John Hatfield Hart
The Ed John "Star Mech"
Reprinted from THE HIDDEN WORLD, #12
It is probable that a few people reading this article are already acquainted with the construction and operation of this receiver. 6 or 7 were built that I know of and operated successfully in different sections of the country.
I believe a person that is a sensitive, in fact this has been proven to me in the past, has much better luck in operating this set, What is received on this set S better left to your own experimentation, Some people that operated it in the past, that were sensitives, received visual impressions. I have had no such luck. All of my work with it has been confined to the audio field; I was present while a woman in San Francisco described in detail some of the activities going on in the caverns below by using the set as a medium.
Resistors and Their Quantity
2 Meg. 1/2 Watt -- 3
5 Meg. 1/2 Watt -- 3
50,000 ohm 1/2 Watt -- 3
1 Meg. 1/2 Watt -- 2
2,000 ohm 1/2 Watt -- 1
Mica Condensers: Quantity
.0005 Mfd.-- 2
.003 Mfd. -- 1
.0001 Mfd. -- 1
10 MMf. -- 1
Tubular Condensers & Quantity
.002 Mfd, 600 Volts -- 2
.02 Mfd. 600 Volts -- 1
10 Mfd. 10 Volts -- 1
General Parts List
Item and Quantity:
250,000 ohm Volume Control -- 1
954 Acorn Tube -- 3
Acorn Tube Socket--3
IN34, or 54, 36, 65, Crystal Diode (Threaded if possible) -- 1
3,000 ohm Headset--1
No. 14 Hookup Wire, Solid--1 roll
Female Phone Jack--1
4 Prong Male & Female Batt. Plug & Cable 1
6/32 Screws & Nuts--1 Assortment
German Silver Wire--6 Inches
45 Volt Battery--3
6 Volt Battery--1
The chassis I built consists of 6/32 screws with their heads sawed off, joined by wide round terminal type nuts, along which the 3 954 tube sockets are spaced in a stack arrangement about 4 inches apart. The filament connecting wires were threaded through the holes in the socket connections in one piece and soldered into place. The crystal diode is soldered to a 6/32 nut insulated from the flashlight reflector, forming the set's antenna plug. I was unable to find a threaded diode.
I made up several different antennas out of German Silver wire in dipole design, by soldering pieces of silver wire in the solts of 6/32 screw heads, to make them easily interchangeable. The dipoles were of different lengths, varying from 1/32nd to 1/2 inch. The male power plug was installed at the bottom end of the chassis, the female on the cord leading to the battery pack. One common negative wire is used from the batteries to the set, while A, B, and C plus voltage each has their own wire in the power cord. The resistors and condensers are soldered directly to the plate and grid wires, leading from the top and bottom of the 954 tubes, respectively. All other connections were made as short and rigid as possible.
On completing the set, I soldered all of the nuts supporting the tube sockets in order to give more rigidity to the chassis. The chassis could be more easily assembled by using two long threaded 6/32 rods in its construction. I used a thin piece of chromium plated tubing, slightly larger than the tube sockets, which I cut to the length of the chassis to form the case and shielding for the set. The volume control was installed at the bottom end of the set. I used a piece of cardboard cut the same length as the tubing and glued it inside to insulate the set from its case. The receiver is powered with ordinary batteries, made up conveniently into a pack for carrying. The current drain of the batteries is negligible, with the exception, of course, of the 6 Volt filament battery.
I am sure that anyone that can read a schematic diagram will find it easy to obtain the parts and construct the set. The receiver is fairly simple to build and I tried here to make the construction details as clear as possible. Anyone with the average radio bench should have the parts on hand to build the set with the exception perhaps, of the 954 tubes and sockets.
In operating this set care must be taken, as it is highly directional. There is no selectivity, except in the fact that it is directional. Perhaps for best results the set should be mounted on a micrometer type feed, or telescope gearing arrangement, so that it could be aimed accurately in a particular direction. I am sure this mechanism is readily available from one of the scientific supply houses, or through war surplus outlets.
No variable condenser can be used in a circuit operating at this frequency to tune stations. The tuning problem in this receiver is one of the great hindering factors in its reception. Perhaps in the near future a way will be discovered to tune at this high frequency, without varying the capacity between the plates of a rotary condenser. As it stands, this set operates much as a simple, untuned crystal set with headphones, antenna and ground. All that is missing is varying a cat whisker on the 1N34.
If the set is in proper operation, the ring of the tubes can easily check it when the set is tapped. Also, if the set is connected to an external antenna, will usually bring in a local A.M. or F.M, station. However, sometimes this is not the case, as I have received unusual broadcasts with the external antenna, when I was receiving nothing with the set in normal operation.
It is best for me to explain here, this set does not operate at all times. It may take much effort to log some fragmentary conversations. Remember that it is not a sophisticated receiver in any sense of the word. Since the set cannot be tuned at this frequency, it is possible to get nothing, disappointingly, then suddenly get several things at the same time. Constant use of the receiver will improve one's results. According to its inventor, steel, high tension wires, etc. do not interfere with the operation of the set. However, I would recommend complete silence and perseverance. I get best results taking it out in a country field at night, where there are no distractions At least it seems that reception is better there anyway. Interruptions, other conversations and appliances turning on and off I do not find helpful while listening. Most of what you will hear will not be shouted by any means. Some transmissions will be received in the barest of audible sound.
In receiving one of these "broadcasts," it is necessary to either tape it, or speak it aloud when receiving into a tape recorder, as you usually do not remember the contents of the intercepted transmission. Before the advent of tape recorders, I had a friend with me that I talked to during the broadcast. He wrote down the information as 1 received it. In the future I am going to purchase a patch cord set sold by Olson Electronics Inc, to pipe the set's output directly into a portable tape recorder. It will still be necessary to listen and place the set in the proper direction at the correct time by use of the headset. With this arrangement, it will be necessary to install a changeover switch, so that as soon as something is received, the switch can be thrown to record it. The switch will have to be external of the set, so that its operation will not jar the set and move it out of line of the beam of communication This can be done by the use of a double pole, double throw switch I doubt if it would be possible to operate the headset and tape recorder at the same time, as power output of the 7 Micron Receiver is not great enough. However, the portable Japanese tape recorder I have, allows you to listen through the earphone, plugged into the recorder, while the recording is being made. The set's inventor states that further stages of amplification would not be of any practical value. Since what I get out of the receiver is in the form of audio speech, I cannot fully agree with him until I experiment further. The set does not give me mental impressions, as I am a non-sensitive.
The set's inventor warned me that if a steady beat tone was received in the headset, to immediately turn off the receiver, as it is a heartbeat-matching signal trying to tune into sympathy with your own pulse rate. According to him, if this signal locked into resonance with your pulse rate, the signal would slow down and your heart action would slow to a stop in sympathy with it.
The inventor of the 7 Micron S.A. Receiver designed many other circuits in this same field. As an example, a surplus radar antenna connected to a set and large power supply, with electrodes placed on the head of the operator, which could receive thoughts from anyone it is beamed at. The main danger of using this apparatus, according to the inventor, is the high voltage of the power supply, over 1,500 Volts, in connection with head electrodes. I do not know if this set was built but I have seen the diagram in detail.
I have experimented with one other set, much more sophisticated than the 7 Micron S.A. Receiver. It was a large chassis of many stages and I intercepted two transmissions with it in the space of 15minutes. Two witnesses in the room wrote down the broadcasts as I received them and their comments were quite interesting. This receiver worked with an external antenna, though it was designed for use without it.
The inventor told me of another set he had built, with a pearl used as the detector stage and the entire unit mounted inside a pocket watch case. Once assembled, this set began to operate continuously on a thought transference level, thoroughly annoying anyone in its area. The inventor tried to dismantle it and found that the watch case could not be pried open, nor could. the set be destroyed with a heavy hammer. In desperation, he threw it into a roaring furnace and finally destroyed the receiver.
I recently contacted the inventor again and he informed me that he isn't doing anything further in this field. I asked him for a diagram for any of his other sets and he said that he had thrown out all of his old material on this subject Thus, this is the only circuit I have had any experience with. I will not mention his name here, as he was kind to me and I am sure he would not like an invasion of his privacy.
After I have operated the 7 Micron S.A. Receiver, described in this article for a week or so, it usually develops problems and is rendered unusable until I repair one or more minor things. Once, when it hadn't been used in sometime, I found 8 different things that needed attention before it could be put in operating condition. Before moving recently, I packed the set carefully away in a black metal trunk. Upon completing moving, I opened the trunk and found the set missing. I have been going through all boxes, suitcases and trunks in the outside chance that it was misplaced. At least if it does not turn up, I can easily build it again, with some improvements that I have in mind. Luckily, I haven't misplaced the diagrams.
In conclusion, I would like to point out once again, that The 7 Micron S.A. Receiver is in a highly experimental stage. It is not a Telaug, nor communications receiver. Nothing has yet been invented by our scientists to operate properly in this frequency range. To interest a scientist in inventing a practical receiver operating at such a frequency, it would be necessary to convince him that communication is possible at a 7 micron level. One of the greatest assets to anyone operating this set will be the virtue of patience. Results may be sometimes disappointing, but I can guarantee that I have fair success with it.