Yes, I saw the picture of your setup. I made a search on this group, in the messages section, to find out more about your tuner (schematic, type, etc) but O.K., now I understand that someone else build it, and you probably don't know much about the tuner itself.
I noticed that the tuner buttons look like the kit from LDG, the EZ...something. It is an antenna tuner kit. It comes with its own case, but it looks like the guy who build you Sierra, prefered to put his tuner in another empty Sierra casing.
So, here is a clue...
I know how to find out who build your Sierra. It is a simple idea. And it has good chances to work.
Ask QRPBob : who had ordered a Sierra, and two other empty Sierra casing. Simple enough eh ?
There must be only one guy who did that. Since he did the same with the power supply, my guess is that he build the three in the same time (he needed power and tuner to operate his Sierra), so he must had ordered them all in the same time. ;-)
QrpBob certainly keep records somewhere of all the ordering he got.
And euh,, yeah... QrpBob is probably still very busy with the Joplin tornado aftermath, but he would come back eventually...
It is like going fishing. Maybe you will have an answer only in a couple of weeks or months, but it worth the effort to try. ;-)
Chris from Canada.