Note
QST, Jun 1967, p. 5.
QST, Feb 1968, p. 5.
QST, Jan 1970, p. 5.
QST, Aug 1971, p. 143.
Ham Radio, Nov 1975, p. 120.
Refered to as a "frame grid preamplifier."
From the catalog:
A continuous tuning 6–160 meter pre-amp specifically designed for use with a transceiver. Complete with power supply and interconnecting cables, wired and tested. Features a frame grid pentode to provide a low noise figure with the ability to handle strong signals, greatly improving the sensitivity of the receiver section of a transceiver. A unique built-in transfer circuit enables the PT to by-pass itself while the transceiver is transmitting. The PT also feeds the antenna input of a 2nd receiver as well as muting it. Front panel control transfers antenna and control circuitry "in-and-out" at will. A built-in attenuator provides variable off-channel signal protection.
PT-2
QST, May 1978, p. 179. (Solid state version of the PT).