The UK Cluster network

This page will eventually give you information on the layout of the UK network. I intend to show not only the location of the Clusters but also the nodes they use for inter-Cluster links and User access too. This will undoubtedly highlight the holes in the network, which we may need to in-fill with quality links to enable us to continue to provide the best quality service possible.

The above map shows the Inter-Cluster links, as they would be in a "normal" situation. However, due to network problems individual SysOps will connect their Cluster via an alternative route into the network to ensure continuity of service to their users. This re-routing process will often be invisible to the user.

The link between GB7DXK and ON0DXK (not shown) provides us with our European spots. Unfortunately many DX Clusters in Europe suppress the "hop count" (this governs the number of adjacent Cluster nodes that will see their Cluster protocol) and as a consequence many spots are not propagated to the UK. Unfortunately, as far as I am aware, there is no reliable method of upping the hop count on AK1A Pavillion Software. AK1A Pavillion Software is by far the most commonly used DX Cluster software in the UK. Although it does have its faults, it is generally accepted to be the most reliable piece of software of its type (so far). There are many other programs available such as CLX (UNIX based), Clusse, Dxnet and more. Most of these have been evaluated and although some provide more useful features than AK1A other features are not yet up to scratch. For the time being AK1A will continue to provide the backbone of the UK DX Cluster network.

GB7CDX (located in Red Lodge, Suffolk) links direct to GB7DXM on 70cms and has user access ports on 144.900 and 70.325MHz. There is no Support Group but some users have made donations towards the upkeep of the node and others have offered.

GB7DXC (located in Gloucester) links to GLOS (GB7GH) node with a 23cms up link and 4m down link at 1200 baud. The route from GLOS to GB7BPQ is via BM (G7AXC-11) Birmingham and RP (GB7RP) in Ripley, Derbyshire on 23cms at 1200 baud. The route from RP to GB7BPQ is on 70cms 1200 baud. The link to GB7DXB is via LH node (G8DIT) Lickey Hills on 70 cms at 1200 baud then to GB7DXB on 23cms, again at 1200 baud. GB7ADX, GB7DXD, GB7DXW and GB7WDX connect to GB7DXC via the network.

User access is via a 1200 baud 12.5kHz port on 144.900MHz and also via GB7GC and GB7GH (GLOS) nodes.

Future plans include upgrading the link to and from GLOS to 23cms full duplex at 9600 baud. This depends on DANPAC, node keepers of RP changing one of their transmit frequencies. Once DANPAC have sorted their end out the whole link (GLOS to RP) will be going to 9k6. We also plan to upgrade the DXC< >LH link to 9k6 sometime in the future. Gloucester Repeater Group and Fourpack are planning a new link into West Wales, which will give some of our more distant users faster access. A new link is also planned by GRG & Fourpack to go from GLOS to Winter Hill (Near Manchester) which may give us alternative (fast) links into the network at some point. Another GRG & Fourpack project will see the new regenerative repeater (GB7RR) coming on line, opening up Cluster access to new users to the East where the Cotswold Hills preclude easy access at present.

GB7DXC has a well-supported Support Group with around 80 members at present. Members pay an annual subscription of 10, which is wholly reinvested in the DX Cluster itself and the network on which it relies. All running costs (power, phones etc) are met by the SysOp and remote SysOps. We support the local packet and repeater groups and also a number of remote nodes with equipment where we are able to see that improvement there would benefit our users and the Cluster network.

GB7DXH (located in Harrow on the Hill) connects via G7OTV (Chelmsford) to GB7DXM on 23cms and GB7DXI also on 23cms. User access ports are on 433.675MHz, 144.900MHz (lots of QRM from non-cluster traffic on this one), 70.325MHz and 50.530MHz. The HOTH node also provides access and connects to GB7DXH on 23cms. In the near future, Neville, G3NUG will be installing a further node at his QTH, which will be known as FELDEN. The frequency applied for is in the 70cms band.

GB7DXK is located in Canterbury, Kent. The node provides the UK network with its European feed via ON0DXK. A new node, GB7UK (located at the University of Kent, Canterbury) has recently received site clearance and will provide the following ports. There will be three user access ports on 50.750, 70.4875 and 144.900MHz, the European link on 70cms and the GB7DXK and GB7DXM links on 23cms. All ports currently run at 1200 baud, but in time and given a reliable path the link ports will change to 9k6. GB7UK will be 4db better on line loss alone and the English Channel that is visible from the shack is some 15km away. This should make for a solid link between Europe and the UK.

GB7DXM (located in Martlesham near Ipswich) links direct to GB7DXK on 23cms and GB7CDX on 70cms. The link to GB7TLH is also on 70cms but routes via GB7NP. GB7DXH routes via G7OTV (Chelmsford). There is also a link to GB7DXB via hard wire.

User access is via 70.325MHz and 432.650MHz.

GB7MBC (located in Morecambe Bay, Lancashire) has user access ports on 144.900 and 70.325 MHz. GB7MBC links to G6CRV on 70cms and soon, hopefully, from there to the IOM. This should create a permanent link between GB7MBC, GB7ADX and GB7UDX. Work is currently in hand in setting up another user access node for users in the Fylde area to help those users down there who struggle to get in on 144.900MHz. GB7MBC has a user base of about 40, which will hopefully increase when user access nodes come on line.

The main link for GB7MBC is by telnet over the LURPAC gateway at Lancaster University. This is to PE0MAR-11. Although an RF link would be preferred, linking to the main network is difficult. Hopefully it will not be this way for long as several link options are being considered.

GB7MBC uses CLX (LINUX based) software and does not currently have a support group.

GB7SDX (located in Glasgow) has trunk routes on 70.3375Mhz, 144.900Mhz, 430 and 439Mhz.


Stranraer Area

GB7XS-2 - 144.900

GB7XS-7 - 433.650

GB7XS-9 - 439Mhz link to NI (Currently on 433Mhz)

Ayrshire - Baidland Hill. Covers Irvine, Kilmarnock, Ayr, etc

GB7XB-4 : 70.3375

GB7XB-2 : 144.8875

GB7XB-7 : 433.650

GB7XB-9 : 439 Trunk route





430 Trunk






Stirling/Falkirk/Dunblane Area

GM0VRP-2 : 144.8875

GM0VRP-7 : 432.675

Edinburgh/Largo/North Berwick/Kirkcaldy

GB7XS-4 : 70.3250

GB7XS-2 : 144.900

GB7XS-11/9 : 430/439 Trunk

(Note: 433Mhz user access to be installed this year)

Eymouth Area G <> GM link - Ayton

GB7XA-4 : 70.3250

GB7XA-9/11 : 439/430 Trunk route

Central Scotland - Eastfield

GB7XE-4 : 70.3375

GB7XE-9/11 : 430/439Mhz Trunk

Note: 2m Flexnet node to be installed this year

Dundee/St Andrews/Perth





Old Meldrum/Aberdeen/Bannf/Elgin

GM7SDX-2 : 144.900

GM7SDX-7 : 432.650

GB7NDX (located in Brechin NE Scotland) - User access on 144.900 and 432.650Mhz


Plans are underway to improve the links to GB7NDX and also to move the new link to GB7UDX to 439Mhz this summer. The group will also be installing a new FLEXNET link between GB7SDX and GB7XG on 430Mhz in September.

GB7TLH (located in Dereham, Norfolk) has user access frequencies on 144.900 and 432.675 at 1200bps. TLH links to GB7DXM on 70 cms, currently @ 1200bps, via GB7NP but soon this link will be upgraded to 9600bps. This frequency will in fact link all Norfolk BBS and user nodes eventually (via what will become a full 9600bps regenerative repeater at GB7NP). This will mean that all nodes participating will effectively become access nodes to the cluster.

Although nobody uses it, GB7TLH effectively has an access node via G4VLS @ 1200bps (link on 430.675) which can give user access from all sorts of frequencies. There are no plans to provide 4m access because of lack of demand but one could be put up within a week or so if required.

There is no formal cluster support group (personal donations are not accepted), however, Dirk, Sysop of TLH is an enthusiastic member of the Norfolk AX25 Group (to which all donations received are directed). They support some of the equipment at TLH and are supplying cash toward the GB7NP 'super-node'.

The Norfolk AX25 Group can be contacted via G3LDI or G3PDH QTHR

GB7WDX (located in Worle near Weston-Super-Mare) links to GB7DXC via G7OPJ-3 to G6TJZ (TJZ) on 70cms, GB7FD (FOD) and GB7GH (GLOS). There is also a link to GB7CN (Crediton, Devon) via G2BJK-4 on 4 metres to facilitate user access to those in the Devon area. GB7CN has an access frequency of 144.900 MHz for DX Cluster users. For local user access to GB7WDX there is a 144.900MHz port.

The link to TJZ and on to GB7GH (GLOS) will be changed to 9k6 full duplex as soon as the equipment can be sorted out. This assumes that the link will be as good on 9k6 as it is at present on 1k2. When converted to 9k6 full duplex, user access may be introduced on 433.675 MHz.

All links are currently at 1200 baud.

GB7WDX runs a Support Group, which is known as the Western DX Cluster Group and has at present about 40 members.

GB7YDX is located 20 miles Southeast of York, an excellent VHF site just two metres above sea level. It might not sound too impressive, but this is about the highest spot for 15 miles in any direction!

Direct user access ports are 144.900, 433.675, and 70.325MHz at 1200 baud. The direct access ports serve users from Pickering in the North, Hull to the East, Huddersfield to the West and Gainsborough to the South. YDX normally runs with around 30-35 users, and over 50 during big openings, expeditions or contests. Users on YDX receive spots from WU3V when the link from GB7MDX is connected.

YDX links to a number of user access nodes on several 23/24 and 70cm trunks at 9k6 and 1k2. Those with a * are either run by the Yorkshire Cluster Support Group or are supported and assisted by YCSG in some way. The other nodes are general-purpose network access that is used by YDX folk to connect here.

All user ports 1k2 unless marked otherwise.

User ports for East Yorkshire

*EYDX: G4BYG on 144.8875 and 433.675 near Hull and DRIFF: G6TNZ on 144.900 near Driffield

North Yorkshire

CATT on 70.325 and 432.675 near Catterick, *G4KUX on 70.325 and 433.625 County Durham and RHB nodes, Robin Hoods Bay

West Yorkshire

*BRAM: GB7YW on 144.8875 and 433.625 near Bramham, *LSDX nodes on 144.8875 (moving to 144.900) and 433.675 in north Leeds, JEM: G6UNC on 144.900 near Huddersfield

Many other nodes link here via the WP series of nodes

South Yorkshire

*SHEF: GB7YS on 433.625 and 70.325 north of Sheffield, *DXCUD: G4LUE on 433.675 from near Barnsley WKSOP2: G8UAQ-3 on 70.325, 144.850 and 433.650 in Worksop, FLAN and WOLF nodes in Sheffield, various bands. Between Sheffield and Barnsley

Lincolnshire *LINCS: G3XYP 144.8875 14 miles south of Lincoln and *FENDX: G3TMA 144.900 near Spalding. Other nodes digipeat into FENDX at present from Peterborough, Northampton, Boston etc on 144.900. We hope to find a new home for FENDX as G3TMA is moving house, other links will be developed when a new home is found.

GB7YDX has dedicated 23/24cm links to GB7BPQ in Nottingham via SHEF and GB7MDX in Shropshire via our link node on top of the Pennines. The link to GB7TDX runs over our 9k6 link to BRAM, then via the 900ft A.G.L. node at Emley Moor TV tower and northwards through Durham over the shared links.

The Yorkshire Cluster Support Group owns all of the equipment and antennas used at YDX and loans kit, antennas, PSU's, PCs and TNC's to node sysops. We have over 150 members at present. Funds can only be used to pay for capital items for use on cluster nodes; all running costs, electricity and insurances are met by the sysops.

Hopefully this has given you a brief insight into the some of the individual Clusters. I need more information on the rest of the network so please harass your local SysOp and ask him to forward your local Clusters information if it is not here already.


The Marnet project (Manx Amateur Radio Network) was set up by the Isle of Man Digital Radio Group to provide 5 user access node sites around the Island and also forwarding links for services in the United Kingdom including the DXCluster

Our small nation has a high proportion of licensed amateurs per capita compared to the UK and there is a healthy interest in DXing. Those that use the cluster subscribe to the GB7ADX Support Group.

Marnet provides trunk links for THREE cluster mailboxes via the front end ports of the GB7BIG TCP/IP mailbox

The link between GB7ADX and GB7UDX has been running as a primary link for 3 years and as a back up to a GW-EI-GI link for the previous 2 years.

Marnet now provides a dedicated direct link between GB7MBC and GB7ADX to replace the temporary link we were using via BBS forwarding routes. The super cluster should now be more reliable.

All cluster forwarding is done on 2 channels in the 70 cm band using simplex 1200bps. All GB7BIG ports are 9600 bps ready when the British ends want to change over.

Marnet users include GD/MD calls as well as a few G, GI, GM and GW users where no local direct access is possible for them at present.

2 metre user access is on 144.875 (North and West), 144.950 (East and South) There is an additional user access is on 144.975 at 9600 bps. All Isle of Man user nodes are designed to carry all types of packet traffic.

4 metre access is also possible on 70.4875 (GB7BIG) and 70.3375 (GB7IOM) These ports are designed not to be heard off-island. BBS forwarding is separate from Cluster Trunk Routes.

Created by Mark Trotman, G1FYC / G0TYA, SysOp - GB7DXC on Tuesday, 21 July 1998

Last modified on Monday, 31st August 1998

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