Accession Number:

AD0627904

Title:

OBTAINING A LOGARITHMIC AMPLITUDE CHARACTERISTIC IN AN R-F AMPLIFIER BY CATHODIC DETECTION,

Descriptive Note:

Corporate Author:

ARMY FOREIGN SCIENCE AND TECHNOLOGY CENTER CHARLOTTESVILLE VA

Personal Author(s):

Report Date:

1965-12-01

Pagination or Media Count:

10.0

Abstract:

An analysis was made of a logarithmic amplifier with cathodic detection, giving high logarithmic accuracy. The report examines sequential summing with cathodic detection. All of the amplifier tubes are in amplification and cathodic detection mode so that each stage in addition to amplifying h-f voltage and feeding it to the next stage, detects r-f voltages and, independently of the other stages, feeds the video component of the output voltage to a common load. The load of the cathode detector is a large bias resistor R sub k in the cathode circuit of the amplifier stage. The video voltage appearing across this resistor automatically controls the amplification of the stage with respect to the r-f frequency as the signal increases. The time constant of the cathode circuit must be much shorter than the rise time of the pulse. In order for signal detection and amplification control to be effective at relatively low signal levels, and for amplification of these signals to be maintained, it is necessary to use such tubes as the 6Zh1B and 6Zh1P, that have short plate grid characteristics, with the operating point on the lower part of the linear segment of the characteristic. The detection and amplification control effects of the stage increase as the value of resistor R sub k is increased, but the initial bias voltage E sub sn also grows. Author

Subject Categories:

  • Electricity and Magnetism

Distribution Statement:

APPROVED FOR PUBLIC RELEASE