The General Electric TD252  (P/N 152-0214-00) is a 4.7 mA, 6 pF tunnel diode.

Type	 	Ip		Iv,max		Cmax	Vp		Vfs		Vf		Rs(typ)	tr	 	 	 	 
 	 	(mA)		(mA)		(pF)	(mV)						(ohms)	(ps)	 	 	 	 
TD252	 	4.7 ±10%	0.6		4	80 typ		435 min		500-650		3.5	320	 	 	 	 

Some instruments using part TD252

Instrument Manufacturer Class Model Description Introduced
1S1 Tektronix Plug-in 1S1 1 GHz sampling system 1965