Also, there are a couple of shots (in the Nazi episode) where you can see the brass rod mounted just under the center plate at the bottom. This rod was used to push the stem of the stop watch to start and stop the moiré action.
Another tidbit of information: the two moiré systems seen on Star Trek – i.e., those of the communicator and tricorder, were made from the same moiré pattern. The tricorder pattern was identical to that visible at Mr. Spock’s science station in the view screen. One was cut out on center, while the other was cut off center from the same ring of radiating circle of lines
What about the knobs, you ask? In fact, these did not hold up well at all on the set, and on most original classic communicators, the knobs are ratty, worn-out little things now, because they were made of plastic. In fact, they were the wheel hubs of a toy car – a model slot car that came out in 1964: the Aurora Model Motoring Slot Car.
There were essentially three body styles: the full textured; the lightly textured, which was a full textured body that was either well worn or intentionally sanded to nearly smooth; and last, the completely smooth body.
There were only two styles of speaker grills seen on the Classic Communicator. The most common was the "spider" moiré, while the other was the “wavy lines” version. These both came in two sizes, a larger one of one inch diameter, and three sixteen’s wide and three sixteen's high and then a smaller one of about one inch and one eight diameter with the same height. Of both sizes I have seen, all had three grooves cut into the side wall of them.
There were two colors of microphones grills: gold and silver. Their construction was identical.
The antenna grill was perforated brass and soldered to the wire frame, which mounted both to two brass disks at the rear of the grill via the wire soldered to the two side and the front lower edge of the grill, forming an hinge that turned on a metal rod mounted to the center plate. The back edge of the grill had no wire trim and was left bare.
Yellow, red, and green plastic rhinestones were used on all original communicators that I have seen, and they were arranged from left to right in that order. However, the mounting bases for these stones were different from unit to unit. Some seem to sit on ordinary washers, while others seem to be set on round aluminum rods that projected through the face of the bodies. Such rods would have countersunk holes for the rhinestones to set into, and with this style in particular, the center (red) rhinestone was always a touch deeper. The last ring set was made from HO train wheels. The flange of the train wheel became the ring with the rhinestone glued to the top and center hub of the wheel.
So the next time you flip out your cell-phone don’t be too surprised if you reach the Enterprise, they had them first.
Next up, the Classic Tricorder