[David Dunlop]

I had to do some thinking before proceeding with the next step of reinstalling the two PA LOADING Tuning Knob assemblies. These consist or two main assemblies.

The first to go back on to the Sender is the PLATES, Metal, Dial Locking. This is an interesting little design that is nothing more than a tapered piece of sheet metal, split down the centre, with a large hole at the wide end and a split cone fitted to the narrow end. When in place on the front of the Sender, the large hole accepts the central brass core of the KNOBS Assembly used to turn the tuner it is fitted to. The small end of the PLATES, with the split cone, drops over a threaded pin and a burled nut screws down over the pin and split cone. As it does so, the two halves of the cone get pulled closer together. This in turn, steadily reduces the diameter of the large hole surrounding the brass core of the KNOBS until it locks it from any further turning.

The problem with the two PLATES assemblies on my Sender was the hostile environment they had been sitting in had eaten away a good portion of the original factory zinc plating, and the remainder had turned near black. If I went with a full re-plating of the zinc, these assemblies would have looked virtually unused and would not fit in well with the overall plan for the Sender front panel: a set that had been a working set, but well cared for in its service life.

I then remembered the Coil, Aerial Tuning for the 52-Set also uses this PLATES and KNOBS arrangement and had a look at it. It had the exact look I wanted. Lots of zinc plating still on the PLATES but wear patterns evident that created lighter and darker regions on the metal. I decided to try a quick, flash plating of these two parts rather than the usual one or two hour process. I had noticed on the other parts I had plated that after about 15 to 20 minutes, you could really notice the zinc starting to build up on the metal I was working with, while still seeing lighter and darker spots where the rate of plating was different. What I came up with was exactly what I was looking for and a very close match to the PLATES on the COILS, Aerial Tuning panel.

Next will be restoring the two KNOBS for the PA LOADING assemblies.

David