M

A probable value for coupling coefficient, kt . between primary and secondary is 0-5, so that If the detector load resistances i , in Fig. 13.7 are 0-5 M 2, the damping resistance due to diode conduction current is very nearly 0-25 M 2. Hence the resonant impedance of the tuned secondary, in the absence of diode conduction current, must be which is a practically realizable value. Circuit 2. Since the resonant frequency of circuit 2 is so close to that of 1, the circuit constants are almost...

Rb Q

Of which the damping resistance due to detection is that from the conduction resistances in series, i.e., 0-1 MQ. Hence 100,000 X 18,800 40 81,200 The coupling capacitor C52 in Fig. 15.17 is 100 zF, the r.f. by-pass capacitor C51 is 50 fipF and in the r.f. filter before the a.f. amplifier Rt3 0-2 M.Q and C56 100 pfiF. The mutual inductance coupling Ms between L12 and LX3 is kVLltL13 1-255 H. k 0-067 . Correct tuning and adjustment of the phase discriminator is best carried out in the manner...

Oly

At the right-hand side is drawn the B-H curve for Stalloy, the figures being taken from Table 11.2, whilst on the left-hand side from the same origin is drawn a curve of B against --Hi derived from the B-H curve and the values of Afi given in the table above. For a given air-gap ratio j and d.c. polarizing force Ht oersteds corresponding to OP in Fig. 11.16 , a line is drawn from P to meet the BH curve at S', such that the ratio pjjf of the sides of the right-angled triangle...

Info

A.c. to d.c. power conversion efficiency 25 . Hence for a given d.c. anode voltage Ex, case 2 gives more power output and a higher a.c. to d.c. conversion efficiency than case 1. On the other hand, a larger input a.c. voltage is required at the grid. Conversion efficiency is increased to 50 if E2 can be taken to zero. This condition can be approached with a tetrode without grid current, but the grid current region must be entered if a triode is used. Class AB Section 10.8.7 and Class B...

Oht

A Voltage Doubler Rectifier. The d.c. charging currents for capacitors, C1 and 02, oppose in the secondary winding of the transformer, and the permeability of the core is unaffected by the rectifier action. The most popular type of rectifier for receiver h.t. supply is the high vacuum diode valve. It is robust and can be made to have a high inverse negative voltage. The inverse voltage is the negative voltage which can be withstood without taking appreciable current in the reverse...

Output Transformer Winding Interleaving

There is little essential difference between the two types of Class B operation, quiescent push-pull q.p.p. and positive drive. With quiescent push-pull, tetrode valves are employed and the input voltage is restricted to the region where there is no grid current. Positive-drive Class B operation is applied to triodes to obtain a high anode circuit efficiency by reducing the minimum anode voltage see Section 10.2 , below that permitted by the bias line Eg 0. Grid current is taken during the...

Kk

A resistance potential divider is not satisfactory for the line deflection amplifier because the input capacitance of F2 including the Miller effect of anode-grid capacitance has a comparatively low reactance. i 6 is therefore replaced by a variable capacitance, which forms a potential divider with the input capacitance of F2. J 7 is fixed and has a value much greater than the grid input reactance of F2. Other possible methods of achieving phase reversal are...

Q

Some Notes on Video Amplifier Design. A. Preisman, R.G.A. Review, 9. Effect of the Receiving Antenna on Television Reception Fidelity. S. W. Seeley, R.C.A. Review, April 1938, p. 433. 10. Television Receivers. E. W. Engstrom and R. S. Holmes, Electronics, April 1938, p. 28, to Aug. 1938, p. 18. 11. Television Topics, Wireless World, April 21st, 1938, p. 354. 12. The Line Structure of Television Images. H. A. Wheeler and A. V. Loughren, Proc. I.R.E., May 1938, p. 540. 13. Laboratory...

Espley Method For Distortion In Push Pull Amplifier

An Apparatus for the Projection of Frequency Output Characteristics. C. G. Garton, and G. S. Lucas, Wireless Engineer, Feb. 1929, p. 62. 2. Output Characteristics of Thermionic Amplifiers. B. C. Brain, Wireless 3. Push-Pull Amplification. F. Aughtie, Wireless Engineer, June 1929, 4. A Thermionic Voltmeter Method for the Harmonic Analysis of Electrical Waves. C. G. Suits, Proc. I.R.E., Jan. 1930, p. 178. 5. Effect of Output Load upon Frequency Distortion in Resistance Amplifiers. H. A....

Jkzk k

The output voltage Ek is therefore less than the input, and the valve equivalent slope resistance is reduced to a very small value by the factor J and, if x 1, it equals This type of negative feedback generator has two important advantages, low equivalent generator internal resistance and low grid input admittance. The first means that it is particularly useful when constant output voltage is required across a variable load impedance. This property makes it a very satisfactory driver stage...

Bibliography

Dinsdale, Wireless World, Sept. 23rd p. 290 , and Sept. 30th p. 327 , 1932. 2. Automatic Volume Control. C. H. Smith, World Radio, Dec. 30th, 1932 p. 1378 , and Jan. 13th, 1933 p. 63 . 3. Practical Automatic Volume Control. W. T. Cocking, Wireless World, Jan. 6th p. 2 , and Jan. 13th p. 29 , 1933. 4. Automatic Volume Control. C. N. Smyth, Wireless World, Feb. 17th, 5. The Influence of Fading Compensation on Contrast in Music. T. Sturm, Funktechnische Monatshefte,...

Automatic Frequency Correction

Two effects, sideband screech and harmonic distortion, become very pronounced if the i.f. carrier frequency at the output of the frequency changer stage of a superheterodyne receiver is not correctly centred in the comparatively narrow pass-band of the i.e. amplifier. Sideband screech is characterized by high-pitched distorted reproduction, and it occurs when the i.f. signal carrier is detuned to the side of the i.f. selectivity curve. In this condition the equivalent of...

Ag

A Circuit for Reducing Distortion due to Biased Diode a.g.c. Westinghouse Brake and Signal Company, Patent No. 413,731. There are two important methods of obtaining amplified a.g.c. 1 by r.f. amplification between the last controlled valve and the a.g.c. diode it is assumed that the a.f. detector is connected to the output of the controlled valve and not to the output of the a.g.c. amplifier , and 2 by d.c. amplification between the a.g.c. bias voltage source and the controlled...