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Figure 8. Typical high-frequency response characteristics of the probe and tee connector operating in a 50-ohm system.

O 500 IOOO 1500

O 500 IOOO 1500

Figure 8. Typical high-frequency response characteristics of the probe and tee connector operating in a 50-ohm system.

Because of the high accuracy of the meter, the dc amplifier, and the ohm-meter circuit, we have conservatively rated the accuracy of the ohmmeter as ±5% of indicated resistance value, from 1 to 10 on the scale, decreasing to ± 10% at 100 on the scale. For comparison of two resistances of approximately the same value, much smaller percentage differences can be observed. The wide range, absence of full-scale adjustment, and zero stability of this ohmmeter make it an extremely useful addition to the voltmeter.

External Description

The Type 1806-A Electronic Voltmeter is shown in Figure 1. This instrument is mounted in the by-now familiar Flip-Tilt case pioneered by General Radio. This case permits the instrument to be tilted so that the meter can be read without parallax from almost any angle. Figure 9 shows several possible attitudes for this voltmeter and illustrates the wide latitude that one has in

Figure 9. Various methods of placing the Flip-Tilt case for convenience in reading the meter.

Figure 10. View of the Type 1806-AR Electronic Voltmeter for relay-rack mounting.

Figure II. The Type I8O6-A Electronic Voltmeter with cover closed and the power cord around the rubber feet for storage or transporting.

readability. The probe is visible in Figure 1, and at the lower right-hand corner of the panel is the storage socket for it. The probe cable can be stored in an internal reel and pulled out or pushed in as necessary. When the cover is closed, the power cord, which is permanently attached, can be wrapped around the large rubber feet, as shown in Figure 11.

Another unusual convenience feature of this voltmeter is that the range-selector switch turns in the same direction as the desired motion of the pointer on the meter. This is most easily seen on the ohmmeter, where, if the pointer is near zero, the range knob should be turned clockwise to bring the pointer clockwise, nearer to center scale. Similarly, on voltage measurements, if the pointer is off scale, the range knob should be turned counterclockwise to bring the pointer counterclockwise until it is again on scale.

This new design embodies several important advances: in performance, increased accuracy, wider ranges, and greatly improved stability; in convenience, the Flip-Tilt case, the ten-to-one range switching, the new small probe with storage provision, and the large meter.

These features combine to produce unusual simplicity of operation and accuracy of measurement.

setting it up for convenience and accuracy in reading.

The Type 180G-AR Electronic Voltmeter is shown in Figure 10. This instrument contains the same electrical circuits as the Type 1806-A, but is mounted in a cabinet designed especially for relay-rack mounting.

In these photographs the large, easy-to-read meter is clearly visible. The arc length of the outer scale is 6 inches, which contributes considerably to the

Figure II. The Type I8O6-A Electronic Voltmeter with cover closed and the power cord around the rubber feet for storage or transporting.

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