Story 44A - Signals and ACV's - Part 1 Vietnam

By Denis Hare OAM BEM

Introduction

1st Australian Task Force (1 ATF) was located at Nui Dat in Phuoc Tuy Province, South Vietnam from April 1966 to October 1971.

Headquarters (HQ) of 1 ATF commanded the Task Force which included infantry battalions (three from December 1967), special air service squadron (SAS), artillery regiment, armoured squadron (from February 1968), cavalry squadron, signals squadron, and other supporting arms and services.  By December 1968 the approved establishment for HQ 1 ATF was 35 officers and 150 other ranks to plan and control operations.

During the war HQ 1 ATF deployed away from the Nui Dat base in support of operations, starting late 1966.  At this time, the enemy had been blooded at the Battle of Long Tan.  The Nui Dat base was well developed and Tactical Area of Responsibility (TAOR) was under constant patrolling and secured, allowing the Task Force to move further away from Nui Dat into its Area of Operation (AO).  However, until the Task Force manpower was increased to three battalions in December 1967 deployments remained within the AO.
 

First Deployment

The first forward deployment of HQ 1 ATF Main, away from the Nui Dat base area, occurred on Operation (Op) Hayman in November 1966.  This was also the first full scale airmobile combat assault into unsecured Landing Zones (LZ) by the Australians.  The area of operation was Long Son Island, which is just off the coast to the West of Baria and surrounded by swamp.

HQ 1 ATF Main (84 personal) setup the Tactical Operations Centre (TOC) in tents, protected with sandbags.

 
Overview of the Communications Operation Hayman November 1966
Graphics from Pronto in South Vietnam 1962-1972 (Slide 9)

103 Sig Sqn (39 personal) deployed the communications to support the HQ, which included a Signal Centre (SIGCEN), Telephone Switchboard (Ebony Forward) and the Radios, all housed in 16’ x 16’ tents.  Telegraph and cipher equipment for the SIGCEN was carried in a Landrover loose and then setup on tables for use.  Radio sets were remoted to the TOC.  Detachments from 145 Sig Sqn (4 men) and the US Army 53 Sig Bn (10 men) provided rear links by both Radio Relay (RR) and High Frequency (HF) Radio to HQ 1 ATF Rear at Nui Dat and HQ II Field Force Vietnam at Bien Hoa.
 

HQ Requirement

By middle 1967, HQ 1 ATF Main and now 104 Sig Sqn, started deploying further away from Nui Dat, still using a tented HQ, with a back up plan to use Armoured Personnel Carriers (APC), if the situation called.

Australian staff and signals had concerns with the HQ 1 ATF deployment arrangements because of the time to setup, protection for the staff and communication equipment.  In July 1967, on Op Paddington the Australian HQ deployed with the US Army, including the 11th Armoured Cavalry Regiment (11 ACR) and saw first hand how the American Army deployed.  The US Army used Armoured Command Vehicle (ACV) Type M577 for Command Post (CP), which was a variant of the APC M113 series used by A Sqn, 3 Cav Regt at the time in the Task Force. 

The M577 had its hull height extended so that its occupants could work in relative comfort. These vehicles contained a number of radios and map-viewing facilities. To facilitate the number of radios operating in the ACV, a generator was mounted above the engine deck, opposite the driver's compartment.  A tent was carried on the top rear and attached directly to the rear of the track to provide greater work space.  Multiple ACV’s could be connected via the tents forming a larger operations centre.  They were usually armed with a single, pintle-mounted Browning L3A4 (flex version) .30 caliber machine gun, but a 7.62mm GPMG M60 machine gun was sometimes mounted as an alternative.

M577A1 Armoured Command Vehicle (ACV).  Photo supplied by Bryan Brackin.

In fact, the Cavalry Squadron HQ had one ACV, Callsign OA (ARN 134456) which was the OC’s vehicle.  This vehicle allowed the Task Force to test the HQ requirement and was used as backup for the Task Force CP during high threat periods at Nui Dat.  In late 1967, HQ 1 ATF made a request for four M577A1 vehicles, with crews, for its HQ deployment requirements.

HQ 1 ATF CP concerns were highlighted and addressed in a paper by the OC, 104 Sig Sqn, Major Gerard Lawrence in November 1967.  Lawrence’s paper concluded:

The communication systems and main CP layout have undergone a number of changes resulting from the different ways in which new members of the G staff wish to work and from changes in requirements.  The present arrangements seem to work reasonably well.  No significant improvement seems likely without a radical change in concept.

The use of ACV’s as the basis of a forward HQ should enable the HQ to be more quickly established and will eliminate the need for emergency forward HQ.  In most circumstances it will still be necessary for radios to be located at the best communications site and operate remotely.  An intercommunication system will be desirable.
 

Vietnam 1968

The deployment of HQ 1 ATF Main became routine in the first half of 1968 and further away from Nui Dat.  Op Duntroon (Jan), Op Coburg (Feb) and Op Toan Thang (Apr/May/Jun). 

Another ACV, Callsign OC (ARN 134459) arrived with C Squadron, 1 Armoured Regiment (Tank Squadron) in February 1968.  This ACV was equipped with both American and British Radio Sets and was used for command and control.  This was important as the Centurion Tanks only had the British Radio Sets and were not compatible with the Task Force Radio Nets, which used only the American equipments.

On Op Toan Thang at Fire Support Patrol Base (FSPB) Coral in May 1968, the deployed Australians along with its Task Force HQ and supporting Signals came within an ace of being wiped out by the North Vietnamese Army.  The HQ was most vulnerable and the complete command, control and communications had to be dug underground in bunkers.  This took a number of days which was handicapped by enemy action, limited defence stores and poor weather.

Command Post  ARTY and AIR at FSPB Coral - May1968.  Photos supplied by Ralph Bilsby

SIGCEN bunker almost complete at FSPB Coral - May 1968.
Photo supplied by Graham Arnold.

After this action, now known as the Battle of Coral, the four ACV’s that had been requested in 1967 were urgently demanded by HQ 1 ATF.

The four ACV’s were available in Australia but were missing some radio equipment.  HQ 1 ATF requested the vehicles be forwarded to Vietnam less missing radios.  This would in the following years cause the Q Staff many problems in accounting but four ACV’s were shipped on MV Jeparit (Trip 17) in August 1968 and the vehicles arrived in Vietnam in September and were quickly moved to the Task Force for service.

The ACV Callsigns (85) were drawn from the Cavalry Squadron radio net, in particular its Support Company Troop.  APC vehicles in this troop were predominantly M125A1 mortar carriers and were grouped in sections which carried Callsigns 81 to 84 and 85 was the next for assignment.

The first deployment of the HQ 1 ATF Main using ACV’s was on Op Capitol at FSPB Lion in early November 1968, as follows:

Callsign 85 (ARN 134469) – Operations Command Post

Callsign 85A (ARN 134470) – Air Support Command Post

Callsign 85B (ARN 134465) – Artillery Fire Support Coordination Centre

Callsign 85C (ARN 134457) – Signal Centre – 104 Sig Sqn

HQ 1 ATF deployed at FSPB Lion for the first time in ACV's - November 1968.    Note the wire at the front of the vehicles to deflect rockets.   Photo supply by Neil Westwood

ACV HQ

The use of ACV’s for the HQ functions was very successful and a fifth HQ 1 ATF ACV was added Callsign 85D (ARN 134472) in April 1969 for use by the Task Force Intelligence Group, including 547 Sig Tp in its Signals Intelligence (SIGINT) role.

The radio equipment installed in each ACV, was normally as follows:

 Callsign 85 (ARN 134469) – Operations Command Post

AN/VRC-49 (TF Comd Net (Control) and backup set)
AN/VRC-49 (Higher Formation Net)
AN/GRC-125 (ACV and Local Defence Net)

Callsign 85A (ARN 134470) – Air Support Command Post

AN/VRC-49 (Possum Control and Common Air Net)
AN/VRC-49 (TF Comd Net and Backup Set)
AN/GRC-125 (ACV and Local Defence Net)

Callsign 85B (ARN 134465) – Artillery Fire Support Coordination Centre

AN/VRC-49 (TF Comd Net and Regt Comd Net)
AN/VRC-49 (Arty Air/Admin Net and Backup Set)
AN/GRC-125 (ACV and Local Defence Net)

Callsign 85C (ARN 134457) – Signal Centre/104 Sig Sqn

AN/GRC-125 (ACV and Local Defence Net)
Other from Signals resources as required

Callsign 85D (ARN 134472) – Intelligence Group/547 Sig Tp

AN/VRC-46 (TF Comd Net)
AN/GRC-125 (ACV and Local Defence Net)
Other from Signals resources as required

Note:  AN/VRC-49 (2 x RT-524/VRC VHF Radio Sets), AN/VRC-46 (1 x RT-524/VRC VHF Radio Set) and AN/GRC-125 (1 x AN/PRC-25 VHF Radio Set)

The establishment paperwork for 1 ATF was approved and issued by Army Office for the first four ACV’s along with some additional manpower in December 1968 with the fifth approved in April 1969.  Later the ACV’s were to be transferred to the Cavalry Squadron establishment to ensure their maintenance.

All the APC’s and the ACV’s in Vietnam undertook belly uparmouring in late 1970 as a high priority to decrease vehicle and personnel casualties suffered for enemy anti vehicle mines.

ACV Callsign OA undergoing uparmouring in Vietnam in late 1970.
Photos from internet source.

With the Cavalry Squadron fostering the HQ ACV’s, they remained in service until the end of Task Force operations in Vietnam late 1971.  Callsign 85, 85A, 85B and 8D were manned by the HQ Staff and left Nui Dat on the 16 Octocter 1971, redeploying to Vung Tau.  The last 1 ATF vehicle to leave Nui Dat was Callsign 85D with its two 547 Sig Tp operators.  However Callsign 85C with its 104 Sig Sqn detachment remained until the 7 November 1971 supporting the 4RAR/NZ (ANZAC) Group, the last Australian troops to leave the Nui Dat area.

Three of the HQ 1 ATF ACV's (Callsign 85, 85A and 85B) ready to lead the convoy out of Nui Dat
on the 16 Oct 1971.  Vietnamese vehicles line up on the outside waiting to help themselves
  to the goods being left by the Australians.  Photo supplied by Pete Bird

104 Signal Squadron Callsign 85C (SIGCEN)

The OC, 104 Sig Sqn, Maj Norm Munro wrote in the June 1968 monthly report;

1 ATF is ultimately to be issued with four tracked Armoured Command Vehicles (ACV) for use at a forward HQ.  A request has been submitted for allocation of one ACV as the forward Signal Centre vehicle.  It is proposed that the ACV be fitted out with two TT/TA-TG, one TT-76/GGC-3 and associated equipment, two RS AN/GRC-106 and two KW-7.  This will enable a secure RTT circuit (HF) to be established between Main and Rear HQ immediately the HQ deploys.  Following establishment of normal RR system the HF link would serve as the back up to the RR.

Maj Munro confirmed in his July 1968 monthly report that HQ 1 ATF has agreed to 104 Sig Sqn getting an ACV for the forward Signal Centre.

In his October 1968 monthly report, Maj Munro reported that ACV had been received and was being fitted out as follows:

1. AN/GGC-3, TT-4A/TG, 2 x TH5/TG, 2 x TA/182-U for Duplex Radio Teletype (RTT) circuit HQ 1 ATF Main to HQ 1 ATF Rear (Nui Dat).
2. TT 4A/TG, TH-5/TG, TA-182/U – Simplex RTT Circuit HQ 1 ATF Main to HQ 1 ATF Rear (Nui at).
3. 3 x KW-7 (cipher equipment for the telegraph circuits)
4. AN/GRC-106, AN/PRC-47 – HF RTT/CW/Voice as required.
5. 2 x SB-22/PT – Ebony Forward Switchboard.
6. Radio Set AN/GRC-125 – VHF Voice.
7. One commercial 6000 BTU/Hr air conditioner.

On the first deployment to FSPB Lion, John Koosache can remember sitting in the SIGCEN ACV on the code box with a red grenade in his hand with the instructions 'if this thing hits a mine or is .... attacked, pull the pin and get out the best way you can'.  Obviously John did not have to blow the codes and this was his last job outside the wire.

Callsign 85C at FSPB Julia- Xmas Day 1968.  Note the wire at the front of the vehicles to deflect rockets. 
Photo supplied by Gordon Taylor. 

Normally the telegraph circuits were connected via RR circuits, with the HF Radios remaining as backup.  Small changes were made to the equipment configuration over the following years, including a SB-86/P Switchboard replacing the SB-22/PT equipment and a VHF Teletype link for the last deployment in Oct/Nov 1971.   The KW-7 Crypto equipment caused lots of problems to the communicators, as it did not handle the heat and normally had a fan blowing air over the equipment.

The communications equipment inside Callsign 85C (SIGCEN) - July 1969.   Note the fan
 trying to keep the KW-7 equipment cool on the right.   Photos supplied by Bryan Brackin.

The Troopers who manned the ACV’s trained some of the Signalman to drive the vehicle at Nui Dat as they had enough problems looking after the other four vehicles and Signals was always working on their vehicle plus had cipher equipment that the troopers were not cleared to view.

Geoff Sanders, was one of the first signal drivers and remembers in mid 1969 during a demo for the staff getting into some problems;

I worked out of the ACV at FSB Julia and FSB Kerry during 1969, including brewing up our own specially sourced ground coffee, which Brig Sandy Pearson would  come over late at night to cadge a pannikin from us whilst we told him what was really happening around the AO.  I subsequently obtained a licence to drive the sucker and have the dubious distinction of nearly drowning it in the Nui Dat Dam during an exercise we had to put on within the wire of 1 ATF to show the incoming Brigadier how we operationally deployed.  The bloody tankies had omitted to teach me about the bungs the sucker had for amphibious work!

Callsigns 85C and 85D being prepared for deployment at 104 Sig Sqn, Tech Maint, Nui Dat in 1969.
 Note the 10KVA generator trailer on the left.  Photo supplied by Dick Meager.

John Bertini remembers his first experience at a FSPB and the SIGCEN ACV;

It was late February 1969, I had just arrived in country and had spent one day in the SIGCEN at Nui Dat and was told the next morning to get my gear as I was going to the 104 Sig Sqn Forward SIGCEN with HQ 1 ATF at FSPB Kerry.

When I got there, I couldn't believe how I had got myself into such a mess.  I was just completely unprepared for constant heat, dust, artillery fire, sleeping in a hole in the ground, cocked rifle on my first clearing patrol which almost ended in disaster when the signalman behind me forgot to remove his magazine, when we came back through the wire and there was this almighty bang!  I just about shit my pants on the spot.  Fortunately he had pointed his SLR to the ground.

Then came my night in the SIGCEN.  It was the ACV Callsign 85C.  I was working by myself and like a cat on hot bricks.  At about ten o’clock I got a call from the SIGCEN at Nui Dat.  They said they were ready to do a ZNP4.  I said "mate, what the fuck is that?”  The irate reply that I got was,"its a key change you stupid bastard, didn't they teach you anything at Balcombe.  O the ignominy of it all!  Off course it was the key change on the KW-7 in the ACV.

Note:  ZNP* is part of the Z radio code.  Transfer operation of channel now to (1) normal; (2) top secret; (3) conference; (4) engineering; on-line cipher operation.

104 Sig Sqn Callsign 85C SIGCEN and Radio Relay from 110 Sig Sqn plus other HQ 1 ATF ACV's
 at Courtenay Hill during Operation Overlord June 1971.  Photo supplied by Pete Bird.

Most of 1 ATF including 104 Sig Sqn relocated to Vung Tau completing this task on the 16 October 1971.  However Callsign 85C and its 104 Sig Sqn detachment remained at Nui Dat, under command of 4RAR/NZ (ANZAC) Group providing VHF Radio and Teletype for the group to the HQ 1 ATF SIGCEN now at Vung Tau.

On the 7 November 1971, the 104 Sig Sqn 4RAR/NZ detachment (Names ?), with their ACV, were the last RASigs personnel to leave Nui Dat, to join the unit rear party at Vung Tau now hosted by 110 Sig Sqn.

This remarkable painting "Signals in Vietnam" proudly hangs at the Defence Force
Signal of Schools (DFSS), Watsonia.   The painting is a representation of Signal Units
 deploying to support HQ 1 ATF featuring the ACV SIGCEN, Callsign 85C.
Graphics from Pronto in South Vietnam 1962-1972 (Slide 15)

547 Signal Troop Callsign 85D (SIGINT)

The solution of couriering SIGINT forward by a 547 Sig Tp officer, normally by helicopter, with classified papers and a thermite grenade, became a problem, following an incident with 9 Squadron RAAF, in early 1969.  It became evident that the carriage of classified information by helicopter to any forward base introduced operational and security difficulties!

The OC, 547 Sig Tp, Major Steve Hart, was confronted with a requirement for a new way to get classified SIGINT timely to the SO2 (Int), when he was deployed with the Commander at HQ 1 ATF Main.

The solution was to use a channel on the RR and terminate it on a Telegraph circuit protected with KW-7 equipment using exclusive cipher keys, all installed in an ACV for the exclusive use of the SO2 (Int).  547 Sig Tp manned the equipment at both ends and this also allowed the unit to deploy operators forward to monitor enemy transmissions from the FSPB. 

Until the ACV Callsign 85D materialised in late April 1969, 547 Signal Troop did get an immediate loan of a M113 from the Cavalry Squadron as an interim solution.

Garth Brown gives an overview of how the ACV was used;

When we initially started to deploy to FSPBs using Callsign 85D we were totally reliant on 110 Sig Sqn and their AN/MRC-69 equipment to provide the radio bearer path for our telegraph traffic between the FSPB and the 547 Sig Tp Comcen at Nui Dat.

This was a totally unsatisfactory arrangement because the radio bearer had frequent outages, and when it was up, the signal was so marginal that we continually ended up with corrupted (read unusable) traffic which had to be re-sent; re-sent; re-sent.  This to a degree negated the real time value of having SIGINT Operators on the ground at the FSPB.

The advent of the ACV gave us the opportunity to look at an alternative radio bearer path which, hopefully, would be both easy to transport into site and easy to set up.  Because most of our TAOR was reasonably flat and generally suitable for VHF line of sight from FSPB to HQ 1ATF Rear, John Harding and myself decided to explore the viability of utilizing the RT-524/VRC transceiver as our bearer.  We knew that the transceiver itself was a robust and extremely reliable unit but we had some concerns that it may not handle a higher transmission ratio above the normal 1 – 10 transmit – receive cycle.

It turned out that the RT-524/VRC was perfect for the task.  After a lot of trial and error we came up with a standard ACV fit-out comprising Kleinschmit teleprinters connected to TSEC/KW-7 crypto gear (mounted on incendiary slabs) which was connected via a TA-182/U tone converter and TH-5/TG FSK unit to the RT-524/VRC transceiver, which itself was connected to a RC-292 antenna.  It was all standard equipment except for a resistive attenuation pad we had to knock-up to match the TH-5/TG output to the RT-524/VRC input.  We used the same setup at the Nui Dat end with the RC-292 antenna mounted on top of the 72ft DECO mast.

We also installed HF equipment in the ACV for intercept tasks.  These were Racal RA-329 units which comprised a Racal RA-217D HF receiver and Racal MA323 FSK unit mounted in a “ruggedised” casing.

When the ACV deployed, it also took a 10KVA generator and 16 jerry cans of fuel.  This made for a decidedly uncomfortable trip for the troopies who were conveyed out to the FSPB on the ACV because the jerry cans had to be stowed on top of the ACV and the troopies had to ride outside the ACV perched on top of the jerry cans – that certainly increased the “pucker factor” by a few degrees.

In summary, notwithstanding the necessity for the Cav crew to drive the ACV, 547 Sig Tp was able to deploy a totally independent sub unit which was able to sustain intercept operations in the FSPB environment while maintaining (most of the time) ZBZ5 secure telegraph traffic back to base.  Another good example of the Troop’s collective ingenuity serving to get the task done.

Up until I left in Aug ’70, I know we lobbied to have some 547 members trained to drive the ACV (even if only in Nui Dat) but unfortunately it never happened – we were allowed to power it up – and drop the ramp – but we weren’t allowed to move it.

Callsign 85D dug-in on FSPB Colorado - L-R John Pearson (A Sqn, 3 Cav), Harry Lock
(547 Sig Tp), Des Williams (547 Sig Tp), Tony Luck (547 Sig Tp) and Bob Harland
(547 Sig Tp) - January 1970.   Photo supplied Bob Harland

Bob Harland remembers the OC, 547 Sig Tp became very concerned for their welfare when the SIGINT operators and Callsign 85D went missing after the convoy they were travelling in from FSPB Picton came under enemy fire;

“On the 8 December 1969, we are all of a sudden "missing" - bit hard to 'miss', but that's when the Boss found out what happened, and the orders were 'don't care how you do it, just get them out of there'-- OK for him, he didn't have to follow the only surviving Centurion in low low gear, trying to bask it's way through the boonies, with all us dickheads sitting on top of it --- never was fond of that rule !!!”

The 547 Sig Tp members and their ACV made it out safely but sadly two Australians were KIA and two WIA in the convoy mine ambush with an APC (Callsign 23A) heavily damaged.  Also a Helicopter attempting to land to effect dustoff of the injured, detonated another mine resulting in another WIA and a badly damage Huey.

In should be noted that the vehicle generator was petrol and all the jerry cans were full of it.  The last thing you want on top of a vehicle with or without troops, particularly when the floor of the vehicle is an aluminum/magnesium alloy!

In the Nui Dat pull out, the new site for 547 Sig Tp, at Vung Tau, was ready on the 1 October 1971 and only the rear party remained at Nui Dat, which included the ACV.  Only the ACV and two operators remained after the 7 October with Callsign 85D leaving Nui Dat for the last time on the 16 October 1971.  Lt Ian Bowen and Peter Dencher plus their Cav Sqn driver were the last HQ 1 ATF vehicle to leave.

Callsign 85D dug-in at FSPB Colorado - January 1970.  Note the underground work area
behind the ACV.  Photo supplied Bob Harland

Return to Australia (RTA)

104 Sig Sqn’s OC plus 60 embarked on HMAS Sydney for the return trip to Australia on the 6 November 1971.  Radio Operators doing Liaison Officer  (LO) radio tasks returned to Detachment 104 Sig Sqn at Vung Tau in November to help complete cleaning and packing of the unit stores for RTA.

104 Sig Sqn’s return to Australia was completed in late Dec 1971 without its ACV and it would take a few years for the unit to be reunited with a number of the vehicles.

On the 13 December 1971, 547 Sig Tp ceased operations from their Vung Tau location and on the 23 December 1971 in the early hours boarded buses for the airport to start the journey home to 7 Sig Regt, Cabarlah.   Post Vietnam would see Electronic Warfare (EW) developments and a special signals field force squadron (72 EW Sqn) to support future deployments.

During December 1971 to February 1972, HQ 1 ATF was primarily concerned with maintaining the security of the Vung Tau base and continuing the preparation plus dispatch of personnel and equipment to Australia.  All vehicles were steam-cleaned after washing to fumigate them, in line with the Australian quarantine rules.   The last 1 ATF troops including 110 Sig Sqn (doing both TF and Force RASigs roles since early November 1971) boarded HMAS Sydney Voyage 4 (South) for the trip home to Australia.  Included in the stores were the last armoured vehicles, ten M113A1 APC, two M125A1 81mm Mortar Carriers and one M577A1 ACV.  The Vung Tau base was handed over to the Vietnamese on the 29 February 1972.

A member of 3 Cav Regt lowers the flag during the hand over ceremony at
 Vung Tau to the ARVN - 29 February 1972.    In the foreground, another member
 of 3 Cav Regt sits  on top of an ACV armed with a 7.62mm M60 general
 purpose machine gun.  Photo from the AWM PO5243.007

Remaining in country was HQ Australian Army Assistance Group Vietnam (AAAGV) with a small special Signals Troop until December 1972, when all were recalled to Australia by the new Labor Government.   Thus ended Australian involvement in the Vietnam War.

HQ 1 ATF on RTA was located at Holsworthy and supported by 104 Sig Sqn as its TF Sig Sqn.  See detailed in Signals and Armoured Command Vehicles, Part 2 – Post Vietnam.

Click Signals and ACVs - Part 2 Post Vietnam

References (Part 1 - Vietnam)