Radio Experimenter 1950

Polariscope For Dynamic Stress Analysis

Polariscope Stress Analysis

One of the more useful tools in mechanical research is the photoelastic polariscope for stress analysis. The science of photoelastic stress analysis is based on the property of certain transparent materials which causes them to exhibit, when strained, a degree of optical double-refraction exactly proportional to the net stress. Such materials, under stress, are no longer isotropic to light, a ray of which, entering such a stressed material, will travel faster in one plane than in the plane at...

Improvements In The Countingrate Meter

SINCE ITS INTRODUCTION three years ago, the Type 1500-A Counting-Hate Meter has found considerable application in laboratories engaged in nuclear physics research. Basically, a laboratory measurement device, rather than a survey instrument, this meter is particularly useful where it is desirable to have a permanent graphical record of changes in rate over a considerable period of time, since a pen recorder, such as the Esterline Angus 5-milliampere model, can be operated directly from the...

Bolometer Bridge For The Measurement Of Power At High Frequencies

Vintage Bolometer

In the u-h-f region, power measurements are of fundamental importance. While, at lower frequencies, current or voltage is generally measured in preference to power, at ultra-high-frequencies most practical devices for the measurement of these quantities are relatively large with respect to a wavelength, and their accuracy is impaired by the effects of resonance and standing waves. Power measurements, however, can be made with good accuracy at high frequencies by dissipating the power in a...

Vhf And Uhf Unit Oscillators

The Type 1208-A and Type 1209-A Unit Oscillators are compact, moderately priced, general-purpose power sources for the electronics laboratory. They cover the frequency ranges of 65 to 500 Mc and 250 to 920 Mc, respectively, and can deliver 100 to 500 milliwatts of v power. Output terminals are Type 874 Coaxial Connectors, for connection to General Radio measuring equipment as well as to the wide variety of Type 874 Coaxial Elements previously described.1 These oscillators are recommended as...

Applications

Slotted Line Section Diagram

The Type 874-LB Slotted Line is useful in matching a load to a line by means of a matching transformer as shown in the block diagram in Figure 8. The adjustment of the two transformer elements may be very tedious unless a systematic procedure is followed. One procedure which usually gives good results is as follows7 1. Set the probe in the slotted line to a minimum point and adjust the detector sensitivity until a reading of about twenty per cent of full scale is noted on the detector meter. 2....

Quarter Plate

Able, and registering for right- or left-hand circular polarization. Plane polarizers carry a degree scale calibrated from zero to both plus and minus ninety degrees for isoclinic (loci of equi-directional stresses) determination. The Type 1534-P4 Camera Bridge has a captive M x 20 thumbscrew for mounting the user's camera by means of its tripod socket. All elements are horizontally adjustable along the Type 1534-P7 Shafts and vertically adjustable over some nine inches. Vee and flat ways...

In This Issue

Phototube 1p39

A Variac Phase-Shift Circuit Miscellany ALL PHOTOGRAPHIC flash lamps, whether electronic or chemical, present a measurement problem that cannot be solved with the ordinary exposure meter, because of the transient nature of the light. What must be measured for flash photography is an integrated value of light vs. time, that is, exposure. The Type 1501-A Light Meter has been designed to make this measurement, and it will be found particularly useful for color photography with electronic flash...

Specifications

Light Range A light range of 64 1 can be measured at mid-scale deflection, corresponding to 100 to 6400 lumen-seconds per square foot (foot-candle-seconds). The extreme readable range is about 50 to 12,800 lumen-seconds per square foot. Attenuator Range F 3.5 to f 22 corresponding to a range of 1 to 64 on the proportional scale. Tubes One RCA 929 and one RCA 124. Batteries One Burgess 2F, three Burgess XX30E. Calibration Meter is standardized in terms of a xenon flash tube operated from a known...

Bibliography

I.R.E., Standards on Radio Receivers, 1938, Section E6. 2. J. G. Frayne and R. R. Scoville, Variable-Density Recording, Journal of the Society of Motion Picture Engineers, v. 32, June, 1939, pp. 648-673. 3. J. K. Hilliard, Distortion Tests by the Intermodulation Method, Proceedings of the I.R.E., v. 29, No. 12, December, 1941, pp. 614-620. Discussion, v. 30, No. 9, September, 1942, p. 429. 4. G. W. Read and R. R. Scoville, An Improved Intermodulation Measuring System, Journal of the Society of...

Strobolume Power Unit

Quarter plate can be installed or removed without tools as shown here. to 40 microseconds, which effectively stops motion in a dynamic stress pattern as well as pattern motion originating in vibration. As a result, the Type 1534-A Polariscope is much lighter in weight and lower in cost than polari-scopes designed for longer exposures, where vibration effects must be minimized. The blue-green monochromatic light band used in the Type 1534-A Polari- scope is peaked at 4800 Angstrom...

Bayly Engineering Offers Repair Service To Canadian Customers

Canadian users of General Radio instruments can now have their equipment repaired and recalibrated in Canada, thus avoiding the red tape, expense, and delays that often occur in customs when material is returned to our factory. Bayly Engineering, Limited, of 5 First Street, Ajax, Ontario, has been appointed Canadian service agency for General Radio products. This firm is . equipped to give prompt and competent repair service on all General Radio instruments. Their repairs and calibra tions are...

Rf Oscillators

Structurally, the two carrier oscillator units are much alike. They differ in carrier frequency range covered, but each uses as the tuning element a butterfly circuit1' , in which the inductive and capacitive components are built integrally, and tuning is achieved by simultaneous variation of both without use of sliding contacts. The U-H-F Unit, uses a 23 diameter symmetrical butterfly circuit adapted for use with the Sylvania Type 5767 Coplanar U-H-F Triode, or Rocket Tube, while the V-H-F...

Frequency

Standing-wave ratio as a function of frequency of the Fuse Bolometer and Thermistor Units. Figure 8 shows the standing-wave ratio as a function of frequency for the various elements. At the higher frequencies it is necessary to use a matching transformer between the source and the bolometer when the power into a line terminated in its characteristic impedance is desired. A matching transformer can be easily assembled using Type 874 Coaxial Elements2 as indicated in the block diagram...

Rf Oscillator

Elementary wiring diagram of Type 1330-A Bridge Oscillator. 2A Radio-Frequency Source for the Laboratory, General Radio Experimenter, November, 1937. Figure 4. View of oscillator unit removed from cabinet. Servicing cable is shown coiled in its storage position. Figure 4. View of oscillator unit removed from cabinet. Servicing cable is shown coiled in its storage position. Figure 5. Output characteristics of the Type 1330-A Bridge Oscillator. Figure 5. Output characteristics of the...

External Coupling Elements

Allows coupling an external wavemeter or heterodyne frequency meter to the fields within a coaxial system. Consists of short coaxial line with hole in outer conductor that can be partially or completely covered by a rotatable sleeve. Type 874-MA Adjustable Coupling Loop A general-purpose coupling loop. Consists of short coaxial line with a one-turn loop at one At left. Type 874-LR Radiating Line above, left, Type 874-MA Adjustable Coupling Loop above, right, Type 874-MB Coupling Probe. At left....

Type A Toroidal Transformer

This transformer is designed for use as an impedance-matching or bridging transformer in low level 600-ohm communication systems. It employs a toroidal, doughnut-shaped core, which is preferable to the familiar shell-type core in two respects.* (1) The toroidal core is much more astatic and thus less susceptible to external magnetic fields while, conversely, it produces smaller external magnetic fields. (2) A tighter degree of coupling between primary and secondary windings can be obtained than...

Resistance Balance Ohms

To zero, r-f power is applied to the bolometer, and the bolometer current adjusted for balance. The r-f power is then removed and the bridge rebalanced by means of the K dial. The r-f power is then the simple product MARK as read from the bridge dials and meter. The circuit is also adaptable to direct-reading measurements of r-f power, but with somewhat less accuracy than is obtainable using the substitution method. It is convenient when a large number of measurements are to be made at power...

Eshift Circuit

This differs from the conventional open delta three-phase control in that, as one brush moves from phase 1 to phase 2, the other brush moves from phase 3 to phase 1, this latter being opposite to the motion in the conventional open delta. The output, therefore, follows the curves of Figure 2. Obviously, some refinements of the circuit are possible, and the remainder of these remarks will be devoted to their development. The first refinement concerns a means of correcting the voltage change...

Adjustable Line Elements

For matching or tuning, and use as reactive elements. Can be used with indicator and scale as reaction-type wavemeters. Stubs consist of a coaxial line with a sliding short circuit of the multiple-spring-finger type. The short circuit is moved by a bakelite tube having a sliding reference marker to facilitate use as a wavemeter. Characteristic Impedance 50 ohms. Maximum Travel of Short Circuit 20 cms. for 874-D20 50 cms. for 874-D50. Type874-LA Adjustable Line (Line-Stretcher) An...