With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: Silicon Valley is a region in California.
text_B: The type 955 triode `` acorn tube '' is a small triode thermionic valve -LRB- vacuum tube in USA -RRB- designed primarily to operate at high frequency ; although data books specify an upper limit of 400 -- 600 MHz , some circuits may obtain gain up to about 900 MHz .. acorn tube. acorn tube. triode. triode. thermionic valve. thermionic valve. vacuum tube. vacuum tube. acorn. acorn. Interelectrode capacitances and Miller capacitances are minimized by the small dimensions of the device and the widely separated pins .. Miller capacitances. Miller effect. The connecting pins are placed around the periphery of the bulb and project radially outward  : this maintains short internal leads with low inductance , an important property allowing operation at high frequency .. inductance. inductance. The pins fit a special socket fabricated as a ceramic ring in which the valve itself occupies the central space .. The 955 is one of about a dozen types of `` acorn valve '' , so called because their size and shape is similar to the acorn -LRB- nut of the oak tree -RRB- , designed to work in the VHF range .. acorn. acorn. VHF. VHF. The 954 and 956 types are sharp and remote cut-off pentodes , respectively , all with indirect 6.3 V , 150 mA heaters .. Types 957 , 958 and 959 are for portable equipment and have 1.25 V NiCd battery heaters .. NiCd battery. Nickel–cadmium battery. The 957 is a medium-μ signal triode , the 958 is a transmitting triode with dual , paralleled filaments for increased emission , and the 959 is a sharp cut-off pentode like the 954 .. triode. triode. The 957 and 959 draw 50 mA heater current , the 958 twice as much .. In 1942 , the 958A with tightened emission specs was introduced after it turned out that 958s with excessively high emission kept working after the filament power was turned off , the filament still sufficiently heating on the anode current alone .
not_related.