ETI's ADH NETCOM with optional front panel display

The highly configurable ADH NETCOM waveguide pressurization system is Environmental Technology Inc.’s flagship product for telecom and satcom applications. Waveguide dehydrators use low pressure dry air to create the optimal environment for signals to pass through antenna waveguides and dielectric coaxial cables. Here we review a couple of considerations when managing an ADH NETCOM: how the low pressure dry air condition is reported and how one troubleshoots a lost communication connection.

ADH NETCOM Pressure Reporting

ADH NETCOM DISPLAY 6pt99 psi detailHow does the ADH NETCOM report waveguide environment pressure? The dehydrator always reports pressure in pounds per square inch as “pounds per square inch [gauge],” or psig. It has a programmable operating pressure range — 0.10 psig – 7.50 psig (7mbar – 517mbar) — which can be monitored and controlled with an Internet web interface or SNMP.

Meanwhile, we hear the term “atmospheric pressure” nearly every time we listen to a weather report. Though not normally expressed as such in general conversation, this atmospheric pressure’s pounds per square inch is “pounds per square inch [atmosphere],” or psia.

Understanding that the dehydrator is reporting in psig, we now know that any value greater than 0 psig is greater than ambient air pressure (which at sea level is 14.7 psia). The minimum goal when pressurizing a waveguide environment is to maintain this positive pressure – psig > psia – in the waveguide.

If it won’t be connected to a network, ADH NETCOM pressure reporting is achieved through an optional front panel with a display, shown above and in our examples. This also allows for IP configuration and status monitoring.

No News is NOT Good News

ADH NETCOM DISPLAY offAt least as far as your ADH NETCOM is concerned, it’s not.

A loss of network communications with the ADH-NETCOM is often assumed to be circuit board failure, requiring repair or replacement.  While this is not strictly an impossibility, perhaps simpler explanations and fixes are likelier.

Assuming the power supply is functioning properly, we’ll get the obvious fix out of the way: Is everything connected correctly?

Look Up My Number

If everything is properly connected physically, you may have tried calling a wrong number, as it were. Initial set-up is typically done with a standalone PC or laptop computer configured for use in the 192.168.52.0 network.

ADH NETCOM DISPLAY eTi logoThe factory default setting for the ADH NETCOM is the fixed IP address 192.168.52.9, a fixed subnet mask 255.255.255.0 and a fixed gateway 192.168.52.1. In a web browser, confirm you’re connected to 192.168.52.9 – your computer may have to be “renamed” to the correct network.

Detailed instructions may be found in the ADH NETCOM’s manual, beginning on page 33. Click 

Further, a Reset button is located on the back panel. This button is used in the event it becomes necessary to reset the unit’s IP address back to its original factory default IP address. The Reset button should never be used during normal operations and only by qualified personnel performing troubleshooting work on the unit.

Lights Are On: Is Anyone Home?

When you know you have power to the unit, perhaps you should check if the power and alarm LED indicators on the front panel are either flashing or if they are not lit. If so, this problem can be caused by a bad compressor drawing extra energy away from the power supply.

Captive Securing Screws detailTo test this, remove the front top panel to expose the compressor. Next, loosen the two Captive Securing Screws for the compressor connector and remove the connector from its mating bottom half (photo; click to enlarge). Power the unit without the compressor: the front panel lights should come on and you should be able to communicate with the unit.  You will get a low pressure alarm because the pump is not connected, but this will prove that the circuit board is fine and will communicate. If this is the case, you’ll need to order a replacement pump, part number 24085.

Sometimes, It Is What You Think It Is

If removing the compressor – or any one of the other suggestions mentioned above – does not solve the communication problem, perhaps the circuit board is compromised. You’ll need either 1) to remove the circuit board and send it back to ETI for repair or replacement, or 2) to send the complete unit back to ETI for repairs. Be sure to contact Customer Service for a Return Merchandise Authorization number to help your waveguide environment operate at its best.