Monday, 22 April 2013

Plugs and sockets

One task I have to complete, which at face value should be simple, is to add a connector to my Time Lapse controller for my SLR. Unfortunately, when I first set up the controller system, my camera was a Minolta Dynax 404si, a film 35mm SLR, and it only took a remote release, or a simple timer controller. I now have a Sony SLT, which although it takes all my Minolta accessories, also takes a digital time lapes intervalometer. It is to this I need to add a connector, but sadly, the connectors I used were extremely expensive and rare Lemo miniature multipole locking connectors. I have none of these left spare, and in the very few places in the world I can find them for sale, they cost upwards of £40 each.

So, I have to embark on the process of replacing the connectors across the whole system, with something much cheaper and more readily available. Luckily, there is such a connector system, one which I already make good use of - 3.5mm audio jacks. The camera system uses three connections - focus, release, and ground. So stereo connectors are ideal. I also have a need for a custom lead from my gear lever mounted PTT control to the microphone interface box on my rig in the car, which uses 3.5mm jacks. So, I have a batch of connectors on order to allow me to complete these tasks.

My run of night shifts is now complete, so after a decent sleep and a few bevvies, I can finally get back to work on the various projects that require my attention. I should be well on the way to having a completely overhauled No. 1 mast soon.

As I type this, G4FONs Koch trainer software, is sending me random Morse characters at 12wpm (character speed 20wpm). This time, I really want to crack it. I want to start using CW in anger, and would love to be able to use if on GB2LDS. Which reminds me, I must get the license application sent!

Thursday, 18 April 2013

Show Antenna Designs

The paint for the Larkspur mast arrived yesterday. Theres still plenty of work to be done on it, but now I can get one with more than one task at a time!

The Doncaster Show will also need an antenna that will give us access to the WARC bands. Ive decided on a vertical system for this. I was intending to make something that would work on the fishing pole mast, but have decided instead on a Fan Vertical design that will utilise the 5.4m Clansman mast, there are several good reasons for this -

1. The 5.4m mast is much sturdier and will withstand the wind loading of the extra antenna wires better
2. It is already designed to be used as a vertical and has suitable fixings for the 20m element to run up the mast
3. I have spare mast sections that can be used to form a sturdy horizontal cross member support for the other four bands antenna elements
4. It will also be capable of supporting a VHF lightweight antenna at the top
5. Its guying radius is 3m, add on a 2m safety zone, and you have 5m. The required ground radials are to be 5m 30cm. A bit extra safety margin and its all contained.

My worry is being able to fit the 40m inverted V dipole into the antenna field, and having sufficient coax available if the shack has to be a distance from the antennas.

Ive also taken a punt, for a few quid, on a little digital voice recorder unit. The reason for this, is i'd like to do more CQ calls while mobile, but find it a bit tedious! If this sounds decent, and I can suitably modify it to feed into the mic audio and PTT system of the FT-857D, then it should just be a touch of a button to put out a CQ. I know its just a promotional toy, but it is from Cisco, so with any luck its half decent audio.

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)