The Eta Dummy

This page is an accumulation of our various studies and essential screencaps of this not-yet-found communicator.
Here's our guess as to what this prop might look like today:
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Eta's Jewels
While the information available to determine Theta's and Iota's rhinestones is scant, it actually dwarfs what we have on Eta's. In only two episodes can be found even the slightest hints of this comm's jewels; in Shore Leave and Spock's Brain. For the filming of "Shore Leave" the prop was one of probably only two communicators (the other being Iota) that made the trip to location, so it fortuitously shows up in a number of the scenes shot there. First, held by McCoy in the clear outdoors, we see here the two outer stones, appearing roughly to be the same size, shining sky blue or even flashing a Sun-white: This indicates both jewels are AB-coated, as demonstrated in this photo of vintage AB Swarovskis taken outside: Next, the left rhinestone scarcely makes it into frame in what is the only close-up of this comm's control well, this time held by Kirk while talking with Ruth. The gem - sized in these pics to likely be a 20ss - is again undoubtedly reflecting the sky above: A final fleeting outdoor appearance, held once more by Kirk as a frightened Sulu runs to him, at last captures a bit of the center gem: Its orange-red easily makes our call here a Hyacinth, perhaps a 16ss like in most of the other comms. Though given how poorly it does show up, it's quite possible that it is either (or both) recessed into the hub or a smaller 12ss, like in Zeta. What's needed to judge the two other rhinestones' true colors is a view of them under different (i.e. indoor) lighting, and thankfully there is one, barely, in "Spock's Brain" after Kirk and crew beat up the brawny guards: The left has a greenish lean and the right maybe tints violet. So based on these measly few pixels, and giving preference to those jewel types already seen in the other comms, the most logical choices would be on the left a 20ss Emerald AB and on the right a 20ss Black Diamond AB. .
	Left	Center	Right

Top Choice Other Possibilities	20ss Emerald AB 20ss Olivine AB 20ss Blue Zircon AB	16ss Hyacinth 12ss Hyacinth 16ss Light Siam	20ss Black Diamond 20ss Amethyst AB 20ss Burgundy AB 20ss Tanzanite AB 16ss Crystal AB .
Eta's Moiré Pattern
As was said above, Eta got almost no airtime whatsoever. Just a few hard-found distant glimpses inside are all we've got to go on: What stands out in these caps above is of course that white spot at the center. Very distinctive. Within The Science of Moiré Patterns book, there are two patterns that are a close match: the Pattern #7 "Fresnel" concentric circles (printed on the same Page 9 where Wah cut the images out for Epsilon's and Zeta's), and another even-cruder version of the Pattern #4 radial from Page 1 (at right in order >>). Both, however, look to have a larger white center than what Eta's screencaps suggest. Might there be another option? There is. One other possible source within the pantheon of Edmund Scientific products had just become available. A year after they first offered their "Series (A)" Patterns #1 thru 8 moiré patterns / transparencies in 1965 came their second, lesser-known "Series (B)" kit of Patterns #11 thru 18: Pattern #18, technically called a "30-line logarithmic spiral," also resembles what we see in Eta. It just so happened to have been used as well in the very first replica made after the show's cancellation (at right >>) by a small operation called Starfleet Fabrications, some of whose members had reportedly visited the set during production and could have seen original comms to base their later builds on. This possible connection, and the pattern they used, may be a coincidence, but perhaps not. In our considering this pattern, it should be noted no other comm used an image cut from the Series B kit (of course Wah had at least three Series (A) kits to put in the two heroes and later his Tricorder "A"). So to decide among the three possibilities, we compare below some screencaps with our best simulation of how the candidates would look under similar fuzzy filming conditions: While the individual lines that comprise the various patterns cannot be seen, the size of the central white patch along with the absence of any darker inner rings or black dot is entirely consistent with the #18 spiral. There is indeed adequate evidence here to conclude Wah had, and made use of, the Series (B) set of patterns: For what it's worth, Edmund Scientific put an exact copy of this pattern on the back of its 1968 catalog. Given the later timing, this obviously wasn't the source for this comm, but it is at the same scale: More information on moiré patterns can be found on our A Moiré Story page. And a high-resolution print-ready scan of the original source material can be found here. .
Eta's Bezel Ring Grooves
No data can be found to support any conjecture here. .
Essential Screencaps
This above is the only time we see Eta's antenna opened without interference from an actor's hand, so clearly it swung all the way back. We see the three communicators laid out on the table a total of three times, twice before the fight with the guards (the pic above and below left) and once after (below right). And in that "after" shot they're in a different order, as shown in our labeling: And in fact Kirk luckily picks up the left-most comm and begins talking to the disembodied Spock, resulting in the caps below: .