The "unavailability" of Motorola RF transistors is confusing to many radio amateurs .. due to sale of many Motorola divisions over past decade. Avoid rumors based on decade old information about production issues. Motorola and some of these divisions are my past clients. I had to sort through the aftermath of many of these divestitures and sales.
American Semiconductor, SiliconRF (SiRF), Freescale, and M/A-Com today produce many of the original Motorola RF transistor designs. CCI provides Motorola Application Notes, RF transistors, and key parts for RF experimenters and designers.
RF Parts is you BEST SOURCE ... to ask about specific availabilty of US and Eastern Asia RF Power transistors.
Dennis Cobbe (sk 1997), who was the founder of Transworld Electronics in Escondido CA,
designed this Metron amplifier for radio amatuer market after he sold Transworld to Datron.
Datron no longer services the Metron HF amplifiers.
In the Transworld amplifiers, the RF transistors (28 VDC) were OEM house marked Motorola MRF-422 transistors which are still mfg. by ASI, SiRF, and M/A-Com and available from RF Parts.
Since the Metron is a 12.5 VDC unit (mobile power usage), it used the Motorola MRF-454 RF Power transistor.
M/A-Com lists this RF transistor as a "current production part" ... and available from RF Parts.www.macomtech.com/datasheets/MRF454.pdf
M/A-COM ... MRF-454 .. MATCHED QUAD SET (4 RF transistors) are $191.80 from RF Parts ... IN STOCKhttp://www.rfparts.com/transistors_MRF-TP.html#MRF401
The ARRL Handbooks (1981-1983) featured the Helge Granberg, K7ES (SK, 1996) HF amplifier design using the MRF-454 RF transistor. Helge was the Finnish-born Motorola designer responsible for modern solid-state RF Power transistors.http://www.foxdelta.com/products/mrf455.htm