# Oral-History:Howard Doolittle

Howard Doolittle got his BS at Trinity College, his PhD in nuclear physics from the University of Chicago in 1936, and he then taught at Trinity College for five years. Recruited by Luis Alvarez (a fellow graduate student at the University of Chicago) for the Rad Lab in December 1940—January 1941, he became its 92nd member. At the Rad Lab he worked on modulators; Doolittle believes his most important work was on the 584, and on developing pulse transformers and pulse networks. Doolittle generally notes cooperation between industry and the Rad Lab; his knowledge base includes EIMAC, Machlett Laboratories, GE, Westinghouse, Bell Labs, and ITT. He talks somewhat about the design and production process, though he had relatively little to do with the production end. He also mentions collaboration between the Rad Lab and Germeshausen at MIT, building hydrogen thyratrons. After the war, Doolittle went to work for Machlett Laboratories; he stayed at the same job when they were bought by Raytheon in 1960; he retired in 1975.

HOWARD DOOLITTLE: An Interview Conducted by Andrew Goldstein, IEEE History Center, 11 June 1991

Interview #076 for the IEEE History Center, The Institute of Electrical and Electronics Engineers, Inc.

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It is recommended that this oral history be cited as follows:

Howard Doolittle, an oral history conducted in 1991 by Andrew Goldstein, IEEE History Center, Piscataway, NJ, USA.

## Interview

Interview: Howard Doolittle

Interviewer: Andrew Goldstein

Date: 11 June 1991

Location: Boston, Massachusetts

### Background

Goldstein:

This is an interview at the Haines Convention Center in Boston with Dr. Howard Doolittle from the MIT Rad Lab on June 11, 1991. Dr. Doolittle, thank you for meeting with me. Could you tell me briefly about your background, your education?

Doolittle:

I graduated from Trinity College, with a bachelor of science degree, at Hartford, Connecticut. Then I went to the University of Chicago where I got my Ph.D. in June of '36.

Goldstein:

Doolittle:

Yes. I taught physics in Trinity College in Hartford five years. Then I moved up to the Radiation Lab, and I was the 92nd member of Radiation Lab. After Radiation Lab was over, I went to work for a company known as Machlett Laboratories in Stamford, Connecticut. They were working on tubes of various sorts: x-ray tubes, high-powered radio transmitting tubes, light amplifier tubes and eventually on x-ray imaging intensifiers for use in hospital applications, fixing people's innards. Raytheon bought Machlett out about 1960, and I retired in 1975. I've been retired since then. I've done a little consulting but mostly on historical matters. Some math problems that arise from stuff that was done a long time ago.

### Education and Recruitment to Rad Lab

Goldstein:

You say you were the 92nd member of the Rad Lab staff.

Doolittle:

Yes.

Goldstein:

How did you become aware of the Rad Lab or the subject of radar?

Doolittle:

Well, one of my colleagues was a graduate student in physics at Chicago, Luis Alvarez, (a Nobel laureate in 1968). He picked three or four other people that were at the University of Chicago at that time, and recommended them for coming to MIT. I was at teaching at Trinity, and this was in January of '41. Trinity College was all for supporting the war effort. Of course the physics department didn't like it too well because they had to get somebody to fill in for me, and there was a demand arising at that time for physicists in military and other associated work. It wasn't easy for them to find somebody that was qualified. I must admit I had some misgivings about leaving them in the lurch, but what can you do?

Goldstein:

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What was your relationship with Alvarez prior to Rad Lab? You said you came to know him at Chicago?

Doolittle:

Yes. He was a student there for a Ph.D. at Chicago at the same time I was there. There was a graduate fraternity called Gamma Alpha, and Luis and I were members of that. There were about a dozen other physicists, too. In fact, half of the members of Gamma Alpha were physicists. There were a couple of medical students, two or three chemists, and some geologists in this group there. The advantage of Gamma Alpha in those days was that somebody had given them a house. It was a regular, three-story house near the university. This was run as a project by the members. We had hired a lady as a cook and her husband as a house cleaner. Those were our two employees to keep the house going. We had upstairs bedrooms. There were three people to a bedroom, each had a desk. Then there were two larger bedrooms in the front and back of the house upstairs, and they had several double-deck bunks. They would put two side by side with an aisle so you could get to the next two. And everybody was sleeping up there in that area. That gave the main bedrooms enough room so we could have a desk and a little place where we could do some work.

At that time room and board cost me approximately $45 a month, in that arrangement. Luis Alvarez describes it in his book as a pretty ratty place, but for many of us it was a godsend and I don't know what we would have done without it. Luis Alvarez's father, as you may know, was a medical doctor. So I'm sure his father had the necessary finances for him to live in better quarters. But there was a camaraderie of a group of physicists living in close proximity that was something that he thought more than compensated for the rather primitive conditions under which we lived. Goldstein: After you left the University of Chicago and returned to Trinity, some years after that, did Luis Alvarez get in touch with you? Doolittle: Yes. December of '40. Goldstein: What was your training in physics? What work had you been doing? Doolittle: Oh, I worked in nuclear physics. My Ph.D. project was accelerating protons to bombard lithium, which broke down into two alpha particles. So I plotted the alpha particles yield versus the energy of the incoming proton, from as low as 60 kV up to about 110 kV. A theory had just come out and was called tunneling, which said that the proton could penetrate the potential barrier of the lithium at lower energies than anybody had previously thought. So it was my job to get together equipment and stuff to see if you couldn't do this at lower energies, and indeed you could. I think 60 kV was about as low as I got. It was very easy to detect the alpha particles because they were very high energy alpha particles. So any accidental radiation from stray sources permitted a high signal-to-noise level because there weren't many other radiation items with that energy. Goldstein: So Alvarez contacted you to come work at Rad Lab. What job did he have in mind for you? Doolittle: Well, he didn't have anything in particular. He just recommended these various people. The general theory at Rad Lab among the founders was that they would pick people who had worked in nuclear physics because that was new and modern and up-and-coming. They thought that people in that trend were more apt to be live wires than somebody who was willing to work in something obscure. It might be just as important, but who knows? So that was their basis originally, to pick those they thought would be in the leading edge. Goldstein: They were looking for the personality traits that led someone to be a nuclear physicist? Doolittle: Yes. Goldstein: Not their training? Doolittle: Right. Not their training at all. ### Modulators and EIMAC Tubes Goldstein: What was your first job at Rad Lab? Doolittle: Well, a Dr. Dunning was running the modulator group for the first year or so I was there. He got ill, and I superseded him. He was still capable of operations, but they put him in a job that didn't have administrative duties. When I arrived they asked me what I'd done recently. I'd done some work with 10-meter generation of radio waves. So they said I should be in magnetrons or modulators. I could see they wanted somebody in modulators, so that's where I went. The first job I had was to get together the modulator to operate the SCR-584, a ground based radar to follow planes and buzzbombs invading England. I had to deal with the manufacturers after the pilot model was worked out. When I got the job, it was about half done. Goldstein: Was this the fall of '40? Doolittle: This was '41. Goldstein: Oh, okay. This was the time when you were under Dunning. Doolittle: Yes. The low power levels were fairly well worked out. Now the problem was to get up to magnetron power levels and to find some suitable vacuum tubes. We had Raytheon build some special tubes — and see what we thought was best. We ended up with some EIMAC production tubes. The EIMAC tubes took more drive because they were triodes instead of tetrodes. But on the other hand, they had been in production a while, and so the production techniques were well known. We ran into a problem with EIMAC because they were up-and-coming people in the radio power tube area at that time. They considered all their know-how to be very secret. But the services who wanted the SCR-584 wanted a second supplier, and they picked Machlett Laboratories, who was willing to get into the business although they hadn't been in that business before. Mr. Machlett started making x-ray tubes in 1931. Prior to 1931 GE had a patent known as the Coolidge Patent. The Coolidge Patent involved having a tungsten coil as a cathode emitting electrons. If anybody wanted to make an x-ray tube, GE held the patent and would not license it. So Machlett started working on x-ray tubes when the patent expired in 1931. Mr. Machlett's father was a glassblower from Germany. Machlett started out with gaseous x-ray tubes. These operated by generating ions in the x-ray tube, but they weren't very reliable. With a hot cathode, you could get a good vacuum, emit electrons, hit a target, and generate the x-rays. You could even govern the spot size on the target. The gas tubes worked after a fashion. They suffered from gas clean up giving a higher vacuum and stopped working. They had a little do-hickey in the tube which you would spark to, that would generate enough gas, and hopefully not too much, to let you operate it again. So they played with those for about a year. Then the Coolidge Patent expired. Ray Machlett knew this was coming, and he was getting things ready. He went ahead and started making x-ray tubes. At that point he found out there were a number of companies making x-ray equipment. But they had to buy their tubes from GE, and GE's latest and hottest tubes for the best possible equipment were available only through GE. They were tickled to find another source of x-ray tubes at Machlett. That's what got Machlett started in the Depression years. Machlett could make the latest improved type of x-ray tube. In fact, he was more successful than others in getting a rotating anode tube to market. This allowed much more intense and controlled x-rays. Machlett came out with the tube for that. You had to have ball bearings in the vacuum, and he got the ball bearings in the vacuum to work by coating steel balls with a very thin layer of silver. These balls would stand up to, say, 100,000 exposures. Now of course an x-ray exposure covers a pretty short time. The cost of replacing the x-ray tube every 100,000 exposures was about two to five cents per exposure, which was less than the cost of the film. So it was economically feasible. When the war came along, the services were looking for a second source for transmitter tubes and they shopped around. They knew Machlett labs had a good reputation in the x-ray business, and most of those tubes are concerned with very high voltage, 100 to 150 KV. Machlett labs started out by making tubes for this SCR modulator for the SCR-584. They rented a space in Norwalk, CT and started making them. The idea was they could get information on how to do it from EIMAC because EIMAC invented the tube. I don't think they had a particular patent on it. The only secrecy they had was that they had some tricks. They weren't anxious to say, "Well, come on out, we'll show you how to make it." In fact, the first time Machlett sent the vice president out there to look into it, he never got near it in the plant. Machlett learned how to make them by cut-and-try, the same way as anybody else would do, and they succeeded. So they became the second supplier, and that was where I first met Machlett. Goldstein: Was that a common procedure on the part of the Rad Lab, to determine a certain tube was needed, find it in the product catalog of EIMAC or others and then, for reasons of economics, find a second supplier? Doolittle: Not just economics. Suppose somebody blew up EIMAC? Goldstein: Security as well? Doolittle: Yes. Goldstein: Was that common? Doolittle: It was fairly common, I'd say. Yes. Goldstein: In your design work, when you were working on modulators, did you often rely on existing tubes? Or did you discuss with other Rad Lab departments the feasibility of constructing your own to specific specifications? Doolittle: We didn't actually make any transmitter type tubes there at Rad Lab. Rad Lab did make magnetrons and hydrogen thyratrons but not in production. We dealt with somebody in the tube-making business. So we dealt with Raytheon and others. We got them to build some high-powered modulator tubes, 100 kV. As I say, we ended up with the EIMAC triode in the modulator, mainly because it was a production tube. Raytheon really had its hands full with magnetrons and everything else. Cost-wise it was better to use something that existed. But if it didn't exist, then we certainly went out and created it. So that was my first job, getting the whole modulator together. Our measuring techniques for pulses were just being developed, and we had to establish means for determining pulse shape and amplitude. If you want to measure a 100 kV one-microsecond pulse, how do you do it? The resistor dividers for a 100 kV in those days weren't good. You can put two resistors in series, but in the microsecond pulse there's inductance to worry about, and capacitance. So it was a pretty tough job to know when you had a suitable pulse, but of course you could always connect it to a magnetron to see if it worked properly. But on the other hand, you really wanted to know just what the voltage was, if for no other reason than to put it on the specification so that production is uniform. ### Relations with Private Industry and Military Doolittle: The 584 was made by both Westinghouse and GE. We didn't run into any great problems transferring the information there. When it came to 100 kV DC power supplies, this wasn't a big problem — 100 milliamps supply, on the average. Both Westinghouse and GE had very good know-how on how to cope with that sort of thing when we gave them the specifications of what we wanted. GE and Westinghouse were also working out the driver's stages. When they got their models in, we checked one or two out to make sure they were okay. I remember probably the first test I ever made involving the first complete SCR. That was one put together in some part of the Radiation Lab. We had these people from the Signal Corps up to see what we could do with the device. I remember this sergeant walking through the place. We had cables and lots of equipment spread into two trucks this way and that. And the sergeant said: "You expect to get all this shit to work at once?" Goldstein: Did it work in the demonstration? Doolittle: Yes. But he wanted to know what happens when you get out in the field and somebody walks across these cables with muddy boots on. Goldstein: Well, it's an interesting question. To what degree was the military involved in specifying the design requirements? Doolittle: Well, that was Ivan Getting's job. He dealt with them, and he would tell them about the overall specifications for the equipment. Then of course that was broken down into what magnetrons are needed. We had to get a modulator that would drive the magnetron. I didn't get connected with the whole system. I knew what was going on. That was probably one of the most successful parts of Radiation Lab. Nobody there with clearance could be denied knowing what the hell was going on anywhere else in the place. Now contrariwise, I note that out at Los Alamos, when they were working on the atom bomb, the Army tried to keep things departmentalized but spies were still successful. The modulator group, if it were out there, would not know anything about magnetrons other than how many volts and amps they wanted and how long a pulse. Goldstein: Were they working with black boxes? Doolittle: They were working with black boxes and so on. Of course the reason the Army did this at Los Alamos was that they were scared of all the secrets getting out. And why did you have to know anything about magnetrons if your only concern is the modulator? But you know as well as I do, if you know what the whole picture is, you're a lot more efficient than if you're confined to one quarter. Goldstein: Can you think of any examples where your understanding of the full system improved your design? Doolittle: Yes. One thing that helped a great deal was that somebody in each group knew who an expert was in any area you wanted expertise. As we were working on the modulators you get into pulse transformers which were developed in my section, we were wondering "how are you going to find out the state of the art?" Nobody in my group had ever built a pulse transformer before. What are the requirements, and how do you get at it? We didn't have any native expertise in the group, but by stating our problems to anybody and everybody, somebody would say, "Well, Sy Sonkin in New York University has a little expertise on that." You'd get a hold of him, and hire him. Somebody else would say, "Westinghouse is pretty good." They'd give you the name of the person, so you could get these people together. Westinghouse developed a transformer iron core. You need very thin insulated laminations for the transformer core. Nothing like the 60-cycles transformer. You use very thin cores; very unique, very thin. Westinghouse C cores. You need no air gap in the core if you allow transformer cores to be stacked. If there's an air gap, it ruins everything. Westinghouse developed this C core. Do you know what a C core looks like? Goldstein: Instead of an iron core, it's a loop that way. Doolittle: Yes. It looks like two C's put together. And they put a strap around the two parts. You could put the coils in the C's. Then you put the metal strap around the two C's and pulled the two halves together so that there was very little air space. A Mr. Zanzimeer had developed a machine to produce the very thin lamination required. Westinghouse was their customer. Bell Labs had some pulse transformers, they had their own expertise, and they developed something different than we did through Radiation Lab and Westinghouse. We started to get into gaseous discharge devices like hydrogen thyratrons and spark gaps. For high-voltage equipment there weren't many vacuum tubes available at that point in time. But spark gaps were the original high-voltage rectifiers for x-ray tubes way back in the 1920s. So we did a lot of spark-gap work, and there we got involved with a fellow, Harry White, who worked with smoke precipitators. He had a lot of experience with spark gaps. Goldstein: You said you were one of the earliest at the Rad Lab working on modulators. In the beginning, did you and your group turn to Bell Labs or some other industrial manufacturers? Doolittle: We worked very closely with Bell Labs. Bell Labs was very open. Goldstein: Had they already been doing work with modulators? Doolittle: Yes. They were building systems. They didn't build a 584. They worked a lot on aircraft systems. A fellow by the name of Glasoe in our group developed an airborne radar for support and deployment in fighter planes. It used a pulser tube of BTL. Find the other guy and shoot him down. Bell Labs developed some equipment of that sort. They developed some of their own spark gaps, and we developed with Germeshausen at MIT the hydrogen thyratron. In connection with that we needed pulse-forming networks, which are an L.C. arrangement much like electrical filters. You charge up the condensers, and when you discharge them to a load, you get a microsecond or two microsecond pulse, depending upon how you designed it. So all you had to do was talk to Germeshausen at MIT, and he'd say, "Oh, you ought to go see so-and-so." MIT had experts on filters and L.C. circuitry, Prof. E.A. Guillemin. ### Internal Communication Goldstein: I understand that there were weekly seminars, but there was also informal communication between colleagues across the benches. Which network was more effective? Doolittle: Well, I think the general seminars were more effective to brief you on the overall picture, just what the 584 was supposed to do, and how it was supposed to do it, and what the requirements were. We would get from seminars a sense of the whole thing. For example from W.W. Hansen an expert on microwave generation, from S. Schwinger an expert on microwave wave guides. Also there were seminars by armed service people defining their needs and discussing their problems. I would say our informal seminars helped in two ways: you were trying to find some help in an area in which you needed help; or you had some questions that you didn't quite understand about part of the overall picture that came out in the seminar. You just chatted with people and got yourself straightened out on that. You could say that you got to have thus and so solved, and it was a lot easier and quicker, you could straighten it out between yourselves. Are we good enough to go ahead with it, or have we got to get better? ### Hydrogen Thyratrons Goldstein: I'm trying to understand the daily operation of you and your group. You said you were working on hydrogen thyratrons. Doolittle: Thyratrons. That's a gaseous discharge, but it's in a controlled environment i.e. a sealed-off tube. Goldstein: Would that work, developing a tube which would perform a particular function? Doolittle: There existed mercury thyratrons, but those have some disadvantages. The temperature of the tube is crucial to its proper operation. So if you're going to stick it out in the Saudi Arabian desert, you've got to carry a lot more garbage to be sure that the ambient temperature of the mercury thyratron is proper. Germeshausen had the idea of developing a thyratron with hydrogen gas instead of mercury. Such a tube would operate over a wide range of ambient conditions. Goldstein: If you found yourself in a situation where you needed a specific tube, a tube that didn't fit, what were your options? Could you work within the Lab to develop it? Or could you discuss this with Raytheon or some other manufacturer to develop it? Doolittle: Well, this particular development was actually done by Germeshausen at MIT. He was a professor at MIT. However we dealt with any tube manufacturer as needed. Goldstein: Oh, he wasn't working with the Rad Lab? Doolittle: Oh, he was working with Rad Lab, they had assigned him to Rad Lab as part of his work. But on the other hand, he was still doing some work on his own stuff. One thing he was working on was short intense beams of light for airplanes to take night pictures of some location. He developed strobe lights that would give a very intense light source that you would need for taking the pictures. That had nothing to do with microwaves, and he was doing that at MIT. He had developed spark sources in the Lab, and he had this idea about hydrogen thyratrons. He did work with our modulator group on the hydrogen thyratron, but he actually made the first tubes himself in his lab where he made flash bulbs for this night photography. So he made the first tubes himself. Then we became involved with what was then called Bomac. Sylvania bought them out eventually. They picked it up and worked the hydrogen thyratron into production. They wanted us to work with 50 or 60 tubes and find out how long they would live. We ran light tests for them. Then Bomac would build the quantities involved. Goldstein: So this is a case where you worked essentially internally to develop this tube. But did you ever consult with a tube manufacturer? Doolittle: Oh, yes. We consulted with them. Another fellow made hydrogen thyratrons for us is a company called Kuthe Labs. They were down in Newark, New Jersey. We worked very closely with them. We gave them all the details, and they worked it out. Mr. Kuthe was very successful at making tubes. He was a lone wolf. He'd made some gaseous tubes for Bell Telephone Labs. That's how we got hold of him. We would hear, "Well, there's this little guy over in Newark at Kuthe Labs. Why don't you go talk to him? He's done a very good job with some fancy gaseous tubes that we had him make." Kuthe's stock-in-trade at that particular time was making little starters for fluorescent light fixtures — you know those little plug-in things? He made those, and I've still got a few of them kicking around the house. Kuthe Labs are no longer in business. He was bought out by Bendix. Mr. Kuthe's wise supervising production of flourescent light starters. They had these girls assembling these fluorescent starters. They each had a little job to do. I don't know how you could keep up that concentration. But every hour there would be a five-minute coffee break. She would ring a bell and everybody left their seats instantly and went and got a drink or a coke. Five minutes later she'd ring a bell. Zoom! Everybody was back there. I never saw anything like it. Goldstein: So you went down to Kuthe Labs? Doolittle: Oh, we went down there many, many times. Goldstein: To supervise production? ### Relations with Private Industry Cont'd. Doolittle: To provide equipment design for testing tubes and answering questions. When you talk about the relations with industry, one thing I ran into with pulse transformers, which was a little annoying, was besides the power pulse transformers to drive the magnetrons, there were little inter-stage transformers. We did develop some of those. Then we would go out and get some manufacturer. It might be Westinghouse or others. Sometimes it depended upon who said they could afford the manpower to crank the stuff out. So we would get this all made up, with specifications for the transformer. We'd develop the initial transformer. Some company would get a job to build a complete system. Then we'd go out to his modulator group and tell them to get this little pulse transformer. I'd use specifications from Westinghouse. "Well, I'm sorry, we don't deal with Westinghouse. We get all our transformers from Joe Zilch." So will you kindly tell Joe Zilch & Company how to make the transformer? We don't have the time. I mean, we've got our suppliers. They always won out because they just held you up from doing anything else. We then assisted their supplier in making the desired unit. Goldstein: Really. And then you had to get White Westinghouse to license to Joe Zilch? Doolittle: No. There was no license involved. It was our design. Westinghouse built our design at first. We didn't have a patent on it, but Westinghouse would have a hard time saying that they designed it. They might find some nook or cranny, but things were much more open [then]. I don't think even the commercial companies worried too much about it. More than likely, when Machlett started making the Coolidge-type x-ray tubes, GE started looking around for all the other patents. Okay, they can't cover that one any more. It's expired. But maybe we can get them on something else. RCA and most any of them would talk with anybody from Radiation Lab and discuss where they were. I always remember a couple of years after Radiation Lab closed, I called up a fellow named Spitzer in the power tube business in RCA, and I asked him a question. He said, "Well, you know, now that the war is over, we're not quite as open as we used to be. So I'm afraid I can't answer your question." Goldstein: Did you feel that industries were being cooperative in the enterprise? Doolittle: Oh, yes. The only place where I could say that they weren't particularly cooperative was when we'd say, "Well, we've developed this pulse transformer, and it's in production over here. Why don't you buy it from there?" "No, no. You give the specifications to our supplier, and we'll buy it from him. That's who we buy from." That's about the only real case I can think of where I learned that certain radio manufacturers had their usual sources for components. Goldstein: How involved were you in these contractual negotiations or supervision? As you were the designer, what was your responsibility? Doolittle: It was my responsibility to see that the specifications and requirements were transferred. But I didn't get involved in the financial end of it. Goldstein: Did you recommend any particular manufacturers? Doolittle: Oh, yes. We could recommend particular manufacturers. But there was a problem there too. If you have GE and Westinghouse tied up in manufacturing 584s and maybe a couple of other radars, and you want to start a new system, can they handle it with what they've already got? Goldstein: Do you think industries coveted Rad Lab contracts? Did they come looking for business from you? Doolittle: Oh, yes. EIMAC had a local representative in the Boston area who made a fortune out of it because he had a contract with EIMAC before Radiation Lab had gotten started. His contract was based on a percentage of sales. When Radiation Lab was buying 6C21 tubes and various other IMAC tubes, they sold great quantities of them. EIMAC told him we should cut your contract down to 2 percent — I'm just picking a figure out of a hat, of course — instead of 5 percent. But he had a contract, and he held them to it. Goldstein: Did you work cooperatively with industrial research labs? Bell Labs was one we said before. Doolittle: Right. Goldstein: And what about the others, GE, Westinghouse? Doolittle: Not too much in the design. That was pretty much done here in the early days. Later on, various manufactures did their own design for a particular service. When it got to the point where companies were so loaded when you had a new development, Radiation Lab started a pilot manufacturing plant, I guess you could call it. What did they call it? It was on Albany Street. Goldstein: Oh, are you talking about the RCC? ### Selling Ideas to Military Doolittle: Yes. So if you had a new radar, say, for chasing submarines or MTI, Moving Target Indication, or something like that, this group would take Radiation Lab's design — modulator, magnetron, etc., and build a limited number of units, maybe a couple dozen sets, which would then go to whatever service was interested. There had to be a little selling in some cases. I remember one time somebody said: "Why is it it's so much easier to sell the Navy a radar set than it is to the Army?" Guy said, "Well, that's easy because in the Navy the captain is on the ship." I tell you that just because it illustrates that you didn't just build the stuff and tell the Signal Corps, "Oh, this is wonderful. Take it and use it." You had to get them to agree it was wonderful. Goldstein: Even if they had requested a particular piece of equipment or capability? Doolittle: Yes, they had to be shown. I guess with the SCR-584 and some of the earlier stuff, it wasn't quite so much of a job. Although I told you about the sergeant who said, "How do you get all this shit to operate at one time?" So there was some skepticism on their part. There's another thing. With the Army you have to go through channels which bottled things up a little bit. In Radiation Lab, if somebody had a bright idea for a microwave mixer and he was actually in the systems group, he might look for somebody else who would go talk to Bob Pound, an expert in that field, and say, "Hey, I've got an idea how to do this." He didn't have to go up through DuBridge and come down through channels to talk to him. He just walked across the hall and talked. So when you get to the Army, you might even satisfy a sergeant that this was a helluva good equipment and he ought to have it, but that doesn't solve the problem. Goldstein: Right. Doolittle: You've got to get it through their top brass. Now he can go up his ladder and say to the top brass, "I think it's great." Or go up through his ladder and say, "I don't know how you can get all this shit to work at once." Well, it's not just his say-so. I'm sure that it would involve other sentiments from other people that witnessed the original tests. ### Modulators and Bell Labs Goldstein: So who were you working under in the modulator group? Doolittle: M.G. White at first, then Zacharias. Goldstein: What was your next assignment at Rad Lab? Doolittle: I stayed the head of the modulator group until the end of the war. Goldstein: Were you always working on the modulator for the 584? Doolittle: No. That job was completed by early 1942. We did various and sundry modulators for land-based, ship-based and for aircraft. The first airborne radar used a Model 3 Pulser. It was for a lightweight airborne search radar for aircraft interception. It was used for other things, too. Then we built a modulator for submarines. In those days the submarines had to surface for air every now and then. So a submarine with radar could come up, and if he saw something around that wasn't to his liking, he could dive, or try to torpedo it, or what have you. That unit was actually manufactured by Raytheon. Then there were various ground-based radars such as MEW, the Microwave Early Warning. We collaborated with Bell Labs on X-band radars for aircraft. Goldstein: What would Bell Labs bring to a collaboration like that, and what would you bring? Doolittle: They would bring their idea of what the modulator requirements would be and how they proposed to do it. They would ask you for your opinion. You have information that says we could do better in some other direction. At one point we tried to talk them into hydrogen thyratrons, but they had developed a spark gap to discharge a pulse network to give a microsecond pulse. They were a little skeptical about the hydrogen thyratron. There was a problem in avoiding gas cleanup. We had about ten Thyratrons built in which nine tubes lasted for at least a thousand hours. And I don't think their spark gaps were much better — maybe a couple thousand hours. But after all, they were responsible for the complete system, not just the modulator. And they preferred to go with spark gaps, so we didn't succeed in selling them the hydrogen thyratron. In general, if we developed a pulse transformer, they didn't use silicon cores which we used. Bell Labs developed their magnetic material, and they preferred to use their own material. So in that case, they would not take our design. They would take our specifications: input power, current, output, and make their own. Their magnetic material was somewhat different from ours. All they had to know was the input and output. Goldstein: Would you at the Rad Lab seek out collaborations like that? Did you think there was a lot to be gained by working with Bell Labs? Doolittle: Oh, yes. They had a lot of expertise, of course. Particularly at the lower power levels, from telephone equipment that was a lot more refined. They started out with perhaps not much more information in the modulator area than we had. Goldstein: Was their staff in physics as heavy as yours was? Doolittle: Yes. Goldstein: Really? There were physicists working there? Was this specially geared up for the war effort, or was this part of their ongoing research projects? Doolittle: Ongoing research programs, they had quite a few physicists. Goldstein: Was there any limitations on the sort of information you could disclose to Bell Labs? I'm thinking now of security issues. Doolittle: Not as long as we were talking with people who were cleared. As far as I know there were only two types of clearance: Q clearance and the general clearance that most everybody at Radiation Lab had. Q clearance was primarily for the atom bomb. As I recall, the Air Force cleared you. The Signal Corps, the Army, and the Navy accepted that. So if we were going down to Bell Labs, we would get a clearance form through separate channels. We couldn't just knock on the door and walk in. If we said we wanted to see so-and-so, we would set up a date. They didn't have fax machines in those days, I guess, but Radiation Lab personnel were cleared at Bell Labs. I never had a case of their objecting, they might have pointed out so-and-so is going to be out of town. How about another date? Because in those days plans sometimes changed at the last minute. Goldstein: Did concerns like that disincline on any occasion a collaboration between Rad Lab and outside industries? Doolittle: Not as far as I knew. Goldstein: Did any sense of competition exist? Doolittle: No, I don't think so. ### Postwar Career Goldstein: Audio File MP3 Audio (076 - doolittle - clip 2.mp3) What did you go on to do after? You said you were at Rad Lab until it closed up in '45. Doolittle: Then I went to Machlett Laboratories. They were starting from the war effort with the pulser tubes for the SCR-584; they had gotten into radio transmitters tubes. Machlett Laboratories built the first transmitter tubes for GE's FM stations. Those tubes came out of a design of Bell Labs. I also got involved with Los Alamos and Q clearance and tubes for altimeters to be used in the atom bombs. When you drop an atom bomb, you want it to explode 200 feet off the ground, 500 feet off the ground, or what have you. So they built radar altimeters using UHF triode tubes, which Machlett made. So we went ahead and built various and sundry other power transmitting tubes. A lot of the effort was in the industrial area for Rf heating, curing plastics, rayon drying, making steel tubing. They take a sheet of steel and some rollers. They would gradually bend it up to make a tube, say 3" diameter and bring it together, and weld a seam down uniting the two halves, turning the sheet of steel into a tube. So that took a lot of high power. This wasn't a particularly high frequency, 13 or 27 megacycles, pretty high compared to normal AM broadcast. But we built a lot of tubes for FM. It was around 1952. Bell Labs was impressed with Machlett's coming up with some innovations in this area. They faced a problem. They were making and selling regular radio broadcast transmitters and tubes. But they weren't making the profits that they were making on the telephone business. Goldstein: Right. Doolittle: It wasn't a big business to them, so they decided to quit making transmitters. But their problem was that there are transmitters out which would need tube replacements. Machlett took over the line of power tubes that Bell Labs made via Western Electric in order to keep the sockets going. They may have sold an FM set the next week before this decision was made. Now they can't very well tell the customer "Sorry. You go find somebody to make your tubes." Goldstein: You became involved with Machlett Laboratories through your interactions with them during Rad Lab? Doolittle: Yes. Goldstein: Was that a common experience? What were the circumstances? Rad Lab was closing down. Doolittle: Yes. We were looking for jobs. I could go back to Trinity and teach physics. It's a small liberal arts college. I liked teaching. But on the other hand, I also liked the type of work I'd been doing at Radiation Lab. So from some of our meetings, Ray Machlett decided to enlarge the business they'd started during the war. Ray thought I would be a good guy to head up that group, so Ray offered me the job, and I took it. Goldstein: Was your job an engineering-oriented job or management-oriented? Doolittle: Engineering. No, they had good management. They had a good sales department. They could sell the stuff. But they didn't have any experience designing transmitting tubes, heaters for industrial heating, or for radio or anything of that type. So they wanted somebody that knew the technology. Goldstein: Were you at liberty to bring with you specific technologies or techniques? Doolittle: Oh, nobody hamstrung the other. Goldstein: What was the experience of some of your colleagues? Did they go to work for companies? Doolittle: Yes, some of them did. I don't know what the percentage would be. Some of them went back to administration, some went back to teaching, and quite a number of them went into industrial work. Luis Alvarez went back to the University of California. They subsisted mainly on government contracts, this, that and the other thing, and worked on the H bomb. There was a lot of work on particle acceleration. Most all of that was government financed. Goldstein: Actually I understand that Machlett took this tube business from AT&T, but what was their marketplace right after the war? Was it on technologies that were associated with Rad Lab technology? Doolittle: Not a great deal. Goldstein: Oh, really! Doolittle: Yes. They had built these tubes for the SCR-584 on a government contract. But such tubes existed before 1940. I told you that we tried to sell Bell Labs on the hydrogen thyratron instead of a spark gap. Well, as usual, the Navy wanted a second source, and Machlett picked that up and also made the spark gaps which Bell Labs had developed. They made a couple of other radar things that Bell Labs had developed. But, you know, there was no particular commercial market for that stuff. Goldstein: Did they return to the x-ray tubes? Doolittle: They never left it. But they had thought, well, we've got a little bit of the edge of this business, let's get into the radio broadcast transmitter business. And they wanted somebody that knew something about it because their x-ray people were only very good in x-rays. ### Most Important Work at Rad Lab Goldstein: What do you consider was your most important assignment at Rad Labor, in other words, the most important work you did there? Doolittle: Well, I guess getting the 584 going. After that we got going the other ones a lot easier. I guess getting the pulse transformers and pulse networks going was equally as important. Most of the rest of the modulators were semi cut and dried. Sure, the hydrogen thyratrons we developed were supposed to be a big business and it is today for military applications. But I wouldn't say that as far as the war was concerned it was that important. Spark gaps in general did the job. Goldstein: It sounds like you're saying that those were important because of the system in which they were incorporated. The 584 was a significant device. Was it the application that rendered it important rather than the innovativeness of the technology itself? Doolittle: Well, the desired end use pushed the technology. We didn't know how to make or measure microsecond pulses or hardly anything else in the microwave area. Now you can buy an oscilloscope that goes up to 100 MHz or higher. In those days getting up to a few megacycles was not too easy. To start with, we played in the dark. Sure, the magnetron was working, it was putting out power, and everything was fine. But how efficient was the device? How much voltage could you get out? Developing measuring techniques was an important key to nailing the thing down. If you're going to submit a specification to somebody and say, "I don't know how the hell you measure it, but this is what we want," it's no good. You've got to tell him how to do it, and how to measure it. ### Working with ITT Goldstein: Would you be involved with the industrial contractors at each stage of it? For instance, if you developed something, would you consult with an outside firm to work not only on its manufacture, but also on its testing? Or was the testing done in-house? Doolittle: Well, the testing was pretty much done in-house. If he developed his own transformers, we suggested some of the people to assist him. We always checked out the results to be sure it looked okay. But other than that we were concerned with the overall problem of operation of the equipment, of course. A lot of them got their information on measuring techniques from us. Goldstein: Could you give an example? Doolittle: Well, I remember a crew that came up one time from ITT. ITT had international connections, so getting clearance to them was a little bit difficult. They first had to assure the people in the Air Force that they weren't going to transfer this information to their overseas connections. I can't remember now just how long this went on. But maybe a year or a year and a half. Finally they got clearance to come up and talk to us about modulators. They wanted to bid on some radar equipment that the services were putting out bids on. Goldstein: You had a modulator design that they wanted to manufacture? Doolittle: No. They wanted to bid on some job, and the Army and Navy and the Air Force, or whoever was involved, was perfectly willing to have them bid once they had obtained the clearance because they had some manpower. However they had to know what was involved technically to submit a responsible bid. So if the GE's and everybody else were overloaded and some service wanted to get this new radar set out, they found a facility where there was some capability, they would seek a bid. ITT had intelligent people who knew electricity and magnetism and stuff. So a contingent came up from ITT. Sokaloff was one. They wanted to get information: How do you do this modulator stuff? How do you generate it? He had heard about pulse-forming networks, and hydrogen thyratrons. But they hadn't got as far as figuring out how do you charge these networks up? If you charge a condenser up through a resistor, you throw half the power away. Well, you can charge it up through an inductor and throw 3 percent of the power away in the resistance of the inductor. So we use an L.C. resonance circuit, which is tuned to the frequency you want the pulses to repeat at. Well, they didn't know anything about that. But it didn't take them long to catch on because they were capable engineers. They were very, very grateful. Apparently I satisfied them 100 percent and gave them reports on this and that and everything else, and got them to a position where they could sit down and start to bid on a piece of equipment and know just what they were doing. Of course all the measuring stuff went along with it. You've got to measure the results you get to prove to the Army, Navy, and Air Force that you could meet the specs. Goldstein: I'm going to just make sure I understand this. They were bidding to develop a device for the military, and they came to you for assistance? Doolittle: Yes. They wanted to know what we knew about modulators. Now giving them a year, they probably could have developed the expertise that we had. But between that and the few phone calls, we spent a couple of days just going over this with three or four people. Between that and subsequent shorter visitors and a few phone calls, we probably saved them six months. There was nothing here so difficult that they couldn't handle it. But if you can talk to somebody who's already been through it, it saves a lot of time. Goldstein: Was this Bell Labs? Doolittle: ITT. We couldn't talk to them for the first year or so I was here because they weren't cleared. Somebody in the higher brass in the Army/Navy was afraid that their buddies in Occupied France or somewhere might learn some secrets that they didn't want to get out. So somehow or another — I don't know the details — ITT had to satisfy whoever was clearing them that they were going to keep this information in the United States and not send it to their cohorts. Goldstein: Apart from the international security concerns with this particular case, was it common for industrial firms to seek out consultation with Rad Lab? Doolittle: Oh, sure. I think nine cases out of ten, the basic design was done at Radiation Lab. So obviously for them to come here and get the information on what we knew, having been through this development process, would save them a lot of time. They were very anxious to get it. They would run into problems in the course of developing the stuff, and they'd be back to see if we could help. Goldstein: Well, if Rad Lab were working on a similar project, why would the military have gone out to the industrial firm? Why wouldn't they have worked through Rad Lab? Doolittle: I'm not sure that I understand your question. Goldstein: It seems to me what your describing is a situation where the military approaches ITT to develop some particular technology that Rad Lab itself is working on independently. Is that what you're describing? Doolittle: No, I don't think so. I think the motivation was a little different. In the case of ITT, when they finally got clearance, they wanted some work, so they could go to the Army and Navy and say, "We've got clearance. We want to do something. What have you got that we could do?" The Army/Navy/Air Force could easily say, "Well, hell, we've got Bell Labs, we've got GE and Westinghouse, and you name it, and we don't need you." But they did need them. That's why RCC got started, because all these other companies that had the expertise were so tied up in making SCR-584s, airborne radars, shipborne and other things. So in this case it's a question of mutual satisfaction. ITT wanted desperately to get in the business. Otherwise the war would end, and there'd be a whole area that they hadn't been able to get into. But the services, on the other hand, needed a supplier because all their current suppliers were overloaded. Sure, GE could add it on when they finished this job, and maybe they could spare a few people to get it started. But that means holding the thing up. So I think it was mutual. ITT wanted to get in on it, they got their clearance, and somebody in the service was anxious to get them involved. Goldstein: You see, I think what I thought, when you were saying this before, was that the services were approaching ITT in a different manner than the service was employing the services of Raytheon or Bell Labs or GE, which they had done through you. But was ITT in that case communicating with Rad Lab? Was Rad Lab acting as the go between? Doolittle: The services dealt directly with Bell Labs, GE etc. for production equipment and also with Rad Lab on ROD. Maybe they said, "well, we'll arrange for you to send a certain number of engineers up to Rad Lab." Well, there were five component sections: modulators, magnetron tubes, RF components, antennas, and receivers. You can send five guys up to each of these departments to get caught up because we can't give you a contract now. You don't know what we're talking about. I'm just guessing that's the way it happened. I know that ITT wanted a piece of business, and as soon as they could get clearance, they were after us. They couldn't say, well, we'll bid on a radar set for an MTI system when they didn't know what it was all about. Goldstein: Again, I'm not sure if I understand the system. The way I understand it works is Rad Lab would develop the design. This is one scenario. Rad Lab develops a design and draws up a contract with some industrial supplier to manufacture it. Doolittle: No. Goldstein: That never happened? Doolittle: Radiation Lab didn't let out a contract for production as far as I know. The contractor, say GE, for the 584 made a deal with the Signal Corps to build these sets once they knew what the specifications were, and they'd been to Rad Lab and worked with one we had. Goldstein: Okay. Doolittle: Now they were in a position to bid on it. But the basic design was ours. I had nothing to do with how much the Signal Corps paid GE to make sets. That was the Signal Corps's business. It wasn't Rad Lab's business. I don't think Rad Lab ever let a production contract out for a complete system. Goldstein: Okay. That was done through the Signal Corps, through the military. The branch of the service itself. Doolittle: Yes. Radiation Lab tried to sell the military on how to build it. Luis Alvarez tried to "sell" the military an idea for a blind-landing system, and he met with a lot of opposition. He had some design faults with his first attempts. He was trying to develop a landing system. He tried to use the 584 but the plane got lost in the ground clutter. It just didn't work. So the brass was not about to let a contract out for a GCA system. He had to go back to the drawing board and start over again and cure the faults that he had encountered. ### Influence of Rad Lab Goldstein: I wonder if you have any comments on the effect of the Rad Lab experience on your personal career or the state of technology. Doolittle: Well, it affected me quite a bit of course. When I got my Ph.D., which was in '36, Ph.D.'s in physics were a dime a dozen. It was hard to get a job anywhere. Fortunately, the professor at Trinity that I had as an undergraduate needed somebody and signed me up for a teaching job at Trinity. I was one of the lucky few that had enough connections to get somewhere at that point in time. By the time the war came along, things were much better. The Radiation Lab and the Manhattan Project opened up a demand, and there were a lot of people moving in. People that got their Ph.D. in 1940 didn't really have to worry about a job. I know I had a good friend at Chicago who was a chemist. He got a Ph.D. the year before I did in chemistry. He took a job in a women's college in Pittsburgh for something like$1800 a year. He spent one year there, and he said he never saw so much bickering among faculty members in his life. He couldn't take it any more. He took a job at Columbia University with Urey, the Nobel Prize winner in chemistry, at a thousand dollars a year, almost half of what he had made as a teacher. He wanted to be in the forefront. Urey was working on isotope separation by chemical means. My friend was a Canadian, and he ended up in the Canadian atomic energy establishment. So he got a real boost by getting out of the teaching. I wasn't that desperate. I quite enjoyed teaching, and my salary wasn't bad. I got an annual raise. My Ph.D. work involved the use of vacuum systems, nuclear physics high voltage, and all that. At Machlett, I could be my own boss there. I wasn't hired to work under somebody else. I was to develop new products for Machlett Laboratories, which I did, and it was quite successful.

Goldstein:

Doolittle:

No. They were both along the same lines, as a matter of fact.

Goldstein:

Do you have anything you want to add to that?

Doolittle:

I can tell you a story about I.I. Rabi.

Goldstein:

Feel free.

Doolittle:

Later on in the Rad Lab he spent a lot of time at Columbia Radiation Lab in New York, and he would come up here. Sometimes when he came up on the train to South Station in Boston. I don't know if you know Boston.

Goldstein:

Yes.

Doolittle:

He came into South Station, and he got off the train, and he started walking, and he saw this long line. (This is wartime now.) He said, "Whenever I see a line, I get in it." He said, "You know what I got?" I said, "No, I don't know what you got." He said, "I got a copy of Life Magazine."

Goldstein:

Quite outside my experience.

Doolittle:

I enjoyed talking with you.

Goldstein: