TraNK
The constants A and B may be obtained from the curves given in Fig. 1, and Nagaoka's constant K from the curves in Fig. 2. The whole of this data is either based upon or taken directly from information and tables given in Part III of the Bureau of Standards Circular No. 74 p. 252 . The data in the latter circular permits calculations with an accuracy of about one part in one thousand. In practical cases with turns wound close together the wire diameter to winding pitch ratio S usually lies...
Voltage Dividers and Dropping Resistors
Voltage dividers and dropping resistors for R.F. stage common dropping resistor for R.F. and converter A.C. receivers 6A8-G and 6K8-G battery receivers using 1C7-G anode grid dropping resistor screen supply for I.F. stage when no R.F. stage is used Magic Eye Tuning Indicator resistance coupled audio amplifier pentodes. In the R.F and I.F. stages of a receiver it is possible to use either a voltage divider or dropping resistors as means for providing the correct voltages on the screen grids of...
Null Point Indicator Using Magic Eye
A Magic Eye Tuning Indicator may be used in many applications as an indicating device, one of these being as a null point indicator for use with A.C. bridge circuits. Such an arrangement is preferable to the use of head phones or sensitive instruments, since it may be used without disturbance from external noises and is capable of withstanding considerable overload without damage. The sensitivity of Radiotron 6E5 is 0.1 volt R.M.S. for a very clearly marked indication. When used as a null point...
References to Articles on Audio Transformer Design
Glenn Koehler The Design of Transformers for Audio Frequency Amplifiers with Pre-assigned Characteristics, Proc. I.R.E., Vol. 16, p. 1742, December 1928 . Paul W. Klipsch Design of Audio Frequency Amplifier Circuits Using Transformers, Proc. I.R.E., Vol. 24, p. 219, February 1936 . This article deals with resistance loading of the secondary . J. G. Story Design of Audio Input and Intervalve Transformers, Wireless Engineer, Vol. 15, No. 173, February 1938 . For general reading see also the...
O Nrt
Causes of hum insufficient filtering neutralising hum hum-bucking coil induction hum electromagnetic coupling R.F. interference from mercury vapour rectifier valve or barretter in magnetic field capacitive coupling heater to cathode leakage emission from heater emission from cathode to heater modulation hum miscellaneous cures for hum vibrator interference. Hum in a receiver or amplifier may be due to numerous causes such as 1 lack of sufficient filtering, 2 induction into a high impedance...
Converter Valve Oscillator Grid Current
The oscillator grid current of the converter valve in a receiver, whether it be pentagrid, triode-hexode, or mixer with separate oscillator, should he measured by inserting a 0 1 milliammeter in the cold end of the oscillator grid leak. The grid current should be measured at each of the standard test frequencies. On each short wave band, it is particularly important that it should also be measured at the low frequency end of the band, where the condenser gang is at maximum capacity and the L C...
Input Loading of Receiving Valves at Radio Frequencies
The input resistance of an R.F. amplifier valve may become low enough at high radio frequencies to have appreciable effect on the gain and selectivity of a preceding stage. Also, the input capacitance of a valve may change enough with change in A.V.C. bias to cause appreciable detuning of the grid circuit. It is the purpose of this Note to discuss these two effects and to show how the change in input capacitance can be reduced. It is convenient to discuss the input loading of a valve in terms...
J A 1
Since with a loudspeaker we are concerned with voltage across the voice coil and not with power output, it is found with an ideal transformer that at the bass resonant frequency a slight rise in output occurs with a triode valve. With a pentode or beam tetrode valve a very pronounced rise in output voltage occurs at the bass resonant frequency At high audio frequencies similar rises occur with both triodes and pentodes, the former being very slight and the latter pronounced. With a triode...
O Jno
A.V.C. Simple A.V.C. Delayed A.V.C. Differential distortion- Methods of feed Series feed Shunt feed Maximum resistances in grid circuits Typical Circuits A. V.C. Application Amplified A. V.C. Audio A.V.C. Modulation rise A.V.C. with battery valves and zero bias Special case with simple A.V.C. Time constants A.V.C. Characteristic Curves. An automatic volume control is a device which automatically reduces the total amplification of the signal in a radio receiver with increasing strength of the...
Formulae for Superheterodyne Oscillator Design
C, C Gang condenser trimmer capacitance on R.P. circuit. C3 Oscillator trimmer capacitance R.F. trimmer capacitance . If 04 is small compared to 02 it may be considered as part of C3. Let f1 be the resonant frequency of the oscillator circuit be the resonant frequency of the R.F. circuit. j o for exact tracking. Exact tracking can only be obtained with this circuit at three frequencies Flt b and Fs which should be situated one near but not at each end of the band and F2 near the centre of the...
Selective Harmonic Distortion
When a signal containing harmonics is applied to the grid of a tone-compensating stage, the harmonic distortion components may be either increased or decreased owing to the frequency response characteristic of the stage. This effect is quite independent of any harmonic distortion which may be introduced by the tone-compensating stage. For example, consider a tone-compensating stage which has the following characteristic Frequency Gain above that at 400 c If now an input voltage having a...
O Phu
Tuned Circuits, Calculation of Inductance and Design of Low Loss Inductances Natural resonant frequency Resonant frequency Logarithmic decrement Series impedance of tuned circuit Series resonance Currents and voltages Q factor- Parallel resonance Currents Equivalent series and shunt resistances Dynamic resistance Selectivity Phase angle Experimental method for determination of Q Transformer with tuned secondary Transformer with tuned primary and tuned secondary Critical coupling factor...
O Xwy
CHAPTER 16 continued Part 3- Design of Low Loss Inductances Division of coils for high frequency tuned circuits into three classes papers dealing with the practical and theoretical design Pollack's summary Barden and Grimes' summary Harris and Siemen's summary Butterworth's con-. elusions Austin's summary dielectric losses eddy currents skin effect current in coil concentrates at the minimum diameter multistrand litz wires solid round wires insulating materials screens iron core materials...
Transit Time In Voltmeter
Valve voltmeters loading effect probe construction for high frequencies acorn diode type R.M.S. reading voltmeters Mean-reading voltmeters Peak-reading voltmeters A.C. operated linear reflex peak voltmeter Battery operated valve voltmeter. Owing to its relatively high input impedance, the valve voltmeter provides a convenient method for the accurate measurement, across high impedance sources, of both D.C. voltages and A.C. voltages up to very high radio frequencies. The input impedance is a...
Modulation Distortion
This test is carried out to determine the distortion produced in a receiver when the modulation percentage of a constant signal is varied from 10 to 100 . A 5,000 fiV, 1,000 Kc s. signal modulated at 400 c s. is fed to the aerial terminal through the standard dummy antenna. The output of the receiver is maintained constant, by means of the audio volume control, at some convenient low level say 50 mW. so that any distortion due to the audio system, although present, may be a constant factor. The...
Hannas Method
The following design holds only for conditions in which the direct-current is considerably greater than the peak A.C. current. A further assumption is that the cross-sectional area of the core is constant throughout the magnetic path, so that in a shell type core the outside legs should each be half the cross-sectional area of the centre leg. L inductance in henries at low A.C. flux density. 1 length of magnetic circuit inches . A cross-sectional area of core. V 1A volume of iron in cubic...
References to Pickup Alignment
E. A. Chamberlain, Correct Pick-up Alignment, Wireless World, Vol. 26. No. 13, pp. 339-340, March 26 1930 . P. L. Wilson, The Gramophone 1934 . R. P. Glover, A Record-Saving Pick-up, Electronics, Vol. 10, No. 2, pp. 31-32, February 1937 . J. R. Bird and C. M. Chorpening, The Offset Head Crystal Pick-up, Radio Engineering, Vol. 17, No. 3, pp. 16-18, March 1937 . See also addendum below D. G. Knapp, The Offset Head Crystal Pick-up addendum , Communications, Vol. 18, No. 2, pp. 28-29, February...
O Mkv
One or two stages Selectivity Crystal filter Regeneration Requirements for high fidelity Variable Selectivity 1 Mutual inductance, 2 Tertiary coils, 3 Bottom coupling, 4 Top coupling Choice of frequency Stability Detuning due to Miller Effect and A.V.C. I.P. amplifiers are required for amplification, for selectivity and for the application of A.V.C. All three requirements must be considered in designing an I.F. amplifier. Should the I.P. amplifier have one or two stages A single stage has the...
Info Tov
F. E. Terman, Fundamentals of Radio, reviewed Proc. I.R.E., p. 1178, September 1938. H. A. Brown, Radio Frequency Electrical Measurements, 2nd ed. , reviewed Proc. I.R.E., p. 1175, September 1938. F. E. Terman, Radio Engineering, 2nd ed. reviewed Proc. I.R.E., p. 122, January 1938. W. L. Everitt, Communication Engineering, reviewed Proc. I.R.E., p. 159, January 1937. R. D. Bangay, Elementary Principles of Wireless Telegraphy and Telephony, reviewed Proc. I.R.E., p. 909, May 1931. J. H....
Mutual Inductance
Accurate methods for the calculation of mutual inductance between coils of many different shapes and relative dispositions are given in the Bureau of Standards Circular No. 74. The case of two coaxial single layer colls is dealt with very exactly by Grover Proc. I.R.E., Vol. 21, p. 1039, July, 1933 . The Bureau of Standards Scientific Paper No. 169 also provides exact formulae and tables. The possible accuracy of these methods is always better than one part in one thousand. There are few simple...
Barretters and Current Regulators
A barretter or current regulator is a device incorporating a filament usually of iron mounted in an atmosphere of gas usually hydrogen , the characteristics of which are that the current passing through the filament remains very nearly constant for a wide range in voltage drop. A barretter type 302 may ' e sed, for example, in series with the heaters of the valves in a radio receiver provided that the barretter is suited to the valves being used Fig. 7 . Since the filament of a barretter is...
Info Qwm
Figure 8. Frequency characteristics due to grid coupling condenser with a grid resistor Rg 1.0 megohm. It is assumed that the plate resistance and load resistance in parallel of the preceding valve are negligibly small in comparison with Rg. When this does not hold as with a pentode valve in the preceding stage , the attenuation is less than is shown by the curves, but may be obtained accurately by making Rg represent the grid resistor, in series with r and Rl in parallel. These curves may be...
EXAMPLE Condenser Input Filter
Q. A condenser input filter in which C 8 tF, La 20 Henries and Ci 8,uF Fig. 4 is to be used with a full wave vacuum rectifier on a 50 c s supply. The D.C. output is 260 volts 65 mA. It is required to find the percentage of ripple. A. The effective resistance of the load Ri. is 260 0.065 or 4000 ohms. Reference to Fig 1 shows that the curve for 4000 ohms cuts the 8 iF line at Er 7 . This is therefore the ripple in the input to the second section of the filter. In the second section the product...
Audio Amplifier Design
Input and output specifications Examples of design 1 Amplifier with triode output 2 Amplifier with pentode output 3 Push-pull amplifier with triode output stage' 4 Push-pull amplifier with pentode output stage 5 Single beam power tetrode with feedback Frequency Response Examples - Equivalent Circuit's for resistance capacitance amplifiers. In this chapter it is proposed to give an outline of the methods to be used in the accurate design of amplifiers on the basis of information which is...
Radio Tron 1989
For correct tracking, the oscillator frequency must be maintained at a constant frequency difference from the R.F. signal frequency, the oscillator frequency generally but not always being higher than that of the signal. When the oscillator frequency is higher than the signal frequency, the band-frequency-ratio of the oscillator circuit must be less than that of the signal circuit, and if similar ganged condenser sections are used for both it is necessary to restrict oscillator the capacitance...
Info Unr
Approximate only value must be adjusted to give full scale deflection with individual valves. tTotal Supply Current. Battery Operated Reflex Peak Voltmeter. The circuit of a battery operated valve voltmeter using type 954 as a conventional reflex or self-biased anode-bend detector is shown in Fig. 2, Type 954 is triode-connected and two ranges are provided by means of the bias resistors Rj and R2, low range, 1, and a high range, 2. The network composed of the resistors R3, R4 and R5 is used in...