Trans-Cal Altitude Encoder Model Ssd120-35N

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Part# 11-09608
MFR Model# SSD120-35N


Introducting the world's smallest, lightest altitude encoder.

The SSD120-35N is an all solid-state Altitude Encoder. This device provides a rugged and reliable means of measuring air pressure and converting this measurement into the ICAO parallel data as set forth in the International Standard for Pressure Altitude Transmission. In accordance with U.S. National Standards for Common System Component Characteristics for the I.F.F. Mark X (SIF)/Air Traffic Control Radar Beacon System SIF/ATCRBS.

  • The Best Warranty in the business: 42 months manufacture direct replacement. If your Trans-Cal encoder experiences a warranty covered failure, we will replace your unit with a brand new unit with a new 42 month warranty.
  • Average MTBF: 9.7+ years. That’s right: Trans-Cal encoders are among the most reliable on the market, commonly providing reliable service for over 10 years.
  • Pin for pin replacement for most other manufacturers encoders.
  • Comes with mating connectors with cable clamps and mounting bracket.
Click here to download the product brochure (PDF).
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WARNING: Cancer and Reproductive Harm -


  • Dual 1/8-27NPT Static Port Inlets
  • One ICAO pressure altitude grey code output
  • One RS-485 compliant data output
  • Serial ports may be installer configured to transmit separate data protocols (message & baud rate)
  • FAA TSO-C88a and EASA ETSO-C88a Approved
  • Tested and Conforming to MIL-STD-704E and RTCA DO-160E
  • Power, ground and data I/O lines provided on Industry Standard D-Subminiature Connectors
  • Operating Voltage +10 to +33Vdc
  • Operating Current: Low Altitude +12Vdc @ 220mA / +28VDc @ 270mA
  • Operating Current: High Altitude +12Vdc @ 55mA / +28Vdc @ 60mA
  • Operating Temperature Range: -20° to +70°C
  • Altitude Range -1000 to +35,000 feet
  • Weight: Low Altitude 5.9oz. / High Altitude 6.8oz.
  • Aluminum housing treated to resist corrosion.



Please note, Aircraft Spruce's personnel are not certified aircraft mechanics and can only provide general support and ideas, which should not be relied upon or implemented in lieu of consulting an A&P or other qualified technician. Aircraft Spruce assumes no responsibility or liability for any issue or problem which may arise from any repair, modification or other work done from this knowledge base. Any product eligibility information provided here is based on general application guides and we recommend always referring to your specific aircraft parts manual, the parts manufacturer or consulting with a qualified mechanic.

Q: Can this Trans-Cal Altitude Encoder SSD120-35N be used as a replacement for the Ameri-King AK-350?

Yes, they are both encoders so the Trans-cal unit can replace the Ak-350. However, since they are from different manufacturers, the wiring will be different and it will not be plug and play. It will require a new install.

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