VLF X2000A Receiver
The Receiver is based on a low noise design. Each section is built in a separate compartment. The compartments are made of un-etched copper pc board material soldered together. Each compartment is filled with candle wax. The wax keeps moisture from condensing on the parts inside the unit, which could cause Internal noise, feedback,  and reduced sensitivity. This design allows the unit to work in cold temperatures, providing the batteries can withstand the cold. The receiver is housed in a hermetically sealed box, to keep the batteries dry during the wettest and coldest of field conditions.

Click here to see the Schematic Diagram

Close-up of the Antenna input
First Stage Low pass filter and antenna input junction
 


Antenna input


here is the second stage low pass filter.


 


Second stage amplifier section
 


Third stage amplifier and filter sections
 


Third stage Amplifier
 


The power (v+)  is fed through holes in the top with bypass caps on every feedpoint. The 9.0 volt regulator is also soldered on the top. This section is filled with wax also.

Finished!! (4-28-00)
  
The entire assembly is filled with wax to further seal it from water/moisture intrusion.