Are you absolutely sure 97.3 was on Beacon in 1977?
Quite sure - I hung around Mt.Beacon while I was in high school and then was KRQR's Transmitter Supervisor from 1988-1998.
KEAR moved to Mt. Beacon in 1969 and installed a Sparta 620 transmitter and an RCA 8 bay circularly polarized antenna. It was designed with a slight amount of downward beam tilt to put the peak of the main lobe at the horizon in San Jose. I think it was something like 0.5 degrees, but I'm not sure. In the late 1980s Hammett and Edison did a helicopter survey of all the Mt Beacon stations and determined the antenna was working exactly as designed. In spite of earning the nickname "Big F***ing Ember" in several other markets, this antenna performed flawlessly at it's full rated power until it was replaced in 2006.
In 1977, the KCBS-AM transmitter in Novato had only a 50 Kw standby generator. It was installed in 1959 along with the Continental 10 Kw auxiliary transmitter and could (obviously) only power the 10 Kw aux, not the 50 Kw main transmitter. Prior to that, KCBS had only the original 50 Kw G.E. transmitter and no standby power at all.
When CBS purchased 97.3, they decided to upgrade the KCBS generator to 250 Kw and moved the 1959 Caterpillar generator to Mt. Beacon. They also installed a McMartin FM25k transmitter and moved the Sparta to auxiliary status.
The McMartin proved to be unstable when I was there - it's synchronous AM was atrocious which added to received multipath and drove our two SCA clients nuts. The Sparta was much better in this regard, so around 1990 we returned the Sparta to main duty and made the McMartin the aux, pending it's replacement. That finally happened in 1995, when we installed a BE FM20B. The Sparta continued as the aux until it was finally retired in 2005.
KMPX (106.9) was also on Beacon, with a 5 Kw RCA transmitter feeding a 16-bay horizontal-only antenna to make 80 Kw. When Family Stations took over 106.9, they replaced this with a parallel pair of AEL 20 Kw transmitters for 40 Kw TPO and a 4 bay circularly polarized antenna. The transmitters were installed in a new room under the existing carport, and the top third of the KMPX tower was replaced with a pylon holding the new antenna. The pieces leftover pieces were later assembled on another foundation and today hold the auxiliary antennas for KDFC and 98.1