UHF C3 Flashcards by Michael Morgan

What is the purpose of UHF C3?

It is a high-power, LOS airborne communications system with both voice and data capabilities

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What is the Frequency Modulation (FM) range for C3?

225.000MHz- 399.975MHz

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Where are the 5 UHF C3 antennas located?

Tx 1- Top of the fuselage, forward of MILSTAR antenna. (FS470)
Tx 2- Below Tx 1 bottom of fuselage (FS470)
Tx3- After of Tx 2 on bottom (FS570)
Receive(RCV) 4- Bottom of fuselage, at FS1150
RCV 5- Top of aircraft forward of VLF receive antenna. (Cross dipole antenna)

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What is the nominal RF impedance for the C3 antennas?

50 ohms

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The UHF C3 can provide RF power handling capability of up to _____ Watts?

1,500

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What is the function of the UHF C3 antennas?

To provide voice and data TX and RCV capabilities.

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Where are the UHF CONTROL panels located?

P30 bay 1 and 2

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What are the power requirements for the UHF CONTROL panel?

28 VDC from CONT 1&2 C/B’s on 28 VDC DISTR 2 panel on P30

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What is the function of the UHF CONTROL panel?

To select and control individual RF, operating mode, and R/T output power.
**Either of the UHF CONTROL panels can control the 3 UHF C3 R/T’s.

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How many preset frequencies and manual frequencies can the UHF CONTROL panel have?

20 preset.

7,000 manual

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The UHF AUX CONTROL panel is located in?

The P30 bay 2

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What is the power requirement for the UHF AUX CONTROL panel?

28 VDC from AUX CONT C/B from 28vdc DISTR 2 PNL on P30

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The function of the UHF AUX CONTROL panel is..

To provide primary input power, associated equipment selection, control and indications for the UHF C3 Radio subsystem…
Provide selection between UHF Control # 1 & 2
Provide squelch override

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The UHF C3 MODE SELECT panel is located in ..

P30 bay 2

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The function of the UHF C3 MODE SELECT panel is…

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

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What is the power requirement for the UHF C3 MODE SELECT panel?

28 VDC MODE SEL C/B from 28 VDC DISTR 2 Panel on P30

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Where is the BCA (Baseband Control Assembly) located?

C2 cabinet above the UHF C3 HPAs

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What is the function of the BCA?

It is the interface that links the transmit and receive baseband signals between the UHF C3 modems and their designated DAISS MUX’s.

Where is the UHF C3 Power Meter located?

Control panel- P30 console above the MCS Display

Three power sensors- C2 cabinet

What is the function of the UHF C3 power meter?

To allow for individual selection of forward power(F) or reflected power (R) for the UHF C3 -1, -2, and -3 radios

How many Watts of power for the measurement of F (Forward)?

How many for R (Reflective)

2,500 Watts

500 Watts

The UHF C3 R/T’s are located in…

C2 Cabinet

The power requirements for the UHF C3 R/T’s are…

115 VAC 400Hz R/T 1,2, or 3 C/B on E60-2

What is the function of the C3 R/T’s?

To translate the received RF signal to a 70 MHz Intermediate Frequency (IF) and send it to the UHF C3 Modem for demodulation

The 70 MHz Select Switch is located in

The C2 cabinet

The 70 MHz Select Switch power requirements are ..

28VDC MODE SEL C/B from 28 VDC DISTR 2 Panel on P30

The function of the 70 MHz Select Switch is..

To interface the UHF C3 Radio Subsystem with the ALCS subsystem and operate IN RESPONSE to the UHF C3 MODE SELECT panel.

The UHF C3 HPAs are located in the...

C2 cabinet

The UHF C3 HPAs power requirement are..

115VAC 400Hz HPA 1,2, or 3 C/B from E60-2 panel

The function of the UHF C3 HPA's are...

To deliver 1 KW over a 225.000 to 399.975MHz range into a 50 Ohm load. And provide amplification of the R/T Tx signal to supply 250 Watts (AM) or 1,000 Watts (FM) of RF power to an associated C3 TX antenna

The UHF C3 MODEM's are located..

In the C2 Cabinet

The UHF C3 Modem's power requirement are..

115 VAC 400Hz MODEM 1,2, or 3 C/B's on E60-2 | 28 VDC MODEM 1,2, or 3 C/B's on E60-2

The function of the UHF C3 Modems are...

To interface with the UHF CONTROL panels and the UHF C3 MODEMS provide radio power ON/OFF, tuning, R/T enable, self-test, fault detection, and mode of operation

The UHF C3 Multicoupler/Receive Bandpass filters are located in

Aft P20 bay 1

The power requirements for the C3 Multicoupler/Receive Bandpass filters are..

28VDC RCVR FLTR 1,2, and 3 C/B's from 28 VDC DISTR 1A on P20

The function of the C3 Multicoupler/Receive Bandpass filter is..

To act as a fixed-tuned filter network that permits simultaneous transmission of two signals, one wideband and one narrowband, on a single antenna.

The UHF C3 Multicoupler consists of two Bandpass Filters, one with a _____ to _____ MHz Bandpass for wideband signals and the other with a ____ to_____ MHz Bandpass for narrowband signals.

291. 8 to 298 MHz for wideband | 314. 9 to 400 MHz for narrowband

The UHF C3 Transmit Bandpass Filters are located in..

C2 cabinet

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

28 VDC XMTR FLTR 1,2, or 3 C/B on E60-2

The function of the Transmit Bandpass Filters are to..

Take the 225.000 to 399.975 MHz transmit RF from the R/T's and route it to the UHF C3 HPA's for amplification.

The UHF Receive/Preamplifier is located in..

Aft P20 bay 2

The power requirements for the UHF Receive/Preamplifier are

28VDC PRE AMP C/B from 28 VDC DISTR 1A panel

What is the function of the UHF Receive/Preamplifier?

It amplifies the received RF signals from each of the Receive Bandpass Filter before routing them to the C3 R/Ts for the applicable system!