Trig Dimensions?

Hi All

Firstly I must warn you this is a slightly odd topic, but I was hoping that somebody on the reflector may be able to help!

Yesterday (15/02/2013) I activated G/WB-003 on 144 FM using my HH, mag mount (for support) and my super slim jim. The activation went very well generating about 20 odd QSOs. I simply mounted the mag mount on top and used the slim jim as you dont need a ground plane. However being the slight eccentric that I am, I thought instead of the mag mount could I build a bracket for the support job!

The plan at the moment is to cut some sheets of aluminium approx 25 inches by 1.5 inches wide. Yesterday I had my tape measure with me and the top of the trig measures 15 inches by 15 inches.

I plan to mount them in a cross and bend the excess 5 inches down. Holes will be 2 small holes will be drilled for nuts and bolts to go in. In addition a larger hole will be drilled to mount a chassis RF socket (Yet to be decided but most likely N) I can then run Coax to this and connect a rig. Clearly though I may put a step in the bends to elevate the connector above the trig.

So I have the rough dimensions on top, what I am missing is the angle to which to bend the metal. Has anyone got a clue what the slope is on the standard UK trig points? I am not expecting anything, it may even come to being as sad as to take a protractor to my nearest one and work it out!

I just think that on summits where there is easy access to a trig setting this up would be a doddle with the slim jim or a mobile antenna with a set of radials. And would be a lot lighter than a mag mount that odes not work on trigs as the metal is brass!

Trig points are at least 1 metre high so act as quite a good platform to mount things on, so any ideas people?

73 all

(from a very sad man) Matt G8XYJ

In reply to G8XYJ:

They’re a bit varied Matt - not all the same shape, some up here are not plain concrete. And some of the concrete ones are falling to bits.


This group is for photos of Ordnance Survey Trig Points.
	These were constructed across the UK to help provide an unparalleled level of mapping accuracy.
	Please tag your photo with the tag:
	"Trig Point"
	Include the quotes as this will keep...

You’ll be able to find some photos to measure angles off!


In reply to G8XYJ:

Hi Matt,

No dimensions I’m afraid but this site may be able to help:

There is some quite interesting info about the different types of trig points etc here.



In reply to G8XYJ:

Hi Matt

When I was making my “Trig Jig” I took a spirit level up Walton Hill and determined that the slope was about 1 in 7, or an angle of just over 8 degrees to the vertical. This seems to have worked for all the “Hotine” type trigs I’ve encountered :slight_smile:

73 de fellow sadsack Paul G4MD

In reply to G4MD:
Cheers Paul

I could borrow the angle"o"meter from work and pop to my local trig!!

Many thanks for the other suggestions, I had no idea trig points had a dedicated website!!!

73 all


In reply to G8XYJ:

They should all be exactly the same size excepting wear and tear etc.


Except for the ones that aren’t!

I don’t know the dimensions of the square trig points but I can give you a big of info regarding trig points across the country…

The majority of Trig pillars were painted to provide protection from the elements. The colour white was generally chosen to improve the visibility however this is not as important as it might seem as long range trig observations were often made at night to lamps.

However, as to why some are painted and others not, this was simply down to the request of the original landowner:

  • Some landowners stipulated that some pillars must be constructed of unpainted local stone and not concrete.
  • Some landowners (farmers) stipulated that the pillars not be painted at all as they were concerned that livestock might ingest the paint.
  • Other landowners stipulated that pillars emplaced on their land be painted to actually blend-in with the landscape.

I have seen several kinds and many are in a very poor state. Apparently they are not maintained any longer and the freshly painted white ones are usually just landowner or bored individual with a pot of paint and a brush.

73 Neil 2M0NCM

In reply to MM0FMF:

No Andy, look at the photos. Some are straight blocks, not tapered. And a fair number are like cemented cairns. Then, as you say, a number are in a bad way due to lack of maintenance - as you must have seen in GM/SS!


In reply to GM8OTI:

Sorry I should have said the concrete Hotine Pyramids and concrete Vanessa Cylinders will all be the same size. The others made from local stone etc. will be of the same overall size. The height of the brass insert where the theodolite was attached should also be the same across all points.


In reply to MM0FMF:

The height of the brass insert where the theodolite was attached should also be the same across all points.

Relative to where? -

Sorry, couldn’t resist. :wink:

73, Gerald G4OIG

In reply to G4OIG:

Relative to “The Bolt”.

Don’t you know nuthin’ about trig points.


Should we really be using trig points as an antenna mount?

Certainly on popular summits I’d say this is a big No No.
The trig point is often the focus of others day out and very often somewhere where they wish to take a photo of their day’s conquest. For that reason I always activate some distance away and have never used the trig point as an antenna mount.

I expect there are many summits where there are not a great number of other people around and then activating in this way would not be a problem.
I haven’t found any of those yet!

I suppose we need to make that decision on a case by case basis.


In reply to MM0FMF:

Yeah the trigs I was referring to were the bog standard English/Welsh ones that were cast from concrete!

I will pop up my local one and take some real measurements!

73 all

Matt G8XYJ

In reply to G4ISJ:

I expect there are many summits where there are not a great number of other
people around and then activating in this way would not be a problem.
I haven’t found any of those yet!

A trip to Alex Salmond’s Peoples Republic of Alba and the insertion of an M into your callsign will allow you to experience more deserted trig pointed summits that you can imagine.