BK 2425 Electronic Voltmeter 电路图.pdf

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1、type 2425 Electronic Voltmeter FEATURES : Calibrated Amplifier with line-level output True RMS detector with 40dB range and 5:1 (14 dB) crest factor capability Input for external meter time constants Mains or external battery operation Average detector with vu response Positive, Negative and Max. Pe

2、ak detector with 50 s rise time USES: Peak Hold function Measurement of true RMS, -Peak, + Peak, Max. Linear frequency response from 0,5 Hz to 0,5 MHz Peak and Average voltage Indication of volts, dBV and dBm Calibrated amplifier Fast and Slow meter time constants General purpose voltmeter Sensitivi

3、ties from 1 mV to 300 V FSD vu measurements The Type 2425 Electronic Voltme- ter is a versatile general purpose volt- meter. It has a full-scale measurement range of 110 dB from 1 m V to 300 V full-scale, manually switched in steps of lOdB. The linear scale (fitted as standard) can be replaced by sc

4、ales calibrated for dBm and vu measure- ments. The voltmeter can be powered from an AC mains supply or by two batteries of 22 V to 35 V each. The 2425s true RMS rectifier has a dynamic range of 40dB and can han- dle signals with a crest factor of 5:1 (14dB). The Average detector, when used with the

5、meter response set to Fast, conforms to standards for vu measurements. The Peak detector has a rise-time constant of 50 s with the Fast response selected (500 s with Slow response) and can be switched to capture positive peak voltage, nega- tive peak voltage or maximum voltage irrespective of polari

6、ty. A Peak Hold facility can be used to capture very short transient signals. The Peak Hold facility has a decay rate of 0,05 dB/s with the meter Fast response select- ed and 0,005dB/s with Slow select- ed. Calibrated Amplifier The AC Output on the rear panel of the 2425 provides a line-level signal

7、 POwt On Hold I Re,et Slow I Electronic Volt meter 9 0.5 Hz - 0.5 MHz 0 dB - 60 dB - Type 242 5 r-Ma:i., Peak.-, ,.,. Br(iel l:W+M 30 20 10 0 range of the Voltmeter for accurate reproduction of the input signal. The 2425 has a frequency response which is linear to within 0,5 dB from 0,5 Hz, Slow met

8、er response; 20 Hz, Fast response, up to 0,5 MHz. 77 RadioFans.CN 收音机爱 好者资料库 DC Output A 7-pin DIN socket on the rear pan- el of the 2425 provides a DC output voltage which is proportional to the input signal. An output level of 1 V is equivalent to full scale deflection on the meter; the output ran

9、ge is from + 10 dB to -30 dB referenced to 1 V. The output impedance of less than 10 Q allows the DC Output to be used Amplifier +/. Peak, Attenua tor maxlPcak , with chart recorders and other data recording equipment. Meter Time Constants The rear panel DIN socket also in- corporates connections to

10、 the meter time constant circuit. By placing a re- sistor or capacitor between the Ext. Time Constant connector and Ground, the RMS averaging time and AC output V DC output Input -50 to Peak Hold, 0 60 dB RMS, Avg Meter l .L Ext. time const . 273004 Fig. 1. Block diagram of the Type 2425 Electronic

11、Voltmeter INPUT: Standard BNC socket, mating plug JP 0035 Input Impedance: 1 Mf! II 47pF Max. Input Voltage : 250V DC; 110V peak In mV ranges, 600 V peak In V ranges Amplifier/ Att enuator Range: -50 dB (300 V full -scale) to +60 dB (1 mV full-scale) in steps of 10dB Accuracy: better than 1 % Rectif

12、ier Dynamic Range : 40dB Accu racy: 0,5dB, + 10dB to -20dB 1 dB. -20 dB to -30 dB FREQUENCY RESPONSE: Fast : 0,2dB, 20Hz to 0,2MHz 0,5dB, 0,2MHz to 0,5MHz Slow : 0,2 dB, 2 Hz to 0,2 MHz 0,5 dB, 0,5 Hz to 0,5 MHz RMS MEASUREMENT: Accuracy : 0,5 dB for signals with crest fac- tor up to 5:1 (14 dB) Ave

13、raging tim e: Fast, approx. 270 ms; Slow, app rox. 3 s External capacitor time constant: 10 s per 2,5F AVERAGE MEASUREMENT: Fast response for standard vu measure- ments , and Slow respon se PEAK MEASUREMENT: + Peak, - Peak and Max. Peak measurement selected by front-panel switches Input time con sta

14、 nt: Fast, 50s; Slow, 5005 Hold leakage rate: Fast, 0,05dB/s; Slow, 40dB 3 mV Range: 50dB Other Ranges: 60dB INHERENT NOISE: typically 31,6 V with maxi mum amplification and input short-cir- cuited AC OUTPUT: Standa rd BNC socket on rear panel; mating plug JP0035 Output Voltage: 1 V RMS 2% at full-

15、scale deflection Max. Output: 5,6 V peak Output Impedance: 100f! Minim um Load: Resistanc e 10k f!; Capaci- tance 200pF DC OUTPUT: Via 7-pin DIN socket on rear panel; mating plug JP0703 Output Voltage: 1 V DC 2% at full-scale deflection Max. Output: 5,6 V Output Resis tance : 1 O fl Minim um Load :

16、1 kf! ENVIRONMENTAL LIMITS : Tempe ratur e Rang e: +5C to +40C (41 F to 114F) the Peak decay time can be modified. For every 2,5 F of capacitance con- nected to the Ext. Time Constant con- nector, the RMS averaging time and the Peak decay time are increased by 10 s. The Peak decay time can also be m

17、odified by adding a resistor to the Ext. Time Constant connector. 2?- V DC lffV I -r- a 11- h T .,.c:.n-, 1. II? 1 -3! V DC 81tv 1 - Fig. 2. Rear panel of the Type 2425 Humidity: Up to 90% RH non-condensing at 30c External Magnetic Field: Up to 80A/m at 50Hz MAINS POWER SUPPLY: 100; 115; 127; 200; 2

18、20; 240V AC, 50-60Hz, 9VA Complies with Safety Class I of IEC Publica- tion 348 BATTERY POWER SUPPLY: External batt ery connections to rear panel DIN socket; requi res 2 batteri es. 22 V to 35 V each DIMENSIONS : Metal cabinet. exclu ding connectors and feet Height: 133 mm (5,2 ins) Wid th: 140mm (5

19、,5 ins) Depth: 200mm (7,9 ins) WEIGHT: 2, 1 kg (4,63 lb) ACCESSORIES INCLUDED: Mains Cable . . AN 001 O BNC Plugs (2) . . JP 0035 7-pln DIN plug . JP0 703 Fuses T100 mA (3) . VF 0026 Fuses T63 mA (2) . VF 0047 Scale Lamps (2) . VS 1273 ACCESSORIES AVAILABLE: Meter Scale, dBm . SA0163 Meter Scale, vu . SA0168 BNC-BNC Cables . A00087, A00 135 RadioFans.CN 收音机爱 好者资料库 RadioFans.CN 收音机爱 好者资料库