A study of the physical mechanism of ion oscillations was begun after the discovery of spurious sidebands in the spectrum of a DC-operated low-voltage reflex klystron which was undergoing development at this laboratory. These sidebands were observed to be as strong as 40 db below 1 mw in some tubes and were separated from the carrier by as little as 0.6 mc or as much as 15 mc, depending on which klystron was examined and what voltages were applied to it. It was observed that the frequency separation and magnitude of the sidebands were a function of the exterior cooling conditions, an observation which suggests a relation between the sidebands and the gas pressure within the tube. It has been recognized 1 that ion plasma oscillations can be a source of noise in microwave tubes; consequently it was decided to build a cylindrical tetrode structure whose DC configuration was similar to that of the klystrons and to study the details of the oscillations.
Using an electronic model which consists of a stream of uniformly charged laminae accelerated in an electron gun, ac velocity and current at the anode will be given in terms of the corresponding quantities at the potential minimum. The physical principles on which the calculations are based will be summarized and possible application of the results to traveling-wave tube noise theory will be outlined.
Three types of Philips Dispenser Cathodes and their several advantages and limitations: a) L or cavity cathodes; b) impregnated cathodes; c) pressed cathodes. These developments have already reached the state where useful cathodes of uniform quality can be produced in quantity. Improvements that may be expected to result from researches in progress: a) reduction of evaporation; b) larger sized units. 'The cost of making Philips Dispenser Cathodes: efforts to reduce production costs are giving ground for hope that it will be possible to produce some types at lower cost.
Summary form only given, as follows. In special electronic devices a flat, elongated, cathode is required which may be six to eight inches long and 1/8 inch or more wide. For successful operation this structure must be held firmly in position and maintain its geometry. This objective has been achieved by mounting two telescoping U-channels on a sapphire rod and placing the heater in the interspace. The structure is simplified when one channel is replaced by square-cross-section tubing to which the second channel is spot-welded or brazed. The sapphire or ceramic rod is supported at its ends by suitable brackets which permit free sliding of the rod on heating.
For many years the vacuum tube industry in this country has used a standard glass-to-glass seal in the production of miniature tubes. Recently some work has been done to evaluate other methods of sealing and to consider new ideas tor the construction of vacuum tube seals. This paper reports the results of a-project for the development or sealing techniques by the use of low temperature "solder" glasses and by the use or an inductively heated chrome iron ring.
Previous methods of analyzing the low-frequency noise spectrum of microwave oscillators have employed the usual scanning-type spectrum analyzer or an arrangement of fixed-tuned filters. The visual presentation of the spectrum analyzer makes high accuracy difficult, while a series of filters does not provide the necessary frequency discrimination. The present system makes use of a chart recorder to present noise level versus frequency as a continuous plot from 0 to 16,000 cycles.
Oxidation of the input jack of magnetrons by warm moist ozone has been the cause of open heater circuits. This condition can be temporarily corrected by field maintenance; however, a more satisfactory and permanent solution, involving the treatment of the jack to render it non-corrodible, has been evolved and will be reported on. The treatment can be widely applied in electronic apparatus where high potentials are employed between closely spaced elements in air.
0.. - I Many of the variables in tube making such as parts, processing, regular and accelerated burning are discussed with reference to their effect on true contact potential. The retarding field technique has been used as the method of measuring contact potential and all measurements we're made on the 6AK5. Various lighting schedules on the exhaust machine were investigated, and the results reported. Quantitative evaluation of bombing temperature influence on contact potential was made. Contact potential was checked after each of the various steps in the aging schedule. A plot of true contact potential vs time is shown for tubes 'Which were burned 46 hours. The correlation between true contact potential and oharaoteristic5 is discussed.
Investigations on receiving-type electron tube processing methods were made because of high rate of electron tube failures experienced in USAF electronic equipment subjected to high temperatures. The tube type selected for these investigations was the 6AR6 tried in two versions, distinguished from each other only by the processing and aging patterns applied. Both versions were subjected to a high temperature life test specified at 300° bulb temperature. The result obtained was related to the processing pattern applied in each of the versions tried. In the case of setting the transconductance slump at the limit of 10 per cent, the 6AR6 processed on the sealex exhaust system did not comply with the specified limit. It was found, however, that the 6AR6 subjected to an improved processing schedule was capable of complying with the specified limit. In following up these investigations, a project was initiated relating to the design and construction of an improved exhaust equipment incorporating advanced processing features and applicable to full scale electron tube productions to be used for USAF electronic equipment operating at high temperatures. This project forma a part of the current USAF electron tube program aimed at continuously improving modern aircraft reliability.
Many of the variables in tube making such as parts, processing, regular and accelerated burning are discussed with reference to their effect on true contact potential. The retarding field technique has been used as the method of measuring contact potential and all measurements we're made on the 6AK5. Various lighting schedules on the exhaust machine were investigated, and the results reported. Quantitative evaluation of bombing temperature influence on contact potential was made. Contact potential was checked after each of the various steps in the aging schedule. A plot of true contact potential vs time is shown for tubes 'Which were burned 46 hours. The correlation between true contact potential and characteristics is discussed.
This paper concerns the general problems connected with the use of electron tubes. We are primarily concerned with obtaining the utmost reliability when vacuum tubes are employed in circuits to perform certain functions in guided missiles. It is first desirable that we define what we mean by "reliability." Unfortunately, each person has his own definition and idea of just what reliability concerns itself with. The following definition has been developed by a committee on reliability set up by the Radio Television Manufacturers Association and probably fits the bill closer than any definition developed up the present time. The definition is: Reliability is a measure of the probability that a device will perform its purpose adequately for the period of time intended under the operating conditions encountered. This definition covers, in reality, almost every conceivable kind of application and it becomes apparent almost immediately that reliability for one type of service may not necessarily constitute reliability for another application at all. This causes much of the confusion which exists in determining reliable operating. conditions for tubes in specific particular applications. This is brought about by the fact that some applications require the tubes to operate for only a relatively short time, say one-half hour; other applications require the equipment to run for twenty-four hours a day for days on end without any operator being within hundreds of miles of the equipment. In this instance, replacements cannot easily be made and therefore the equipment, to be reliable, must operate thousands of hours without any attention.
