013 CATHODE RAY OSCILLOSCOPE Type R6673 (c 1950)
013 CATHODE RAY OSCILLOSCOPE Type R6673 (c 1950)
Amalgamated Wireless (Australasia) Ltd. Type R6673 Serial Number 4 32*25*21 This early Australian made oscilloscope has a 2 inch Cathode Ray Tube display, with two amplifiers, one Horizontal and one Vertical. The oscilloscope has adjustable focus and intensity controls, and horizontal and vertical shift controls (controlling the dc bias on the plates). The CRO includes a timebase which could also be controlled (1-8 coarse switch plus a fine control) or externally synchronized. An external input can also be applied to the horizontal deflection.The CRO has 6 inputs, 3 for each pair of plates, including inputs to the amplifier or directly to the plates. The oscilloscope used the conventional method for displaying waveforms in the CRT, i.e. Electrons are emitted from a heated filament, accelerated and focused into a narrow beam. This is then passed through a set of orthogonal parallel plates, one vertical and one horizontal. The input voltage signal is placed on the plates causing deflection of the beam. An interesting property in this model is that no calibrations were made. The 2 inch screen is not big enough for any precision measurements to be made, and no calibrations were made on the knobs. Thus the CRO was used for viewing waveforms only, and not for measurements. Bandwidth was quoted as 30c/s to 12 kc/s. This model was constructed completely from tube technology and does not have a PCB. All connections were made through soldered wire, as was typical of that time.
References:
M.C.
043 THERMIONIC VOLTMETER (c1925) The Cambridge
Instrument Company/England/No.L26466
Moullin Patent No 105403 150H ´ 160W ´ 95D
Wooden box with black top and base. Glass window to read non-linear scale from 0.5-1.5. Two pairs of brass terminals above the window marked 'applied potential' and '6 volts'. Zero adjustment and clamping controls are below the window along with on/off and rheostat control dial. The first vacuum tube voltmeter which uses a 6 volt supply and a triode valve. The voltage to be measured is applied to the grid of the valve and when the circuit is balanced the net current is sensitive to this voltage. This current is measured using a Cambridge "UNIPIVOT" galvanometer. This instrument allows measurement of voltages in the range 0.5-1.5 volts only, which are displayed on the scale which is linear between these voltages.
References:
1.K.Lyall, The Whipple Museum of the History of Science Catalogue 8
L.B.
Amalgamated Wireless Australasia, AWA, Australia
Type 2R7077, S/N 167
32*21*20
A Beat-frequency Oscillator (BFO) is a device for generating oscillations of approximately sinusoidal waveform by combing two radio-frequency electrical oscillations of different frequencies. The BFO circuit produces an internally generated signal that "beats" against a second signal, producing a waveform that oscillates at a frequency that is equal to the difference of the frequencies of the waves. The difference frequency can be varied over many decades.
Established in 1913, AWA is a leading electronics company. Renowned for being at the technological forefront, AWA pioneered the introduction of both television and radio in Australia.
This AWA BFO (Type 2R7077, Serial Number 167) uses several evacuated electron tubes, so called, Radiotrons, mainly made in Australia and England, in a pre-PCB (Printed Circuit Board) circuit. It uses a variable capacitor to control the frequency of one of the signals, which is varied by the frequency knob on the front of the unit. The zero is also controlled by a variable capacitor and the output amplitude is controlled via a variable resistor. Still in working order, the BFO encounters problems as the frequency is brought down to approximately 60 Hz, at which point the produced wave is far from an ideal sine wave. Also the frequency drift is quite bad. A beat indicator is located in the top left-hand corner. The earth, centre tap and output terminals are located in the top right-hand corner, with one of the output terminals missing, obviously broken in the past.
Enclosed in a steel case with a leather carrying strap (currently broken) the BFO requires an external power source and has a power lead and connector for this purpose.
References:
Paul A. Tipler, Physics for Scientists and Engineers, Third edition, Worth Publishers, USA 1923, p449.
Probert Encyclopaedia Online Edition
QRP Projects, BFO Synthesizer
www.Dxing.com The Web resource for Radio Hobbyists.
18*8D
The CV35 klystron was an English designed radar tube and manufactured in Australia during the second world war. The tube itself was designed in Britain by Electric and Musical Industries Ltd., in 1941 and was adopted for Australian equipment in 1942. The Council for Scientific and Industrial Research (C.S.I.R.) Radiophysics Division assembled several samples prior to contracting.
The klystron was developed in 1939 by R.H. and S.F. Varian at Stanford University USA. This basic design was improved upon by R. Sutton and his team at the Admiralty Signal School Extension, Bristol, towards the end of 1940 by the development of an operating reflex klystron which was subsequently tested in early 1941. The reflex klystron was often referred to as the Sutton Tube.
When developed the klystron's purpose was to serve as an oscillator in radar receivers in WWII. In fact the invention of the microwave radar was made partially possible by this development.
The basic operation of the klystron is described by the Stanford University Web page detailing the klystron background3;
Klystrons are high-vacuum devices based on the interaction of well-focussed pencil electron beam with a number of microwave cavities that it traverses (resonators), which are tuned at or near the operating frequency of the tube. The principle is conversion of the kinetic energy in the beam, imparted by a high accelerating voltage, to microwave energy. Conversion takes place as a result of the amplified RF input signal, causing the beam to form 'bunches'. These give up their energy to the high level induced RF fields at the output cavity. The amplified signal is extracted from the output cavity through a vacuum window.
The first use of the reflex klystron was in the Type 271 Naval Radar System mid 1941. Klystrons after the war have been used in high powered linear accelerators, radar, UHF-TV, satellite communications and industrial heating.
References:
1. E.A. Findlay and W.B. Lasich, The Design of a Klystron of the L Band. C.S.I.R. Radiophysics, RP.238, 9th February 1945.
2. D.L. Hollway, The Manufacture of a Reflex Klystron. I.R.E. Proceedings, October 1947.
3. Klystron Background, Stanford University, 1998,
URL:http://www.slac.stanford.edu/grp/kly/kly_background/kly_background2.html
4. Robert Sutton, Centre for the History of Defence Electronics Museum, 1998,
URL:http://chide.bournemouth.ac.uk/people/robert.sutton.html
5. Klystron (Sutton Tube), Centre for the History of Defence Electronics Museum, 1998,
204 LEE DE FOREST DIATHERMY GENERATOR
Lee de Forest Laboratories, Los Angeles, Calif. Serial No. E-1080
41*29*34
A black plastic board with the controls and meters for DC plate current and RF current on it. The electronic circuit is right behind the control board. The case of this device is missing. The circuit has two triode valves, two diode valves, a transformer and some other components. They are mostly connected by copper strips. Cleaned by the Electronic Workshop. This device can generate a frequency of 18 MHz with power up to 250 watts. The filaments must be heated up 30 minutes before switching on the plates in the triode valves. The generator was made by the Lee De Forest Laboratories, L.A. The manufacturing date is unknown. It was used for surgery or therapy. Triode valve was invented by De Forest in 1906. He introduced a third electrode, called the 'control grid', to the two electrode diode. Before 1912, the triode was called Audion.
References:
1. A.L. Albert, Electronics and Electron Devices, Macmillan Company, New York, p.106.
T.C.
067PALEC VALVE TESTER Model VCT-V (c1935)
Paton Electrical Pty. Ltd., Sydney. 30*30*19 The tester is encased in a wooden stained box with various pin sockets for testing tubes and a milliammeter so measurements can be made of the plate current. Furthermore, there are switches for the zeroing of the milliammeter, for biasing of tubes and for the power to the unit. By placing the defective tube in the appropriate socket, selecting the power source input, i.e. AC or DC and throwing the biasing toggle switch to zero, the plate current can be determined via the milliammeter. When the value of plate current has been noted the biasing toggle switch is flipped to its biasing position and the plate current is measured again. Consulting the tube testing table for that particular tube,the condition of the tube can be judged. Valve radios were so popular in the early 1930's that even today, valve testers are still being used. References:
1. "Fred Paton: from screwdriver and pliers to purpose-built test equipment", Electonics Australia, Dec 1993, p42
A.H..
138
and 151 (Two) MAGNETRONS Microwave 10cm
138: markings on face: NT.98 /
A.P W.2510 / SERL No S1775
30 cm long, 7.5 cm diameter anode block, 2.5 cm evacuated glass tubes.
This Magnetron most likely dates back to 1943.
151: markings on face one: DAD /
Cathode Side / SER.No.FR95/MARK III
markings on face
two: NTA98 / Standard Telephones and Cables Pty. Ltd. /Made
in Australia
31.5 cm long, 7.5 cm diameter anode block, 3 cm evacuated glass tubes.
This magnetron was most likely made in the years 1942-1945.
The two Magnetrons are very similar in appearance. Outwardly discernible
features of the two Magnetrons are an anode block, two filament leads and an
output connection. The cylindrical anode block has copper end plates attached
and also has metal cooling fins. The output connection comes out of the
curved surface of the anode block and is joined with a copper thimble to a small
glass evacuated space through which a tungsten lead travels, stopping approximately
1 cm beyond the glass tube. The two filaments have similar connections
to, but on the opposite side from, the output. At the end of the glass
tubes the filaments turn into wires (one of the wires is broken on Magnetron
138) and finally into small plugs.
Internally, the two filament leads are attached to the cathode which runs through
the center of the anode. The cathode is likely a nickel tube coated with
an emission mixture, heated by a spiral of tungsten wire.
The Magnetron is a device designed to emit microwave power ( wavelength 10cm) through the output. It does this by placing a potential difference between the anode and the cathode and crossing this with an externally provided magnetic field. The electrons emitted by the heated cathode form a hub of rotating charge which interacts with cavities in the anode block to cause resonances and the conversion of electric potential energy to electromagnetic radiation. This type of Magnetron was used in W.W.II for radar and communications.
The NT.98 came in a wooden casing which had a worn label indicating some of
its specifications:
Peak output: 6.5 kW, Filament rating 6v at 1.5A, Peak voltage 8.64 kV. (not
all info. stated here.)
The NTA98 is thought to have a peak output of around 10-20kW
References:
- Handbook of Symposium on Radar, 5th December 1945, presented by members of
the Division of Radiophysics C.S&I.R, part I ch.2
- www.Subr.edu/~ericm/cover
- www.acadia.net/michelle/tubehist
295 ASTROPHONE CRYSTAL RADIO RECEIVER (c 1920)
Amplifiers Ltd., England.
25*25*6
Housed in a wooden box lined with blue fabric in the lid. On the facade, there are dials for the 'tuning' of the circuit to the desired station and two plugs by means of which extra capacitance may be added. The headset consists of two black cylinders suspended in a steel spring frame. Incoming modulated radio waves set up voltages across the antenna which is connected to a tuning circuit which consists of a capacitor and variable inductor 'tuned' to filter out all but the frequency of a desired station. Contact between a metal wire and galena crystal rectifies the output signal to allow the headphones to respond to the audio frequency components of the modulation. The circuit has been designed to accept extra capacitance to extend the range of reception to lower frequencies. In spite of the name of the manufacturer, there is no amplifier involved, and the energy to drive the headphones comes out of the received signal. The simple but effective receiver is the predecessor to the modern Hi-Fi systems of today.
References:
1. J.Hill,Radio! Radio! fig 118 2. P.Lankshear, Electronics Australia, July 1994, p98 A.H.
323 VALVE FABRICATION DISPLAY (c 1950)
Amalgamated Wireless Valve Co. Pty. Ltd. Sydney/Melbourne
50*32*7
White painted frame with glass cover houses board displaying main components and steps in manufacture of thermionic heptode valve 6BE6. Developed extensively in the 1930's, electron valves (commonly referred to as electron tubes) were used in a wide range of applications including the circuitry of radios, transmitter/receivers, televisions and the first computers, before the advent of transistor technology. Our display specimen gives an insight into the 'heart' of early electronics showing the assembly of a thermionic heptode (7 electrodes) Super Radiation 6BE6 valve with seven electrodes, manufactured - as the name indicates - for use as an amplifier in radio technology. The main components of the electron valve displayed on the board are: heater element, cathode, grids 1 to 5, plate, micas, ring getter, base, cage assembly, bulb and a completely assembled valve. Electron valves work by generating electrons at the cathode which move in the direction of the positive anode allowing a current to flow. No current flows, however, if the anode is not positive and it is this characteristic that allows the valve to act as a rectifier of AC current. Grids placed between the cathode and anode impede and repel the flow of electrons, thus altering the characteristics of the valve and hence its applications. Common types of valves include the tetrode and pentode, with two and three grids respectively. Early valves were large and fragile, before the manufacturing of smaller ones. An electron valve will be destroyed if heated to more than 20°C above its maximum operating temperature. In their heyday electron valves were produced all over the world with manufacturing plants also here in Australia in Sydney, Melbourne and Adelaide. Today they are still found in high power systems, televisions and are valued by the military due to their ability to resist voltage pulses, such as that created by an atmospheric nuclear explosion, which in many cases will destroy transistors. An accompanying Phillips brochure to the display provides a thorough explanation of the manufacturing of electron valves.
References:
1. K. Henney, Electron tubes in industry, McGraw-Hill, NY, 1937.
2. G.W.A. Dummer, Electronic Components, Tubes And Transistors, Pergamon Press, Oxford, 1965, p.114-131.
3. J.J. DeFrance, Electron Tubes and Semiconductors, Prentice-Hall, 1958.
MT
371 BLEECK RADIO BATTERY, 1925
Bleeck Radio Batteries Ltd / Brisbane Queensland / Patent No. 21917
(W.A.Bleeck (Inventor) Managing Director, Bleeck House, Burnett In, Brisbane)
16*27*13
Black rubber "deluxe model"; two cells; graphite/Zn electrodes, separated by porous earthenware pot. Designed to give reliable power source for radios and various other electrical items, esp. when rural areas did not have power supply. Fully charged, gave 50 ampere hours of current supply. Recharged by adding solutions and powders to water in cells. Zn cathode slowly dissolved, solution ions moved through pot. Was heralded as a breakthrough in battery technology, supplying relatively high voltage per cell with low internal resistance, large power storage, easily recharged in a short time, no toxic fumes given off.
References:
VALVE 512 MARCONI TRANSMITTER MOCK-UP
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