Show Pass By-Pass Condenser and Shielded Grid Tube Due to the fact tact that the shield grid ot of the new z type tube Is connected directly to the 4 43 volt tap of ot the D B battery It has commonly teen ns as assumed assumed that It played a negligible part partIn partIn partIn In causing Instability and other trou troubles troubles bles bies which arise from the use Ue u of ot a common B battery Actually this shield grid grill has a mu or amplification constant with respect to the plate ot of between 40 and CO riO This means that any variation In Its voltage produces a change In the plate current 40 or 50 t times as RS great greal as the same change to In plate voltage would produce lor I or this reason It Is Important to see that any ant common Impedance through the B battery Is eliminated This 1 I I be bedone bedone e edone done by connecting a by pas pass con conden condenser den denser ser from the shield plate terminal of the socket to the e ter terminal minal The fact tact that the circuit I Is not nor unstable does docs not Indicate that coup coup- coupling coupling coupling ling Is not taking place since am an disturbance an disturbance In the lie B u circuit of ot one particular tube will cau cause e a variation In the shield of ot that thal tuL tine tulo e which will produce c e regeneration or tend to lo reduce the amplification |