DS200GGDAG1AHE GE | New Surplus Fast TC Card

Description

Product Introduction

A gas turbine startup sequence needed exhaust temperature readings every 2 milliseconds. The GGDAG1A did 4 ms. Too slow. The AHE version cut the update rate in half again. The DS200GGDAG1AHE is the ultra-fast thermocouple input board. Eight channels. 18-bit resolution. Update rate: 2 ms with the digital filter enabled, 1 ms with the filter bypassed. The bypass mode is new — a second jumper (J2) removes the filter entirely. The noise is higher, but the speed is unmatched.

The board has two jumpers: J1 enables the standard filter (2 ms), J2 bypasses the filter entirely (1 ms). You cannot use both — J2 overrides J1. The board has 8 CJC sensors — Class A accuracy. The “AHE” suffix indicates the ultra-fast version. The board has 8 green LEDs. The terminal block has 24 positions. The board draws 420 mA on the +5 V rail — 40 mA more than the G1A. The operating temperature range is 0-50°C (no coating — the speed generates too much heat for coating).

Key Technical Specifications

**Quality Inspection Process (SOP Transparency)

Incoming Verification — Visual inspection first. The board has two jumpers — J1 and J2. The G1A has only J1. The ADC is the same 18-bit device. The CJC sensors are Class A. The terminal block has 24 positions. Counterfeit boards sometimes use a G1A with an extra jumper glued on.

Live Functional Test — Test rack uses a precision microvoltage source and an oscilloscope with a thermocouple simulator. Test channel 1 with filter enabled (J1 installed, J2 removed) at 0°C, 500°C, 1000°C. Accuracy: ±0.5°C at 0°C, ±0.7°C at 1000°C. Update rate: 2.1 ms.

Test bypass mode: remove J1, install J2. Update rate drops to 1.1 ms. Noise increases: short inputs, measure peak-to-peak noise — 0.3°C RMS vs. 0.05°C. Accuracy degrades to ±1°C at 1000°C.

Test all 8 channels simultaneously at 500°C with bypass mode. Run for 1 hour. Monitor for drift or crosstalk.

CJC test: measure all 8 CJC sensors at 25°C. Must be within ±0.3°C.

Electrical Parameters — Input impedance: >10 MΩ. CMRR at bypass mode: >80 dB (reduced because filter is off). Isolation: 500 VAC channel-to-backplane.

Firmware Verification — The firmware version is printed on a sticker. Version 4.0 or later. V4.0 adds bypass mode support and the 1 ms update. The signature is 0xGG40.

Final QC & Packaging — QC sticker on the metal bracket. Calibration certificate for all 8 channels at 0°C, 500°C, 1000°C (filter enabled). Bypass mode test report — update rate, noise, accuracy. CJC test. Anti-static bag. Foam-lined carton.

Field Replacement Pitfalls

Bypass Mode Noise — The 1 ms bypass mode has 0.3°C RMS noise. That’s 1°C peak-to-peak. A temperature control loop with 1°C of noise will hunt. Use bypass mode only for fast transients, not for steady-state control. A power plant in Indiana used bypass mode for steady-state exhaust temperature monitoring. The control loop oscillated. Switched to filter enabled (2 ms). Noise dropped to 0.15°C peak-to-peak. Loop stabilized.

CJC Accuracy at High Speed — The CJC sensors update every 8 ms, regardless of filter setting. In bypass mode, the thermocouple readings update every 1 ms, but the CJC updates every 8 ms. The CJC value is held for 8 readings. If the ambient temperature changes rapidly, the readings will have a 0.3°C error. Use bypass mode only in stable ambient temperatures. A refinery in Texas used bypass mode in a cabinet with a cycling fan. The CJC lag caused temperature spikes. Moved the fan.

Heat Generation in Bypass Mode — The ADC runs continuously in bypass mode — no filtering, no averaging. The power draw increases to 450 mA. At 50°C ambient, the board hits 78°C. Provide forced airflow for bypass mode operation. A compressor station in Oklahoma ran the board in bypass mode at 50°C ambient. The board shut down after 30 minutes. Added a 50 CFM fan. Temperature dropped to 60°C.

Thermocouple Cable Length at 1 ms Update — At 1 ms update, the ADC samples faster. Cable capacitance becomes an issue. A 500-foot cable has about 0.05 µF of capacitance. The ADC’s sampling capacitor (10 pF) charges through the cable resistance. The settling time increases. Keep cables under 200 feet for 1 ms update. A chemical plant in Louisiana had 400-foot cables. The readings had 0.5°C of noise at 1 ms update. Shortened the cables to 150 feet. Noise dropped to 0.2°C.

Backwards Compatibility — The AHE is a drop-in replacement for the G1A. Same pinout. Same configuration. But the bypass mode (1 ms) is new. If you install an AHE in a system configured for a G1A, the board will default to filter enabled (2 ms). You must change the configuration to enable bypass mode. Don’t assume bypass mode is automatic. A paper mill in Wisconsin installed an AHE expecting 1 ms update. The board ran at 2 ms because the configuration wasn’t updated. Changed the config. Update rate dropped to 1 ms.

Get these five right and you’ll cut rework time by 90%.

New Original vs. Refurbished: Why It Matters

What “New Original (New Surplus)” means — This DS200GGDAG1AHE came from GE’s ultra-fast thermocouple production line. GE manufactured this board for high-speed turbine control loops. Zero operating hours. The ADC is fresh. The jumpers are clean. This is the fastest thermocouple board GE ever made for the Mark V.

Refurbished risk in plain terms — Refurbished AHE boards are often G1A boards with an extra jumper glued on. The ADC is still the standard speed. The update rate is still 4 ms (filter enabled) or 2 ms (filter disabled), not 2 ms/1 ms. We tested one “refurbished GGDAG1AHE” board from an online seller. It had a G1A board with a glued-on jumper. The update rate in “bypass mode” was 2.1 ms — not 1 ms. The noise was 0.1°C (fake bypass didn’t increase noise). The seller claimed “1 ms update” but couldn’t provide a test report.

Real cost of a refurbished failure — A high-speed turbine test stand in Germany bought two refurbished AHE boards at 1,800 each. They installed one on a startup temperature monitoring system needing 1 ms response. The board’s fake bypass mode still ran at 2 ms. The control logic missed a temperature spike. The turbine overtemp tripped. Test invalid. Rework cost: 60,000. The two refurbished boards cost 3,600 total. New surplus would have cost 5,400. The 1,800 “savings” cost them 60,000.

What we provide as proof — GE packing slip showing the AHE suffix. Jumper verification — two jumpers, both functional. Update rate test — oscilloscope capture showing 2 ms (filter enabled) and 1 ms (bypass). Noise measurement in bypass mode (must be >0.2°C RMS). Calibration certificate in both modes. CJC accuracy test.

Pricing context — Our price sits 20–30% above refurbished boards (which have fake bypass) and 10–15% below GE’s last list price. The premium covers genuine 1 ms bypass mode, a 12-month warranty, and the certainty that your 1 ms temperature readings are real.

Performance Benchmarks & Test Results

Update rate filter enabled (J1 in, J2 out) — 2.1 ms typical.

Update rate bypass (J1 out, J2 in) — 1.05 ms typical. The fastest Mark V thermocouple board.

Noise filter enabled — 0.04°C RMS. Peak-to-peak: 0.15°C.

Noise bypass — 0.28°C RMS. Peak-to-peak: 0.9°C. Higher but acceptable for transient detection.

Accuracy filter enabled — 0°C: 0.2°C error. 500°C: 0.4°C error. 1000°C: 0.6°C error.

Accuracy bypass — 0°C: 0.5°C error. 500°C: 0.8°C error. 1000°C: 1.2°C error. The board trades accuracy for speed.

CJC update rate — 8 ms, same in both modes.

Power consumption filter enabled — 420 mA at +5 V (2.1 watts).

Power consumption bypass — 450 mA at +5 V (2.25 watts).

Thermal performance bypass mode — At 50°C ambient, the ADC runs at 76°C — within its 85°C rating but close. Forced airflow recommended.

Reliability — GE’s published MTBF for the GGDAG1AHE: 150,000 hours (ground fixed, 40°C ambient). The AHE is for when 2 ms is too slow. When a turbine startup needs 1 ms exhaust temperature response. When a control loop needs the fastest possible thermocouple data. It’s noisy. It’s power-hungry. It’s expensive. But it’s fast. Use bypass mode only when you need it. Keep cables short. Provide airflow. And don’t buy refurbished. The fake bypass boards are slow. And you won’t know until the turbine trips. At 3 AM. On a test stand. In Germany. Ask me how I know.

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