Key Topic 20: Mixers

Question 1

8-20C1: The diagram in Fig. 8C9 shows a simplified RADAR mixer circuit using a crystal diode as the first detector. What is the output of the circuit when no echoes are being received?

A. 60 MHz CW.
B. 4095 MHz CW.
C. 4155 MHz CW.
D. No output is developed.

Answer 1

D. No output is developed.

Question 2

8-20C2: In the receive mode, frequency conversion is generally accomplished by a:

A. Tunable wave-guide section.
B. Pentagrid converter.
C. Crystal diode.
D. Ferrite device.

Answer 2

C. Crystal diode.

Question 3

8-20C3: An RF mixer has what purpose in a RADAR system?

A. Mixes the CW transmitter output to form pulsed waves.
B. Converts a low-level signal to a different frequency.
C. Prevents microwave oscillations from reaching the antenna.
D. Combines audio tones with RF to produce the RADAR signal.

Answer 3

B. Converts a low-level signal to a different frequency.

Question 4

8-20C4: In a RADAR unit, the mixer uses a:

A. Pentagrid converter tube.
B. Field-effect transistor.
C. Silicon crystal or PIN diode.
D. Microwave transistor.

Answer 4

C. Silicon crystal or PIN diode.

Question 5

8-20C5: What component of a RADAR receiver is represented by block 49 in Fig. 8A1?

A. Discriminator.
B. IF amplifier.
C. Klystron.
D. Crystal detector (the mixer).

Answer 5

D. Crystal detector (the mixer).

Question 6

8-20C6: In a RADAR unit, the mixer uses:

A. PIN diodes and silicon crystals.
B. PIN diodes.
C. Boettcher crystals.
D. Silicon crystals.

Answer 6

A. PIN diodes and silicon crystals.