This product is no longer available and has been replaced by: CS506-L. Some accessories, replacement parts, or services may still be available.


The CS505 Fuel Moisture Sensor was retired on September 22, 2009. It consists of an epoxy-encapsulated electronics package. It uses Time Domain Reflectometry Technology to measure the moisture content of the 10824 10-hour Fuel Moisture Stick. The 10824 is a USFS-specified, 10-hour, ponderosa-pine dowel that is purchased as a Common Accessory (see Ordering Info).



Operating Range 0 to 70% moisture content
Power Supply 9 to 18 Vdc
  • ±1% rms @ 0 to 10% moisture content
  • ±2.4% rms @ 30 to 40% moisture content
Current Use
  • 70 mA (active)
  • 10 µA (quiescent)
Output Signal ±2.5 Vdc square wave (with an output frequency of 600 to 1500 Hz)


Fuel Temperature

The CS506 is typically measured alongside the CS205/107, which measures the fuel temperature.


The 10974 Mounting Stake is often used to mount the CS505/10824 with the CS205/107. This stake places the probes twelve inches above the forest floor. Because the probes are mounted parallel to each other, shadowing is minimized. Cable ties are included for securing the cables to the side of the stake.

Datalogger Considerations

Compatible Contemporary Dataloggers

CR200(X) Series CR800/CR850 CR1000 CR3000 CR5000 CR7X CR9000X

Compatible Retired Dataloggers

CR500 CR510 CR10 CR10X 21X CR23X CR9000