The horizontal output tubes for some years were popular for illegal CB Radio not so linear amplifiers, and for many amateur radio HF transceivers as well, the Yaesu FT 101 line, the Swan 350 as two well known examples. They were cheaper in this era than Eimac 3-500z or other RF tubes when these transceivers were new, or not very old.

The 12BY7 was more of a video output. They haven't obtained the value that 6LB6 tubes and the like have.

Very true. But some types of sweep tubes are expensive like the 6LB6, the 6DQ6 because of their use by Amateur Radio equipment and Illegal CB linear amplifier use. And yes, the 12BY7 was much more a video output tube.

John Meck Industries also acquired the remains of E.H. Scott and Scott Radio Labs in this time frame, so they're in this era, related companies. They died out in the 1960 time frame roughly.

OK, so then this was related to the E. H. Scott Philharmonic then. :scratch2:

Yes, corporate relatives in this era. As they were sister brands, under the John Meck Industries umbrella. The brands being Philharmonic Radio & TV, and E.H. Scott aka Scott Radio Labs.