Rockwell-Collins Aircraft AN/ARC-174 or 718 series system

Updated 24 Febraury 2008

The AN/ARC-174 or commercially known as the 718U-5 series, enjoyed very wide scale deployment in a number of applications both in aircraft and in several specific "fixed" or land mobile applications. It operated between 2 MHz and 29.9999 Mhz for a total of 280,000 channels. The system could support a number of operating modes such as SSB (LSB and USB), AM, CW, and various data modes such as secure voice and low speed teletype service. Output power ranged from 100 watts up to 1 kilowatt with the average installation being 100 (average or peak). Or in some limited cases, the 400 watt versions of the amplifier being popular (those with lots of spare DC power!). In one specific case, the 671U module was used as the exciter for a Collins 208U-10 10 KW Amplifier. There were some unusual vehicle mounted versions also such as the AN/VRC-81 (see below) and the AN/VRC-114 series. The input power used was 28 VDC for the basic 100 watt version. The basic backage as a AN/ARC-174 was 33 lbs or about 14 Kilograms.

A drawing of various modules within the 718U family we have found information on.

The systems were later upgraded to support selective calling used by the airline transport companies ("SelCall") and the United States military created the Automatic Link Establishment (ALE) capability. It should be noted that Collins was one of the key pioneers in this technology. The original Collins name for their solution was called "Selscan" which was basically ALE 1st Generation. The Harris RF organization also was big in the ALE area for the fixed, marine mobile HF community and their solution was called "Autolink".

In ALE 2nd Generation period, it all came together in one US Standard (see our section on ALE) and this work was later used by NATO for their HF deployments. The technology has since evolved to become a basic global standard used in all commercial and military applications.

The main thing to remember about the 718 series was that it had a very successful life and is still in service in nearly all airlines today and is still installed in many miliary aircraft around the world. It has had perhaps one of the most understated successful products within the Rockwell-Collins life. Clearly crossing the gap between the commercial world and the military world. With one exception (the 548S-5), the product more or less remained the same.

The initial documents of the 718U (6 MB of TIFF 5.0 files) with more to come. The material gathered from the Maintenance document and other sources.

An overview of the various variations is here.

This radio is being replaced by the AN/ARC-220 series in order to support datalink (HFDL) requirements required by the commercial airline world as a backup to the existing Satellite and VHF based system.

There are some images yet to be processed in the main directory under "unsorted" images that may be useful. See here

The AN/ARC-174 or 718U family is made up of several key modules. These include: 
Receiver-Exciters
 671U-1A  Panel Mounted
 671U-4   Special version with CCCS control signalling
 671U-4A  Shelf Mounted - Modulo 2 control CPN = 787-6934-007
 671U-4AN Shelf Mounted - Modulo 2 control and also has a narrow bandwidth for marine use
 671U-4B  Shelf Mounted - FSK control
 671U-4D  Shelf Mounted - FSK control
 671U-4E  Shelf Mounted - FSK Control

Ampfilier/Antenna Couplers (solid state final)
 548S-1   100 Watt - used with front panel system (rare)
 548S-3   100 Watt - Basic Amplifier and Antenna-Coupler (most common version)
 548S-3A  100 Watt - Recent version
 548S-5   100 Watt - Pressurized (Also known as the AM-7202/ARC-174)
          	Front View
	  	Side View
          	ID Plate View (Left side)
          	ID Plate View (Right side)
          	Antenna Connector (back) View
 548S-6   Unknown

Amplifiers (no antenna coupler)
 548T     400 Watt (tube in Final)
 548T-1A  400 Watt 

Antenna system
 437R-2   Monopole

Power Supplies (used with the 548T Amplifiers or various system packages)
 636W     Supply (3 phase, 400 Hz)
 636X     Supply (28 vdc, 150 Amp?) 
 636X-2A  Power Conditioner (28 VDC filter in essence)
 639G-1   Supply (28 vdc, 75 Amp) used with the 718U-2B family
 PP-4415  Supply, AC input, 28 VDC at 50 Amp output

Control Heads
 514A-3   Modulo 2, Manual control
 514A-4   Modulo 2, Manual control
 514A-7   Modulo 2, Manual and stored programming control (also know as C-11289/ARC-174)
 379H-1   Used to control dual 718 systems to provide "split channel" operation

 514A12   Used in ARC-190 only
 514A13   Used in ARC-190 only

 313V-8   FSK control only 
 514N-1   FSK Control only
 C-4526   FSK Control only, Vehicle mount or remote mount for field applications

Antenna Couplers
 490T-1
 490T-1A  Used with the 618 series. AKA CU-1669A system. Supports 630 Watts and requires 115 VAC, 400 hz
 490T-2   Used with high power systems
 490T-2A
 490T-3   Used with high power systems (fan cooled)
 490T-4
 490T-9   Used mostly with the 618T-2 series, Part number 522-4994-001, 115 VAC/400 HZ power requirement
 490M-20  Marine use

Mounting trays or cases
 990C     Used for the 671 series
 990C-1   Used to mount the 671 and the 548S-3 on a common tray
 990C-2   Used to mount the 548S-3 only
 990C-2A  Used to mount the 548S-3 with a feed-line antenna connection
 990C-3   Used to mount the 671 series only
 990C-3D  Used to mount the 671 series but also has an output for SelScan
 990C-5   Used to mount the 548S-3 with a long-wire antenna connection
 990C-6   Used to mount the 548S-3 with a coaxial antenna connection (HN style)
 990C-8   Used to mount the 548S-5 version
 990C-9   Used to mount the 548S-3 with a special antenna connection for 15-30 long-wire antennas
 990C-12  Used to mount dual 548S-3 units
 
RT-4402/MT-4405  Used to support the AN/VRC-81 system

ALE modules
 309L2    1st Generation protocol - not really usable these days (At Murphy's for $195 each)
 309M1    Early version of 2G technology, supports Mil 188-141A and FS-1045
 309M3    Current generation - 2G protocols

Selective Calling

HF Datalink (HFDL)
 309P
 309P2    Used for ARC-190 series

HF Modems
 953      FSK
 2201     DSP based (current production)

Preselectors - Post selector
 
 635U-1   Used with the 671D series (FSK)
 635U-2	  Collins Part number 622-0402-009  8.1 lbs - modulo 2 control (was used with the 671U series and 651S series)

This then created several basic system configurations:

 718U     System with 400 watts, the 635U-1 pre/post selector (not modulo 2 in normal configuration)
 718U-1   100 Watt Backpack version
 718U-2B  400 Watt Aircraft
 718U-4A  400 Watt Aircraft
 718U-4B  400 Watt Aircraft - Retrofit for 618 Series
 718U-5N  100 Watt Aircraft for narrow bandwidth applications
 718U-5M  100 Watt Aircraft and Marine use (both "N" and "M" functions)
 718U-9   100 watt Fixed/mobile/transportable version that is based on 718U-1 version

 HF-104   Base Station version of the 718U-2B and included the 635U1
 HF-117   Base Station was two 718U-4A with two 635U2
 HF-120   Base Station (unknown configuration)

 MR-150   Marine system

Note: Fixed based or land mobile

Information on the AN/VRC-81 System is here

Information on the MP-150 System is here

Inter-shelf and aircraft cabling
	Partial Drawing - A
	Partial Drawing - B
	Partial Drawing - C

Control head model 514A-3 and 514A-4 equipment manual

One user's story of the 718U

Unpacking a 20 year old 718 system that had been in long term storage from a Rockwell-Collins depot level upgrade

The 718U system

The next images of the AN/ARC-174 are from David Ross at Hypertools.com

Note the minor changes in the 548S-5 compared to the 548S-3 in the commercial 718 series


Some information from the user's manual

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please contact us by sending us a mail at tsc-60@cellmail.com!