Receiver tubes are the heart of your Scott AM/FM, FM-Mono or
FM-MPX Stereo, tuner or receiver. The outstanding sensitivity and selectivity
of Scott RF products was a tribute to conservative design and careful
attention to detail. Many of the receiver (RF) circuits use tube types that
are also used in typical amplifier (AF) circuits. Such examples would be the
frequently used 6U8 and 12AX7
types.
Scott RF designs used fairly common tubes that, for the most part, were
designed for the emerging television industry of the 1950's. Fortunately,
today, most of these tubes are readily available, as NOS (new-old-stock)
replacements.
Some later vintage H.H. Scott tube-types featured "Compactrons,"
followed by hybrid designs that featured "Nuvistor"
tubes in the FM front-end, (i.e., the FM Cascode RF amp and the
Mixer-Oscillator). The Scott Nuvistor-based "tube" tuners were
actually hybrid designs, utilizing solid-state components for IF, MPX and
final preamp output stages. The Nuvistor tube Cascode front-end was a
short-lived transition to the FET Cascode front-end.
Note: Scott RF engineers were the first (outside military
applications) to adopt the use of FET (Field Effect Transistors) in RF
Cascode front ends, which permitted their solid-state tuners to achieve the
outstanding cross-modulation rejection standards set by their earlier vacuum
tube designs.
