NEWS | Oct. 13, 2020

Sentinel Radar: Steps to Sentinel Success

This article initially appeared in PS 798 (May 19), p. 42-45.
Your Sentinel Radar System can alert you to danger if you remember these steps to success…
  • Be careful out there! The Sentinel produces lots of voltage and rotates very fast. Just a moment of carelessness can spell disaster.
  • ​Maintain cybersecurity. See the Sentinel systems administrators manual (SAM) for how to establish and maintain cybersecurity. Your AMCOM LAR can help. 
  • Before doing any maintenance, set the ANTENNA/DUMMY LOAD switch to DUMMY LOAD on the tactical control unit (TCU). That way the Sentinel sends RF into the dummy load and not into space where it could microwave anyone on top of the Sentinel.
  • ​Check and re-check that the azimuth (AZ) drive circuit breaker is set to OFF to prevent accidental rotation before climbing on top of the Sentinel. If the AZ circuit breaker isn’t set to OFF, you could go flying if the Sentinel is activated and its antenna whirls around.           
When you climb around the Sentinel, always use three points of contact. That stops falls.
Before rotating the Sentinel, always make sure everyone is out of the way. That’s especially important when you’re operating remotely.
  • Keep the compartment doors closed as much as possible. Sand causes abrasions and other problems for electrical components. Wipe the compartment clean daily when operating.
Wipe out compartments daily in desert
Wipe out compartments daily in desert
  • Don’t use rubbing alcohol to clean. That strips the protective coating off the compartment walls, which leads to corrosion and arcing. Use technical isopropyl alcohol, NSN 6810-00-753-4993, for cleaning. It’s 70 percent isopropyl and 30 percent water and won’t affect the walls’ coating.
  •  Clean the filters. The Sentinel produces lots of heat. If it’s not getting lots of cool air, it overheats and shuts down. Check the filters. If they’re clogged, clean them either with soap and water or blow them clean with low-pressure air.
Remember there are 12 filters:
  • antenna intake
  • antenna exhaust
  • BSU intake
  • BSU exhaust
  • IFF intake
  • IFF exhaust
  • R/E intake
  • 1 eRCT exhaust
  • SIU exhaust (the Sentinel IETM calls this an SIU intake filter, but that’s a mistake)
  • Two (2) PAM exhaust filters
  • eRCT intake
Clean all 12 filters daily when operating in sandy conditions.
All but the PAM exhaust and eRCT intake and exhaust filters should be checked at least weekly by the crew. The PAM exhaust filters are a monthly check by the maintainers and the eRCT filters are a monthly check by the crews. But if you’re operating in a sandy field environment, check all filters daily. If you must constantly run the Sentinel, it’s a good idea to get an extra set of filters. That means less downtime for your Sentinel.
  • Wear electrostatic discharge (ESD) protection to handle circuit cards. Some of the Sentinel circuit cards cost thousands. One spark can ruin a circuit card. Before handling any circuit card, put on an ESD wrist strap and plug it in. Make sure the Sentinel itself is grounded or the ESD won’t do any good. Never put circuit cards down on a metal surface. Lay them down on an ESD mat or place them in an antistatic pouch. NSN 4940-01-253-5368 brings an ESD work station kit with two wrist straps, a grounding cord, mat, three antistatic pouches and three barrier bags. The kit is part of the Sentinel radar maintenance tool kit, NSN 5180-01-407-3286
 Wear ESD protection to handle circuit cards
Wear ESD protection to handle circuit cards
  • Protect cables. When disconnecting cables, turn the connectors, not the cable. Twisting the cable breaks wiring.
Turn connector, not cable to connect and disconnect cables
Turn connector, not cable to connect and disconnect cables
When storing cables, roll them up completely on the reels. Put on connector caps. Make sure the cable reel straps are fastened and the cable reel nuts are tightly locked.
Roll up cables completely on reel and then fasten straps
Roll up cables completely on reel and then fasten straps
The power cable reel has a cotter pin to keep the reel’s hub bolt tight. If the pin’s missing, the bolt can work loose and the reel comes off. Check that the cotter pin is installed and its ends are bent so it can’t work out.
Cotter pin installed and end bent?
Cotter pin installed and end bent?
  • Keep it level. The Sentinel needs to be level to operate. So when you emplace it, try to put it on as solid ground as possible. In the desert, that’s not always possible. In those cases, put something solid under the jack pad, such as a flat piece of metal or sturdy plywood, to increase the footprint of the jack pad. Use heavy duty materials that can support the weight of the trailer. When you’re finished checking the circular levels, put their caps back on. If the gauges are left exposed, sun and moisture can ruin them.

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