Aitech E121

Rugged 3/4-ATR-Short, Eight (8) User-Definable Backplane Slots

Manufacturer: Aitech
Aitech E121

Aitech’s E121 3/4-ATR Short air-cooled enclosure is built to be rugged and reliable as well as lightweight and compact. EMI/RFI protected and environmentally sealed, the E121 is capable of withstanding extreme environmental conditions of altitude, temperature, moisture, shock, vibration, EMI and chemical exposure, making it ideal for use in military and aerospace environments.


The E121 is constructed of durable CNC machined 6061-T6 aluminium. Fasteners are stainless steel and removable cover threads have self-locking stainless steel helicoils to withstand severe vibration and shock. All I/O connectors are located on the front panel of the enclosure for easy access. The chassis is air-cooled. Designed with a built-in handle, the E121 is also equipped with two front mounting hooks and two rear hold-down pin receptacles to facilitate installation in standard ARINC 404 3/4-ATR mounting trays.


The E121 accommodates 8 standard VMEbus boards with 0.8-inch pitch, including:

  • 8 conduction-cooled cards (IEEE 1101.2 or VITA 30.1)
  • 3/4-ATR conduction-cooled power supply


The backplane is VME64x compliant with 160-pin, 5-row J1/J2 DIN connectors and 95-pin P0 connectors in all slots.

Any of the pins in rows A and C and user-defined pins in rows Z and D of the J2 connectors as well as the 95 I/O pins from each of the P0 connectors (up to a maximum of 512) can be routed to front panel I/O connectors. DC input power is routed to the power supply via a separate screened harness so as to prevent radiated or conducted EMI.


The front panel features a flexible configuration of user-defined 38999-style connectors that conform to military standards, one for input power and all others for I/O. It may also be equipped with any of the following options: elapsed-time meter, LED indicator to track system operation, On/Off switch and external grounding lug.


GeneralRugged Chassis for Military and other Harsh Environment Applications
CapacityThe E121 accommodates 8 standard VMEbus boards with 0.8 inch pitch, including:
• 8 conduction-cooled cards (IEEE 1101.2 or VITA 30.1)
• 3/4-ATR conduction-cooled power supply
BackplaneThe backplane is VME64x compliant with 160-pin, 5-row J1/J2 DIN connectors and 95-pin P0 connectors in all slots
PSUVoltage Range (DC): 16 - 36 Vdc
Nominal Input Voltage: 24 - 28 Vdc
Capacity: +5 @ 25A, +3.3V @ 6A, +12V @ 1A, -12V @ 1A
Total Output Power: 170 W
Transient Suppression: Meets requirements of:
– MIL-STD-1275AT (with minor exceptions)
– MIL-STD-704D
CoolingThe E121 is cooled by natural convection. The conduction-cooled, 1101.2-compliant boards are environmentally sealed within the chassis.
IP/NMEAThe E121 is sealed against intrusion of external environment contaminants found in military applications, including: humidity, sand and dust,
and contaminant splash. Enclosure mating surfaces are sealed with silicon rubber O-ring seals. Connectors and other accessories are protected also in the same manner


ExpansionVME64x compliant
ElectricalSee above for PSU specification
Power Dissipation Capability: More than 150W at 60C forced air temperature (maximum delta T of 25C at card edge).
MechanicalStandard 3/4-ATR Short mounting footprint: 7.50” x 12.52” x 7.62” (W x D x H)
Maximum external dimensions: 7.50” x 16.53” x 7.62” (W x D x H), includes carrying handles, etc.
TemperatureOperating Temperature: -46C to +60C
Humidity5% - 95% relative humidity with condensation
WeightLess than 20 lbs (without boards installed)
VibrationSine* Cycling of 10 g (max) at 5 - 500 Hz
Random* 16 grms at 20 - 2000 Hz
Transportation Loose cargo vibration
* Mounted on Aitech mounting tray
ShockShock* - Single half-sine shocks:
40 g peak, 3 axes, 11 ms duration
* Mounted on Aitech mounting tray
EMCMeets emission and susceptibility limits (MIL-STD-461B, part IV, class A3 as per MIL-STD-462 requirements CE102, CS101, CS114, & RE102)
Warranty1 Year



BoardRefer to datasheet for ordering part number scheme
Recab UK
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