This section of the Desch/Mumma interview runs from page 88 to page 125 of the transcript of Tape 2 from the second day, January 18, 1973
DESCH AND MUMMA
TAPE II, SIDE II
HT: Let’s continue then with your tube interest and your work at Ohio State.
JD: Yes. this is in answer to your question, how did I develop any expertise in, in tubes and know anything about it, because there’s quite a store of knowledge. And, of course, I had .. quite a library by that time on this subject, too. A lot of stuff published in, in book form generally on how to handle glass and the different kinds of glass.
HT: When did you get started with glass blowing — we might — that might take us back to the earlier origins; and pheraps even into your ham origins, ham radio?
JD: Well, I would say that it was in the first or second year of college.
JD: No, it was ealier than that. I think it was while I was in high school. I became interested.
HT: Where did you go to high school?
JD: At the University of Dayton .. They had a high school and a university.
HT: That’s right. That was fairly common before.
JD: Yes. And, so I went eight years to that institution.
HT: In a sense, what they called the University High School?
JD: And, of course, when I went to college there I was well acquainted with the place I had just spent four years there anyway. So .. now then I think is when I started it.
HT: What kind of research were you and Professor Heil doing? What were you primarily interested in?
JD: Well, .. I was interested in making vacuum tubes for radio use because I wanted to put them in my transmitter. Big tubes. I bought the envelopes from Corning and then all I had to do was put in the elements. And I had to use tungsten, and molybdenum, and tantalum, and all kinds of rare metals to fabricate the parts
and to make the grids and make the plates, and put in the thoriated filaments and activate them and so forth.
And … the … work at Ohio State was to find the–and this was quite a, a subject at the time–to find the velocity of emission of electrons from a hot body versus the temperature of the body; and a filament is a hot body. The initial velocity, because of the effect that the electron cloud has on the control element, the grid. It does effect the, the grid potential necessary for certain types of conduction. And, there were no data available. Saul Dushmann from .. General Electric gave some of the only early estimates of it and we had his books and so forth. But, what I, what I didn’t have, why Heil had up there, so we exchanged and I, I gave him a lot of material for his laboratory, what he didn’t have, I
could get for him. But.. and I did it out of appreciation for what he was doing for me, because he – I got a good education just over two days a week for two years from that man, because I was working with a very high level man. And he treated me as an equal, anyway, and I treated him with a great amount of respect which I had for him because of his status in the physical world. No question about that.
HT: But he was a professor of physics who was interested in –
JD: He was dean of physics.
HT: Dean, dean of the College of Physics at Ohio State.
JD: And that, that was the experience that aided me in my learning how to blow glass and, and, and of the equipment available, because he had it. And, and some of the work that we did was rather hazardous work. I think that one of the transformers that we used for powering this large set up was apout six feet high and four feet square and it had an input of 2,200 volts and I don’t know what power output it had, but it was certainly a
powerful device. But, he accomplished his objective. And, when he died I got a very lovely letter from his wife. .. He would have been in his eighties or nineties by now, I imagine, or more. And I got a very nice letter from her and it made me feel very good.
HT: So your interest then in tubes and their characteistics and their .. potential research involved in them goes back then really to your early education?
JD: Yes. It goes back very far. .. I even did some glass work down at Fridigaire. Remember all the manometers?
RM: Oh, yes. You made the manometers for us.
JD: I made all the manometers we were using and these were not simple manometers. These were manometers that were on an angle.
RM: Well, then they had the glass contacts welded into —
JD: Yeah, I put contacts in them
RM: I think y’ used
JD: for the control.
RM: platinum wire or something like that for ’em, yeah.
JD: Yeah, so that the – we, we could control apparatus when the pressure would change, it would uncover
or cover a contact and either close or open a circuit. And those kind of things.
RM: See, we developed a device down there that would measure the amount of refrigerant. Well, at first we would check the status of the equipment we were going to charge to find out whether there was any vacuum, whether the vacuum was good enough,
RM: because in this process that was developed while Joe was there, you’d pull a high vacuum on a refrigeration unit, heat it to 250 degrees, and if that vacuum would be maintained through that process, we knew we had a no leaker and no moisture. And then this device, this manometer Joe made, we’d use to detect that, and then we’d charge the refrigerant automatically into the unit, and that was developed.
JD: That–Bob, you yourself largely, except for one or two little items in there like you’re mentioning, you–you’re the one that really developed that machine.
RM: Well, I don’t know.
JD: You know darn well you did. You know the headaches you had.
RM: But, that machine was down there for years and years after that until Bob Goebel made this newer one, but I was amazed how long
JD: Bob’s got an entirely different scheme.
RM: Yeah, I know it. Oh, yes.
JD: I was down there just … a month ago.
RM: He’s got a flow meter or something like that.