[Doc Ewen]
Ewen and Edward Purcell with the 60 foot antenna. (Photo courtesy of Doc Ewen)


[Ewen and the horn antenna, Harvard, 1951]
Ewen and the horn antenna, Harvard, 1951. (Photo courtesy of Doc Ewen)


NATIONAL RADIO ASTRONOMY OBSERVATORY ARCHIVES

Papers of Woodruff T. Sullivan III: Tapes Series

Interview with Harold Irving "Doc" Ewen
At Weston, Massachusetts
August 12, 1979
Interview Time: 2 hours, 10 minutes
Partially transcribed for Sullivan by an employee of Ewen-Knight. Transcript completed by Sierra Smith in 2013

Note: The interview listed below was either transcribed as part of Sullivan's research for his book, Cosmic Noise: A History of Early Radio Astronomy (Cambridge University Press, 2009) or was transcribed in the NRAO Archives by Sierra Smith in 2012-2013. The transcription may have been read and edited for clarity by Sullivan, and may have also been read and edited by the interviewee. Any notes added in the reading/editing process by Sullivan, the interviewee, or others who read the transcript have been included in brackets. If the interview was transcribed for Sullivan, the original typescript of the interview is available in the NRAO Archives. Sullivan's notes about each interview are available on the individual interviewee's Web page. During processing, full names of institutions and people were added in brackets and if especially long the interview was split into parts reflecting the sides of the original audio cassette tapes. We are grateful for the 2011 Herbert C. Pollock Award from Dudley Observatory which funded digitization of the original cassette tapes, and for a 2012 grant from American Institute of Physics, Center for the History of Physics, which funded the work of posting these interviews to the Web.

Please bear in mind that: 1) This material is a transcript of the spoken word rather than a literary product; 2) An interview must be read with the awareness that different people's memories about an event will often differ, and that memories can change with time for many reasons including subsequent experiences, interactions with others, and one's feelings about an event.

Part 1 | Part 2

Ewen

I did. At the meeting at the Faculty Club, Bok insisted that not only would we implement this engineering wise, as Purcell suggested, but that additionally I would join the staff and teach the engineering aspects of radio astronomy to the grad students.

Sullivan

Oh, you did have a position on the Harvard staff?

Ewen

Yes, I was immediately appointed to the staff, and jointly with Bart teaching the course in radio astronomy, which was the first course taught in radio astronomy anywhere in the U.S.

Sullivan

Well hold it now, to be fair Van de Hulst, he gave a two semester course.

Ewen

Oh, you're right. Iím talking about leading to... [Ewen: a Ph.D. in radio astronomy.]

Sullivan

So, it's a little bit different than I was thinking then. I was thinking that you were off with your company and Bok was at Harvard, but really you were both actually at Harvard.

Ewen

That's right.

Sullivan

How long did that sort of continue?

Ewen

As long as Bok was there. Right up until he left.

Sullivan

í56?

Ewen

Right and it was shortly after, I guess, [Thomas] Gold left and I recommended to Bok that Lilley be brought on from Yale. And after Lilley had accepted and moved in and Bok went to Australia, I left Harvard, actively teaching.

Sullivan

Right but you still supplied receivers and...

Ewen

Well, not really that much. Receivers for academia are a place to really put yourself out of it [?], thatís not really a good thing. My problem was I didnít want to be in business in the first place. There was another question, how this lasted so long because I delivered a receiver. But we were about half into it and John Hagen called from NRL and said they wanted one. I didnít occur to me at the time the reason he wanted one, of course, was that if he had one and these graduate student- which was really what I meant by the first course, it was a graduate course leading to doctorates and the students were the Drakes and the Heeschens and the Lilleys. They were all students we were producing and many of the places they were going, the instrumentation wasnít available. And when Hagen called, I thought, "Well, weíve got about three months into the Harvard machine. At least we know enough about our mistakes, if another 15K- so it was a 15K type thing. I would build two, one for NRL and one for Harvard and that will be it." And I was saying that all the way through the one for Berkeley, and the one for British Columbia, Michigan...

Sullivan

DTM?

Ewen

Yeah. Everybody wanted one. And then Green Bank, I think about the last one was for the National Radio Astronomy Observatory. And they said Doc, you got to do it because many of these fellows thought the contribution Iíd made was getting the line, thatís one thing, but then putting the United States in the business of getting data and cranking out doctorates, showing that an astronomer and a [???] could work together to produce hardware and doctorates and put the U.S. in the business almost over night

Sullivan

Now by the time you made this last receiver for NRAO, of course, Ewen-Knight had gotten into many other things.

Ewen

Right.

Sullivan

It was just a very minor part of the...

Ewen

Yeah, the problem was that there were so many of these going along and then I had to make some pretty basic decision whether I was going to stay on at Harvard and that was about the time that Bok was making some basic decisions whether he was going to stay. I had enough interfacing with the academic life to have some question in my mind whether that was really the life. So when he left, I pretty much made up my mind and bit the bullet and gone in other directions so that- Actually at the time he left, Ewen-Knight was very much into things like tropo-scatter. We build the 22 tons of transmitters that went on the Texas Towers and things like that. Doing completely different things and thatís was I formed E-Dae at one point was in case there was a need for these receivers, to have them done separately in a way that I could keep track of my losses. Thatís my friendship club and that was wise and thatís their thing.

Sullivan

Now, I hadnít heard about this before, this E-Dae company. Was that just a play on Knight, Dae?

Ewen

Thatís right. It also was the initials of- í56, Mary Ann and I were married. So we decided our first born would either Donald Arthur or Debra Ann. So we had DAE and we had the initials and said, "Ok, how about Ewen-Dae?" Very shortly, I plan to liquidate both of those corporations because Iím now very much in real estate as well. They are in too many things. Iím trying to condense it all into another company and that company, I would think, very shortly is going to be on the books. Iíll be using the initials of my fourth son and heís Mark Edward Ewen. And I thought the Ewen-Mee and donít spell "me" right, with two Es. So I assure you within a couple of years or maybe this year, we will have a Ewen-Mee Corporation. So Knight, Dae, and Mee and we never sell any of this right but...

Sullivan

Now, getting back to the mid '50's. I agree with you on your assessment of getting radio astronomy going in the U.S., but what would be your comments on the science? I mean, certainly the people it produced were critical for the U.S. in the late 50's and 60's and even today, but what about the observations that were done themselves at Harvard. It seems to me that there was a loss because these people were not building their own receivers as was the mode of radio astronomy up until then. There was over-interpretation of bumps and so forth, which lead to some well-known misinterpretations. I mean, do you agree with me on this and if so, how did this come about?

Ewen

Well, the question is: Should the observer be more than intimately familiar with the design? Should he be a hands-on type? I think the students knew enough about the instrument. I would in the long term haul and I made a comment at the time that I felt ultimately we should be able to hook a computer up to an antenna, and let it operate remotely somewhere and provide the information for astrophysicists to interpret. And the assurance that the data was valid should be provided by engineers on-site who maintain and operate the equipment. But other than specifying what is to be measured and then transferring that to the other mountain- I would leave responsibility for instrumentation, calibration, and operation with engineering. I would insist that the one that is to publish the paper and carry out the research be responsible for all the pointing programs. In other words, where are we going to look? For what period of time? What will be the parameters?, etc.

Sullivan

Not the calibration also?

Ewen

Calibration as well. Calibration is external. The fellow should think about the "box" that is going to do something for him and he should never have the calibration in that box.

Sullivan

Well, this is the philosophy on which the National Observatories operate now, of course, where the user comes in for a few days and has manuals given to him and so forth. And you were thinking then this was your policy also?

Ewen

That was my plan at the very beginning and I did not see that that much was being gained by having the students run out to Agassiz, diddle with the knobs and more than anything else upset the instrument than to just hire one engineer who would worry about keeping that system in operation at all times and assure them... come on, I would rather spend more time describing the details and the philosophy of the approach or provide assurance that is external to the system. Iíd like him to perform a measurement to assure himself that the box is really performing its function than just pushing a button that says: "CAL"- I wouldnít believe that. So the idea of we all have to run out to what I termed "Agony Station" [Sullivan: Agassiz] and diddle with knobs, I found not really the way to go. And I was very happy when Haystack came on line with computer operated control. I suggested even in the days of NEROC that perhaps what we should do or at Green Bank- I liked the idea of Green Bank and Charlottesville, I really pushed hard for that because I was on the committee for site selection for the National Radio Astronomy Observatory. And the game was we were going to find the quietest possible site. Well, there are various forces that enter into selecting a site. There were also forces that suggested that we should be in some of the best deer hunting country and very nice places like that. Why donít we just pick one thing and focus our attention on radio astronomy like radio noise, quiet from a radio standpoint? And then consider for human beings that there would be perhaps some other place that we should locate the people who were going to operate on the data. It is very important that they have some place to get together and talk- not a place to go and diddle with knobs, when they are not that familiar with what's behind the panel. Again, I don't think that they should be that familiar with hardware. That's really asking a "mountain" to perform another "mountain" without recognizing the "valley" that exists. You would never get the "mountain" strong enough.

Sullivan

But, of course, the British and Australians were precisely those sort of people that built and interpreted the data.

Ewen

Well, a fortunate circumstance, I think. In both cases probably just a different approach in education that they were able to go down that road. I would think depending on the particular phenomena and also the, of course, as we mentioned earlier, the club type arrangement- we had the phenomenon of clubs here more strongly in place- astronomers, engineers, and so on, physicists- where you donít see that, at least I havenít in my visits to Australia and Europe...

Sullivan

More interdisciplinary approach...

Ewen

Absolutely. There was more mutual respect between disciplines, there isnít the looking down on engineering. I could even feel that at Harvard. We had Cruft and we have Jefferson and of course, at Jefferson we have the great physicists and at Cruft we have these so-called engineers. And that sort of clubby type class system, itís very, very American for some reason. I think all going away now but then it was pretty horrendous.

Sullivan

While we are touching on this, could you comment on why the US really didn't get going in radio astronomy despite the Radiation Lab and all the radar development during the war, like the British and the Australians did. What do you think was the ingredient that was missing, if that's what it was?

Ewen

I think there was as much interest in the U.S. among the disciplines that were capable of moving ahead as rapidly as England or Australia. The missing ingredient in the U.S. was the recognition of the value of this as a separate science or as a combination of important disciplines. There was no "requirement" for it. And we were, in those days right after World War II and immediately following into the Korean War and then throughout the Ď50s, searching for "requirements" to be met and it became game of a government laboratory and the Defense Department in particular to demand that a "requirement" be fulfilled by any research. So you almost had to guess the future and then demonstrate your ESP brilliance. And many proposals were filled with this type of hogwash that the Defense Department insisted on and this was all to benefit the taxpayer, to assure that...

Sullivan

It was all relevant.

Ewen

Yeah, just so that we wouldnít get this Proxmire funding that Iím glad Proxmire finally got his funding

Sullivan

So, really what you're saying is that the Cold War, the military domination of scientific funding was the difference between this country and the others.

Ewen

That was it- focus on requirements and there was no requirement for this. And as far as the work that was done in Australia and England, it was motivated by the need for better knowledge of this new emerging field. This was very pure, very basic, very natural.

Sullivan

Right, there was no military funding.

Ewen

The thing that I found very interesting was that though there appeared to be no interest in this- lack of publications, meetings of disciplines that you would imagine would be active here, etc.- there was underground here and it was quite active. And people at NRL and AFCRL [Air Force Cambridge Research Laboratory] and within the Universities were pursuing this, but were not advertising it. When the spark- as much as the respect was allowed in the discipline, suddenly overnight the U.S. came out of the woodwork. We had all of these research facilities immediately ready to go. NRL had plans, antennas were going up and AFCRL with their solar work. So what were they doing in the mean time? They were able to pursue the research despite the fact that they were held back by these "requirements".

Sullivan

When do you see this blossoming period?

Ewen

The early 50's.

Sullivan

The early Ď50s.

Ewen

Right. I think throughout the Ď50s things took off. Once we were able to say that Harvard for example is giving a course for a doctorate in radio astronomy, that papers are being published by California, Michigan and the Government Labs- that everyone is coming together and recognizing this. That the American Astronomical Society is going to admit that engineers existed. That all of this shortly thereafter, just each little piece of it fell together quickly.

Sullivan

There was a meeting in 1954 in Washington, D.C. that was sponsored by the National Academy of Sciences, I believe, about radio astronomy in the U.S. I don't know if you actually went to it. Do you know the one I mean?

Ewen

I may have. I don't recall.

Sullivan

It was in Washington, D.C. The proceedings were published in JGR [Journal of Geophysical Research]. I was going to ask you if you thought it was an important meeting or not in the terms of the way things went. They came out with strong recommendation for a national observatory, decrying how the U.S. had lagged behind and so forth.

Ewen

I remember being on several committees with fellows like [Lester C.] Van Atta and Merle Tuve...

Sullivan

I think this was probably one of those early committees that decided to have such a meeting.

Ewen

Right and trying to get the National Observatory off the ground. I think the biggest problem at that time was the regional impact. If we are going to put up a large antenna in West Virginia, what are we going to do for California and at Harvard? That was part of the problem with the VLA.

Sullivan

Sure, that sort of thing continues between the universities and the national labs, of course.

Ewen

I think what really made radio astronomy more than anything else was Bart Bok's sheer guts to make it happen. Prolific writer...

Sullivan

Oh yes. He wrote all sorts of PR articles.

Ewen

He was going at it all the time. Just grinding it out, just insisting that it was going to happen. I recalled, well you asked about this Ewen-Knight-Dae, where I was at Harvard. He had me running around doing so many different things and ust getting the first antenna up there and pasting that together down in Cochicuate and we did that down at the D.S. Kennedy Company. It was 24 feet in diameter. We had no idea of how we were going to move it. Bart said we didn't have enough money to build a template and we canít therefore bolt it together later. So I said, "How are we going to move it?" "Thatís your job." "Alright, Bart." So I went off on a trip to Australia and when I got back Kennedy had the 24 foot antenna ready to go. So I called and said, "Weíll take it up 128." The company said, "No way, we are not going to drive up 128. Itís impossible- congestion, traffic." So weíll fly it, helicopter, make the arrangements to fly it up with a chopper. And I recall the phone call very well. I got on the phone to the Vice President of the Harvard Corporation, "I want to talk to Doc Ewen." I said, "Speaking." He said, "Which one am I talking to? Is this the president of the Ewen-Knight Corporation, the president of the Ewen-Dae Corporation, the member of the Harvard faculty, or the guy that is going to fly an antenna with a helicopter over the top of Cambridge? Which one of these guys are you? Are they all the same?" "They are all the same." He said, "I was afraid of that." He said, "Itís all the same guy." He said, "I just want to tell the fellows in charge of the helicopter operation that if you drop that antenna on anyoneís head, you better have it insured for $2.5 million." And so that meant I didnít get it up there with a helicopter. But it was at some point Bart said, "Just figure out how you are going to do it." So I said, "Weíll get a Harvard governor in and weíll have it made." And we got [Christian] Herter in, went down, boom, we ran it up 128 in a truck.

Sullivan

Which governor was it again?

Ewen

Herter

Sullivan

Herter.

Ewen

Yeah, he let us take it by truck. We had to wait until the election went through

Sullivan

We got off the subject of the style of doing radio astronomy, more or less. Do you think I'm being unfair by saying that some things were over-interpreted in the data that came out of Agassiz, both with the first dish and the second? Of course, you werenít so involved with that side of things.

Ewen

My feeling was, looking back, this is the difficult part of it- the question you ask involves an assessment after the fact, which is the way I had assessed it anyway. While it was going on, I was preoccupied with Agassiz and its operation and that sort of thing but I think a good deal of that could have been brought about by about by what might have been a natural anticipation concerning certain models. Itís not common just to that era.

Sullivan

Oh sure. You mean wanting something to be there?

Ewen

Right and thatís not in large measure just the student. Although I know in my own case, as we discussed earlier, I was very convinced that it was there in three days of the discovery, but Purcell was not, which is far more realistic. Now the reverse, I'm sure, has happened historically and I happened to have been favored with a conservative advisor. I think it would be not appropriate for me to comment on what the motivation was, only that I feel that it was not so much as an instrument problem as a motivation in the Astronomy Department. I feel that it probably was overactive anticipation. [Ewen: A perfectly normal reaction.]

Sullivan

So, you might say that there was considerable enthusiasm about running with these results?

Ewen

Because we were certainly in a competitive race at the time - once the Dutch gauntlet had been dropped.

Sullivan

Now, you mentioned that before the line was detected that you went around to AAS and URSI meetings and found them not of much use. But in the years when you and Bok were running the show there, you went to many AAS meetings it looks like. Did you find that you were then becoming accepted?

Ewen

Yes.

Sullivan

Was it Bok, the traditional astronomer, had bridged the gap?

Ewen

Yes. He kept pounding on that door, and said, "Open the door." Of course, internationally in the IAU, Oort was a "Bok" and so the doors were just blown open by those two Dutchman- Oort and Bok.

Sullivan

What about your relationship with the Dutch? I guess you were not so much in on the decisions about the science that was to be done. "Where shall we look?"

Ewen

That was Bok.

Sullivan

You really weren't part of that, ok.

Ewen

No.

Sullivan

But were you influenced at all about what was going on with the Dutch and the Australians. Or for instance, did you pick up any engineering things from Muller and the Australians, or did you pretty much operate by yourself?

Ewen

I did visit Holland...

Sullivan

Dwingeloo?

Ewen

Right and those in Australia. I didn't see anything in Holland or Australia that competitively would really make that much difference. There was so much that was going on here in electronics, particularly in the Boston area, that it became more a question of the radio astronomy community being able to afford what was available. It is pretty much the same today. So I see fellows struggling to build a 95 GHz. You can buy it for $10,000 but...

Sullivan

They just donít have the money.

Ewen

Theyíll say, "I just donít have the $10,000." So theyíll have some student over in the corner discovering whether he can get his chip working or...

Sullivan

Well, this is the same story that society will give to the military but not to a scientist.

Ewen

And I think that from that standpoint, my familiarity with that side of it, which if I were completely an academic, if I werenít looking to the other side or have access to that, my whole life would have been a good deal different. So rather frequently, I do get calls from people in academia that want to know what is really going on. At that time for example in í50 [???] historically, the first maser was successfully demonstrated by Lincoln Lab. Ninety days later, and the first in industry, was demonstrated by Ewen-Knight.

Sullivan

I noticed you had an article here on masers?

Ewen

Well, that wasnít really on masers. Well, it says masers in the title but it is more on problems you have if you have a maser. And many people have commented, not so much on the title, but it was the first paper that really took a look at all of those and we were working on the details of how to measure the noise figure of a maser, the gas discharge.

Sullivan

We are talking about a paper in Microwave Journal in 1959.

Ewen

Right.

Sullivan

So Ewen-Knight had one going at a very early stage?

Ewen

We were second on the air in eight days and Bell followed us eight months later. So now, the way that was done- and then Harvard got on the air, I guess, right about the time Bell did- so here was Nicolaas Bloembergenwho couldnít get his maser on. Lincoln got it running. But by sitting in the outer loop, it was very simple and this was a typical example that Ewen-Knight was deeply involved in the Polaris Program at that time, í55-í60. We were doing something on the order of $10 million worth of research in navigation, using radio starts for celestial navigation under foul weather conditions, and we were the central part of getting the azimuth right. As Red Rayburn or the Admiral used to say, "In Polaris, I know exactly where I am because if I donít get my azimuth right, it could land on Washington." So we were then charged with the responsibility to make sure that he fired in the correct direction and under all weather and that brought on radio stars. And we were looking at radio stars at about the time NRL was publishing with Haddock and with the 50 footer. Thatíd seen a few radio stars. You see those- well, you can probably appreciate those in terms of X Band on the 28 footer- thatís [centroid sensing and sequential lobing?] are Cas A and Taurus. And thatís radiometric sextant at its best. Thatís about as good...

Sullivan

This is beam switching so first you get positive and then negative.

Ewen

Yes. Itís just scanning constantly

Sullivan

But now the submarine came to the surface with a dish?

Ewen

No, this was brought up. The submarine stayed belong and this came up on a post and a [?] and all that good news and the transmission line was something like 75 feet long and that did not include all the bends and quick disconnects. You see if we had to submerge immediately, we had to have a quick disconnect and a guide. And this had to be very low transmission line so I transitions of X band into C band in circular guide and then gather it all back into X band, get it into the receiver that was way down in the bottom deck. So while I was building these things for $10K- $15K- well, when the maser was first announced by Bloembergen, Red Rayburn called and said, "Doc, we need low noise. If there is one thing youíve told me about radiometry its low noise." I said, "Yes sir." I smiled and [???]. So I said, "Come on, I got to have one of these. It sounds terrific, great gadget." I said, "Letís be second. Letís not be first because up to this point itís a theory." Soon as Lincoln Lab got on the air, he got on the phone, "Doc, they did it. When do I get mine?" I said, "Admiral, itís expensive." "How much?" "$1 million" "Come on down. Iíve got $1 million." I went down and he said, "I want this guy on contract that pays $1 million and I want a maser quick." Alright and I said, "A maser is going to give you low noise amplifiers. Itís way down in the bottom of the ship. Youíve got all of this transmission line. Weíd need liquid helium. You donít have closed liquid helium systems." "What are those?" "Liquid helium, like [???]. When youíre out there in the submarine, you canít say, ĎHey, bring me one of those them there..."

Sullivan

...Liquid helium.

Ewen

No, he said, "Letís build one. Letís get on that. Letís have a closed helium system." Then I got that going. So I had guys under contract building a closed liquid helium system and get the maser going. I called Lincoln Lab and said, "What did you use to get the maser going? What did you use?" They said, "[Potassium-cobalt cyanide?], just a simple minded crystal. You can build it in a home refrigerator." I called Nicolaas Bloembergen and said, "Why arenít you using [potassium-cobalt cyanide?]" "Well, we donít know how to do it. There is a trick to it." Back to Lincoln, "Whatís the trick?" "A fellow by the name of Professor [Wolf?] over at BU, he knows how to do it and heís got the refrigerator." I called [Wolf?]. I said, "You just got hired by the Ewen-Knight Corporation. Bring your refrigerator. We are building [potassium-cobalt cyanide?]." We had crystals out the kazoo and they didnít care. So I sent him to Harvard and helped him. I am a Harvard man. We canít say we [???], "So here you are. Put a maser on the air."

Sullivan

Now, which sources were being used by the Polaris submarines?

Ewen

The Polaris was originally a ship launched missile and it was a Jupiter missile. The navigation system therefore was ship-born and it used a 28 foot antenna and the prototype of that was the one we assembled and put in at Needham. The radio stars available to that were Cas, Taurus, Virgo...

Sullivan

Just the big half dozen there?

Ewen

Right, exactly and adequately dispersed to be good navigational aids. The next step in Polaris then was to move it to the submarine. There we didnít have the advantage of 28 feet of aperture. So we were moved to about a 1 meter aperture and settled on the centroid of the Sun and the Moon. As a result, I became very interested in the centroid of the Sun and the centroid of the Moon and whether we were going to be seeing relationships in the centroid.

Sullivan

Or if a flare went off on one side of the Sun?

Ewen

Right and where would you look for a very quiet band? In those days in the late Ď50s, the quietest band we were able to find where we werenít going to be interfered with atmospherically and where we could also get a very broad bandwidth through the virtue of low noise traveling wave tubes was 7.5 to 8 GHz. So we blocked that out for the U.S. Navy and immediately Lincoln Lab blocked that out for the Deep Space Communications System. So that was a very quiet place.

Sullivan

In fact, you developed along with- Frank Drake was just telling me this a few months ago- the traveling wave tube for 8 GHz, this apparently was the same receiver.

Ewen

Right, the same one was built for Polaris.

Sullivan

With a bandwidth of about 1 GHz.

Ewen

Exactly. That's the one we used to get the rings of Saturn and the comparison with the Jupiter intensity.

Sullivan

In ending can you tell me a little bit about the actual receivers that you delivered over to Agassiz, and what improvements were made during those five years or so?

Ewen

The approach taken on the receiver was primarily in packaging. Early on and as it continued and that was to make it easy for the astronomer to understand what the radiometer was all about. One of early, novel approaches which we continued throughout was to engrave the block diagram on the front panel...

Sullivan

Which NRAO still does.

Ewen

And put the knob in that part of the circuit so it is very easy to explain to anyone coming online just exactly what is happening in there. Other than that, very little was done in the way of improving noise figure. It remained the crystal mixer, the 1N21. Of course it was done in coax rather than waveguide. I would say improvements possibly for those that understood those who understood how it operated, the gain modulator was an interesting advance. A number of persons, particularly astronomers, however, did not understand some of the problems a gain modulator can carry you into encouraged me within 5 years after that was developed to drop it as a technique. Perhaps I became most convinced by the group in British Columbia who did not know what it was at all...

Sullivan

Penticton?

Ewen

Yes, Penticton and just tore the whole machine apart trying to find out what that was all about. So I said, "Never again." It was written up by a group at NRAO but we did nothing further with it. [Ewen: That technique was written up by NRAO with an introductory comment to the effect: "Look what we found under the hood of one of Ewen's radiometers." We did nothing further with it.] So until the paramp came along some years later and well after we were out of the business of providing radio telescopes. We did provide some radio telescopes with masers to the military, but not to academia.

Sullivan

Just too expensive.

Ewen

Right, absolutely. So I would say our contributions to that field ended with one technique. Knowing we couldn't improve noise figure nor could we slow the earth down, the time was pretty much set for us, weíll go to multichannel and I think we were probably the first to attempt that and followed shortly thereafter by the group at Carnegie...

Sullivan

The Australians also were putting together a multichannel thing.

Ewen

Right. So we tried for 100 channels with bandwidths from 1 to 10 kHz and digital outputs with a driver 2 typewriter. And that was an effort we launched in '54 and it really "launched" us! As I recall, the NSF grant was for something like $40,000 to build that. We spent an awful lot of time on that. We learned a lot. The education should have probably been documented and thatís something I think all of radio astronomy would have benefitted from and probably still would, is if we could teach the engineers that are coming along that are doing the building, to document mistakes. That would be so helpful.

Sullivan

Thatís true in all of life actually.

Ewen

If we could only have a publication for mistakes only with the guts to do it. So that was our big mistake.

Sullivan

What were the problems with it?

Ewen

It was just a matter of inadequate funds to do a prototype study in adequate detail to determine if there would be any problems. There was the need to go onto a schedule where you commit to a design. And if you made a mistake on paper, itís too late. You donít have the money to buy the... so it was just a horrendous kludge.

Sullivan

Well from a management point of view...

[Tape malfunction]

Ewen

Now from the technical standpoint, the problem was primarily the determination of the zeros baseline between the various channels and that was because we did not have contiguous filtering as a consequence of the selection of the very narrow bandwidth.

Sullivan

But the centers 5 kHz apart.

Ewen

They were possible more as I think they might have been as much as 20 or 30 kHz. Even the 10 had to be scanned.

Sullivan

Because you wanted to cover the entire Galactic line in one shot.

Ewen

Right. We were trying to get as much bandwidth as possible with a small amount of tuning fill in the gaps and hopefully to operate on a broad resonant characteristic of the frontend so the baseline would not be distorted. And that sunk. It didnít work. We struggled with it, let me say. So it was to the point that with a lot of care and tweaking and picking the correct frequencies for the various heterodyne currents, we were able to type out a line that was realistic, correct...

Sullivan

[???]

Ewen

We did that by everyone inhaling and exhaling at the same time.

Sullivan

And your hat and your shirt hung up on that rack.

Ewen

We took it all down and said, "Forget it." We put it back on a strip chart. So other than that, Iíd say it seems like low noise amplifiers and computer processing, getting rid of tail ends and doing the job right, I think that now we are getting close to a point as the speed of computers builds up and as hopefully the Josephson effect can be used by the [???]. Then we can tie a computer to the tail end of an antenna and weíve got something. [Ewen: If I were to search for a "bottom line", I failed to perceive the difference between a grant for research in support of grad students and a grant in support of an engineering technique investigation. The availability of funds for the latter was unfamiliar to me and as a result Ewen-Knight operated on a fixed-price, fixed-time basis with academia. Harvard always wanted the new and better machine first, so the risks and blunders were borne by Harvard. Ewen-Knight, as well, was frequently bent out of shape by these moments of technological advancement.]

Sullivan

What was the noise figure of your initial 21 centimeter radiometer?

Ewen

Iíd say it was around 10db, 3000į noise temperature. We probably never did see better than 2000į until the late '50's, while in our same labs we were playing with much better masers which could not be afforded by academia.

Sullivan

Something that just occurred to me is a picture of you and other 21 cm people at the URSI meeting Sydney in 1952. Can you tell me what your impressions were of the Australian group at that time? You probably toured around all the sites.

Ewen

My first impression was a very gung-ho group. Just a wonderful group of people particularly Paul Wild. It was a thrill chatting with him, interested in so many things. And of course, Pawsey was there and...

Sullivan

Bolton?

Ewen

Bolton, yeah, and that was before Bolton came here.

Sullivan

Oh yeah, and Mills?

Ewen

Mills, It was a meeting with eager minds just delighted with the opportunity to get together and chat about what we were really going in this field . A meeting that at that time was not typical of what you would find here in the U.S. in the field even at that time, a year later, or even five years later. Just an excitement. There was a camaraderie. It was wonderful.

Sullivan

What about the equipment you saw around there? Was it sort of shoestring stuff?

Ewen

It was shoestring stuff, but it was cute, a lot of cute tricks. They had thought it through. They wouldn't waste much time in the hardware areas where it wasn't all that important, to make it look pretty or whatever. But wherever a part was critical to the operation of the device, they spent a lot of time thinking about it and they had a lot of innovative techniques that theyíd use. Just a feeling of someone who wants to do a good job, knows where you have to exert the effort and is very familiar with what counts and what doesnít. It was a just very, very pleasant experience.

Sullivan

OK. That pretty well covers I think up until 1960. Thank you. That ends the interview with Harold "Doc" Ewen at his home in western Mass. on 12 August 1979.

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Modified on Tuesday, 16-Dec-2014 15:52:54 EST by Ellen Bouton, Archivist (Questions or feedback)