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And various other laboratory procedures require the use of an amplifier to obtain sufficient sensitivity. The Type 814-A Amplifier has for years been a popular item in the General Radio line and has been widely used with audio-frequency bridges. Recent developments in tubes and circuits have prompted the design of a new model, retaining all the advantages of the old, but with several distinct improvements. The Type 1231-A Amplifier and Null Detector consists of a high-gain resistance-coupled...

Va Riac

Intermediate between the old Type 200-CM (left) and the Type 100-A (right), the new Type V-10 Variac is rated at 10 amperes for 115-volt input. THERE HAS BEEN an awkward gap between Type 200-C and Type 100 Variacs ever since the latter's introduction. Loads but slightly exceeding 200-C capacities called for the much larger and more costly Type 100 size. V-10 Series Variacs neatly plug this gap, with ratings just double those of the new V-5 or old 200-C Variacs. The 115-volt V-10's are...

Specifications

Note Models are designated by type number. The basic VARIACS, V-5 (for 115-volt input) and V-5H (for 230-volt input), are supplied with terminal strip, but without case, terminal box, switch, convenience outlet, and cord. Models V-5M and V-5HM include the case. Models V-5 MT and V-5HMT are complete mounted models with case, terminal box, switch, cord, and outlet. Dials Dials are engraved for overvoltage connection (135 or 270 volts maximum). Special dials are available for 115- and 230-volt...

The Constant Waveform Frequency Meter

IN THE COMMUNICATIONS INDUSTRY there has been a steadily growing demand for direct-reading frequency-meters. Various counting type circuits utilizing thyratrons, multivibrators, etc. have been designed to provide direct frequency indications on a meter scale. General Radio Type 834-A Frequency Meter, 1'or instance, which has been a very popular instrument, is of the thyratron type. The range of this instrument, however, extends only up to 5 kilocycles which, for many applications, is...

Acknowledgment

DURING THE WAR the load on the American industrial machine was enormous but it didn't break down it delivered about what was expected of it. In our own small corner of industry we were no exception. The requirements of our Armed Services and of our Allies for our regular catalog products grew beyond anything that had ever been estimated, and kept right on growing. On top of this we were called upon to produce to government specifications large numbers of complicated and still classified...

For

Lead Corrections for the Radio-Frequency Bridge 6 PROGRESS IN AN engineering field depends to a considerable degree upon the development of measuring instruments. As the field is extended through laboratory research, instruments are' 'tailor-made for each project, but later commercial development usually brings with it simple, general-purpose direct-reading instruments. Initially of only moderate accuracy, they eventually are developed to an accuracy comparable with that achieved in older...

With Gr Instruments

Not only measurable but extremely accurate. The generators in use in their Figtjhe 1. In the screen room of American Airlines radio-overhaul shop, automatic direction finders are mounted on a revolving test stand and checked against a General Radio Type 805-B Standard-Signal Generator. Here lead mechanic Gerard Miller tests the set with a Type 726-A Vacuum-Tube Voltmeter. Figtjhe 1. In the screen room of American Airlines radio-overhaul shop, automatic direction finders are mounted on a...

Panel And Cabinet

As shown in Figure 1, the meter, mounted in the center of the panel, carries only the basic range of 0 to 1.0 volt. The two main controls, which are the on-off switch and the zero set, are operated by the knobs below and on either side of the meter. The shielded walnut cabinet is of the same construction as that for the Type 1800-A Vacuum-Tube Voltmeter with the storage compartment at the top for the probe and the various fittings supplied. The handle can be locked in either the position...

Multiplier

Bridge Maxwell Construction

Schematic wiring diagram of Type 1631-A Inductance Bridge. Figure 4. Schematic wiring diagram of Type 1631-A Inductance Bridge. 45. With the multiplier initially set for the appropriate range, a bridge balance is easily attained by a joint manipulation of the henrys and Q dials. A balance of this Maxwell bridge is indicated by the two simultaneous equations wherein Ci is the standard capacitor, Ri the resistance small rheostat in parallel with Ci, R2 is the large rheostat and R3 is...

R F Circuit

Butterfly Resonator

Since simplicity was a prime factor in the design of the instrument, a very elementary r-f circuit was chosen. Basically it consisted of a plate-modulated oscillator whose output was fed to an output connector or an antenna through a coaxial cable. The coupling between cable and oscillator was accomplished by means of a rotatable loop which served as the output control. In the frequency range covered by the instrument, a butterfly circuit1.2,3 has several characteristics which make it a logical...

New Vacuumtube Voltmeter

THE TYPE of peak-reading vacuam-t ill gt c voltmeter now considered standard in the communications industry was first introduced by the General Radio Company some ten years ago when the Type 726-A Vacuum-Tube Voltmeter was announced.1 The novel design and excellent performance of this voltmeter has maintained its popularity over the intervening years considerably beyond the time when advances in the art would normally necessitate a new design. The development, during this period, of new tubes,...

In This Issue

Those Iron - Cored Coils Again 2 THE TYPE 654-A Voltage Divider, always a useful laboratory device, was discontinued during the war in order to concentrate production facilities on more urgently needed items. We have had a number of requests for this item and are glad to announce that it is again available from stock. As shown in the accompanying photograph, this voltage divider has three dials, giving division factors of 0.1, 0.01, and 0.001, respectively. Voltage ratios between 0.001 and...

Type A Power Supply

An a-c operated power supply for instruments which use the Signal Corps BA48 Figure 1. View of the Type 1261-A Power Supply. Figure 1. View of the Type 1261-A Power Supply. measuring instrument is necessary if the instrument is to be truly portable and easily used in any location. Many instruments designed primarily for portable use can be and are used in production test set-ups where they are in continuous use. A-c operation for such instruments would eliminate the need for frequent battery...

Popular

General Radio Microphone Hummer

Been the Type 6S0 Impedance Bridge witness a sale of over 3700 of these instruments to date. By means of this bridge resistors, inductors and capacitors can be measured rapidly and conveniently over a wide range of values. Oil many occasions, the need arises for using an auxiliary audio amplifier to increase the sensitivity of bridge balance when employing either headphones or an a-c galvanometer as the null detector. For this purpose General Radio has successively offered the Type 514 and Type...

Test Oscillator

Order to attain maximum performance from the receivers, it was found desirable to test them frequently under actual operating conditions, as installed in a ship or aircraft. Since it was usually impractical to transport bulky test equipment to the operating site, the test instrument had to be a single small unit, simple to use and capable of operating from a wide variety of power sources. The unit developed by General Radio to fulfill this requirement was later manufactured by the Fairchild...

Specifications For Type A Inductance Bridge

Inductance Range, 10 th to 100 h in 3 steps, 10 xh to 10,000 Mh 0.01 h to 1 h and 1 h to 100 h. Accuracy 2.5 of dial reading between 100 th and 10 h. Below 100 uh the error varies inversely as the magnitude of the unknown. Above 10 h the error increases to 10 dial reading at 100 h. Dial Calibration Approximately logarithmic uniform fractional accuracy over two main decades, with a compressed lower decade which is used onlv for measurements below 100 xh. Q Range, 1 to 45. Accuracy, 10 of dial...

Permeability And Frequency

One of the more significant improvements has to do with the method of securing empirically the information needed for a particular lamination structure. This needed information consists of the maximum storage factor Q of a full coil wound on the lamination structure, the frequency at which it occurs, and the law of variation of inductance with center-leg air gap. If reference be made to page 9 in the Appendix portion of the March, 1942, article, it will be seen that for a given structure Dc...

Al

General Radio 200cm Wiring

At the right is shown the new Type V-5MT, Figure 1. The old and the new. At the right is shown the new Type V-5MT, Figure 2. The new General Radio unit brush . . . can be changed without tools. Figure 2. The new General Radio unit brush . . . can be changed without tools. which can be changed Figure 2 without tools. The V-5 Brush has a further advantage in that its low sprung weight reduces hammering and arcing under vibration conditions, injurious to both brush...