[jshorva65]

Another question specific to "roundie" Zenith sets, since I have only seen this set of typically-vacant antenna terminal locations on the backs of Zenith sets from the "roundie" era ...

Many mid-1960s Zenith sets (especially "roundie" Color models) had terminal positions marked VHF, UHF Strips, and UHF Tuner on their terminal boards. Those having UHF tuners always had their UHF terminals inserted into the UHF Tuner positions. Both UHF terminal pairs were left vacant on VHF-only sets. My best guess is that the UHF Strips terminal locations were for use with specially-equipped Space Command sets to allow removal of unused VHF channel segments from the set's tuner turret by a service facility in order to substitute a segment designed to pick up a specific UHF channel or to be preset to a channel within a predefined range like a "pushbutton" car radio, allowing remote access to "favorite" UHF channels without the added complexity of a separate remote tuning function (with the necessary separate relay and drive motor) which a standard UHF tuner would have required. Perhaps channel strips for each of the 70 UHF channels were sold as accessories, or limited-range strips (channels 20-30, 30-40, etc.) were sold to be preset by the service shop to a channel in that range, along with a set of channel number tabs to be installed in the appropriate postion(s) on the knob. A remote set purchased in the Youngstown, OH area might have had its standard 2,3,4, ... 13, UHF, 2 ... sequence modified to provide "instant preset" tuning via remote of 12 active channels in that market (3, 5, 8, 21, 23, 25, 27, 33, 35, 43, 45, 61) or had one or more VHF stations from the Pittsburgh market (2, 4. 9, or 11) substituted if the set's owner rarely or never watched PBS affiliates 25 and 45 and had an antenna capable of receiving Pittsburgh stations clearly from Youngstown. Such an installation might also have been equipped with a manually-operated UHF tuner if a large number of UHF stations were available, which would then receive the last channel manually tuned on its dial each time the remote-operated turret tuner was set to the UHF position.

Are there any Zenith experts here who can provide some insight, perhaps direct from a service manual or other OEM reference materials?