IET continues to produce the 1413 Series Decade Capacitor to the same exacting specs as GenRad. The GenRad 1413 Precision Decade Capacitor is both a high-quality, wide-range standard and a reliable component for systems. It can be used as a bench model for versatility, or it can be rack-mounted.
This six-decade capacitor features fine adjustment over a wide range of capacitance, with excellent accuracy. Any value in the range of 0 to 1.111 11 μF can be set, with a resolution of 1 pF. For a wider range up to 10,000 μF with similar performance consider the HASC-Z Decade Capacitor
Six precision decades are employed to provide a range of 0 to 1.11111 µF in increments of 1 pF and with an accuracy of 0.05% +0.5pF. Air capacitors are used for the two lower decades and highest grade mechanically stabilized sealed 0505 mica capacitors are used for the remainder. Air trimmers are used for trimming the two lowest silvered-mica decades. The stability of the 1413 is such that it should not require readjustment with normal service. However, should it become desirable,the four lower decades contain trimmer capacitors that are accessible for this purpose.
The connections to the inner shield and to the case are shown in Figure 1-1 (on datasheet). Low terminal-to-guard and detector-input capacitance are obtained by dividing the shielding into two parts. When the two parts are connected together, the 1413 becomes a well-shielded three-terminal capacitor with extremely low zero capacitance. The connections are made by means of BNC connectors on the front of the cabinet (Rear output or 874 connectors are also available). The inner contacts provide the connections to the capacitors. The outer shells connect to the shields and, when connected together, form the third terminal of the capacitor.
See IET Labs 1423-A Decade Capacitor which minimizes capacitance at the terminals to ensure the capacitance is the same for either the three-terminal or the two-terminal method of connection.
To improve the resolution from 1 pF on the 1413 consider adding the optional HACS-Z 1pF Trimmer