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THE TRANSMISSION GALLERY

WALTHAM

Photos by Sandi Pyke & Alexander Heath Page last updated: 2013-05-01

Waltham - DSO Helilift

We are very grateful for this set of pictures taken at the time of the heli-lift at Waltham.




When we first received these pictures we wrongly assumed that the pole that can be seen above was part of the process involved in removing the old UHF cylinder. However, we've been contacted by someone "in the know" and in fact this spike is a temporary UHF aerial (possibly a turnstile) which was used for Channel 5 analogue after its own array was taken out of service to make room for the installation of the new reserve S2 aerial. So what we are seeing in these first pictures is the specially designed temporary Channel 5 aerial being hoisted into place atop the mast.

Ed - I should have spotted that the helicopter involved in this stage is completely different to the one shown in photo 11 and onwards!






The temporary Channel 5 aerial now in place.






Below: We've moved on a few weeks and the UHF analogue aerial is no more than a lattice spine now.

The old UHF aerial panels (described as looking a bit like fluorescent light fittings, thus confirming that the original EMI slots had lasted right through to the end of the analogue era) have gone. They were removed in situ, passed down through the access hatch and then taken to the ground in the internal lift. The external GRP Panels were removed using slings mounted off lugs on the platform right up on top of the old cantilever where the temporary antenna was attached; they were removed before the heli-lift day. In the photo below the inner spine, denuded of aerials, is still in place at this stage.










The UHF spine - still with the Channel 5 temporary aerial on top - is lifted off.


... and down it comes.


Safely back on earth, the temporary Channel 5 aerial viewed from the top.....


... and from the side.


Adaptor section awaiting ascent.

This new S1 interface was an interesting piece of work as it was designed to allow the insertion of what was literally a pentagonal peg into a circular hole; the design was virtually identical to that used at Mendip with a few minor tweaks; - 5 RSA braced solid round legs strung between a fabricated pentagonal plinth on which the antenna sits, and a fabricated cylindrical foot section that sits on the mast



The adaptor is lowered onto the top of the mast.


Lower half of new main aerial lifts off....


... and swings into position.










Above and below:

We've never seen them in detail before, but here is the array for the 106.6 MHz service; it consists of four tiers of single slant dipoles - which look as though they're probably Marconis - at 200 m agl.



Waltham index

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