摘要:

An ultra‐high frequency superheterodyne receiver, simple in operation, having high sensitivity and stability, was constructed primarily for direction finding on 1.67‐meter waves. The 220‐kilocycle intermediate frequency amplifier using resistance coupled high &mgr; television type tubes has a constant gain of 110,000 over a 110‐kilocycle band. This flat intermediate frequency response allows for any slight variation in the oscillator or signal frequency, due to temperature variations etc., without affecting the output of the receiver. A high gain and a high signal to noise ratio make the receiver well suited for direction finding observations by the null point method.

ISSN:0034-6748    

DOI:10.1063/1.1751708

出版商:AIP    

年代:1940

数据来源: AIP

摘要:

Although in the use of oil diffusion pumps for the production of high vacuum, extremely cold traps in the usual sense are not required, some means must be provided to prevent both direct backstreaming and diffusion of the oil vapor. The relative advantages of (1) charcoal traps, (2) cold traps, (3) hot baffles, (4) electrical baffles, (5) mechanical baffles are discussed and specific designs for effective high speed baffles are given.

ISSN:0034-6748    

DOI:10.1063/1.1751709

出版商:AIP    

年代:1940

数据来源: AIP

摘要:

A new and reliable technique is described for the construction of thermocouples of high sensitivity, suited especially to astrophysical research. The technique consists essentially of a controlled‐heating soldering process for very small bismuth alloy parts. The mounting of such thermocouples in permanently evacuable glass envelopes is also discussed.

ISSN:0034-6748    

DOI:10.1063/1.1751710

出版商:AIP    

年代:1940

数据来源: AIP

摘要:

An apparatus is described for integrating bioelectric potentials over various time intervals. This is accomplished by recording the number of times a gas‐filled tube discharges a condenser which stores the rectified potentials.

ISSN:0034-6748    

DOI:10.1063/1.1751711

出版商:AIP    

年代:1940

数据来源: AIP

摘要:

The relative speed of evacuation, water consumption, air pumping ability, and final vacuum produced by 14 water aspirators have been measured, making possible a more intelligent choice of aspirator for any job.

ISSN:0034-6748    

DOI:10.1063/1.1751712

出版商:AIP    

年代:1940

数据来源: AIP

摘要:

Details are given for the construction of a time delay circuit of particular value for physiological laboratories using oscillographs for studying action potentials of the nervous system. It permits timing separate events at any interval in a cycle of operation determined by a master oscillator. The operation of the circuit depends on the grid extinction of a thyratron operating at low current.

ISSN:0034-6748    

DOI:10.1063/1.1751713

出版商:AIP    

年代:1940

数据来源: AIP

摘要:

The usefulness, efficiency and economy of cathode‐ray oscillography are improved by sweeping the spot across several successive lines on the face of the tube. There is presented a circuit which does this, with flexibility as to speed, delay, spacing and brightness of the individual traces. A modified sweep circuit actuates a trigger unit which shifts each trace and brightens it during the transit.

ISSN:0034-6748    

DOI:10.1063/1.1751714

出版商:AIP    

年代:1940

数据来源: AIP

摘要:

An electron diffraction camera has been built for use in the study of photo‐ and secondary electron emissive surfaces. The electron beam is produced by a modified cathode‐ray tube gun having an a.c. heated tungsten wire cathode, for which the focusing voltages are supplied by rectifiers. Beam velocities up to 40 kv are available. The maximum beam current, after reduction by a screening aperture, is about 0.1 &mgr;a, which is sufficient to make visible most patterns which can be photographed. The specimen adjustment mechanism and photographic shutter control are of new design and have proved themselves very satisfactory. The pumping system consists of a Megavac fore pump and a four‐inch diameter three‐stage oil diffusion pump.

ISSN:0034-6748    

DOI:10.1063/1.1751715

出版商:AIP    

年代:1940

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1751716

出版商:AIP    

年代:1940

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1751717

出版商:AIP    

年代:1940

数据来源: AIP