2900- 1 00- R Memorandum of Project MICHIGAN RADIO-ASTRONOMY MASERS: TEST AND OPERATIONAL FACILITY JERALD COOK R. W. TERHUNE May 1960 SOLID- STATE PHYSICS LABORATORY THE U N I V E R S I T Y OF M I C H I G A N Ann Arbor, Michigan

DISTRIBUTION OF REPORTS Distribution control of Project MICHIGAN Reports has been delegated by the U. S. Army Signal Corps to: Commanding Officer U. S. Army Liaison Group Project MICHIGAN Willow Run Laboratories Ypsilanti, Michigan It is requested that information or inquiry concerning distribution of reports be addressed accordingly. Project MICHIGAN is carried on for the U. S. Army Signal Corps under Department of the Army Prime Contract Number DA-36-039 SC-78801. University contract administration is provided to the Willow Run Laboratories through The University of Michigan Research Institute.

WILLOW RUN LABORATORIES TECH N ICAL MEMORANDUM PREFACE Documents issued in this series of Technical Memorandums are published by Willow Run Laboratories in order to disseminate scientific and engineering information as speedily and as widely as possible. The work reported may be incomplete, but it is considered to be useful, interesting, or suggestive enough to warrant this early publication. Any conclusions are tentative, of course. Also included in this series will be reports of work in progress which will later be combined with other materials to form a more comprehensive contribution in the field. A primary reason for publishing any paper in this series is to invite technical and professional comments and suggestions. All correspondence should be addressed to the Technical Director of Project MICHIGAN. Project MICHIGAN, which engages in research and development for the U. S. Army Combat Surveillance Agency of the U. S. Army Signal Corps, is carried on by the Willow Run Laboratories as part of The University of Michigan's service to various government agencies and to industrial organizations. Robert L. Hess Technical Director Proj ect MICHIGAN iii

WILLOW RUN LABORATORIES TECHNICAL MEMORANDUM CONTENTS Preface.......................... iii List of Figures........................ vi Abstract.......................... 1 1. Introduction................... 1 2. General Description of the Facility................. 2 3. Physical and Electrical Description................. 8 4. Component Description and Characteristics.............. 11 4.1. Microwave System 11 4. 2. Electronics 14 Appendix A: Component List.................... 17 Appendix B: Maser Cable List..................... 19 References.............. 20 Distribution List............. 21

WILLOW RUN LABORATORIES TECHNICAL MEMORANDUM FIGURES 1. Radio Telescope.......................... 3 2. Modified SCR-584 Van....................... 4 3. Block Diagram of Entire Test Facility.............. 5 4. Basic Block Diagram of Maser System........... 6 5. Radio-Astronomy Maser System................... 7 6. Antenna Positioning Control Unit.................. 9 7. Maser Power Control and Display Center............... 9 8. Waveguide-Dewar-Magnet Assembly................. 10 9. E-Plane Antenna Pattern...................... 12 10. Maser Cavity Assembly 5-186-B.................. 13 11. Relative Coolant Loss Rate.. 14 vi

WI LLOW RUN LABORATORIES TEC H NICAL MEMORAN DUM RADIO-ASTRONOMY MASERS: TEST AND OPERATIONAL FACILITY ABSTRACT A low-noise radiometer using a maser preamplifier has been developed for radio-astronomy measurements. This radiometer uses a reflection-type cavity maser with the highest known gain-bandwidth product in practical use. Satisfactory gain stability and dependable performance are presently obtained with a gain-bandwidth product of 200. This memorandum contains a discussion of the electrical and physical aspects of the maser facility together with its proposed uses and operation. Significant diagrams, circuits, and component characteristics are included. INTRODUCTION The first successful operation of a ruby maser occurred at Willow Run Laboratories of The University of Michigan on December 20, 1957. Immediately following this event, possible applications were considered which would provide much-needed experience in the designing, packaging, and operation of these new devices. Of the several possible applications, the use of the ruby maser in radio astronomy appeared to be the most attractive for two reasons: first, in such an application, full use would be made of the maser's low-noise properties; and second, a radio telescope with a paraboloidal reflector 85 feet in diameter was being installed by The University of Michigan's Radio Astronomy Project at a site near Ann Arbor, Michigan. This radio telescope has the highest antenna gain of any steerable antenna in the world and is usable at Xband frequencies. As a result of the interest shown by Professor F. T. Haddock of the Departments of Astronomy and of Electrical Engineering, a cooperative program was started in the summer of 1958. Under this program, the Solid-State Physics Laboratory of Willow Run Laboratories assumed the responsibility for the installation and initial operation of an X-band ruby maser system. The first objective will be an attempt to detect the extraterrestrial helium line at 8. 665 kmc.

WI LLOW RUN LABORATORI ES TECH NICAL MEMORANDUM The helium atom He II State 12 S 1/F = 0 - 1 transition should occur at this frequency (Reference 1). As a further objective, an attempt will be made to detect the hydrogen line at 9. 869 kmc. Because of the expected width of this line, any investigation is contingent upon obtaining a maser bandwidth of 50 to 100 mc. Results of these investigations will be reported as soon as possible. Operation of the maser radiometer as a radar receiver, and in other possible combatsurveillance applications, will further extend the mobile maser program (Reference 2) of the Solid-State Physics Laboratory of Willow Run Laboratories. The test and operational facility has now been developed and will be in operation on the 85foot antenna in the very near future. The purpose of this report is to describe this facility. Much of the description is of the X-band reflection cavity-type maser now in use. However, future plans include operation at other frequencies and with traveling-wave masers. Consideration has been given to these possibilities in the design of the present facility. In general, any foreseen changes would involve only the microwave portion of the existing system. 2 GENERAL DESCRIPTION OF THE FACILITY The 85-foot reflector is shown in Figure 1. This unit provides a solid surface and equatorial mount. One mechanical specification is that the focus be maintained within 5/16 inch as the antenna, carrying a 500-pound load, is rotated. When the reflector is directed toward the zenith, the focus is 110 feet above the ground. The equipment is serviced by rotating the antenna to point due east and utilizing a 55-foot service elevator. In order to provide the greatest flexibility of purpose while satisfying the primary radioastronomy requirements, it was decided to install the test and operational maser unit in a modified SCR-584 radar van (Figure 2). Although this facility was designed and constructed primarily as a test unit for the radio-astronomy maser program, it also serves the purposes of extending the existing mobile-maser program and providing an elementary radio-astronomy research tool. In its primary function, the facility will provide important data for possible radio- astronomy maser systems, without limiting the operation of the 85-foot antenna. By extending the mobilemaser program, this unit will further demonstrate the use of the ruby maser as a radar receiver (Reference 2), and as a mobile field unit with possible combat-surveillance applications. As a research tool it will be used in extensive noise measurements. Present plans in this

WILLOW RUN LABORATORIES TECHNICAL MEMORANDUM FIGURE 1. RADIO TELESCOPE 3

WILLOW RUN LABORATORIES TECHNICAL MEMORANDUM application call for determining noise figures of the maser system, studying methods of optimizing the maser to specific applications, as well as making extraterrestrial measurements. These activities will be reported as soon as possible. FIGURE 2. MODIFIED SCR-584 Van. (a) Exterior View. (b) Interior View. The test and operational facility provides a 6-foot antenna and positioning system which satisfies the radio-astronomy requirements while being versatile and mobile to comply with both research and field-unit needs. The antenna mount may be lowered into the van, where initial adjustments and servicing can be performed alongside the control equipment. A simplified block diagram of the van appears in Figure 3 (inside dotted line). Power is fed into the antenna-mounted maser system, and the received signal is returned through cables to a terminal panel in the van floor. The signal is detected by a synchronous detector and displayed on a recorder. The maser system is shown in simplified block form in Figure 4. The received signal is transmitted to the ruby-filled cavity through a ferrite circulator. The amplified maser output is returned through this circulator into a balanced mixer and then sent to a detector. Figure 5 shows a more detailed diagram of the microwave system.

85-ft 0 Antenna at 6-ft Peach Mountain Van-Mounted sRcorder Scope, Antenna Antenna c Synchronous Rd Indicator, Positioning Z Detector an ls. Stabilizer, Controls Maser Power Supply and Power and Position - JLighting, Supply Rack Indicators I Plugs, etc. Solar Sorensen > Line Voltmeter Transformer Regulator -- r Ilo-v 1S I I in cTC~1nF G. GRE. Manual 3 BLOCKa DIGA OF ETR T Voltage Adjuster in Floor of Van 220-v 1 220-110 60 10-kva n 3' Transformer FIGURE 3. BLOCK DIAGRAM OF ENTIRE TEST FACILITY

WILLOW RUN LABORATORIES TECHNICAL MEMORANDUM Antenna Magnet Ferrite He Bath Circulator- - - -- ~~~~~~~Matched ~~~~Filled Load Cavity Local K-Band X-Band * Mixer Pump Oscillator Oscillator I-F Amplifier and Detector Indicator FIGURE 4. BASIC BLOCK DIAGRAM OF MASER SYSTEM

Cable No. C Preamp. Pwr. —----- 10-3 z Antenna 01I-F I-F Video Video P 20 O- -0 O- -0Pre- -Postamp d-c D, 14 ~ Optical -0 Preamp Postamp p Postamp Pwr. —---- 3 14 Telescope [6 "~~~~~~~~~~~ ~~~~~~~~~X" Gyraline 4 —-- Antenna Balanced Stabilized -Strand Osc. Pwr.-o 6 Gyraline Ferrite Stal Servo 0 7 PositioningL ______ I Mixer Attnuto Iolto Local 12 Attenuator Isolator 12 Controls & Switchable Oscillator -Strand Xtal — - 13 Indicators Ferrite "K" Gyraline - 4 Circulator IfI ff f fKT Circulator Coils Y 2 Directional~ — Gyraline r Coupler )- Attenuator V Ferrite Cirulaor o Vacuum To Vacuum - System System II II~r Liquid Liquid E~)IIIN 26 Ferrite N N ~~ Xtal Isolator 2 2 ~~~~~~~~~~~~~~Liquid. He Machd Comparison MthdLiquid N2 Load Horn Load K-Band Klystron Permanent Magnet Pm Field Adjusting Coils - IL "K" Klystron - 5 5 "K11 Xtal 19 —-, 9r Magnet Adjusting Pwr. -.- 4 0 Cavity and Ruby Crystal Double Dewar -Phone -—. 9 z FIGURE 5. RADIO-ASTRONOIMY M~ASER SYSTEM

WI LLOW RUN LABORATORIES TECH N ICAL MEMORANDUM 3 PHYSICAL AND ELECTRICAL DESCRIPTION Modification of the van for use with the maser required the removal or repositioning of much of the original equipment. All equipment except that required to operate the antenna was removed, and this antenna-control system was repositioned into more compact, convenient form. The antenna equipment, originally installed in the large control panel across the rear door, was moved to a 5-foot relay rack in the same location (Figure 6). Some of the remaining space is occupied by a small writing desk and the rest is used for working space. Several other items, such as the amplidynes, were repositioned into more favorable locations. The elevator circuitry and mechanical system was repaired to allow raising and lowering of the antenna mount. The manual voltage-adjuster was retained to correct for any local voltage variations. A Y-A, 220-110-volt, 3-phase transformer was installed to provide 110-volt a-c power as well as to distribute the load over the three phases. Two of the three phases are regulated and supply power for the more critical electronics, and the remaining phase provides lighting, auxiliary power, and power for less critical components. The use of this transformer permits more efficient (220-volt) power transfer to the van and also increases the mobility of the unit. Two-way communication between the van facility and the laboratory base is provided by two modified AN/ PRC-10 radio sets. Communication is provided from inside the van to the antenna mount by sound power phones. This local communication is a convenience in positioning the antenna and operating the maser. The maser power, control, and display center consists of one 6-foot and two 5-foot relay racks, in the space originally occupied by the radar system modulator (Figure 7). Refrigerants are transferred to the maser dewar without movement of the two 25-liter storage dewars. The liquid-helium transfer employs a flexible transfer tube. The gas supply, required to transfer the liquid coolants as well as to pressurize various waveguide components, is obtained from storage tanks mounted outside the van. A gas control panel is mounted on the wall behind the storage dewars. The original scan mechanism, reference generator, and receiver-transmitter system were removed from the antenna mount. The waveguide-dewar-magnet assembly required by the ruby maser was mounted in the vacated space. This assembly utilizes the original feed antenna in a simple rigid mount. The antenna feeds into the more complex maser-waveguide

WI LLOW RUN LABORATORIES TECHNICAL MEMORANDUM system. The entire assembly is supported by an angle-iron frame, approximately 2 feet on a side (Figure 8). This experimental design will be replaced in the near future by a more compact, packaged unit. The new design will house the waveguide-dewar-magnet assembly in a completely enclosed package, more adaptable to the 85-foot antenna. It will provide adequate shielding and weatherproofing and achieve complete compatability between the two antennas. FIGURE 6. ANTENNA POSITIONING FIGURE 7. MASER POWER CONTROL CONTROL UNIT AND DISPLAY CENTER

WILLOW RUN LABORATORIES TECHNICAL MEMORANDUM Ii FIGURE 8. WAVEGUIDE-DEWAR-MAGNET ASSEMBLY The output of the maser-control-power panel as well as the input to the display units, is a system of 20 individually shielded cables ducted through the floor and up to the antenna mount. Because of noise introduced by the original slip-ring feed, all cables have been attached directly to the rotating antenna mount. This requires a protective device to prevent excessive rotation from breaking the cables; an azimuth interlock system has been devised, which prevents rotation beyond one complete revolution. Three terminal panels are provided in the maser cable system: one immediately following the racks, one in the van floor, and one on the antenna mount. The terminal panel in the van floor is accessible from the underside of the van. This panel permits operation of the maser on either the 6- or 85-foot antennas by connecting the appropriate set of cables (Figure 3). The other two panels are provided for convenience in servicing components. All electrical equipment installed on the antenna itself is d-c operated. This is a precautionary measure to avoid any possibility of pickup into signal lines. All filaments-and drive 10

WILLOW RUN LABORATORIES TECH NICAL MEMORAN DUM motors are powered by individual d-c supplies. No fans are permitted on the antenna mount; cooling is provided by forced air from a compressor in the van, and ordinary 1/2-inch OD air hoses. A vacuum pump is also available as a part of the van facility, to allow convenient pumping on dewars, transfer tube, and waveguide system as required. 4 COMPONENT DESCRIPTION AND CHARACTERISTICS 4.1. MICROWAVE SYSTEM The microwave system consists of two major subdivisions: K-band (18-26 kmc) and X-band (8. 2-12. 4 kmc). The K-band power is supplied by a specially selected, high-power klystron, which is a velocity-variation oscillator, designed for operation in the 22-25 kmc range. These highpower tubes have an output of 70 mw or more, whereas the average tube is limited to about 40 mw. Mechanical tuning is available, and remote control has been provided. The klystron is housed in its own case to allow forced-air cooling and weatherproofing. An isolator and variable attenuator follow the klystron; the variable attenuator allows remote electronically controlled variable attenuation to 25 db. A directional coupler and crystal mount allow monitoring of the K-band signal. The remaining K-band system consists of standard bends and straight sections. The X-band system includes signal input line, local oscillator supply, and cooled loads. The input line permits comparison of the incoming signal with a reference signal by means of a switching four-port circulator. Application of a square-wave current to an electromagnet switches the device at a rate variable from 40 to 250 cps. The signal path has an insertion loss of 0. 2 db at 8. 6 kmc. A second, nonswitching, ferrite, four-port circulator provides the necessary isolation for a reflection-type maser. The reflection-type maser utilizes a portion of the input waveguide to carry the amplified output. The ferrite circulator, by means of a magnetic field, channels the two waves in the appropriate directions with an isolation of approximately 25 db (Figures 4 and 5). The input path, in this device, has an insertion loss of only 0. 12 db, whereas the output path is 0. 25 db at 8. 6 kmc. One unused port on each circulator is terminated in a matched waveguide load, cooled to liquid-nitrogen temperature. These waveguide systems consist of straight sections and bends, plus two standard matched terminations. The cooled, matched terminations minimize the 11

WI LLOW RUN LABORATORIES TECHNICAL MEMORANDUM random-noise signal originating at the unused ports, a precautionary measure for sensitive measurements. The signal picked up by the 6-foot parabolic reflector is transmitted to the waveguide system by the original Signal Corps antenna assembly AS-23/AP pickup dipole. The parabolic reflector has a rated beamwidth of 1. 4~. An experimental plot of the antenna pattern appears in Figure 9. This pattern indicates an experimental beamwidth of 1. 5~. Local oscillator power is supplied by a stabilized microwave generator operating in the 8. 5-9. 5-kmc range with a power output of 10 mw. The rf section is housed in its own case in the microwave system. It consists of a klystron, ferrite isolator, stabilization discriminator, and reference cavity. Tuning of both the reference and klystron cavities is available, and remote operation has been provided. This unit has an experimentally determined long-term frequency drift of 1 part in 105. A variable attenuator permits remote, electronically controlled variable attenuation to 35 db. The balanced crystal mixer is optimized over the range 8. 5-8. 9 kmc. This conventional superheterodyne mixer system feeds into a 30-mc receiver discussed later. 00? / FIGURE 9. E-PLANE ANTENNA PATTERN. Beamwidth, 1. 50 12

WI LLOW RUN LABORATORI ES TECHNICAL MEMORANDUM An X-band noise source is available for noise measurement. Also a pickup horn is provided for cold sky comparison in radio-astronomy measurements. To match all components, double-stub tuners are provided. These tuners are a specific design with a spacing of 0. 787 inch (3/8 wavelength at 8. 665 kmc). The design permits pressurizing or evacuating the guide by means of an O-ring sealed cap. Stepwise frequency variation to a higher X-band frequency is possible. The cavity assembly (Figure 10) is designed specifically to operate at 8. 665 kmc, with a maximum of gain stability and dependable performance. These features are realized with a gain bandwidth product of approximately 200. The cavity itself represents a radical design, being a solid, silver-plated ruby (Reference 3). This design has demonstrated the possibility of very high-gain-bandwidth products. At present, products up to 600 have been obtained. Closely associated with the waveguide system is the magnet-dewar assembly. The magnet is a permanent Alnico magnet having a 1 1/2-inch gap, with a field of 3850 gauss. The field uniformity is, as specified by the manufacturer, within 0. 1% inside a 1/2-inch cube at the X Guide K Guide a4 I\~~~, n K Coupling Pin Coupling Plate -- - K Coupling Hole X Coupling Hole L _ Silver Ruby Cavity Rubber Filler Clamp FIGURE 10. MASER CAVITY ASSEMBLY 5-186-B1 13

WILLOW RUN LABORATORIES TECHNICAL MEMORANDUM center of the gap. Coils are provided to vary the field through ~150 gauss at ~50 ma. The magnet mount allows a rotation of 350 and a translation of 3 inches along the axis of this rotation. The dewar was designed to contain 3. 4 and 8. 1 liters of liquid helium and liquid nitrogen, respectively. These amounts have been seen to evaporate completely in about 36 hours, with -5 a vacuum of 2 x 10 mm of mercury. Tests have shown that the loss rates of both liquid helium and liquid nitrogen are essentially independent of dewar angle from vertical to approximately 40~ with the horizontal. Beyond this point, both rates appear to rise exponentially to a relative rate of 1. 5 at 220 with the horizontal (Figure 11). 2. 0 1. 9 1.8 |1. 7 ~ Nitrogen Loss 1. 6 l I | Outer Dewar' X 1. 5 * Helium Loss ~ 1. 4 Inner Dewar 10. 0. 8 0. 6 90 80 70 60 50 40 30 20 10 ANGLE TO HORIZONTAL (Degrees) - b. FIGURE 11. RELATIVE COOLANT LOSS RATE 4.2. ELECTRONICS The switching circulator is driven by a square-wave generator. This device supplies a square-wave current to the electromagnet of the circulator over a controlled frequency range of 40 to 250 cps. A regulated supply furnishes the required 500 volts at 400 ma and 6. 3 volts at 10 amp. Two other supplies provide ~300 volts across the multivibrator tube.

WILLOW RUN LABORATORIES TECHNICAL MEMORANDUM The magnet coil supply has an output of 0-300 volts at 0-150 ma with a 2-mv ripple. Requirements on this unit are to provide ~50 ma to vary the magnetic field from 3700 to 4000 gauss. The local oscillator supply is a stabilized unit with a 550-volt output. The unit has been modified so that the klystron filament power is supplied by a d-c supply, discussed later. The K-band klystron is powered by a universal klystron power supply providing the following outputs: beam voltage of 200 to 3600 volts at 0-100 ma, reflector voltage of 0-1000 volts below beam, and control grid voltage of 0-300 volts. The klystron filaments are also d-c operated. K-band frequency stabilization is accomplished by frequency modulation at 100 kc across the cavity frequency. This signal is fed into a transistorized synchronous detector circuit. (See discussion of synchronous detector below.) The crystal mixer output is fed into a miniature i-f preamplifier having a gain of 30 db, a center frequency at 30 mc, and a bandwidth of 8 mc. This output is fed into a second i-f amplifier having a gain of 60 db, a center frequency at 30 mc, and a bandwidth of 10 me to the 1-db points. The d-c power for all filaments on the antenna itself is provided by transistorized d-c supplies. A total of six such units are built into the facility. Three units, supplying 12 volts at 2 amp, power the i-f and 2K33 filaments. One unit, supplying 6 volts at 2 amp, and another supplying 28 volts at 0. 5 amp, power the remote, electronically controlled variable attenuators. The remaining unit provides 12 volts at 1 amp and supplies filament power to the local oscillator klystron. The synchronous detector system is a device permitting the detection of a signal in noise. It is, in essence, a detector followed by an RC filter. The operation may be described as one of integration over long periods (up to T = 200 seconds) whereby the noise contributes a decreasing output as T is increased. The synchronous detector multiplies by a reference signal both signal and noise of all frequencies present at the input. The reference signal is identical in phase and frequency to the signal to be detected. This multiplication process produces a d-c level proportional to the level of the signal to be detected and a-c signals proportional to the levels of all noise frequencies. A low-pass filter is used to reject all a-c signals of frequency greater than 1/T and produce a d-c output the level of which is proportional to the desired signal. Thus as T is increased the error is decreased, since more of the "noiseproduced" a-c signals are rejected. 15

WILLOW RUN LABORATORIES T E C H N I C A L MEMORANDUM Two oscilloscopes having a maximum sensitivity of 0. 1 mv/cm are provided. A sweep oscillator is available to provide an X-band test signal. This signal is used in setting up and testing the maser system. Continuously adjustable frequency over the entire X-band range (8. 2-12.4 kmc) is provided. Frequency regulation is better than 4 mc. Power output is 10 mw or greater into a matched waveguide load. Also, swept-frequency rf is available in stepwise ranges from 4. 4 mc to 4.4 kmc (full X-band range). The sweep rate is adjustable from 32 mcs to 320 kmcs. Remote control of the various tuning devices is accomplished with slow-speed d-c motors. These motors are rated at 1 rpm at 30 volts input. Regulated voltage is supplied to the more critical electronics by means of a 3000-volt-amp a-c regulator and a 1000-volt-amp magnetic regulator. The a-c regulator provides regulated output voltage of 110-120 volts with input voltages of 95-130 volts. Harmonic distortion is below 3%, from zero to full load. The magnetic regulator is harmonic filtered to 3% distortion and provides regulation ~0. 5% over a 95-130-volt input range from zero to full load.

WILLOW RUN LABORATORIES TECHNICAL MEMORANDUM Appendix A COMPONENT LIST 1. Air Compressor: Montgomery Ward Belt Drive. 2. Amplidynes: Original equipment amplidynes SCR-584B. 3. Antenna: Original equipment 6-foot-diameter, parabolic reflector. 4. Antenna Control Rack: Original equipment; Control Unit BC-1085-B; Control Panel PN-24-b; Indicator BC-1076-B; Tracking Units BC-1086B and BC-1090B; Rectifier Unit RA-141. 5. Audio Oscillator: Hewlett Packard Model 200AB. 6. Blower: Electric Ventilating Company, Model G-1. 7. Cables: See cable list, Appendix B. 8. Cavity: Model 5-186-B1 (see Figure 10 and Reference 3). 9. Circulator Electronics: Special design, Airtron Company. 10. Dewars: One 25-liter liquid-helium storage dewar and one 25-liter nitrogen storage dewar. Superior Air Products Company: 1-maser dewar, modified, Hoffman Laboratories. 11. Finder Scope: Edmund Scientific Company, 7-power objective lens, 60 angular field-ofview. 12. I-F Strips: LeL Model IF 20 B and IF 31 BP. 13. K-Band Equipment (a) Detector: DeMornay Bonardi DBE 319. (b) Directional Coupler: DeMornay Bonardi DBW 631. (c) Frequency Meter: Waveline 989R. (d) Gyraline: Cascade Research K-211. (e) Isolator: Cascade Research K-131. (f) Klystron: Raytheon, High-Power 2K33. 14. Magnet: Arnold Engineering Company, Alnico V. 15. Motors: Globe Industries, C-5A-1165. 16. Oscilloscopes: Hewlett Packard Model 130B; Dumont Model 403R. 17. Phones: Wheeler, Sound Power. 17

W I L L 0W RUN LABORATORIES TECHNICAL MEMORANDUM 18. Power Supplies (a) Dressen Barnes, Model 3-150B. (b) Lambda Electronics Company, two Model 28, two Model 29, and one C-482M. (c) Nobatrons: three Q12-2, one Q12-1, one Q6-2, and one Q28-05, Sorenson Company. (d) Strand Model 10X Stabilized Power Supply, Microwave Development Company. (e) Universal Klystron Supply Model Z815B, FXR. 19. Radio Sets: AN/PRC-10, portable, Signal Corps. 20. Regulators: Sorenson; a-c Regulator Model 3000S and Magnetic Regulator Model 1000 MVRH. 21. Stabilizer: Specially constructed synchronous detector. 22. Synchronous Detector: See Section 4. 2. 23. Vacuum System: Welch Mechanical forepump and Consolidated Electrodynamics diffusion pump type VMF-10. 24. X- Band Equipment: (a) Circulators: Special design, optimized by 8. 6 kmc, one switching and one nonswitching, Airtron Corporation. (b) Comparison Horn: DeMornay Bonardi B-520, 15-db gain at 9 kmc. (c) Crystal Mixer: DeMornay Bonardi G-655. (d) Frequency Meter: Hewlett Packard X532A. (e) Local Oscillator: Strand Model 10X RF unit, Microwave Development Company. (f) Tuners: Special design, see Section 4. 1. 18

WI LLOW RUN LABORATORIES TECHNICAL MEMORANDUM Appendix B MASER CABLE LIST Cable No. Use Description 1 Circulator 3-conductor- special 2 Circulator, spare 2-conductor- Belden 8412 3 Postamp power Preamp power 8-conductor - Belden 8418 4 Magnet coils K-band gyraline X-band gyraline 7-conductor- Belden 3427 5 K-band klystron power 6-conductor-Special high voltage, Alpha Wire Company 6 Strand Supply Power 7-conductor- Belden 8427 7 d-c motor supply 7-conductor- Belden 8427 8 Spare - 7-conductor- Belden 8427 9 Phone lines 3-conductor-Belden 8735 10 Preamp filaments 2-conductor- Belden 8790 11 Postamp filaments 2-conductor- Belden 8790 12 Strand crystal 1-conductor-RG 58 AN BNC 13 Strand crystal 1-conductor-RG 58 AN BNC 14 Postamp d-c output 1-conductor-RG 58 AN BNC 15 Spare 1-conductor-RG 58 AN BNC 16 Spare 1-conductor-RG 58 AN BNC 17 Preamp crystal 1-conductor- RG 54 AN UHF 18 Preamp crystal 1-conductor-RG AN UHF 19 K-band crystal 1-conductor double shieldBelden 8233 20 Postamp video output 1-conductor double shieldBelden 8233 19

W I L L O W RUN L A B O R A T O R I E S T E C H N I C A L MEMORANDUM REFERENCES 1. A. H. Barrett, "Spectral Lines in Radio Astronomy, " Proc. IRE, Vol. 58, p. 250, 1958. 2. M. Bair, L. Cross, R. Terhune, J. Cook, report on mobile X-band maser, Project MICHIGAN technical report in preparation. 3. L. G. Cross, "Silver Ruby Maser Cavity," J. Appl. Phys., September 1959, Vol. 30, No. 9, p. 1459. 20

WILLOW RUN LABORATORIES TECHN ICAL MEMORANDUM DISTRIBUTION LIST 6, PROJECT MICHIGAN REPORTS 1 May 1960 - Effective Date Copies Address Copies Address 1 Office, Chief of Research & Develop- 40 Chief of Engineers ment, Department of the Army Department of the Army Washington 25, D. C. Washington 25, D. C. ATTN: Army Research Office ATTN: Research & Development Division 2 Office, Assistant Chief of Staff for Intelligence Intelligent ofthce Army41 Director, U. S. Army Engineering Department of the Army WDepashitmengtonf 25,he D.A. Research & Development Laboratories Fort Belvoir, Virginia ATTN: Chief, Combat Dev/G-2 ATTN: Chief, Topographic Engineering Air Branch Department 3 Commanding General U. S. Continental Army Command 42-43 Director, U. S. Army Engineering Fort Monroe, Virginia Research & Development Laboratories Fort Belvoir, Virginia ATTN: ATSWD-G ATTN: Chief, Electrical Engineering 4-5 Commanding General Department U. S. Army Combat Surveillance Agency 1124 N. Highland Street 44 Director, U. S. Army Engineering Arlington 1, Virginia Research & Development Laboratories Fort Belvoir, Virginia 6 Chief, Research and Development ATTN: Technical Document Center Division Office of the Chief Signal Officer 45 Commandant, U. S. Army Command & Department of the Army General Staff College Washington 25, D. C. Fort Leavenworth, Kansas 7-31 Commanding Officer, U. S. Army ATTN: Archives Signal Research & Development Laboratory 46 Commanding General Fort Monmouth, New Jersey U. S. Army Combat Development Experimentation Center Fort Ord, California 32-33 Commander, Army Rocket & Guided 47-48 Assistant Commandant Missile Agency U. S. Army Artillery & Missile School Redstone Arsenal, Alabama Fort Sill, Oklahoma Fort Sill, Oklahoma ATTN: Technical Library ORDXR-OTL 49-51 Assistant Commandant U. S. Army Air Defense School 34-35 Chief, U. S. Army Security Agency Fort Bliss, Texas Arlington Hall Station Arlington 12, Virginia 52 Commandant U. S. Army Engineer School 36 Office of the Director, Defense Fort Belvoir, Virginia Research & Engineering Technical ATTN: Combat Development Group Library Department of Defense 53 Commandant Washington 25, D. C. U. S. Army Signal School Fort Monmouth, New Jersey 37 Commanding General, Quartermaster Research & Engineering Command ATTN: SIGFM/SC-DO U. S. Army Natick, Massachusetts 54 Commandant U. S. Army Aviation School 38 Office, Chief of Ordnance Fort Rucker, Alabama Research and Development Division Department of the Army 55-57 President Washington 25, D. C. U. S. Army Artillery Board Fort Sill, Oklahoma ATTN: ORDTB, Research & Special Projects 58 President U. S. Army Air Defense Board 39 Commanding General Fort Bliss Texas U. S. Army Electronic Proving Ground 59 President, U. S. Army Airborne & Fort Huachuca, Arizona Electronics Board ATTN: Technical Library Fort Bragg, North Carolina 21

WI LLOW RUN LABORATORIES TECH NICAL MEMORAN DUM DISTRIBUTION LIST 6, 1 May 1960 - Effective Date Copies Address Copies Address 60 Commanding Officer, U. S. Army 76 Headquarters Signal Electronic Research Unit Tactical Air Command Post Office Box 205 Langley Air Force Base, Virginia Mountain View, California ATTN: TOOA 61 Office of Naval Operations Department of the Navy 77-78 Commander in Chief, Headquarters Washington 25, D. C. Strategic Air Command Offutt Air Force Base, Nebraska ATTN: OP-37 ATTN: DORQP 62 Office of Naval Operations Department of the Navy 79-80 Headquarters Washington 25, D. C. Tactical Air Command ATTN: OP-07T Langley Air Force Base, Virginia ATTN: TORQ 63-65 Office of Naval Research Department of the Navy 81 Commander 17th & Constitution Ave., N. W. Air Technical Intelligence Center Washington 25, D. C. Wright-Patterson Air Force Base, Ohio ATTN: Code 463 ATTN: AFCIN-4B/a 66 Chief, Bureau of Ships 82-91 ASTIA (TIPCR) Department of the Navy Arlington Hall Station Washington 25, D. C. Arlington 12, Virginia ATTN: Code 690 92-100 Commander 67-68 Director, U. S. Naval Research 92-100 Commander Wright Air Development Center WLaboratonry 25, D.C.Wright-Patterson Air Force Base, Ohio Washington 25, D. C. ATTN: WCLROR ATTN: Code 2027 101 Commander 69 Commanding Officer 101 Commander Wright Air Development Center U. S. Navy Ordnance Laboratory Wright Air Development Center U.S.Corona, California LaboratoWright-Patterson Air Force Base, Ohio Corona, California ATTN: WCOSI- Library ATTN: Library 102 Commander 70 Commanding Officer & Director 102 Commander U. S. Navy Electronics Laboratory Rome Air Development Center ~~~San Diego 52, Calif ~ornia ~Griffiss Air Force Base, New York San Diego 52, California ATTN: RCVSL-1 ATTN: Library 103 Commander 71 Department of the Air Force 103 Commander Rome Air Development Center WHeadquarters,.USAF Griffiss Air Force Base, New York Washington 25, D. C. ATTN: RCWIR ATTN: AFOIN- 1B1 104 Director, Air University Library 72 Department of the Air Force ~~~~~~Headquarters, USAF ~Maxwell Air Force Base, Alabama Headquarters, USAF Washington 25, D. C. ATTN: AUL-7971 ATTN: AFOAC-E/A 105 Commandant of the Marine Corps 73 Department of the Air Force Headquarters, U. S. Marine Corps Headquarters, USAF Washington 25, D. C. Washington 25, D. C. ATTN: Code A04E ATTN: AFDRD 74 Department of the Air Force 106-109 Central Intelligence Agency Headquarters, USAF 2430 E. Street, N. W. Washington 25, D. C. Washington 25, D. C. ATTN: Directorate of Requirements ATTN: OCR Mail Room 75 Commander in Chief, Headquarters 110-114 National Aeronautics & Space Strategic Air Command Administration Offutt Air Force Base, Nebraska 1520 H. Street, N. W. ATTN: DINC Washington 25, D. C. 22

WILLOW RUN LABORATORIES TECHN ICAL MEMORANDUM DISTRIBUTION LIST 6, 1 May 1960 - Effective Date Copies Address Copies Address 115-116 Combat Surveillance Project 122-123 Cornell Aeronautical Laboratory, Inc. Cornell Aeronautical Laboratory 4455 Genesee Street Incorporated Buffalo 21, New York Box 168 ~~~~~~~~~~~Box 168 ~ATTN: Librarian Arlington 10, Virginia VIA: Bureau of Aeronautics RepreATTN: Technical Library sentative 4455 Genesee Street Buffalo 21, New York 117 The Rand Corporation Buffalo 21, New York 1700 Main Street Santa Monica, California 124 Control Systems Laboratory Santa Monica, California University of Illinois ATTN: Library Urbana, Illinois ATTN: Librarian 118 Chief Scientist VIA: ONR Resident Representative Research & Development Division 1209 W. Illinois Street Office of the Chief Signal Officer Urbana, Illinois Department of the Army Washington 25, D. C. 125 Polytechnic Institute of Brooklyn 55 Johnson Street Brooklyn 1, N. Y. 119 Stanford Research Institute, Document Center ATTN: Microwave Research Institute Menlo Park, California Library ATTN: Acquisitions 126 The U. S. Army Aviation HRU P. O. Box 428 120 Operations Research Office Fort Rucker, Alabama The Johns Hopkins University 6935 Arlington Road 127 Director, Electronic Defense Group U of M Research Institute Bethesha, Maryland Washington 14, D. C. University of Michigan Ann Arbor, Michigan ATTN: Chief Intelligence Division 128 U. S. Continental Army Command 121 Columbia University Liaison Officer Electronics Research Laboratories Project MICHIGAN, Willow Run 632 W. 125th Street Laboratories New York 27, New York Ypsilanti, Michigan ATTN: Technical Library 129 Commanding Officer VIA: Commander, Rome Air Develop- U. S. Army Liaison Group ment Center Project MICHIGAN, Willow Run Griffiss Air Force Base, New York Laboratories ATTN: RCSSTL-1 Ypsilanti, Michigan 23

AD Div. 6/ 6 UNCLASSIFIED AD Div. 6/ 6 UNCLASFE Willow Run Laboratories, U. of Michigan, Ann Arbor 1. Radiometers- Willow Run Laboratories, U. of Michigan, Ann Arbor 1. RadiometrS RADIO-ASTRONOMY MASERS: TEST AND OPERATIONAL FACIL- Equipment RADIO-ASTRONOMY MASERS: TEST AND OPERATIONAL FACIL- Equipmn ITY by Jerald Cook and R. W. Terhune. Memorandum of Project 2. Radio astronomy- ITY by Jerald Cook and N. W. Terhune. Memorandum of Project 2. Radio asrnoy MICHIGAN. May 60. 20 p. inl. illus., 3 refs. Equipment MICHIGAN. May 60. 20 p. incI. illus., 3 refs. Equipmn (Memorandum no. 2900-100-R) 3. Masers - Applications (Memorandum no. 2900-100-R) 3. Masers pliain (Contract DA-36-039 SC-78801) Unclassified report I. Title: Project (Contract DA-36-039 SC-78801) Unclassified report I. Title:Prjc A low-noise radiometer using a maser preamplifier has been devel- MICHIGAN A low-noise radiometer using a maser preamplifier has been devel- MICBIA oped for radio-astronomy measurements. This radiometer usesa II. Cook, Jerald, and oped for radio-astronomy measurements. This radiometer uses a II. Cook, Jead, n reflection-type cavity maser with the highest known gain-bandwidth Terhune, R. W. reflection-type cavity maser with the highest known gain-bandwidth Signal product in practical use. Satisfactory gain stability and dependable III. Cogntact DA-r-ps product in practical use. Satisfactory gain stability and dependable III. CogntactD-lperformance are presently obtained with a gain-bandwidth product IV.Contract pA309erformance are presently obtained with a gain-bandwidth product IV.Contra of 200. of 200. This memorandum contains a discussion of the electrical and phys- This memorandum contains a discussion of the electrical and physical aspects of the maser facility together with its proposed uses ical aspects of the maser facility together with its proposed uses and operation. Significant diagrams, circuits, and component char- Armed Services and operation. Significant diagrams, circuits, and component char- ArmedSrie acteristics are included. (oe) TcnclIfrainAgency acteristics are included. (oe) Technical InfrmainAec UNCLASSIFIED UC AD Div. S/S UNCLASSIFIED AD Div. 6/6 UNCLASFE Willow Run Laboratories, U. of Michigan, Ann Arbor 1. Radiometers- Willow Run Laboratories, U. of Michigan, Ann Arbor 1. Radiomees RADIO-ASTRONOMY MASERS: TEST AND OPERATIONAL FACIL- Equipment RADIO-ASTRONOMY MASERS: TEST AND OPERATIONAL FACIL- Equipmn ITY by Jerald Cook and N. W. Terhune. Memorandum of Project 2. Radio astronomy- ITY by Jerald Cook and N. W. Terhune. Memorandum of Project 2. Radio atooy MICHIGAN. May 60. 20 p. incl. illus., 3 refs. Equipment MICHIGAN. May 60. 20 p. incI. illus., 3 refs. Equipmn (Memorandum no. 2900-100-R) 3. Masers - Applications (Memorandum no. 2900-100-N) 3. Masers-Apiain (Contract DA-36-039 SC-78801) Unclassified report I. Title: Project (Contract DA-36-039 SC-78801) Unclassified report I. Title:Prjc A lw-niseradomeerusing a ae rapiirhsbe ee-MCIGNA low-noise radiometer using a maser preamplifier has -been devel- II. CooJrad n low-nois radiomesteronm masurmanser prempifierhasio beten dseves a II. Cook, Jerald, and oped for radio-astronomy measurements. This radiometer uses a TerhuneoR, opedfletornai-astronomiy maeasurements. Tihistnw radiometerdusesh Terhune R. W. reflection-type cavity maser with the highest known gain-bandwidth Ter product in practical use. Satisfactory gain stability and dependable IVI iga Corps product in practical use. Satisfactory gain stability and dependable III. CogntactD-3-3 performance are presently obtained with a gain-bandwidth product I. Contract DA-36-039 performance are presently obtained with a gain-bandwidth product IV.Contr01 of 200. SC-78801 of 200. SThis memorandum contains a discussion of the electrical and phys- This memorandum contains a discussion of the electrical and physical aspects of the maser facility together with its proposed uses ical aspects of the maser facility together with its proposed uses and operation. Significant diagrams, circuits, and component char- Armed Services and operation. Significant diagrams, circuits, and component char- ArmedSrie acteristics are included. (over) Technical Information Agency acteristics are included. (over) Tech.iical InfrainAec UNCLASSIFIED UNCLASFE

AD UNCLASSIFIED AD UNCLASSIFIED UNITERMS UNITERMS Radiometer Radiometer Maser Maser Radio astronomy Radio astronomy UNCLASSIFIED UNCLASSIFIED AD UNCLASSIFIED AD UNCLASSIFIED UNITERMS UNITERMS Radiometer Radiometer Maser Maser Radio astronomy Radio astronomy UNCLASSIFIED UNCLASSIFIED

AD Div. 6/6 UNCLASSIFIED AD Div. 6/6 UNCLASSIFIED Willow Run Laboratories, U. of Michigan, Ann Arbor 1. Radiometers- Willow Run Laboratories, U. of Michigan, Ann Arbor 1. RadiometersRADIO-ASTRONOMY MASERS: TEST AND OPERATIONAL FACIL- Equipment RADIO-ASTRONOMY MASERS: TEST AND OPERATIONAL FACIL- Equipment ITY by Jerald Cook and R. W. Terhune. Memorandum of Project 2. Radio astronomy- ITY by Jerald Cook and R. W. Terhune. Memorandum of Project 2. Radio astronomyMICHIGAN. May 60. 20 p. incl. illus., 3 refs. Equipment MICHIGAN. May 60. 20 p. incl. illus., 3 refs. Equipment (Memorandum no. 2900-100-R) 3. Masers - Applications (Memorandum no. 2900-100-R) 3. Masers- Applications (Contract DA-36-039 SC-78801) Unclassified report I. Title: Project (Contract DA-36-039 SC-78801) Unclassified report I. Title: Project MICHIGAN MICHIA A low-noise radiometer using a maser preamplifier has been devel- II Cook, Jerald and A low-noise radiometer using a maser preamplifier has been devel- II. Cook, oped for radio-astronomy measurements. This radiometer uses a oped for radio-astronomy measurements. This radiometer uses a Ter e.W reflection-type cavity maser with the highest known gain-bandwidthTehnRII.SgaCop production-typrcacitic uase. Satisfctoy higastabilityk andneopendable III. Signal Corps reflection-type cavity maser with the highest known gain-bandwidth omete sina product in practical use. Satisfactory gain stability and dependable IIV. Contract DA-36-039 product in practical use. Satisfactory gain stability and dependable IV. Contr performance are presently obtained with a gain-bandwidth product SC-78801 performance are presently obtained with a gain-bandwidth product SC- l of 200. of 200. This memorandum contains a discussion of the electrical and phys- This memorandum contains a discussion of the electrical and physical aspects of the maser facility together with its proposed uses ical aspects of the maser facility together with its proposed uses and operation. Significant diagrams, circuits, and component char- Armed Services and operation. Significant diagrams, circuits, and component char- Armed Services acteristics are included. (over) Technical Information Agency acteristics are included. (over) Technical I UNCLASSIFIED UNCLASSIFIED AD Div. 6/6 UNCLASSIFIED AD Div. 6/6 UNCLASSIFIED Willow Run Laboratories, U. of Michigan, Ann Arbor 1. Radiometers- Willow Run Laboratories, U. of Michigan, Ann Arbor 1. RadiometersRADIO-ASTRONOMY MASERS: TEST AND OPERATIONAL FACIL- Equipment RADIO-ASTRONOMY MASERS: TEST AND OPERATIONAL FACIL- Equipment ITY by Jerald Cook and R. W. Terhune. Memorandum of Project 2. Radio astronomy- ITY by Jerald Cook and R. W. Terhune. Memorandum of Project 2. Radio astronomyMICHIGAN. May 60. 20 p. incl. illus., 3 refs. Equipment MICHIGAN. May 60. 20 p. incl. illus., 3 refs. Equipment (Memorandum no. 2900-100-R) 3. Masers - Applications (Memorandum no. 2900-100-R) 3. Masers- Applications (Contract DA-36-039 SC-78801) Unclassified report I. Title: Project (Contract DA-36-039 SC-78801) Unclassified report I. Title: Project A low-noise radiometer using a maser preamplifier has been devel- MICHIGAN A low-noise radiometer using a maser preamplifier has been devel- C oped for radio-astronomy measurements. This radiometer uses a.erald, and oped for radio-astronomy measurements. This radiometer uses a Ter. reflection-type cavity maser with the highest known gain-bandwidth Terhune, R.C W. reflection-type cavity maser with the highest known gain-bandwidth product in practical use. Satisfactory gain stability and dependable IV. Sinal Corps product in practical use. Satisfactory gain stability and dependable I. Signal Corps performance are presently obtained with a gain-bandwidth product performance are presently obtained with a gain-bandwidth product of 200. of 200. This memorandum contains a discussion of the electrical and phys- This memorandum contains a discussion of the electrical and physical aspects of the maser facility together with its proposed uses ical aspects of the maser facility together with its proposed uses and operation. Significant diagrams, circuits, and component char- Armed Services and operation. Significant diagrams, circuits, and component char- Armed Services acteristics are included. (over) Technical Information Agency acteristics are included. (over) Techaical I UNCLASSIFIED UNCLASSIFIED

AD UNCLASSIFIED AD UNCLASSIFIED UNITERMS UNITERMS Radiometer Radiometer Maser Maser Radio astronomy Radio astronomy UNCLASSIFIED UNCLASSIFIED 3( i AD | UNCLASSIFIED AD| UNCLASSIFIED E _ UNITERMS UNITERMS Radiometer Radiometer Maser Maser Radio astronomy Radi o astronomy UNCLASSIFIED UNCLASSIFIED