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A-17. Unwanted noise-generated frequencies are rejected.
A-18. Zero.
A-19. (a) Phase. (b) Amplitude.
A-20. E-transformer and control transformers.
A-21. The method of primary excitation (ac and permanent magnet).
A-22. To convert a dc error signal into an ac error signal.
A-23. To convert an ac error signal into a dc error signal.
A-24. To switch control of the amplifier between either the coarse signal and the fine error signal.
A-25. Two saturable reactors and a transformer.
