Tektronix 475A Oscilloscope and DM44 digital multimeter

Tektronix 475A oscilloscope with digital multi meter DM44

Die Spezifikation des Tektronix 475A ist ähnlich zu dem 475 Oszilloskop, die vereinfachte Spezifikation ist dort beschreiben, das 475A ist dem 475 ähnlich. Das DM 44 hat eine sieben Segment Anzeige mit 3 1/2 Stellen und einem Vorzeichenindikator und zwei Leuchtdioden zur Anzeige in ms oder µs. Das DM 44 hat fünf Meßfunktionen: Spannung, Widerstand, Temperatur, Zeit und 1/Zeit. Das DM 44 kann in der Röhre zwei kontrastreiche verstellbare Marker einblenden, das Gerät mißt die Zeitdifferenz, Frequenz, Periode, Phasenverschiebung, Anstiegszeiten mögliche Anwendungen. Auf der linken Seite befinden sich zwei Bananenbuchsen für die Spannungs und Widerstandsmessung. Ebenso befindet sich dort der Anschluß für den Temperatur Tastkopf.

The specification of the Tektronix 475A oscilloscope is similar to the 475 oscilloscope. The  DM44 uses a 3 1/2 digit LED Dispaly with five seven segmet arrays. It can measure in on of these modes: voltage, resistance, temperature or 1/TIME and TIME (in ms or µs and 1/ms or 1/µs indicated by two LED). The instrument can measure time by using two moveable intensified horizontal zones within the CRT. For example measures delay sweep time, rise time, frequency, period and phase shift. On the left side of the DM44 there are two banana jacks and a temperature probe tip connector.

DM44 simplified specification

• DC Voltage Ranges 0 to 1.2 kV in 5 steps from 200 mV, 2 V, 20 V, 200 V and 1200 V

• Resolution 100 µV

• Accuracy within 0.1% of reading, +/-1 count

• Input Resistance 10 megohm, all ranges (user option, remove an internal wire strap to increase input resistance to 1 Gohm on the 200 mV and 2 V range.

• Rejection Ratio Normal Mode, at least 60 bD at 50 and 60 Hz

• Rejection Ratio Common Mode, at least 100 dB at DC and 80 dB at 50 and 60 Hz

• Recycle Time approximately 3.3 measurements per second

• Temperature Dependence 45 ppm/°C

• Maximum Safe Input Voltage +/-1200 V (DC + peak AC) between + and COM inputs or between + input and chassis

• COM (Common) Floating +/-500 V (Dc + peak AC) to chassis

• Resistance Ranges 0 to 20 megohm in six steps 200, 2k, 20k, 200k, 2M and 20 M

• Resolution 0.1 Ohms

• Accuracy 200 and 2k ranges within 0.25% +/-1 count, + probe resistance, other ranges similar up to 0.3%

• Recycle time approximately 3.3 measurements per second

• Response Time 200 through 200k Ranges within 1s

• Response Time 2M and 20M Ranges within 5s

• Maximum Safe Input Voltage 120 Vrms between + and COM inputs for an indefinite time

• Approximate current supplied to unknown resistance 200 and 2k 1mA, 20k 100µA, 200k 10µA, 2M 1µA and 20M 100nA

• Temperature (using a temperature probe) range -55°C to +150°C.

• if the probe is calibrated to the DM44, accuracy +/-2°C (if the probe tip has a temperatue of -55°C to +150°C and DM44 ambient temperature  +15°C to +35°C valid for constant temperature and infinite heat source ). The used probe should be calibrated with the instrument resulsts otherwise in a bad accuracy.