AN/TPS-25 Ground Surveillance Radar

I served in the 25th Infantry Division Artillery as a ground surveillance radar operator from 4/69 to 4/70. Our base camp was in Cu Chi, however, we were rarely there. Our 5-man team operated the AN/TPS-25 battlefield ground surveillance radar system primarily along the Cambodian border, near the Angel’s Wing and Parrot’s Beak, AO’s (Area of Operation) of the 25th Infantry Division. These areas were major enemy infiltration points from the Ho Chi Minh trail. Our job was to detect enemy infiltration during the hours of darkness and adjust artillery fire onto the target.

Although we were attached to the 25th Infantry Division Artillery, we moved about independently, via helicopters or trucks, setting up the radar and tower at a dozen locations during my 12 month tour. These locations included Fire Support Bases (FSB’s), Advanced Tactical Support Bases (ATSB’s), Patrol Bases, ARVN Infantry camps, a couple of Special Forces camps and a 2 week stay at the base camp in Tay Ninh.

Under ideal conditions, the TPS-25 (Tipsy 25) radar had a maximum range of 11 miles (18 km). Also, the Tipsy 25 incorporated Doppler which allowed an experienced operator to identify the target by means of a characteristic audio return. Most targets were detected between 1/4 to Console8 miles out. Range was usually limited by tree lines or other obstacles but we minimized this loss somewhat by mounting the radar dome on an 84 foot tower.

Power for the radar was originally supplied by a 1 kilowatt generator but this proved to be marginal in performance and reliability and was eventually replaced by superior 3 kilowatt model.

We operated the radar mostly during the hours of darkness, 1800 to 0600 (6:00 PM to 6:00 AM). Each team member pulled 2 shifts on the radar per night. Shifts were usually performed solo unless it was a new replacement in-training. When a target was detected the operator contacted TOC (Tactical Operations Center) back at our base camp (Cu Chi or Tay Ninh) via 2-way scrambled (encoded, decoded) radio, and give the coordinates, strength and direction of movement. TOC would order a fire mission on the target if there were no friendlies in the area. Somewhere along the line, someone decided what type of rounds would be used on the target. The choices included HE (high explosive), HB (high burst), Firecracker (6 grenade-like bomblets spring out of the warhead on impact) and WP (white phosphorus).

Targets varied in strength from as few as 10 troops and up to 100 or more, all strung out in a disciplined and well spaced column. We detected these infiltration columns almost every night, usually somewhere between the Cambodian border and 2 or 3 miles into Vietnam. On some nights, we detected as many as 6 or 8 targets or more. Most of our targets were fired on, often using the Howitzer gun battery in our camp. When a fire mission took place TOC would advise us the moment the artillery rounds were in the air (even if we knew this before they did). We observed impact and called in adjustments if necessary. When we observed rounds on target, we keyed the mic and said, “Rounds on target, fire for effect.” In the majority of cases, this sealed the fate of the infiltrators.

Although our primary mission was to detect infiltration from the Ho Chi Minh Trail, we often detected hostile movement near our own camp.  We quickly reported this information to our base commander, resulting in everyone going on alert and quickly hitting the berm line surrounding our camp, weapons ready, waiting for the shit to hit the fan.  And it often did just that. We were ready.

Every member of our 5-man team performed their duties faithfully, day after day and night after night, for one year.  I’m proud of the team I served with. We made a difference. I’ll let you do the math.

We were brothers and we have a bond that endures to this day. Above all, we did our job.

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