Tuesday, 16 April 2013

No. 1 Mast overhaul and refirb

As complex as this mast first seemed, its really quite easy to work on. It does of course help to have the field repair guide, which shows the correct method of dismantling.  Due to some rather over zealous repainting done sometime in the past, theres quite a bit more to be done than just clean it out.

First stage then is to dismantle and clean out the crud from about half a decade of neglect. To start with, the F adaptor needs to be removed. This is soldered into the top pole, and needed a bit of brute force and a blowlamp. Once this was out, the base assembly could be taken out. This is only screwed in, but needs a good whack to break the pein over the seam. This assembly was dismantled, degreased and cleaned, given a rust treatment with Jenolite, and then rebuilt with a generous coating of lithium grease.

With the base and F adaptor taken care of, it was time to take a look at the poles. These have to be extracted from the base, with great care taken at the top end to collect the locking roller. These are what works with the cam cut into the locking collars to hold the mast together when erected. Each is a slightly different diameter so has to be kept with its associated collar. As can be seen from the photo, the poles need a good rubbing down and repainting. They are steel with a copper plating, so more care needed when dealing with the worst of the corrosion not to strip off the copper plating.

The first four locking rings are shown removed below. One is missing its lug, which is needed to give purchase to a seized ring. All of them need a complete repaint, it looks like they were last repainted with an emulsion brush! The rollers are inside each ring in the photo.

The top pole was the first to be stripped and primed. Each pole is getting this treatment, although some are not as bad as others and will not be stripped back as far. None are down to bare metal as this isnt required. The photo shows the lower two sections awaiting being taken apart, and the top section after priming. The end shown has a large area of unpainted metal, as this is the area that makes physical contact with the next section and the locking collar and roller. The amount of bare metal isnt obvious in the photo because of the masking tape around it.

The guying rings also needed a complete repaint. These were stripped using an abrasive wheel down to bare metal to ensure the nicks and scratches were rust free, then primed.

To date, three pole sections have been stripped/rubbed down, and primed, as have the two guying rings. Four of the locking collars have been stripped, two are still in the process and undergoing degreasing. One has been primed ready for respraying. The base assembly external parts have also been primed. This will get a coating of VHT matt black rather than the matt NATO green the rest of the mast will be resprayed in. The paint should be on its way now.

Originally these masts were in olive drab, and gloss. I have a personal preference to not use gloss, perhaps that stems from the matt paints we used on the Landys in the squadron. Either way I prefer military kit not to be reflective!

Im still in the process of trying to find the correct guy pegs for this mast, and the specialist spanner and the base insulator. But, its still some time until september, when I need this mast to be deployable, so hopefully something will turn up in the meantime.

Also needed for the Show, is another vertical antenna that will provide our frequency agile station. Im once again looking at a 5-band fan vertical for this job, but need to work out how to make stable spreaders that will work on the fibreglass fishing pole mast. (or the 5.4m clansman)

No comments: