Type A Unit Power Supply

The basic Unit Power Supply is the Type 1203-A, which supersedes the Type 1205-A. The new unit, which is designed to supply plate and cathode heater power to the unit oscillators and other unit instruments, is improved both electrically and mechanically over the older model. Supplying 50 milli-amperes at 300 volts and 3 amperes at 6.3 volts, this unit is also useful as a general-purpose laboratory supply for low-power equipment. Unit instruments lEduard Karplus, V-H-F and U-H-F Unit...

Input

Stage is that it drives each tube from its own grid to its own cathode, so that the tubes are driven in a balanced fashion. In order to achieve this type of drive, it is necessary to feed the plate impedance of the phase-inverter driver from the midpoint of the series-connected output tubes. If the plate load of this driver were connected directly to the plate supply, the upper tube would be driven with respect to ground as a cathode follower, and the balance of the two tubes would be...

Type A Unit Oscillator

This simple two-frequency oscillator (400 and 1000 cycles), shown in Figure 5, is useful as a modulating source for high-frequency oscillators such as the Type 1208-A and the Type 1209-A and as a general-purpose laboratory source for bridge measurements. It will furnish approximately 0.2 watt to a balanced or unbalanced 8000-ohm load at less than 2 distortion. Figure 5. Panel view of the Type 1214-A Unit Oscillator. 1214-A Unit Oscillator (including power supply) allay 60.00 Licensed under...

Noise Tube

Elementary schematic circuit diagram of the Type 1390-A Random Noise Generator. Figure 2. Elementary schematic circuit diagram of the Type 1390-A Random Noise Generator. Figure 3. Oscillograms of three different samples of the output voltage wave of the noise generator. Only a single sweep and not a repetitive one was used in each case. The sweep speed for the middle trace was about four times that of the upper trace, and the wave was spread out even further in the lower trace by...

Robert F Field Retires

Field formally retired from the Engineering Department of the General Radio Company after 21 years of service. Actually, he will be in and out of our laboratories for some time working on various personal investigations he has started. To any regular reader of the Experimenter, Mr. Field's name is certainly a familiar one. His contacts with the engineering profession began long before his association with General Radio because, after graduating from Brown University in...

Intermodul At I O N Ccif Method

The final method of test is the difference-frequency intermodulation method, and some results by this method are shown in Figure 3. Two sinusoidal test signals of equal amplitude were simultaneously applied, and the difference in frequency between the two was kept at 1100 cycles. The amplitude of the un-desired first-difference component at 1100 cycles is shown here as a function of the frequency of the lower-frequency signal. The amplitude of the amplified input signals is also shown for...

July

Push doubler for 460-540 Mc and as a push-pull tripler for 600-790 Me. The self-biasing arrangement used is shown in the photograph, the d-c resistance load being a compromise between the values which give the most output in the doubler and tripler connections. This value of bias resistor is also high enough to give some protection from burning out due to overheating caused by too high current. The available input voltage is not sufficient to cause crystal burnout from voltage alone, partly as...

An Improved Variac Speed Control

Variac Winding Machine Picture

VARIAC SPEED CONTROLS, Types 1700-AL and AH, have given an excellent account of themselves in a large number of applications since their introduction two years ago1. The combination of the Variac with a rectifier and choke has many advantages as a source of adjustable armature voltage for operating d-c shunt or compound wound motors over a wide speed range. The resistance of the armature voltage source can be made low, usually less than half the armature resistance of the motor, so...

A V O Lt Megohmmeter For Insulation Testing

Megohmmeter Diagram

A High-Power Toroidal Output Transformer 5 THE NEW General Radio Megohm-meter, Type 1862-A, has been specifically designed for the rapid measurement of insulation resistance, as well as general resistance testing such as the measurement of high-valued resistors. Consequently, it has a considerably wider field of application than its predecessor, the Type 1861-a. Since insulating materials usually exhibit a marked voltage coefficient of resistance, it is necessary for purposes of standardization...

The Dynamic Microphone

The errors arising from these effects can be avoided by the use of a dynamic, or moving coil, microphone for those applications where a long cable must be used between microphone and sound-level meter, or where extremes of temperature and humidity are encountered. A suitable dynamic microphone for use with the Type 759-B Sound-Level Meter is now available, in combination with a transformer, a cable, and tripod. Figure 2. Variation in response as a function of temperature for the crystal...

Frequency In Cycles Per Second

Variation in output of typical Rochelle salt crystal, diaphragm-type crystal microphone as a function of frequency as the microphone is rotated about axis A A perpendicular to its diaphragm. Sound incidence is parallel to plane of diaphragm. at the input of the Type 760-B Sound Analyzer or the Type 1550-A Octave Band Analyzer. The absolute level can be determined by using the Type 1552-A Sound-Level Calibrator. No corrections are necessary for cables up to 100 feet long.

The Rochelle Salt Crystal Microphone

The Rochelle salt crystal, diaphragm-type microphone chosen for use on the General Radio Type 759-B Sound-Level Meter is a low-cost device, which fulfills all of these requirements satisfactorily so long as the microphone is connected directly to the input terminals of the sound-level meter, and so long as moderate variations of temperature and humidity are encountered. However, when it becomes necessary to make measurements with the microphone separated from the sound-level meter by a long...

Highpower Toroidal Output Transformer

The advantages of the toroidal core transformer over one using a shell-type core are becoming more generally recognized. Chief among these are the high degree of astaticism and the extremely tight coupling which can be attained between windings extending around the complete circumference of the toroid. An impedance-matching toroidal transformer, Type 941-A, w-as announced a year ago.2 This article describes a high-power model, the Type 942-A Output Transformer, designed primarily for coupling...