BF988 datasheet- low noise RF Dual-gate MOS transistor used as the input stage of the preamplifier due to their low noise, lw input capacitance and low reverse-transfer capacitance.
BF998 - (Philips), (Vishay Semiconductors) (differs from BF988 only in the package) -- low-noise RF Dual-gate
MOS transistor used as the input stage of the preamplifier due to their low noise,
low input capacitance and low reverse-transfer capacitance.
BF960 datasheet an old model of dual-gate MOS tetrode from Telefunken.