Which of the following operating frequencies is used for the modern loran navigational system?
A. Loran C: 100 kHz
B. Loran D: 10.2 kHz
C. Loran A: 1950 kHz
D. Loran B: 900 kHz
Answer: Option A
Coupling into and out of a traveling-wave tube can be accompanied by a
A. Waveguide match
B. Cavity match
C. Direct coax-helix match
D. All of the above
A. A long time constant
B. Low-pass filters
C. The shortest possible time
D. The restricted high-frequency response
A. $${\text{S}} = \frac{{2\lambda {\text{R}}}}{{\text{L}}}$$
B. $${\text{S}} = \frac{{3\lambda {\text{R}}}}{{\text{L}}}$$
C. $${\text{S}} = \frac{{\lambda {\text{R}}}}{{\text{L}}}$$
D. $${\text{S}} = \frac{{\text{L}}}{{\lambda {\text{R}}}}$$
The aquadag coating on the inside of PPI tube is used
A. To focus the beam of primary electrons
B. To shield the electron beam from unidirectional magnetic
C. As a second anode and to prevent the build-up of secondary field
D. All of these
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