The Model PA-6 Preamplifier Assembly (Part Number: 230663101 / 230663-101), engineered and manufactured by Smith Meter (a division of TechnipFMC / FMC Technologies, USA), is a mission-critical electronic pulse-conditioning instrument designed specifically for high-accuracy liquid hydrocarbon measurement systems and fiscal custody transfer operations.

Operating Principle & System Functionality:
In Smith Meter turbine flow meters, the passage of fluid causes the internal bladed rotor to spin at an angular velocity directly proportional to volumetric flow rate. As each blade passes a reluctance-type pickup coil mounted on the meter exterior, a low-voltage alternating sinusoidal signal is generated. Because raw sinusoidal pickup signals are millivolt-level and susceptible to electromagnetic interference (EMI) and line capacitance losses over extended cables, they cannot be reliably counted directly by remote instrumentation.

The Model PA-6 Preamplifier mounts directly inside the meter junction head to perform three critical functions:
1. Amplifies and conditions the low-level sinusoidal pickup coil output.
2. Converts the sinusoidal waveform into sharp, high-energy square wave pulses that provide exceptional noise immunity.
3. Boosts pulse transmission power, allowing the flow signal to travel across shielded field cables over distances up to 5,000 feet (1,524 meters) to remote flow computers (such as Smith Meter AccuLoad series or microFlow), totalizers, or plant automation PLCs without signal attenuation or missed counts.

Key Engineering Features & Operational Advantages:
- Jumper-Selectable Sensitivity & Resistor-Adjustable Gain: Features integrated terminal gain straps that allow technicians to match preamplifier sensitivity to specific application requirements:
  + Gain Strap X50 (terminals 8 and 10): 70 mVp-p sensitivity (highest sensitivity, ideal for low-flow regimes).
  + Gain Strap X25 (terminals 8 and 9): 150 mVp-p sensitivity (factory default setting).
  + No Gain Strap X1 (terminals open): 750 mVp-p sensitivity (desensitized mode to reject strong ambient electrical noise).
  + Custom Gain Tuning: Allows installation of a 1/4W resistor across terminals 8 and 10 to establish custom threshold trip points from 70 mV to 750 mVp-p.
- Multiple Pulse Multiplication Outputs (X0.5, X1, and X2): Provides three distinct, simultaneously available output terminals:
  + X0.5 Out: Divides the incoming pulse frequency by 2 (accommodates legacy slow-speed counters).
  + X1 Out: Outputs pulses at a direct 1:1 ratio with the pickup coil frequency.
  + X2 Out: Multiplies the output pulse frequency by 2, doubling measurement resolution for low-flow proving and blending applications.
- Long-Distance Cable Transmission Range: High-current output drivers enable reliable signal integrity across 3-wire shielded cables over long spans: up to 2,000 ft (610 m) with #20 AWG; up to 3,000 ft (915 m) with #18 AWG; and up to 5,000 ft (1,524 m) with #16 AWG cable.
- Fully Potted Rugged Puck Design: Electronics are completely encapsulated in a durable epoxy potting resin inside a circular puck housing, providing total protection against moisture, condensation, vibration, and thermal shock.
- Explosion-Proof Enclosure Mounting: Sized to fit neatly inside standard Smith Meter explosion-proof, Class I, Division 1, Group D junction boxes mounted directly atop turbine flow meters.
- Wide Operating DC Power Envelope: Accommodates input power supplies from 8 to 29 VDC (nominal 12 VDC or 24 VDC), seamlessly interfacing with standard supervisory flow computing instruments.

Typical Industrial Applications:
- Factory-standard preamplification on Smith Meter turbine flow meters: Sentry Series (Models K2DR, K2DV, K2DK, etc.), Guardsman Series (Models K2GE, K2SE, K2GD, K2SD, K2BE, LB Series, LJ-H, LJ-V).
- Electronic pulse transmission on mechanical D-Transmitters mounted on Smith Meter rotary positive displacement (PD) meters.
- Custody transfer metering skids, truck loading and unloading racks, railcar loading terminals, and marine tanker bunkering systems.
- Pipeline transmission monitoring and refinery blending control in demanding oil and gas operations.

• Manufacturer: Smith Meter (Smith Meter Inc. / TechnipFMC)
• Country of Origin: 100% United States of America (Made in USA)
• Component Designation: Model PA-6 Preamplifier Assembly (P.C. ASSY PA-6)
• Part Number / SKU: 230663101 (230663-101 / 230663-1-01)
• Compatible Meter Families: Smith Meter Turbine Meters (Sentry, Guardsman series) and D-Transmitters on PD Meters
• Input DC Power Supply: 8 to 29 VDC ± 1.0 VDC
• Current Consumption:
  - Quiescent Current: 10 mA @ 8 VDC, 15 mA @ 12 VDC, 20 mA @ 29 VDC
  - Maximum Operating Current: 40 mA @ 8 VDC, 50 mA @ 12 VDC, 120 mA @ 29 VDC
• Input Signal Characteristics: Sinusoidal waveform, zero DC offset, 24 Vp-p maximum, 10 kHz maximum frequency
• Input Signal Source: Reluctance-Type Pickup Coil
• Input Impedance: 10 kΩ minimum @ 20 Hz
• Input Sensitivity (@ 25°C, 20 Hz):
  - Gain Strap X50 (Terminals 8 - 10 jumpered): 70 mVp-p
  - Gain Strap X25 (Terminals 8 - 9 jumpered, standard factory): 150 mVp-p
  - No Gain Strap X1 (Terminals open): 750 mVp-p
  - Resistor-Adjustable: Custom trip point selectable between 70 mV and 750 mVp-p via external resistor across terminals 8 & 10
• Output Signal Waveform: Square Wave
  - 12 VDC Power Supply: No Load: 11 ±0.3 Vp-p; 270 Ω Load: 6 ±0.3 Vp-p minimum
  - 24 VDC Power Supply: No Load: 23 ±0.3 Vp-p; 270 Ω Load: 12 ±0.3 Vp-p minimum
• Output Drive Capability:
  - Maximum Sink Current: 300 mA @ 29 VDC
  - Maximum Source Current: 80 mA @ 29 VDC
• Output Multiplications:
  - X0.5 Out: Duty cycle range 30/70 to 70/30 (Maximum input frequency: 5,000 Hz)
  - X1 Out: Duty cycle range 30/70 to 70/30 (Maximum input frequency: 5,000 Hz)
  - X2 Out: Nominal off-time 100 μs (Maximum input frequency: 2,500 Hz)
• Maximum Signal Transmission Distances (Shielded 3-Wire Cable):
  - #20 AWG: Up to 2,000 ft (610 m)
  - #18 AWG: Up to 3,000 ft (915 m)
  - #16 AWG: Up to 5,000 ft (1,524 m)
• Terminal Block Connections (10-Position Screw Terminal):
  - Terminal 1: +8 to 29 VDC Input Power
  - Terminal 2: X2 Pulse Output
  - Terminal 3: X1 Pulse Output
  - Terminal 4: X0.5 Pulse Output
  - Terminal 5: Logic Common (0V reference)
  - Terminal 6: Pickup Coil Input (White wire)
  - Terminal 7: Pickup Coil Input (Black wire)
  - Terminal 8: Gain Common
  - Terminal 9: Gain X25 Select
  - Terminal 10: Gain X50 Select
• Construction: Solid epoxy-encapsulated circular puck housing (moisture- and shock-resistant)
• Dimensions: Diameter approx. 2.6" (66 mm), thickness approx. 0.9" (23 mm)
• Enclosure Compatibility: Mounts directly inside Smith Meter standard explosion-proof Class I, Division 1, Group D junction head
• Operating Ambient Temperature Range: -50°C to +70°C (-58°F to +158°F)
• Operating Humidity Range: 0 to 99% RH (non-conductive condensation permitted)
• Electromagnetic Compatibility (EMC): Complies with Council Directive EMC 2014/30/EU and EN 61326-1.