marconi893b-data 电路图.pdf

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1、AF Power Meter :J Ten power ranges: 300 W to 10 W Juli scale 0 Frequency range: 20 Hz to 35 kHz 0 Impedance: 2.5 0 to 20 ko in 48 steps AF Power Meter 8938 covers the wide power range ot 300 W to 10 W tull scale in ten ranges, and operates over the trequency range ot 20 Hz to 35 kHz. Power delivered

2、 by the source info a load provided by the power meter is measured by a temperature-compen- sated multi-range detector circuit teeding a voltmeter. Ten power range push-buttons are marked in voltage and in dBm, and the meter is calibrated with voltage scales marked tram 0 to 3 and tram 1 to 10, prov

3、iding good resolution, and also with a dBm scale. The required input impedance is obtained by means ot a tapped transtormer and switched resistive matching pads, providing 48 impedances between 2.5 0 and 20 kO. Unbalanced inputs are provided by connecting across the two input terminals, and balanced

4、 inputs by connecting the centre tap ot the source to the CT terminal. 8938 Model 50693-321J with SINAD lilter 147155 Balanced or unbalanced inputs Direct calibration in watts and dBm Version available with SINAD filter p Impedance of one Quarter of the marked value (i.e. down to 0.625 0) can be obt

5、ained by connecting the source between one input terminal and the CT terminal. I mpedance is selected by means of two controls with colour coded panel markings. a six position IMPEDANCE 5ElECTOR and an eight-position IMPEDANCE RANGE MULTIPLIER. A 51NAD version of the power meter incorporates a switc

6、hable 1 kHz filter for making signal-to-noise measurements by comparison of two power level readings. An initial reading is taken with the filter switched out and a second reading with it switched in to remove the 1 kHz fundamental. The difference between readings on the dem scale gives the 51 NAD r

7、atio. The standard version of 8938 can be converted for 51NAD measurement by fitting a filter kit which is available as an optional accessory. RadioFans.CN 收音机爱 好者资料库 With compliments.doc With compliments Helmut Singer Elektronik www.helmut-singer.de infohelmut-singer.de fon +49 241 155 315 fax +49

8、241 152 066 Feldchen 16-24 D-52070 Aachen Germany 8938 MODEL 5O893-920M RANGE Power Ten power ringes wilh tull sclle defleclions trom 300 W to 10 W in I 1-3-1 0 S8quence Decibel ranges are provided wilh a 0 dB reference 111 mW. 48 impedlnce settings bat_an 2.5 CI and 20 ko, with an impedance seleclo

9、r of 2,5, 3. 4. 5. 6. 8. 6,25, 75,10,125,15,20 end with muhiplters X1, X10. X100, X1000. Impedances of one quInar of the above settings (extending the range down to 0.625 CI) may be obtained using the inpul cenlre IIp. bul II reduced Iccuracy. The Impedlnce of Ihe power meier falls when il is connec

10、led InlO 1 circuil Clrrying d.c. AI 50 Hz a drop of approximalely 5% IS produced by 60 mA d.c. al Ihe 100 CI settIng, and by 4 mA ellhe 20 k CI setting Impedance ACCURACY Power%7% of f.a.d. ,10 W.from 100 Hz 1010 kHz .nd from 5 to 35.C. Impedance :7% 811 kMz. FREOUENCY CHARACTERISTICS TERMINALS Powe

11、r level is leIS then 3 dB down (typically 0-7 dB down) et 20 kHz relative to level at 1 kHz. Power level IS less than 1 dB down at 50 Hz relltive to 1 kHz level. The instrument cln be uNd OVef the extended freQuency renge 20 Hz to 35 kHz with reducedeccurecy. The high and low terminals are isolated

12、tram the case earth A separate termInal is provided tor IInklng to the case. The terminals will accept: Bare wires. Crocodile clips. 4 mm plugs (and pln type AVO le). Spade type AVO leads Complles wilh IEC 348. SAFETY LIMIT RANGE OF OPERATION O 10 55OC. Temperature CONDITIONS OF STORAGE AND TRANSPOR

13、T -40to .70.C. Up 10 90% relative humidilY. Up 10 2500 m (pressurized Ireight at 27 kPI differential, je 3,9 Ibl/in). Temper8ture Humidity Altitude DIMENSIONS AND WEIGHT MODEL 50893-321J Depth Weight 338 mm 4 kg 13-3 in 8-8 Ib Width 246 mm 97 in Height 153 mm 6 in The specification tor thls model IS

14、 the same 15 thlt giyen .boye with the t: following additions 1: SINAD FILTER Centre frequency 1 kHz with the SINAD FILTER switch in. Rejection at 1 kHz At least 20 dB It 1 W inPut power. At least 30 dB at 300 mW or less. input power. 3 dB b.ndwidth Not greater than 480 Hz. 20 dB bandwidth At least

15、1SO Hz. Power Maximum total input power with SINAD fiher in circuit is 1 W. VERSIONS AND ACCESSORIES When ordering ple.se quote eighr-digit code numbers Ordering numbers Versions 50893-920M AF Power Meter 8936. 50893-321J AF Power MeIer 8936 wlth SINAD filler. 5O893.0.322F AF Power MeIer 8938. NATO version. CI1. No. 6625-99-541-2891. applied ACC80ri. Instruction Manual 46881-349G. Option. Accessories 54499-041 N SINAD Filter Klt 10 convert model 50893-920MtomodeI50893-321J. 54124-G23J Stowage Cover Assembly. RadioFans.CN 收音机爱 好者资料库