Writer: Lieutenant Colonel Waseem Ahmed Qureshi

AN/GRC-9 is certainly an acronym that brings an instant smile on the faces of our veterans who were serving in Pakistan Army until mid-eighties. Commanders would speak with confidence while communicating on these sets. The speech quality was superb as one would easily identify the person with whom one was talking to. Highly reliable links were established between GHQ (Rawalpindi), Gilgit, Karachi and Dacca (former East Pakistan). These sets were extensively used until the change over of complete inventory to PK 786 (transistor version, compact HF Radio) in 1989.

Units from Corps of Signals and Armoured Divisions in particular were very well conversant with AN/GRC-9 high frequency tube version radio (used for long distance sky wave and short range point to point radio communication).

The name AN / GRC-9 means, AN (Army/Navy), G (Ground, General Use), R (Radio), C (Communication) and 9 is the serial number. GRC-9 was the first shortwave radio which consisted of transmitter and receiver separately. It was used in relatively short range networks that were beyond the range of the emerging Frequency Modulation (FM) voice sets at that time. GRC-9 was also nicknamed ‘Angry Nine’ in the United States. It was used in multiple modes like stationary, portable or mobile unit.

For those who are not familiar with these sets - the GRC9 was originally designed in 1946 in the United States for the military. It was built under licence in France and Germany until 1965. It saw service in Korea and Vietnam as well as Europe. These sets were given to Pakistan Army by US after the Korean War under Mutual Defence Aid Pact (MDAP).

A huge chunk was received by Pakistan Army on raising of 1 Armoured Division in 1956. 1 Armoured Division Signal Regiment which was raised with 1 Armoured Division in 1956 (later redesignated as 9 Signal Battalion in 1963), was assigned the task of training the operators of AN/GRC-9 from all Armoured, Artillery, Air Defence and Armoured Infantry (later Mechanized Infantry) units of the formation.

The Armoured Division Headquarters would have AN/GRC-26, (a high power 400 Watts HF Radio Set) as its base station and AN/GRC-9s would be employed as its substations in armoured brigades and regiments. Brigade below, it would be utilised as base and as substation both. In certain cases it was employed as point to point link also, tailored according to the situation.

It was a rugged steel luggable manpack. Inside, it contained a well-protected HF wireless and a separate transmitter, including an aerial tuner and glow bulb.

The GRC-9 was made of three modular sections: wireless, transmitter and aerial tuner. The power pack was in a heavy steel box containing a vibrator (a mechanical HT generator) to run the radio and a dynamotor (giving higher power output) for the transmitter.

The radio was a straightforward tube version (valve) superhet with three Intermediate Frequency (IF) stages. There were no switchable f ilters or band spread. It could pick up AM and Morse signals. The transmitter had an AM or Morse output of 5 or 15 (high setting) watts. It could be zero beat tuned with the receiver for simplex signalling.

In all, a solid reliable set. There was provision for the inverted dipole, a whip (for use on jeeps) and a long wire.

The operators were always excited to set it up. The old smells of rubber and oily paint wafting back! The shacks power supply was put on duty to input the GRC-9 power pack. Excited hands wired up the aerial and morse key and speaker. Switch on and a hum from the vibrator. This quickly warmed up the radio and it burst into life giving agreeable sounds of distant stations.

The tuning used to be in three bands from 2 Mhz up to 12 Mhz with great sensitivity and selectivity. A modern set is not much better! The 80 metre band was chosen and when the telegraph switch closed, a cacophony of Morse was heard. It jolted the system to have such a wide pass band - and no filters. Switching on the transmitter section (sender) produced a whirring sound from the dynamotor and after a flutter the radio came back on again. So far so good!

This sounded like a real wireless, which whirs and buzzes as well as Morse. Tune up used to be quite straightforward - a twiddle of the Antenna Tuner until the glow-bulb is brightest, giving a brilliant orange glow. A distant signal was selected and `netted’ by tuning the transmitter output over it. Then a quick response on the mic or key and one would have an agreeable communication. Each press of the Morse key produced a loud clang of the changeover relay.

The radio operators of AN/GRC-9 used to be in constant communication with their distant operators and would constantly tune the radio sets with a view to ensure that they maintain the link established precisely. This was due to the fact that frequency of these sets drifted due to various reasons, like temperature of the set, time of the day, power supply etc, and operators needed to be very sharp to retune and apply corrections throughout the day. However, with modern radio sets such problems were eliminated due to frequency lock systems with auto compensation for the drift.

1965 War - Employment in Support of Mechanised Formations

During Indo-Pak war of 1965, our communication assets surged from merely radio communication to Radio Relay (RR) communication and Permanent Line (PL) routes for extended troops deployment. Keeping in view the mobile nature of operations in Rann of Kutch, Khem Karan and Chawinda, vehicle mounted radio communication proved to be the most feasible support for mechanised formations. The ruggedised and self-sustenance features of AN/GRC-9 provided the ultimate solution of matching the requirements of mechanised columns. It may interest our esteem readers, that troops operating in scorching deserts were issued ice for their consumption. However, since AN/GRC-9 was a tube version radio set prone to picking up heat, so to keep it operating under prescribed temperature range, our soldiers made use of their daily consumption ice. Where there’s a will, there’s a way.

1971 - War Employment on Extended Frontages

Induction of communication equipment continued after 1965 War. Radio relay equipment AN/GRC-103 was a multi-channel equipment which changed the concept of communication support to field formations. It was a highly ruggedised and portable radio relay equipment with a communication range of 30 to 40 kilometers. However, Indo-Pak war of 1971 presented an altogether different war-front. East Pakistan theatre of operations involved extended communication distances for deployed troops. Radio Relay (RR) communication was not a feasible mode of communication, so again radio set AN/GRC-9 was considered the most reliable means of communication. Troops deployed on extended distances in East and West Pakistan could not be connected with any other means of communication except high frequency (HF) radio set AN/GRC-9. With the failsafe performance of AN/GRC-9, radio communication remained flawless throughout the 1971 War.

The most significant feature of AN/ GRC-9 was its battle-hardened architecture. Field conditions under which this set was operated, varied astoundingly. Logistic chains were complex and time taxing, putting heavy constraints on availability of spares. All these limitations were offset by robust design and maintenance free functions of AN/GRC-9. Though its hefty outlook featured it as an ‘Angry Nine’ Radio set, however it stood like a promising and cheerful friend with signallers.

The decades of 80’s and 90’s later saw a revolution in information technology with shift from tube-version to integrated circuit (IC) based communication equipment. Frequency hopping (transmission security) and encryption (communication security) changed the concept of both strategic and tactical communication in modern warfare. It took a long effort to traverse this uphill journey, which started from the tedious task of carrying heavy tube version radio sets like AN/ GRC-9, to mountainous / glaciated terrains. This set remained part of our signal inventory till late 80’s and was replaced later by High Frequency (HF) radio sets.

In 1989, when Micro Electronics International (MEI) Lahore introduced an indigenously produced HF Radio Set PK-786, which was inducted in Pakistan Army, the radio operators were concerned for speech quality and comfort level. However, the positive features of the new set which included compact size, easy operation, no frequency drift and no retuning, were later realised and widely accepted.