The Effect Of Humidity On Electrical Measurements

IT IS AT THIS TIME of year that complaints come in regarding the erratic behavior of electrical measuring equipment, particularly precision impedance bridges. The various stories conflict. Sometimes the bridge seems to read high, sometimes low the balance may drift badly or suddenly jump to a new value it may show increasing errors as the frequency is lowered, or the balance may shift with applied voltage. At first glance it seems that there must be as many causes as kinds of error. Actually,...

Overall Free Field Frequency Responses And Tolerances For Sound Level Meters

And different types of sound-level meters may not read exactly alike. In such cases the question of which meter is most nearly accurate is mainly academic and is liable to lead to unwarranted conclusions since the actual error will depend upon the characteristics of the sound. All microphones of the types commonly used with sound-level meters exhibit marked irregularities in the response curve above 3000 cycles, and some types are also irregular in the low-frequency region. The best procedure,...

How To Use A Soundlevel Meter

General Radio Sound Level Meter 759a

Manufacturers have tried to make sound-level meters as simple to operate as possible. The instruction sheets covering the actual mechanics of operating General Radio Company's Type 759-A and Type 759-B instruments are mounted in the covers. For those who may be unacquainted with the instruments, however, the following may be of interest. A standard sound-level meter has, aside from various minor controls, three main controls and indicators which are used in taking the readings. The iirst of...

Torsional Vibration Analysis With The Type A Wave Analyzer

Test setup for measuring torsional vibration at the Lycoming laboratories. Figure 1. Test setup for measuring torsional vibration at the Lycoming laboratories. ALTHOUGH the Type 760-A Sound Analyzer and the Type 762-A Vibration Analyzer are recommended for general purpose sound and vibration analysis, there are specific applications where the use of the Type 736-A Wave Analyzer leads to certain operating conveniences and somewhat better accuracy. In Fig ure 1 is shown a test setup in...

General Radio Opens Chicago Office

TO ASSIST USERS of General Radio equipment in the Chicago and middle western area, the General Radio Company is opening a Chicago engineering oflice on December 1, 1943. The new office is located at 920 South Michigan Avenue, Chicago 5, anil the telephone number is Wabash 3820. In charge of this office is Lucius E. Packard w ho for the past three years has been in charge of the New York engineering office. Mr. Packard is a graduate of the Massachusetts Institute of Technology, receiving his...

Checking The Accuracy Of Aircraft Tachometers

Checking aircraft engine tachometers is one of handling the increased number of tachometers and of making sure that the individual tachometer takes advantage of the full tolerance allowed by the acceptance specification. If the tachometer tolerance is -4-25 rpm and if the checking standard has an error of 10 rpm, the tachometers must each read within 15 rpm to be accepted. If the checking standard accuracy can be improved to 2 rpm, the tachometers need only read within 23 rpm to be accepted....

Reactance Chart

Gekehal radio Compaw . tate street cambridge mass. u.s.a. gekehal radio Compaw . tate street cambridge mass. u.s.a. THOUSANDS OF GENERAL RADIO SIGNAL GENERATORS are working overtime in plants manufacturing military radio equipment. In some plants, we are informed, generators have been operating for months without being turned off. This photograph, published through the courtesy of FM Magazine, shows Signal Corps inspector E. P. Mayer testing receivers with a Type 605-B Standard-Signal Generator...

How To Use The Vibration Analyzer

All batteries for operating the vibration analyzer are contained within the case. Push buttons and a neon lamp on the panel indicate when the batteries should be replaced. The instructions mounted in the cover of the instrument should be followed. Tuning is accomplished by the large knob and the push button range switch. The calibration is direct reading in cycles per second and may be converted to rpm by multiplying by 60. A cord is provided to connect the input of the analyzer to the output...

Ta

1 90-volt block and 1 45-volt block, mounted externally. Any 135-volt combination, mounted externally, if necessary. Any 4.5-volt combination dry cells are satisfactory. I No. 6 dry cell, mounted externally. Any combination supplying 90 volts leads must be short. Not recommended any change in dimensions or location will affect the calibration. External batteries giving the same voltages can be used, but leads must be short. If external batteries are used, battery box must be shielded and leads...