254 



BELL SYSTEM TECHNICAL JOURNAL 



bronze wire. For any other diameter, d, of phosphor bronze wire, the new 

 distance 



X' = X 



/: 



d 

 U063 



Earlier, it was mentioned that the supporting wires for the plates were 

 formed with one or two bends. In addition to the function of suspension 

 these bends also introduce changes in impedance along the wire thus mini- 



LOCATION OF WEIGHTS ON MOUNTING WIRES OF OUARTZ CRYSTALS TO SUPPRESS WIRE VIBRATION DISTURBANCE 



NOTE: Information shown is for 6.3 mil Phosphor Bronze Wire 



(For 3.5 mil P-b wire, weight should be multiplied by .50 and located at .75X) 



For 5 mil P b wire, same weight should be located at .89X 



For 8 mil Pb wire, weight should be multiplied by IR and located at M2X 



Weight 



30 40 50 60 70 8090100 200 300 400 500 600 



FREQUENCY • KILOCYCLES 



Fig. 13.11 — Graph for determining placement of weights on wires for damping vibration. 



mizing the possibility of trouble due to wire resonance. The use of a greater 

 number of bends in the wire would tend to accomplish the same result as 

 that of weights. However, the use of weights is considered more practical 

 and has been adopted. As a result of this change, it is possible to employ 

 wire supports having only one bend in virtually all crystals. In low- 

 frequency crystals (below 2 kc) where the wave-length of the flexural wave 

 in the wire is relatively long it is unnecessary to use weights since the wire 

 length can be controlled adequately by the termination of the support wire 

 at the straight. Depending upon the frequency, the desired length of wire 

 is obtained by using either two or three direction bends. 



