considerably smaller allocations than we enjoy in the UK. Therefore the UK plan is modified somewhat from the European model. There are common areas, particularly the weak signal segments of the band used for CW, SSB and MGM modes and the Amateur Satellite Service.<\/p>\n
However our allocation is also located in a particularly sensitive area of the spectrum where the Primary User can effectively determine what usage is made by the Amateur Radio Service throughout much of the 432MHz band. The major impact of this is that in the UK we must use a repeater system with output channels that are reversed from that commonly used in Europe. And because of this UK users occasionally suffer interference from repeater output channels that are located in other nearby European countries.<\/p>\n
The lower 2MHz of the band is allocated to modes with a maximum transmission bandwidth of 20 kHz. Here you will find a variety of Internet voice gateways, high speed digital links and digital repeaters. Between 430.8250 to 430.9750MHz are located the 7.6MHz repeater system output channels RU66 to RU78.<\/p>\n
The area between 431.000-432.000MHz is used for voice Internet linking but it is recommended that you consult with the RSGB Emerging Technology Co-ordination Committee before considering use of that sub-band.<\/p>\n
This 100kHz wide sub-band is allocated to modes with a maximum transmission bandwidth of 500Hz.
\nEarth-Moon-Earth (EME) activity using CW may often be found in the bottom 25kHz of the band. Occasionally you may also hear JT65C EME activity around 432.065MHz.<\/p>\n
Narrow-band modes with a maximum bandwidth of 2.7 kHz are always located at the low frequency end of any VHF or UHF allocation. This is where you will find Morse (CW), telephony (SSB) and machine generated mode (MGM) activity such as JT65C and FSK441. In addition to the separate CW \u00a0sub-band this is the area of the 432MHz band where operators make long-distance (DX) contacts.<\/p>\n
This area of the band is allocated for IARU Region-1 propagation beacons only. Please do not transmit in this segment especially if you are using FM equipment. Such transmissions cause severe interference to weak-signal users listening for far away beacons. A small segment for\u00a0Personal Weak Signal MGM Beacons at the top edge is available in the guard band.<\/p>\n
This area of the 430MHz band is allocated to any mode with a maximum bandwidth of 25 kHz. Here you can find a mixture of telephony and other modes that include facsimile (fax), radio-teletype (RTTY) and slow-scan television (SSTV). The use of amplitude modulation (AM) is also acceptable within the All Modes segment but users are asked to consider adjacent channel activity when selecting operating frequencies.<\/p>\n
Here you will find the RU240 to RU270 FM\/DV repeater output channels. These use a 1.6MHz repeater shift system as opposed to the alternative 7.6MHz and 9MHz systems found elsewhere in the band.<\/p>\n
This area of the band is allocated to simplex channels U272 to U288 that may either be used for FM or digital voice (DV) communication. The FM calling channel is on U280 (433.500MHz), but note that UK DV calling is elsewhere at 438.6125.<\/p>\n
All modes with a maximum transmission bandwidth of 25 kHz can be found in this sub-band. Here you will find a variety of Internet voice gateways channels and other digital links. An emergency communication priority channel is allocated on 433.700MHz and you may also hear similar traffic on the three channels between 433.725 \u2013 433.775MHz.<\/p>\n
These are the repeater input channels RU240-RU270 for the system employing 1.6MHz shift. Until recently all voice repeaters used frequency modulation (FM) but this is slowly being superseded by digital voice (DV) communication. Therefore you may find a mixture of FM and DV throughout the repeater network.<\/p>\n
This is the only area of the 430MHz band that is also allocated to the Amateur Satellite Service.
\nTake a listen in this segment and you might hear CW, FM, SSB or MGM signals from a series of low-earth orbiting amateur satellites, including the popular Cubesat format. This area of the band is also shared with digital fast-scan television (DATV) centred at 437 MHz, although ATV operators are also encouraged to use microwave allocations where available.<\/p>\n
The top 2MHz of the band is allocated to modes with a maximum transmission bandwidth of 25 kHz.
\nWithin this sub-band are allocated the repeater input channels RU66-RU78 that adopt the 7.6MHz repeater shift system. A new UK digital voice calling channel has been allocated on 438.6125MHz for those operators wishing to experiment with this form of communication.<\/p>\n
One of the attractions of using the 432MHz band is that with 10MHz of bandwidth to play with there are so many different ways of using this amateur service allocation. Some of these aspects include FM and Digital Voice (DV) using either simplex or repeater channel systems. You\u2019ll also find activities that are using Morse (CW), telephony (SSB) and machine generated modes (MGM) for terrestrial DX and Moon-bounce purposes. There\u2019s also activity using a host of other modes, including satellites, APRS, fast-scan amateur television (ATV) and slow-scan television (SSTV). In addition you will also find DX Cluster access channels,\u00a0Internet voice gateways, DV hot spots, high speed digital links and there\u2019s still room for a 3MHz wide band for the Amateur Satellite Service. More than enough for everyone! Growth in digital modes has been considerable and the band plan supports narrow and wideband personal use and experiments including:-<\/p>\n
At this Ultra High Frequency (UHF) you are going to be very disappointed with results if you only use a small vertical aerial fed with a considerable length of very thin coaxial cable.<\/p>\n
There\u2019s no getting round it but at these frequencies you must use a good aerial and even more importantly you must use a high quality low-loss feeder cable. Anything less and it\u2019s all a complete waste of time and effort.<\/p>\n
If you want local communications, possibly for an FM natter-net or to access a nearby repeater then you will probably need omni-directional coverage. A vertical co-linear aerial is very popular for this type of general transmission. Locate it as high as you can ideally above roof level but don\u2019t forget to use low-loss cable, ideally nothing less than 10mm diameter.<\/p>\n
If you want to work long distances (DX) on CW or SSB then you must have some form of horizontally polarised beam aerial. At these frequencies a multi-element Yagi can look very similar to a television aerial so it can become socially acceptable. Indeed you might be able to locate a pair of long Yagis and rotator onto a suitable chimney stack without looking out of place.<\/p>\n
Don\u2019t forget that you can always operate portable from a local hill top site. With a small pole and a directional beam you can often contact stations hundreds of kilometres away even when running relatively low power.<\/p>\n
On this UHF band the only propagation mode that you will normally encounter is some form of tropospheric enhancement. Surprisingly though these events occur much more frequently on this band than on lower frequencies. The only downside is that there is less activity on 432MHz compared to 144MHz or other popular bands. But when the band does open up there will be dozens of stations to contact and many will be at considerable distances away from the UK, in Eastern Europe and Scandinavia.<\/p>\n
If you want up-to-date information regarding the 432MHz band, then take a look at these websites.<\/p>\n