SECTION 1 General Description Page 1.1 Block Diagrams ... ... ...1 1.2 Frequency Ranges ...2 1.3 Valves ...2 1.4 Fuses ... ... ... ... ... ••• ••• 2 1.5 Front Panel and Chassis Layout ...3 1.6 Specification ... ... ... ... ... ... 3 SECTION 2 Signal Frequencies 2.1 R.F. stages (VI and V2) ... 4 2.2 Calibrating Oscillator (V13) ... 6 2.3 Calibrating action ... 6 SECTION 3 Frequency Changing 3.1 Frequency Changers (V3, V4 and V5)... 8 SECTION 4 Intermediate Frequency 4.1 I.F. Stages (V6 and V7) ... 9 4.2 Variable Selectivity ... ... 10 SECTION 5 Desensitising and Muting 5.1 Relay Desensitising ...11 5.2 Cathode Desensitising ... ... ... ... ... 11 5.3 Grid Desensitising ... ... ... ... ... 12 5.4 Muting Circuit ...13 5.4.1 Under no-signal conditions ... 14 5.4.2 In the presence of a signal ... 14 SECTION 6 Detector, Noise Limiter and A.G.C. Circuits 6.1 Beat Frequency Oscillator (V9) ... 15 6.2 Balanced Demodulator ... 15 6.3 Noise Limiter and A.G.C. Circuits ... 17 SECTION 7 page Audio Frequency 7.1 Audio Frequency and Output Stages (V10 and Vll) ... 19 SECTION 8 Power Supplies 8.1 General ... ... ... ... 20 8.2 H.T. Supplies...21 8.3 L.T. Supplies...21 SECTION 9 REVISION 9.1 Points of Interest...22 9.1.1 R.F. Section (VI, V12 and V13)...22 9.1.2 Frequency Changers (V3, V4 and V5) ...22 9.1.3 I.F. Section (V6 and V7) ..'...22 9.1.4 Detector/B.F.O. (V8 and V9) ...22 9.1.5 Noise Limiter/A.G. C. ...22 9.1.6 A.F Amplifier and output stages (V10 and Vll) 22 9.1.7 Power Supplies (V12) ...23 9.1.8 Miscellaneous ...23 9.2 Revision Questions ...23 9.2.1 Section A ...23 9.2.2 Section B ...24 9.2.3 Section C ...25 APPENDICES Appendix No.1. Magnetostriction ...27 Appendix No.2. Balanced Demodulator ... ... 30 Appendix No. 3. Noise Limiter ...35