Fred – “So, this is still spark-gap transmission?”
Absolutely…World War I. Here’s the key, and there’s the quenched gap up there. These are the tuning coils for the transmitter. Unfortunately, we did not succeed in getting the receiver, which connected to those contacts in that section. The receiver was here.
Fred – “Now, how tight a frequency could they get in the transmission so one transmission didn’t interfere with another? Or they did?”
It depends how close they were, you know, I mean, if you were from here to the Mayes building, it didn’t do any good to try to select anything. You’d be blotted out by the other guy.
Some poor mule carried that on his back, slung over the top was a mating box which had a Briggs & Stratton engine in it driving the generator. The poor mule…I mean, it was a big load, and that’s why this Briggs & Stratton is here, just to show that they made those generators for the military in World War I. And up on the pegboard is an assortment of rotary gaps. The idea of the rotary gap was to give a picket fence effect to the note as the different contacts go by…gives it an almost musical tone. And also, the other idea is that, spinning around it would be air-cooled and wouldn’t melt the contacts.
Rotary Gap Spark Transmitter
Anyway, Dick Smith, who is this gentleman here, built this transmitter…he was a Navy Commander. He was also an amateur. He was a good friend of ours for a while, until he died, which was unfortunately pretty soon.
Anyway, this rotary gap spark transmitter…this frame is made out of a shaving mirror…the whole thing is homemade…and the vacuum motor is in the back…and it’s either 500 watts or 1000 watts, depending on what you wanted to do. This is a thousand watts. And Thorn Mayes made this little Tesla coil, and it’s hooked up to the output of this, just for the amusement of it. (Demonstration of keying.)
If you notice, there’s ozone in the air…smell the ozone?
World War I
Now, we’re in World War I, beginning with this row of elegant communications receivers. This is a 106-D, a much sought after collectors item…long wave…all waves. This little century buzzer…the cover doesn’t come off, but…this little buzzer…you push this button, and it gives you a local source of radio static so you can adjust your detector…here’s your crystal detector…and you can tune it…so they mostly had a buzzer, see, here’s another one on this one.
The sets on the counter are somewhat of an evolution of these communications receivers. The IP-501 is also much sought after collectors item. You see, we jump from this version with a separate box…with a detector in a separate box…to self-contained, with a detector in the same box.
This is a 501 and this is a 501-A. See, this one has one tube. This one has three tubes. This is another 501-A right here. See the tubes in there?
This box is a long-wave adapter. Many of those early wireless stations had tremendously long waves and low frequencies and huge towering antennas, you know…they had antennas a mile long to resonate. And most of the ships…well, when I was younger, the typical shipboard receiver would be a 501-A. Military people would use the…these straps would connect here to extend the wavelength longer to have a wider frequency range…by putting this on, but most of the commercial people in my lifetime…this was before my activity in radio…most of the commercial people were happy to have this only. These are quite rare as a consequence.
This is a typical water-cooled triode vacuum tube for a transmitter. These are the filament connections.
This combination of equipment is receiver and transmitter, and, curiously enough…it’s called the CW-924… this, as far as I know, is the world’s first push-to-talk…push the button and talk, let it up to listen…
These are various microphone arrangements, most of them military…
These are marine type…commercial and military…all telegraph.
Testing For A Radio License
What we have down at the end…I knew the FCC man-in-charge in Boston quite well. Nathan Hallenstein was his name, and he was a good friend of mine. I got my various radio licenses in the Custom House building…I think the 20th floor, and I was shaking in my shoes, you know, trying to remember the code, because that was the big thing, you had to know the code. You know a little theory, but the code was the important thing. Anyway, the FCC office had gathered all of these various testers for their purposes, and when they moved out of the Custom House tower, Nathan Hallenstein called me up and he said, “Hey Bob, come on up, we’re cleaning out. So, this bonanza I acquired in one swoop. I should have a testimonial to the FCC here.
And what is particularly close to my heart…in an evil kind of a way…this instructor graph…this is a tape…clockwork drive…various messages on here by the little indentations…they can make and break the circuit into dots and dashes, and that’s what they used to subject you to, to copy the code. And I got my first ham license by listening to that stupid thing. So that has meaning to me but nobody else.
Some of these things…radio stuff was made all over the world…see the CE CO, Providence, Rhode Island…do you remember where Big Chief Market used to be on Eddy Street in South Providence? Well, Big Chief Market was in the CE CO factory. When CE CO went belly up, the market moved in, during the depression.
Various types of tube testers, and so forth…
Text from the transcript of a tour of New England Wireless & Steam Museum’s Wireless Building given by Robert W. Merriam on a winter day in 2012. Transcription by Craig H. Moody, K1CHM. Edited by Fred Jaggi.