New Features

One of the truly basic laboratory instruments, along with the voltmeter and the oscilloscope, is the impedance bridge. Although there is a great variety of impedance bridges, by far the nost popular is the general-purpose type that combines several bridges in one package to permit quick, convenient, reasonably accurate measurements of resistors, capacitors, and inductors. The grandfather of this class of instrument was GR's Type 650 Impedance Bridge, succeeded about a decade ago by the 1650....

Pulser

this the best buy of the pulse generators. in fields from high-speed circuit testing to seismological research. A single pulse for one-shot tests can be triggered manually from a front-panel pushbutton. The 1340 also offers eight decades of pulse-duration times, from 25 nanoseconds to 2.5 seconds. The maximum duty ratio that can be attained varies from 70 to over 95 percent, depending on the combination of repetition-rate range and duration-time range that is in use. In case of an inadvertent...

C

All controls except one gain adjustment are on the front panel. Input and output connections may he made at the rear panel as well as at the front. The jacks for the external filter are at the rear only. Coaxial attenuator controls are designed to prevent overload of the input amplifier stage under all conditions. The relay-rack instrument is ac-powered, but rechargeable batteries can be installed if desired. The primary use for the precision sound-level meter is the measurement of...

TO MHz

The instrument shown in Figure 1 is the 1191-Z 500-MHz Counter, a combination of the already-popular 1 191 Counter and the new 1 157 Scaler. The present article discusses the scaler, an instrument that performs a relatively simple task it accepts an input signal with a frequency up to 500 MHz and provides an output square wave whose frequency is exactly 100 times lower. The 1157, like its companion, the 1156-A Decade Scaler1, is usable alone for any application where precise frequency division...

Receiver For Precise Time Calibrations

A common method of establishing accurate local time is to drive a local clock with a frequency standard, checking the absolute accuracy regularly against standard time signals broadcast by various agencies throughout the world. An elegant variation of this technique involves the use of primary time standards flown to the local site for periodic calibrations. The flying-clock method, though obviously expensive, offers the greater accuracy, since it eliminates the uncertainties of radio...

Highb

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Transistor Measurements With The B

As mentioned in the May Experimenter, the new Type 1650-B Impedance Bridge is useful not only for routine measurements on passive components but also for measurements of transistor A-parameters. The special test jig required for such measurements, as wrell as the procedure, is described below. The -parameters are defined in Figure 1, and the calculations that indicate how to obtain the four-terminal parameters h fe and hre from two-terminal measurements appear in Figure 2. Some thought about...

Widerange Rc Oscillator With Inline Digital Frequency Readout

Central to the popularity of the general-purpose RC oscillator is its continuously adjustable frequency dial. In fact, the RC oscillator did not become popular imtil variable air capacitors were used to provide continuous adjustment over 10 1 frequency bands. This method of frequency selection, with dial and vernier, provides a convenient compromise between ease of reading, settability, resolution, and ability to sweep. It will no doubt continue to be most popular for general laboratory use. As...

New Gr Attenuator Air Lines

The usefulness of any connector type depends to a large extent on the number of different things it can connect to, either directly or through adaptors. In this respect, the G11900 precision coaxial connector measures up very well. General Radio alone catalogs over fifty GR900 components, and the basic GR900 connector is used on many devices made and sold by other manufacturers. A full line of GR900 adaptors provides access to all other popular coaxial connectors. The latest additions to the...

Popular Uhf Oscillator Now Lockable

The Gil 1218 Oscillator has long been valued in many laboratories for its high output power and its spectral purity. Now, the 1218-BV lockable model means that frequency stability too can be achieved by use of a feedback control loop and reference-frequency source. The oscillator can be phase locked to a stable reference of the same frequency or to a harmonic of the reference signal. Absolute stability of the 1218-BV may be less important than the stability of a difference frequency. In...

Component

GR's Type 1680 Automatic Capacitance Bridge and a digital computer are natural companions, frequently used in combination to perform measurement tasks that would have been unthinkable a few years ago. As an impressive example, take the CATE Computer-controlled and Automated Test Equipment system used by The Plessey Co.'s Product Assessment Laboratories at Titchfield, England. The complete system, shown on the cover, is designed primarily to support reliability trials on thin-film components,...

An Exercise In Voltage Division

Voltage ratio, being dimensionless, has no legal unit and no national standard. While resistance, mass, voltage, etc are all defined in terms of standards kept by national laboratories, anyone can make ratio measurements and claim any accuracy he feels his equipment and technique have given him. Whether or not anyone will believe him is, of course, another matter. The GR 1493 Precision Decade Transformer can easily be read to one part-per-billion ppb of input. At reasonable frequencies and...

Precision Soundlevel Meter

General Radio Sound Meter

Recognizing that it is unrealistic to expect one sound-level meter to be all things to all people, we have for the past two years offered two models the 1551-C1 and the compact, less-expensive 15652, both of which meet the USA standard Si.4-1901 for general-purpose sound-level meters. The variety of demands on these instruments and the trend toward more precise measurements in some research work suggested a need for a third member of the family, with even higher performance. Thus the new Type...

Unique Dc Voltmeter

Nanoammeter Circuit

Among the instruments that can he classified as basic or essential to any electrical or electronics laboratory or production test facility is the dc voltmeter. Yet, with the state of the art in the electronic industry demanding increasingly specialized instruments, it is difficult to find one basic voltmeter to meet the needs of even several projects in a given research and development center. General Radio's new Typk 1807 DC Microvoltmeter Nanoammeter was designed to fill this versatility gap....

Redesigned Toneburst Generator Has Customersuggested Features

Increased suppression of signal during off period Timed or counted intervals may be selected independently for both on and off periods When the Type 139G-A Tone-Burst Generator was first introduced early in 1964 it promptly created a name for itself in sonar, audio, acoustics, psychoacousties, electroacoustics, and other fields where the measurement of ac transient response to bursts of coherent sine waves is a powerful testing technique.1 The considerable number of unforeseen uses to which the...

Versatile Level Regulator For Sweptfrequency Sound And Vibration Testing

Swept-frcquency sound and vibration tests can be made more quickly and simply if a control device is used to keep the test signal at a constant level as frequency is varied. With the exceptions of some rather expensive special-purpose instruments, no such control unit has been commercially available, and many people have been forced to build their own, often with only limited success. The new Type 1569 Automatic Level Regulator is such a control unit, designed for use in sound or vibration test...

Winner Of Grs Think Sync Contest

Genrad Model 1925 Multifilter

GR District Manager Frank Thoma left and Sales Engineer Dave McGreenery right present 1312 Decade Oscillator to Dr. Armstrong. GR District Manager Frank Thoma left and Sales Engineer Dave McGreenery right present 1312 Decade Oscillator to Dr. Armstrong. At the New York IEEE Show this year, General Radio announced a technical contest to discover novel applications of the synchronizing capability of GR's low-frequency oscilla tor line. The prize was choice of any of the five syneable oscillators....

More Coaxial Capacitance Standards

The Tvpe 1400 two-terminal capacitance standard1 has been joined by two new series the lower-valued Type 1405 and the higher-valued Type 1407. Altogether, the range of values for two-terminal capacitance standards using precision coaxial connectors now extends from 1 pF to 04 zF. In the 1405 and 1407 standards, as in the 140 5, the combination of the GR900 precision coaxial connector and careful capacitor design and fabrication results in significantly improved performance up into the rf range....

Digital Multimeter With dB Readout

Ramp Type Dvm Block Diagrams

Voltage and frequency range of the 1820 DVM with each of its plug-ins. one then need only select a unit out of this group to meet his other requirements. Digital voltmeters are also becoming increasingly useful in the field of ac measurements. Here, however, the choice is more difficult, because many of the features that one would normally seek in an ac meter have, until now, not been available in a digital instrument. General Radio has addressed its first, digital voltmeter, the Type...

Randomnoise Generators

The uses of laboratory random-noise generators have multiplied rapidly since the introduction of the first commercially available model some years ago. At first they were principally used in laboratory studies of methods of overcoming the effects of noise in communications systems the random-noise generator was a controlled source of noise disturbance for such tests. Now, however, random noise has come into its own, and in many applications it has become the test signal. It is useful in...

Specifications

610 tt to 25 k with int battery removed Input impedance varies as shown in table with setting of input level control. Can be adjusted to remain constant when varying the step attenuator for load impedance of gt 50 li. Internal battery or ext dc source 10 V max 0.04 dB step 151 dB below input level dc to 100 kHz Distortion at 1 kHz lt 0.01 in 1-V-ac mode, lt 0.05 in 10-V-ac mode, with level control at max setting. Output Impedance BOOfi 0.5 . Power Required None required for 10-V-ac range. In...

I

Cos Ox s H H K 2 Zaj 2 Z, If Zx and Z are unequal but the difference is small and x 3 is less than 0.1 radian, this expression reduces to If relatively pure elements are used C, with D less than 0.1 R, with Q less than 0.1 L, with Q greater than 10 , then x s AD of C and L, or AQ of R. The bridge circuit for the AR, AL, or AC mode is shown in Figure 4. The unbalance bridge voltage is Figure 3. Basic bridge circuit in the AO mode. If feedback from the output to the bridge is such that k 1, then...

Dclevel Control For The Pulse Generator

A new accessory can be used to control the dc level of the output pulse of a 1398-A Pulse Generator. The controlled parameter may be average, positive peak, or negative peak, and control is independent of duty ratio and prf. Time constant of the regulating circuit can be selected according to outpu t-p ulse d u ration. The 1398-P1 DC Component Control attaches to the side of, and derives power from, the pulse generator. 1422-CE, with standard calibration 1422-CEP, with precision calibration...

M

Recording showing gain stability with line-voltage changes, as measured on a production The bolometer is often preferred over the crystal detector for accurate measurements. The signal level must be at least five times the residual noise level for an error of O.l dB or less. The power level required to produce such a meter deflection has been measured on a typical instrument to be 52 dBm peak, with a 100 -modulated signal. The high limit for a 0.1-dB error is generally about 0 dBm....

New Members Of The Variac Family Of Adjustable Autotransformers

The W8MT3 and its metered companion, the W8MT3VM, provide the most volt-amperes per dollar of any Variac model, many convenience features, plus the new General Radio light look. The W8MT3 and W8MT3VM are cased units that include a power cord and plug, an on-olT switch that switches both sides of the input line, a dual receptacle for connection of a multiple load, a manual-reset overload protector, and a carrying handle. The W8MT3VM has a 0-to-150-volt meter that indicates output voltage of the...

Ujjj Jujui

5 General Radio Instrument Note in-10 Principles and Applications of Oscillator Synchronization. Figure 9. A low 3Vs-inch rock panel height, rear panel connections, and an easy-to-read frequency indication make the 1312 ideal for systems. Verification of correct operating frequency takes but a glance. Xer function, - , is real and at maximum at a frequency The values of capacitance C are switched in decade steps by means of the dimensional-units switch to obtain the five ranges of the...