Grid square

Hi friends,

Last Friday, I was on F/ON-005, and had a S2S QSO with GW3TJE/P. Peter was on Black Mountain, GW/SW-041. Looking in GW ARM for his grid square, I find “SO 255350” which is a British National Grid Ref (I presume). It seems that this system may extend to Atlantic Ocean and Europe, but I think It would be better for ham community to all use the same coordinate system i.e. grid square locator. If not, please give us latitude and longitude positions in ARM so we will be able to calculate distance between two stations.

Another SOTA rule to improve ???

Best regards
Alain F6ENO

In reply to F6ENO:

It is already in the summit information…

Summit Information for GW/SW-041
Black Mountain - 703m, 6 points
Association: Wales Region: South Wales
Longitude: 3 5 12 W, Latitude: 52 0 30 N
Grid Reference: SO 255350, QTH Locator: IO82KA

Relative to home QTH: 135.8 km, 181 degrees

It might be a big job to update the ARM and the calculation is done for you (most useful).

Regards Steve GW7AAV

In reply to F6ENO:
National grid, lat %long and QRA locator (maidenhead) are all given in the summit information pages accessed from SOTAWATCH 2 (

Roger G4OWG

The GB Ordnance Survey grid has many advantages here. Many road atlases have this grid superimposed on them, our hiking maps (OS 1:25000 and OS 1:50000) use this grid, and so does the popular WAB (Worked All Britain) awards programme.

However, being able to compare positions to outside of the British Isles, is something which has been identified before, and Martyn M1MAJ has already done the work on providing lat/long positions for all the UK summits. You can find this information on the Summit page in SOTAwatch. I think there is also a way of downloading tables or lists of all the lat/long coordinates. Perhaps Martyn or Jon GM4ZFZ will explain further.

73, Tom M1EYP

In reply to F6ENO: An easy grid calculator can be found at .

In reply to EI2CL:
Steve, Roger, Tom, Michael,
Many thanks for your replies.

I only read GW ARM, and of course, Gary’s data base gives all informations about these summits.
I understand now why GBOS grid are usefull.
It was necessary to me to compute distance between stations for QRP Challenge

Many thanks again and see you soon from new summits !
73 Alain F6ENO

In reply to M1EYP:

I think there is also a way of downloading tables or lists
of all the lat/long coordinates. Perhaps Martyn or Jon GM4ZFZ will
explain further.

I am not aware of a public bulk download facility other than my “Summits.kml” file, which has the same lat/long coordinates as SOTAwatch has. I have long wanted one. I can and do assist with data conversions, but I am not in a position to provide a download service.

By the way, I recently became aware that the IARU locators on SOTAwatch are not derived from my conversions, and are sometimes inconsistent with the lat/long values. In some cases it is very hard to know which is correct, owing to a lack of precision in the initial data. However one of the jobs “on the list” is to provide IARU locators for all summits which are at least consistent with the lat/long value.

In reply to M1MAJ:

A Coordinate Conversion site which I have found well worth using for
Postcode/Grid ref/Locator Square conversion is I
found it quite awkward when I first used it, not being very computer
literate, but I soon realised that if for example I had input my postcode
and wanted my locator, this didn’t come up on the initial ‘Go’, but you
had to scroll back to the top of the page where a dropdown menu then
allows you to select various outputs. I found that ‘More conversions
and locator Map’ and ‘Coordinate conversion only’ were most useful to me.
Give it a try.

Kind regards


Dave G0ELJ