UHF C3

Question 1

What is the purpose of the UHF C3 Radio subsystem?

Answer 1

high-power, Line-of-Sight (LOS) airborne communications of voice & data

Question 2

What is the frequency range of the UHF C3 Radio subsystem?

Answer 2

225.000 - 399.975 MHz

Question 3

How many UHF C3 Antennae are there?

Answer 3

5

3 TX, 2 RX

Question 4

Where are the UHF C3 Antennae located?

Answer 4

TX (1) - top FS 470; TX (2) - bottom FS470;
TX (3) - bottom FS 570; RX (4) - FS1150;
RX (5) - top/fwd of VLF/LF RX Antenna

Question 5

What are the power requirements for the UHF C3 Antennae?

Answer 5

Passive

Question 6

What is the function of the UHF C3 Antennae?

Answer 6

TX & RX voice & data; provide a nominal RF impedance of 50 Ohms over a 225 - 399.975 MHz frequency range; handle RF power of up to 1,500 W

Question 7

Where are the UHF Control Panels located and how many are there?

Answer 7

2

P30 Bays 1& 2

Question 8

What are the power requirements for the UHF Control Panels?

Answer 8

28 VDC from CONT 1 & 2 c/bs on P30 DISTR 2

Question 9

What is the function of the UHF Control Panels?

Answer 9

to select and control individual RF, operating mode, and R/T output power

Question 10

How many frequencies are selectable via the UHF Control Panels?

Answer 10

20 preset frequencies or 7,000 manual frequencies between 225.000 & 399.975 MHz selectable in 25 KHz increments

Question 11

What are the 3 operating modes selectable via the UHF Control Panels?

Answer 11

Wideband Frequency modulated (WBFM) - Data
Narrowband Frequency Modulated (NBFM) - Data
Narrowband Amplitude Modulated (NBAM) - Voice

Question 12

Where is the Auxiliary Control Panel (UHF C3 Aux Control Panel) located?

Answer 12

P30 Bay 2

Question 13

What are the power requirements for the UHF C3 Aux Control Panel?

Answer 13

28 VDC from AUX CONT c/b on P30 DISTR 2

Question 14

What is the function of the UHF C3 Aux Control Panel?

Answer 14

provide primary input power, associated equipment selection, control, and indications for UHF C3;
ON/OFF to HPA power supplies; momentary reset of DAISS; indicate link alarms for DAISS; upper & lower RX Antenna selection; selection of UHF Control 1 or 2

Question 15

Where is the UHF C3 Mode Select Panel located?

Answer 15

P30 Bay 2

Question 16

What are the power requirements for the UHF C3 Mode Select Panel?

Answer 16

28 VDC from MODE SEL c/b on P30 DISTR 2

Question 17

What is the function of the UHF C3 Mode Select Panel?

Answer 17

provide the switching controls necessary to select which system will interface with the UHF C3 radios

Question 18

Where is the Baseband Control Assembly (BCA) located?

Answer 18

C2 cabinet above the UHF C3 HPAs

Question 19

What are the power requirements for the Baseband Control Assembly (BCA)?

Answer 19

28 VDC from BASE BAND CONT c/b on E60-2

Question 20

What is the function of the Baseband Control Assebmly (BCA)?

Answer 20

monitors & conditions baseband noise & modem automatic gain control levels to provide discrete signal control over BCA squelching circuitry;
patching capability

Question 21

Where is the UHF C3 Power Meter located?

Answer 21

P30 Bay 4, above MCS Display

Question 22

What are the power requirements for the UHF C3 Power Meter?

Answer 22

Passive

Question 23

What is the function of the UHF C3 Power Meter?

Answer 23

indicate forward power (F) or reflected power (R) for selected UHF C3 radio (1, 2, or 3)

Question 24

Each power sensor for the UHF C3 Power Meter contains ____?

Answer 24

2,500 W sensor element for measuring Forward

500 W sensor element for measuring Reflected

Question 25

Where are the UHF C3 R/Ts located and how many are there?

Answer 25

3 total | C2 cabinet

Question 26

What are the power requirements for the UHF C3 R/Ts?

Answer 26

115 VAC 400 Hz from R/T 1, 2, & 3 c/bs on E60-2

Question 27

What is the function of the UHF C3 R/Ts?

Answer 27

translate received RF signal to a 70 MHz Intermediate Frequency (IF) and send it to the Modems for demodulation; translate 70 MHz IF from Modem to selected UHF frequency, amplify, filter, & rout it to HPAs for TX

Question 28

Where is the 70 MHz Select Switch located?

Answer 28

C2 cabinet

Question 29

What are the power requirements for the 70 MHz Select Switch?

Answer 29

28 VDC from MODE SEL c/b on P30 DISTR 2; | functions with Mode Select Panel

Question 30

What is the function of the 70 MHz Select Switch?

Answer 30

to interface the UHF C3 with ALCS; operate in response to Mode Select Panel, electronically selecting the UHF C3 receiver's 70 MHz auxiliary channel to be used for the ALCS

Question 31

Where are the UHF C3 HPAs located and how many are there?

Answer 31

3 total | C2 cabinet

Question 32

What are the power requirements for the UHF C3 HPAs?

Answer 32

115 VAC 400 Hz from HPA 1, 2, & 3 on E60-2

Question 33

What is the function of the UHF C3 HPAs?

Answer 33

deliver 1 KW over a 225.000 - 399.975 MHz frequency range into a 50 Ohm load; amplify TX signal to supply RF power to an unassociated TX antenna

Question 34

The UHF C3 HPAs amplify TX signal to supply ______ or ______ of RF power to an unassociated UHF C3 TX Antenna.

Answer 34

``` 250 W (AM); 1000 W (FM) ```

Question 35

Where are the UHF C3 Modems located and how many are there?

Answer 35

3 total | C2 cabinet

Question 36

What are the power requirements for the UHF C3 Modems?

Answer 36

115 VAC 400 Hz from MODEM 1, 2, & 3 c/bs on E60-2 | 28 VDC from MODEM 1, 2, & 3 c/bs on E60-2

Question 37

What is the function of the UHF C3 Modems?

Answer 37

interface with the UHF Control Panels; | provide radio power ON/OFF, tuning, R/T enable, self-test, fault detection, and mode of operation

Question 38

Where is the UHF C3 Multicoupler/Receive Bandpass Filters located?

Answer 38

Rear of P20 Bay 1

Question 39

What are the power requirements for the UHF C3 Multicoupler/Receive Bandpass Filters?

Answer 39

28 VDC from RCVR FLTR 1, 2, & 3 c/bs on P20 DISTR 1A

Question 40

What is the function of the UHF C3 Multicoupler/Receive Bandpass Filters?

Answer 40

to receive 1 input signal and split it into 3 signals, allowing the use of a single RX antenna

Question 41

The UHF C3 Multicoupler consists of 2 Bandpass Filters, one with a _____ bandpass for widebandsignals and the other with a _____ bandpass for narrowband signals.

Answer 41

291. 8 - 298 MHz | 314. 9 - 400 MHz

Question 42

Where are the UHF C3 Transmit Bandpass Filters located and how many are there?

Answer 42

``` 3 total C2 cabinet (top shelf) ```

Question 43

What are the power requirements for the UHF C3 Transmit Bandpass Filters?

Answer 43

28 VDC from XMTR FLTR 1, 2, & 3 c/bs on E60-2

Question 44

What is the function of the UHF C3 Transmit Bandpass Filters?

Answer 44

to take the transmit RF from the R/Ts and route it to the UHF C3 HPAs for amplification

Question 45

Where is the UHF C3 Receive Preampfilter located?

Answer 45

Rear of P20 Bay 2

Question 46

What are the power requirements for the UHF C3 Receive Preampfilter?

Answer 46

28 VDC from PRE AMP c/b on P20 DISTR 1A

Question 47

What is the function of the UHF C3 Receive Preampfilter?

Answer 47

amplifies the received RF signals from each Receive Bandpass Filter before routing them to the R/Ts for the applicable receiver system