Frequency In Cycles Per Second

The conseriser microphone system is furnished in a compact leather carrying case of top-grain cowhide. Figure 4. The conseriser microphone system is furnished in a compact leather carrying case of top-grain cowhide. base and sound-level meter without cable correction. Figure 3 is an elementary schematic diagram of the system. As is indicated, no external grid-leak is used to determine the bias for the preamplifier. The insulating material supporting the back plate structure of the...

In This Issue

Portable Test Atjto-transformers 6 Type 561-D Vacuum-Tube Bridge has been used mainly for measuring vacuum-tube coefficients, it has also proved useful for determining the characteristics of more complex circuit arrangements under different load conditions.1 The advent of the transistor emphasizes the versatility of this bridge. Low-frequency coefficients are as easily determined for transistors as for vacuum tubes.2 The bridge indicates the input and output resistance of transistors, their...

Measurements On Ohm Lines With The Admittance Meter

In many television receiving systems, 72- or 75-ohm transmission lines are used. The impedance or VSWR of the line can be easily measured, using either the old or new model of the Admittance Meter. Means must be devised, however, for connecting the 75-ohm line to the Admittance Meter, which is equipped with 50-ohm connectors. One solution to this problem is to fit the 75-ohm line with a General Radio Type 874 Connector. Type 874-C8 Cable Connectors are suitable for use with RG 11 U Cable and...

Laboratory Amplifier For Audio And Ultrasonic Frequencies

The Type 1206-B Unit Amplifier, newest member of the General Radio family of Unit Instruments,1 is a high-quality amplifier, designed for general laboratory use. Its maximum output power of 3 watts is adequate for driving low-power transducers, and its wide frequency range (up to 250 kc) makes it useful as an amplifier for the output of such oscillators as the Type 1301-A and the Type 1302-A or for pulses with rise times as short as one microsecond. In conjunction with a pair of earphones, it...

Very Quiet

The analysis obtained from the charts of Figure 3 is only a partial step in providing the information required for a solution, but it usually gives a better idea of the magnitude of the problem than one can obtain from a single sound-level reading. In addition, subsequent measurements and analyses can be more adequately planned after the preliminary survey has been made. In order to interpret the band levels given by this partial analysis, it is usually helpful to convert...

Visitors From

The recent annual convention of the Institute of Radio Engineers afforded a welcome opportunity to greet many of our friends from overseas. Among those visiting our plant after the convention were Mr. Marius Berlin, of Radiophon, Paris, exclusive distributors for General Radio products in France and the French colonies Mr. John C. Lager-crantz, of Stockholm, exclusive distributor for Sweden and Mr. Harnam V. Montwane, of Eastern Electric and Engineering Co., Bombay, exclusive distributors for...

Index By Instrument Type Number

Smiley May, 1953) Type V-201IM Variac Portable Test Autotransforrners (R. F. Bennington March, 1953) Type 200-B Variac. A New 2-Ampere Variac (G. Smiley May, 1953) Type 214 Rheostats Why Rheostat Burnouts (P. K. McElroy August, 1951) Standardized Terminals and Connectors (Part T) (H. C. Littlejohn June, 1952) Standardized Terminals and Connectors (Part II) (H. C. Littlejohn July, 1952) Type 56I-D Vacuum-Tube Bridge The Vacuum-Tube Bridge and Its Accessories (A. G....

Air Currents Made Visible

This interesting Strobolume photograph comes to us through the courtesy of Prof. F. N. M. Brown, Head of the Department of Aeronautical Engineer ing at the University of Notre Dame, and was taken in the wind tunnel at that institution. The propeller left is one foot in diameter and is turning at 4080 rpm. The air speed is about 45 feet per second, design advance for the model propeller. The smoke that makes the air currents visible is produced by burning wheat straw under a slight pressure, but...

For The Admittance Meter

A complete instruction manual for the Type 1602-A U-H-F Admittance Meter is now available. Copies have been sent to all who returned the cards that were enclosed with admittance meters already shipped. If you are using the admittance meter and have not yet received a copy of the instruction book, please request it on your company letterhead. rpHE General Radio EXPERIMENTER is mailed without charge each month to engineers, scientists, technicians, and others interest etl in...

The Measurement Of Cable Characteristics

Coaxial cables play an important role in today's electronic world. They are vital elements in television circuits, radar, blind landing devices, and practi cally every other electronic device employing high frequencies. The electrical characteristics of the cables used in these applications must meet very rigid specifications1 and the problem of accurately measuring the characteristics is important to the cable designer to enable him to check his designs, to the cable manufacturer to inspect...

Holes

TO REMOVE SHAFT LOOSEN SCREWS IN RADIATOR AND COLLAR. WHEN RE-ASSEMBUNG BE SURE RADIATOR IS PUSHED TOWARD COIL. SET SCREWS REQUIRE ALLEN WRENCH 3 32 ACROSS FLATS. requiring a long cable between microphone and sound-level meter. There are also many measurements where a wide frequency range is essential. For example, when response measurements are to be made over the full range of high-fidelity loud-speaker systems, the measurement microphone must be usable from 20 to about 15,000 cycles per...

S P Ec I Fi

Frequency Response Useful range of the Type 1551-A Sound-Level Meter with Type 1551-P1 Condenser Microphone System is 20 cycles to 15 kilocycles. Typical frequency response curves are shown in Figure 2. Sensitivity Open circuit output of typical microphone and preamplifier is 48 db below one volt per microbar. This sensitivity is about 10 db greater than the crystal microphone supplied with the sound-level meter. When the levels of the sound components exceed 60 db re 0.0002 Mbar , the...

Electrolytic Capacitor Testing At Cycles

Capacitor Testing Bridge Schematic

Current 11ETMA standards call for the measurement of electrolytic capacitors at 120 cycles. As a result, a number of our customers have requested modification of the Type 1611-A Capacitance Test Bridge to permit measurements at this frequency. The inclusion of a 120-cycle source for use over the entire capacitance range of this bridge would require substantial and expensive alterations. Relatively minor and inexpensive changes, however, make possible the use of an ex- ternal 120-cycle source...

This Issue

Measurements on Transformer Oil . 5 Simple Harmonic Kiluaril Karplus, V-H-F and U-H-F Unit Oscillators, General Hudiu Experimenter, Vol. XXIV, No. 12, page 7, May, 19.50. Figure 1. View of the Type 1215-A Unit Oscillator. Two models have hitherto been available, the Type 1209-A, which has a frequency range of 250 to 920 megacycles, thus including all u-h-f television channels, and the Type 1208-A, 65 to 500 megacycles. A new model, Type 1215-A, which will be available for sale next month,...

A M Pl If Er

Elementary schematic circuit diagram of the distortion and noise meter. Figure 4. Elementary schematic circuit diagram of the distortion and noise meter. would develop, at best, almost .5 distortion at rated output. Examination of the distortion by-products by visual analysis, however, indicated that something was wrong to achieve minimum distortion required an abnormal, seriously unbalanced bias in the push-pull stage. Upon further investigation, a circuit error was located and...

Connector

Cross section of the Type 874-QV2A Adaptor to 5T.5 ohm, 134-inch rigid line. between this type of line and General Radio Type 874 Connectors. A tapered section of line is again used for the transition element. However, since the Type 874 line has a 50.0-ohm characteristic impedance and the VHF line has a 51.5-ohm characteristic impedance, a small reflection is produced at the junction. In the adaptor, the change in characteristic impedance is made directly behind the polystyrene...

New Instruction Manual For Slotted Line

General Radio Company Slotted Line

Users of the Type 874-LB Slotted Line will be glad to learn that the complete instruction book for that instrument is now available. Copies have been sent to all who returned the cards that were enclosed with slotted lines already shipped. If you are using the General Radio Slotted Line and have not yet received a copy of the instruction book, please request it on your company letterhead. This book is a more comprehensive operating manual on slotted-line measurements than any other that we have...

Bridge Measurements In The College Laboratory

The efficient operation of a college electronics laboratory for student use requires the permanent installation of certain major items of equipment. Such apparatus as vacuum-tube bridges, Q meters, impedance bridges, and the like, which are so frequently required as accessories to experiments, should be available without the necessity of setup. This does not mean that a student should be deprived of the opportunity to make his own setups. It does mean that a worthwhile experiment, whose subject...

Info

Licensed under patents of the A. T. and T. Co. Patent, applied for. Licensed under patents of the A. T. and T. Co. With literally thousands of R-C band switch oscillators in use throughout the industry, we believe it is high time, particularly with the many younger engineers entering industry who may not have had experience with other types, to mention a few favorable words about the This article is one of the best and fairest summaries that we have seen of the relative...

Vhf Adaptor

In the VHF band, the old standard 51.5-ohm 15A coaxial line is still widely used. The Type 874-QV2A Adaptor, shown in Figure 1, makes the transition Figure 3. Voltage-standing-wave ratio of Type 874-QU3 Adaptor as a function of frequency. Figure 3. Voltage-standing-wave ratio of Type 874-QU3 Adaptor as a function of frequency. TYPE 874-0U3 TYPE B74-QU3 I , ADAPTOR ADAPTOR TYPE 874-0U3 TYPE B74-QU3 I , ADAPTOR ADAPTOR Figure 2. Cross section of Type 874-QU3 Adaptor to 50-ohm, 3 Vs -inch rigid...

Design Considerations

A Variac autotransformer is similar to a conventional autotransformer or two-winding power transformer in many respects. It is also similar to a motor in having a carbon brush, and a moving element and commutator. It differs from a motor, however, in two fundamental respects 1 The brush is often left in a fixed position drawing full current for long periods of time, and 2 Variac brushes operate at current densi- Expanded Repair Handbook of Noise Measurement Instruction Manual, for Slotted...

Index By Title

Accessories, The Vacuum-Tube Bridge and Tts A. G. Bousquet September, 1952 Accessories Adaptors, Line Stretcher, Component Moitnt, Balun, Terminations and Insertion Unit, New Coaxial October, 1952 Adaptors, New Coaxial Accessories October, 1952 Adaptors, Universal Coaxial February, 1953 Air Currents Made Visible January, 1953 Amplifier Circuit, A New Push-Pull A. P. G. Peterson October, 1951 Amplifiers, A Multirange Filter for Audio and Ultrasonic Horatio W. Lamson June, 1951 Analyzer for Noise...

Overseas

We were also privileged to have as guests at our booth in the Radio Engineering Show, and later at our factory, a group of nine overseas business men from Latin America and European countries, who are now on a five-weeks' tour of electronic plants in the United States. This group, all engaged in selling electronic equipment of U. S. manufacturers in their respective countries, are representatives of Ad. Auriema, Inc., New York export agents for U. S. firms. The accompanying photograph shows the...