Can the T1 be built inside a Sierra, FT-817, or other transceiver?
Yes. The PC board is only about 2 by 3 inches, so it could be built into just about any rig. With some effort, the T1 could be installed inside the battery compartment of the FT-817. In the case of a Sierra, you could mount the T1 in the Sierras top cover so that the switches and LEDs were accessible, then aim the BNC jacks out the back by cutting U-shaped channels down from the top. This is an ideal ATU for either rig, and it has been extensively tested with both (not to mention the K2, K1, and KX1).