1422 电路图.pdf

534 Main Street, Westbury, NY 11590 IET LABS, INC. in the GenRad T TEL: (516) 334-5959 (800) 899-8438 FAX: (516) 334-5988 Contents p. 2 Applic. pp. 4-8 Selection pp. 9-11 Products pp. 12-87 GenRad prod ucts pp. 50-87 Index p. 89 66 A laboratory standard For calibrating working standards Working standard Capacitance measurement functions For substitution measurements For calibrating instrumentation Stability: better than 0.02% full scale per year Settleable to 40 ppm Low temperature coeffi cient, low losses Wide selection to suit needs 3 diff erent models Low-loss Variable Air Capacitors Electronic cat/1482/09-15-03 The 1422 is a stable and precise variable air capaci- tor intended for use as a continuously adjustable standard of capacitance. One of the most important applications is an AC bridge measurements, either as a built-in standard for substitution measurements. It is available in a variety of ranges, terminal confi g- urations, and scale arrangements to permit selection of precisely the required characteristics. Model 1422 Precision Capacitor Two-terminal - The 1422-D is a dial-range, two-terminal capacitor, direct reading in total capacitance at the terminals. Three-terminal - The 1422-CB and -CL are three-terminal ca- pacitors with shielded coaxial terminals for use in three-terminal measurements. The calibrated direct capacitance is independent of terminal capacitance to ground, and losses are very low. The 1422-CL has particularly low, constant terminal capacitance, mak- ing it suitable for measurement circuits in which high capacitance to guard cannot be tolerated. Construction - The capacitor assembly is mounted in a cast frame for rigidity. This frame and other critical parts are made of aluminum alloy selected to give the strength of brass with the lightness of aluminum. The plates of most models are also aluminum, so that all parts have the same temperature coeffi cient of linear expansion. A worm drive is used to obtain high precision of setting. To avoid eccentricity, the shaft and the worm are accurately machined as one piece. The worm and worm wheel are also lapped into each other to improve smoothness. The dial end of the worm shaft runs n a self-aligning ball bearing, while the other end is supported by an adjustable spring mounting, which gives positive longitudinal anchoring to the worm shaft through the use of a pair sealed, self- lubricating, preloaded ball bearings. Similar pairs of preloaded ball bearings provide positive and invariant axial location for the main or rotor shaft. Electrical connection to the rotor is made by means of a silver-alloy brush bearing on a silver-overlay drum to assure a low-noise electrical contact. Stator insulation in all models is a cross-linked thermosetting modi- fi ed polystyrene having low dielectric losses and very high insula- tion resistance. Rotor insulation, where used (Types 1422-CB and -CL), in grade L-4 steatite, silicone treated. Accuracy - The errors tabulated in the specifi cations are possible errors, i.e., the sum of error contributions from setting, adjustment, calibration, interpolation, and standards. When the capacitor is in its normal position with the panel horizontal, the actual errors are almost always smaller. The accuracy is improved when the readings are corrected using the 12 calibrated values of capacitance given on the correction chart on the capacitor panel and interpolating linearly between calibrated points. Even better accuracy can be obtained from a precision calibration of approximately 100 points on the capacitor dial, which permits correction for sight residual eccentricities of the worm drive and requires interpolation over only short intervals. This precision calibration is available for the 1422- CL model. A plastic-enclosed certifi cate of calibration is supplied, giving corrections to one more fi gure than the tabulated accuracy. 1422 Series1422 Series p. 1 of 2 RadioFans.CN 收音机爱 好者资料库 ORDERING INFORMATION Accuracy:1422 Precision Capacitors Type 1422 Two-terminal Type 1422-D Three-terminal Type 1422-CB Three-terminal Type 1422-CL Capacitance Range (Min/Max)100/1150 pF 35/115 pF 50/1100 pF 10/110 pF Scale, pF/Division0.2 0.2 0.2 0.02 Initial Accuracy: Picofarads Direct-Reading (Adjustment): Total Capacitance1.5* 0.3* 1.5 0.1 With Corrections from Calibration Chart (supplied) Total Capacitance 0.04 With Corrections from Precision Calibration (extra charge) Total Capacitance 0.01 Residuals (typical values): Series Inductance, H Series Resistance, at 1 MHz 0.06 0.10 0.04 0.05 0.14 0.1 0.13 0.1 Terminal Capacitance, pF, typical high terminal to case low terminal to case min/max scale min/max scale 36/35 58/53 34/33 58/55 * Total capacitance is the capacitance added when the capacitor is plugged into a 777-Q3 Adapter SPECIFICATIONS Stability: Capacitance change with time < 1 scale division (0.02% of full scale) per year Long-term accuracy can be estimated from the stability and the initial accuracy. Calibration: Measured values (supplied) are obtained by compari- son at 1 kHz, with working standards whose absolute values are known to and accuracy of (0.01% + 0.0001 pF). Each comparison is made to a precision better than 0.01%. The values of the working standards are determined and maintained in terms of reference stan- dards periodically calibrated by the National Institute of Standards and Technology. The indicated value of total capacitance of a two- terminal capacitor is the capacitance added when 1422 Capacitor is plugged into a 777-Q3 Adapter *. The uncertainty of this method to connection is approximate 0.03 pF. * Gilbert Engineering Part Number 0777-9703. Resolution: Dial can be read and set to 1/5 of a small division, i.e. to 0.004% of full scale. BACKLASH: Negligible for any setting reached consistently from lower scale readings; 100 kHz; negligible, for < 100 kHz. Frequency Characteristic: 2-terminal model, see Figure 1. 3-termi- nal models: 20 and 40 MHz (approximately) resonant frequency for 1422-CB and -CL (each section), respectively. Dissipation Factor: 2-terminal, loss primarily in stator supports of low-loss polystyrene (the product DC = 10-14), 3-terminal, estimated D 1012 , under standard conditions (23C, RH < 50%). Maximum Voltage: 1000 V pk (all models) Terminals: 2-terminal Model: Jack-top binding posts at standard (0.75 in) spacing. Rotor terminal connected to panel and shield. 3-terminal Models: Locking G874 coaxial connectors. Mechanical: Lab-bench cabinet. Dimensions: 17.8 cm H x 24.2 cm W x 21.5 cm D (7 x 9.5 x 8.5). Weight: (depending on model): 4.8 to 5.7 kg (10.5 to 12.5 lb.)net, 7 kg (15 lb.) shipping. Catalog No:ItemNameCalibration 1422-97041422-DPrecision Capacitor12 points 1422-99161422-CBPrecision Capacitor12 points 1422-99331422-CLPrecision Capacitor12 points 1422-95081422-CLPPrecision Capacitor100 534 Main Street, Westbury, NY 11590 IET LABS, INC. in the GenRad T TEL: (516) 334-5959 (800) 899-8438 FAX: (516) 334-5988 Con tents p. 2 Applic. pp. 4-8 Selection pp. 9-11 Products pp. 12-87 GenRad prod ucts pp. 50-87 Index p. 89 67 Low-loss Variable Air Capacitors 1422 Series1422 Series p. 2 of 2 Electronic cat/1422 p2/02-26-06 RadioFans.CN 收音机爱 好者资料库