Comparison between old and new ones within the same model number
Electronic parts often exhibit different appearances depending on the period of the production even have the same model number. Their diversity fascinates me to considerable extent. I would like to exhibit the intra-model diversity of Japan-made silicon transistors.
2SA838 (Matsushita, presently Panasonic)
application: RF (FM radio) small signal amplification
upper: older
lower: newer
The surface of the older is rounded.
Datasheet Link: Panasonic site [pdf]
2SC380 (Toshiba)
application: RF (FM IF) small signal amplification
upper and middle: older
lower: newer
The older ones have silk-hat-like appearance.
2SC382 (Toshiba)
application: RF (TV VIF) small signal forward-AGC amplification
upper and middle: older
lower: newer
The older ones have silk-hat-like appearance.
2SC387A (Toshiba)
application: RF (UHF) oscillation
upper and middle: older
lower: newer
The older ones have silk-hat-like appearance.
2SC773 (Mitsubishi)
application: HF oscillation and amplification
upper: older
lower: newer
The marking is different.
2SC829 (Matsushita, presently Panasonic)
application: RF (FM radio) small signal amplification
upper: older
middle: intermediate
lower: newer
The surface of the older is rounded.
Datasheet Link: Panasonic site [pdf]
2SC941 (Toshiba)
application: RF (AM radio) small signal amplification
upper: older
lower: newer
The older ones have silk-hat-like appearance.
2SC1047 (Matsushita, presently Panasonic)
application: RF (FM radio) small signal amplification
upper: older
lower: newer
The surface of the older is rounded.
Datasheet Link: Panasonic site [pdf]
2SC1215 (Matsushita, presently Panasonic)
application: RF (VHF) small signal amplification
upper: older
lower: newer
The surface of the older is rounded.
Datasheet Link: Panasonic site [pdf]
2SC1359 (Matsushita, presently Panasonic)
application: RF (FM radio) small signal amplification
upper: older
lower: newer
The surface of the older is rounded.
Datasheet Link: Panasonic site [pdf]
2SC1360 (Matsushita, presently Panasonic)
application: RF (TV VIF) small signal forward-AGC amplification
upper: older
lower: newer
The surface of the older is rounded.
Datasheet Link: Panasonic site [pdf]
2SC1957 (NEC, presently Renesas)
application: RF (HF up to 50MHz band) small power amplification (RF output up to 2 Watts)
left: older
middle: intermediate
right: newer
2SC1973 (Matsushita, presently Panasonic)
application: RF (VHF up to 50MHz band) small power amplification (RF output up to 1 Watts)
upper: older
lower: newer
The surface of the older is rounded.
2SC1976 (Matsushita, presently Panasonic)
application: RF (VHF up to 145MHz band) small power amplification (RF output up to 0.6 Watts)
upper: older
lower: newer
The surface of the older is rounded.
2SC2053 (Mitsubishi)
application: RF (VHF up to 145MHz band) small power amplification (RF output up to 0.15 Watts)
upper: older
middle: newer
lower: probably second source by unknown manufacturer *)
*) I guess that this one is not genuine because the direction of the printing and the fonts of the model number and the rules of the lot number are different from others.
2SC2851 (Matsushita, presently Panasonic)
application: RF (VHF up to 145MHz band) small power amplification (RF output up to 0.9 Watts)
upper: older
lower: newer
Datasheet Link: Panasonic site [pdf]
Mitsubishi small power RF transistors
2SC2538 (older) VHF 0.5W min
2SC2086 (newer) HF 0.3W min
2SC2086 (older) HF 0.3W min
2SC2055 (newer) VHF 0.2W min for lower voltage
2SC2055 (older) VHF 0.2W min for lower voltage
2SC2053 (newer) VHF 0.15W min
2SC2053 (older) VHF 0.15W min