Data Sheets & Manuals
Many old semiconductors can be hard to find now.
The replacements I have listed have worked OK for all my repairs.
The STP4NB80 can be replaced with the IRFBE30 Power MOSFET.
Data for STP4NB80
Data for IRFBE30
For those people needing to know about magneto phones and switchboards
Here is a collection of PMG Technical Instructions (25 pages/1.5Mb)
Data sheets for :-