201.602e 201.602z Determination of ratio and phase angle at an additional value of For tests of voltage transformers at other frequencies, with primary *For current fees, see Appendix C. 201.603 Voltage transformer comparators. Item 201.603z Description Calibrations of voltage transformer comparators are handled on a (*) Fee Fee 201.604a Calibration of kilovoltmeters at five scale points on one range using (*) 201.604b Calibration of kilovoltmeters at five scale points on one range using (*) 201.604c Calibration at one scale point on an additional range (up to 60 kV) 201.604d Calibration of each additional scale point on one of the ranges cali- (*) 201.604z For calibrations at voltages above 60 kV, advance arrangements must *For current fees, see Appendix C. 201.701 Frequency stability calibration of signal sources, up to 30 kHz. (Services available only at the Boulder Laboratories.) (a) Frequency stability calibrations are made on signal sources up to 30 kHz. schedule 201.860 for calibration service at higher frequencies.) (See (b) The signal source should have a power output of at least 10 mW (into a matched load). (c) Frequency stability of the signal source should be better than approximately one part in 107. Item 201.701a Measurement of frequency stability of signal sources, up to 30 kHz. - - (**) **The fees to be charged for these calibration services performed by the Bureau at its Boulder Laboratories are not fixed at this time. Charges will be made for actual costs incurred. Upon request, estimates which should provide a close approximation of actual cost will be furnished for specific tasks. 201.800 High-Frequency Region (a) General: In the high-frequency region of approximately 30 kHz to 1000 MHz and continuous frequency coverage to 18 GHz for certain calibrations, the Electronic Calibration Center, Boulder Laboratories, is equipped to calibrate standards of voltage, pulse and cw power, immittance, attenuation, and field strength.† (b) Fees: The fees to be charged for the following calibration services performed at the Boulder Laboratories are not fixed at this time. Charges will be made for actual costs incurred. Upon requests, estimates which should provide a close approximation of actual cost will be furnished for specific tasks. 201.810 Rf, rf-dc voltmeters, and thermal converters in the frequency range of 30 kHz to 1000 MHz, from 0.2 V to 300 V. Ordinarily instruments equally suitable for use on dc and rf will be calibrated only for rf-dc difference by the procedure †Connectors limit the accuracy of measurements in the high-frequency region to some extent, and particularly at the higher frequencies. To avoid instability from this cause, all interlaboratory standards submitted for calibration, fitted with coaxial connectors, should be equipped with Type N connectors complying with the MIL C 39012/1,2 specification, or with the new precision 7 or 14 mm connectors. The critical mating dimensions required by NBS for Type N connectors are shown in the accompanying diagram. of item 201.810a, since periodic calibrations can be made by the user on reversed direct current. Such reversed d-c calibrations will be made at the Bureau only under unusual circumstances and by advance arrangement. Instruments suitable for use only on rf will be given rf calibrations by the procedures of items 201.810a, b. Instruments which respond to average or peak values or which are not in ASA accuracy class 4 percent or better are not usually accepted for calibration below 30 MHz. Item Description Fee 201.810a Determination of voltage at 30, 100, 300 kHz, 1, 3, 10, 30, and 100 (**) 201.810b Determination of voltage at 300, 400, 500, 700, and 1000 MHz, from (**) 201.810z Special calibrations not covered by the above schedule. (**) **See 201.800(b). 201.811 Rf micropotentiometers, voltmeters, and signal sources in the frequency range from 30 kHz to 1000 MHz from 1 μV to 0.1 V. The Bureau normally accepts for calibration only high-quality voltmeters suitable for use as interlaboratory standards. These instruments should have a stability of one percent or better and an accuracy of three percent or better. Rf voltmeters will be calibrated by the procedures of items 201.811a, b. The Bureau usually accepts only signal sources high enough in quality to be considered as interlaboratory standards. If these instruments are equally suitable for use on dc and rf, they will be calibrated for rf-dc difference by the procedures of items 201.811a, b. Signal sources suitable for use only on rf will be calibrated by the procedures of items 201.811a. Item Description Fee 201.811a Determination of voltage for micropotentiometers, voltmeters, and (**) 201.811b Determination of voltage for voltmeters from 900 to 1000 MHz, from (**) 201.811z Special calibrations not covered by the above schedule. (**) **See 201.800(b). 201.820 Rf calorimeters, 30 kHz to 500 MHz. (a) For maximum calibration accuracy, interlaboratory rf calorimeters should repeat readings to one-half percent or better with a constant power input. (b) At present only rf calorimeter utilizing Type N or precision connectors for rf power input can be calibrated. Refer to 201.800 for special requirements for the connectors used on interlaboratory standards. 201.820a 201.820b 201.820c 201.820z Calibration of rf calorimeter at one frequency at 100 and 300 kHz; 1, Special calibrations not covered by the above schedule. (**) (**) (**) (**) **See 201.800(b). 201.821 Continuous wave low-level power measurement of coaxial bolometer units and bolometer-coupler units. (a) A bolometer unit includes both the bolometer element or elements and the bolometer mount in which they are supported. (b) Power measurements are made on barretter-type bolometer units having nominal resistance of 50, 100, or 200 ohms at a bias current between 3.5 and 10 mA; and on thermistortype bolometer units having a nominal resistance of 50, 100, or 200 ohms at a bias current between 5 and 15 mA. Bolometer units should be of the fixed tuned or untuned broadband type and must have suitable 13 male or female Type N or precision connectors. (c) Power measurements are made on bolometer units at cw power levels of 1 and 10 mW only. (d) Power measurements are made on bolometer-coupler combinations having coupling ratios from 3 to 30 dB. A bolometer unit of the fixed tuned or untuned broadband type should be permanently attached to the side arm of the directional coupler. The directional coupler should have good design features, with a directivity of 30 dB or greater, and a VSWR no greater than 1.10 for the input and output ports of the main arm of the coupler. (e) Effective efficiency for bolometer units is defined as the ratio of the substituted d-c power in the bolometer unit to the power dissipated within the bolometer unit.14 (f) Calibration factor for bolometer units is defined as the ratio of the substituted d-c power in the bolometer unit to the rf power incident upon the bolometer unit.14 (g) Calibration factor for bolometer-coupler units is defined as the ratio of the substituted d-c power in the bolometer unit on the side arm of the directional coupler to the rf power incident upon a 50 ohm load (with a VSWR less than 1.05) attached to the output port of the main arm.14 13 See section 201.800. 14 Desch, R. F., and R. E. Larson, Bolometric microwave power calibration techniques at NBS, IEEE Trans. Instr. Meas. IM-12, No. 1, 29 (June 1963). 201.821a Measurement of calibration factor of a coaxial bolometer unit at one (**) 201.821b Measurement of calibration factor of a coaxial bolometer-coupler unit (**) 201.822 Pulse power, peak measurement, coaxial systems. (a) Instruments submitted for calibration should have a nominal impedance of 50 ohms, and be fitted with Type N, BNC, HN, or precision input connectors.15 (b) Measurements are made with pulsed rf signals having a rectangular envelope. Item 201.822a Description Calibration of instruments for peak power measurement of pulsed Fee (**) 15 See section 201.800 **See 201.800 (b). 201.830 Immittance, 30 kHz to 4 GHz. (a) Maximum accuracy can be achieved only in the case of instruments and components equipped with connectors having a plane of reference directly compatible with the Bureau system with no necessity for special adapters. In the interest of preserving higher calibration accuracies, coaxial connectors should be utilized on standard instruments and components wherever possible. Calibrations are not performed on capacitors with unshielded terminals, e.g., binding posts and banana plug connectors. (b) Power applied to any item under test will normally not exceed 1 W. Where caution in this respect is necessary it should be clearly stated in the calibration request. All calibrations described in this section are performed under ambient conditions of 23 °C (±2°) and 40 percent (2%) relative humidity. |