70MHz Band: 70.0 – 70.5MHz
70MHz Band Licence conditions
In the UK the 70MHz (4 Metre) band is allocated with Secondary status. It is available on the basis of non-interference to other services inside or outside of the UK. For Full Licensees the power limit is restricted to 160W (22dBW) – lower than normal.
Understanding the 70MHz Band Plan
The philosophy behind band planning is that it assigns frequencies for certain activities in such a way that all current users can practice the various modes of amateur radio with a minimum of mutual interference.
The 70MHz UK band plan is based on the International Amateur Radio Union (IARU) Region-1 band plan.
The plan shows the frequency limits of individual ‘sub-bands’ or segments. The allocation of sub-bands enables the indicated category of users to employ any frequency within that sub-band provided that no appreciable energy falls outside that sub-band. Users must therefore take into account the bandwidth of their sidebands when selecting an operating frequency.
The ‘Transmission Bandwidth’ determines the maximum spectral width (-6 dB points) of all emissions recommended in a sub-band. The mode indicates the modulation methods (e.g. telegraphy, telephony, machine generated mode) allowed in a segment. A machine generated mode (MGM) indicates those transmissions relying fully on computer processing, for example FSK441, JT6M, JT65, PSK31 or RTTY.
The ‘Usage’ column indicates the main usage of a sub-band or segment. It contains meeting/calling frequencies agreed upon for the convenience of the VHF operators practising specific modes of communication. These frequencies are not part of the adopted 70MHz IARU Region-1 Band Plan and although in the normal amateur spirit other operators should take notice of these agreements, no right on reserved frequencies can be derived from a mention in the usage column.
70.000 – 70.100MHz Propagation Beacons
This area of the band is allocated to beacon stations with a maximum transmission bandwidth of 1kHz. The primary purpose of beacons is the checking of propagation conditions both for every day amateur use and for special propagation research projects.
70.100 – 70.250MHz Narrowband Modes (CW/SSB/MGM)
Narrowband modes with a maximum bandwidth of 2.7 kHz in common with all VHF, UHF. and microwave band plans are always found at the bottom of individual allocations. This is where you will find Morse (CW), telephony (SSB) and machine generated mode (MGM) activity such as PSK31 and JT6M Most CW and SSB activity will be conducted around 70.200MHz but you must be aware of the specific band allocations of other European countries as these often differ from the UK allocation.
70.250-70.294MHz All Modes
This non-channelised area of the band is allocated to any mode with a maximum bandwidth of 12 kHz.
The 70MHz band is unique insofar that it has an AM.calling frequency on 70.260MHz.
70.294-70.500MHz All Modes (Channelised Operations – 12.5 kHz spacing)
This section of the 70MHz band is allocated to all modes channelised operation where both telephony and digital modes exist. These are narrowband FM (NBFM) channels with 12.5 kHz spacing and in this sub-band area you’ll find FM telephony, packet radio, RTTY and internet gateways.
Incidentally although the UK usage column of this sub-band indicates that the majority of channels are used by digital modes, internet gateways or emergency communication groups that does NOT mean you cannot use them for FM telephony. It is simply a case of listening on these channels to ascertain LOCALLY whether they are in use or not. If you hear no other traffic then you may conduct your contact on any channel you wish to use.
Permanent Authorisations on 70MHz
There are now a number of countries within IARU Region-1 that have permanent access to the 70MHz band. However not all countries possess the 500kHz of bandwidth that we have in the UK and individual band (and band plans) can be exceedingly fragmented.
DX Opportunities on 70MHz
Many countries with permanent and temporary 70MHz allocations are located at an ideal distance from the UK for a number of propagation modes that includes aurora, meteor scatter and Sporadic-E. Numerous stations are now active on the 70MHz band and some of them operate on FM as well as CW and SSB and therefore can be worked on converted private mobile radio (PMR) sets.
For some years stations in South Africa (ZS) have had a 70MHz allocation. The 9000km path between the UK and South Africa is particularly interesting as both ends lie at the extremity of the trans-equatorial zones. A contact over this TEP path is quite possible around Sun Spot maximum and should take place when conditions are particularly good on the 50MHz band. Possible openings between the UK and South Africa will probably occur during the month of October.
Keeping up-to-date about 70MHz
The situation regarding international allocations within the 70MHz band is somewhat fluid with both permanent and temporary authorisations. To keep up to date with recent developments take a look at www.70mhz.org This web site created by Stewart GM4AFF and Allan GM4ZUK and maintained by David G4ASR has up to date details of international allocations, band plans, beacons, contests, equipment and station reports.
Similarly you can register at http://groups.yahoo.com/group/fourmetres/ to participate in a 70MHz e-mail reflector.
Take a look also at the RSGB VHF Contest Committee Web site http://www.rsgbcc.org/vhf as this gives details of 70MHz activity contests that are held throughout the year.
If you have any suggestions regarding the 70MHz band plan please contact the VHF Manager.