The compressor-amplifier-recorder unit received current from (1.e., Supplied electrons to) the probe. The intensity of this current varied linearly with the dose rate. This current is supplied by a cathode~ biased low-m triode (CK6152) and results in a logarithmic variation of the plate voltage of this tube, This plate voltage is connected to the grid of a blocking oscillator (CK5703WA) through a high resistance. frequency of the blocking oscillator is thus made to vary as the log- The arithm of the dose rate, and after amplification through another CK5703WA, the output is impressed on the recording head of the wire recorder, The power supply consisted of six 26A7-GT tubes connected in parallel so as to oscillate at about 1,000 cps when fed 28 volts from the aircraft power supply. The output of the tubes is stepped up, rectified, and regulated to result in +150 volts for B+ voltage in the compressoremplifier~recorder and -1,000 volts for the photomultiplier tube in the probe. The playback unit consisted of a playback recorder of the sans type as was used for taking data during penetrations. The frequency-modulated cutput of the playback unit was amplified, pulse~-shaped, and integrated. This integrated, slowly varying direct current was then applied to the input of a standard l2-inch-strip chart recorder (Bristol Model 1892). A logarithmic presentation of dose rates from 1 r/hr to 5,000 r/hr was given on the chart. Calibration tests at NBS using Co have indicated an overall read-out accuracy of + 20 percent over the range froz 1 r/hr to 2,000 r/hr,. 2.2.2 Bioscel Radiation-Rate Meter, The Bioscel was designed and built by theEvans Signal Laboratory of the U. S. Army Signal Corps in accordance with specifications furnished by the Air Force Special Weapons Center (AFSWC). Type designation 1M-111 (ZE-1)/UD was obtained through Army channels. Twenty of these units were procured. Two com plete Bioscels were installed in each aircraft with the sensing elements located directly behind the pilot's seat. Data obtained with one instrument were recorded by photographing a remote meter mounted in the photopanel, The remote meter from the second instrument was placed in the pilot's compartment, above and to the right of the instrument panel. 4s shown in Figure 2.2, the instrument consisted of an ion chamber, an amplifier, a control panel, a battery container, and an indicating mter which presented rates from 1 r/hr to 2,000 r/hr. All of these compon- ents, except the meter and its cabling, were contained in a cylindrical aluminum housing 3 inches in diameter and 10 inches in length which had a flange at the control panel for mounting. The ion chamber and amplifier were potted together in the ionchambermassembly module, The potting compound was an epoxy resin, which gave an hermetically sealed unit. ~55°F and 0.1 pei. The unit passed tests for leakage at The ion-chamber volume was 85 cm’. sweep~out voltage was approximately 7 volts. The applied This resulted in nonsat- urated operation and produced a roughly logarithmic indication on the meter, Calibration was obtained by varying this voltage between 6.3 and 8,8 volts, Zero adjustment was made before use (or calibration) by adjustment of coarse and fine rheostats in the cathode circuit, through which resistances a voltage drop was obtained to actuate the meter, 15 REST ANMLO GLE COPY