Here are some clarifications and a bit of history on this topic.
Due to the size of this radio enclosure, there is a significant volume of space inside the housing (behind the antenna). There is a breather vent (a one-way valve) designed into the seal between radio and antenna. The intent of this vent is to allow the pressure inside the housing to equalize with the outside pressure, and allow moisture to vent out of the interior of the housing. We found that on the initial design, the vent wasn’t big enough to equalize the pressure fast enough when weather conditions cause rapid temperature shifts. (For example, in Texas when it’s very hot and a cold front / rainstorm comes through, dropping the temperature significantly and very quickly). If the pressure differential is not equalized quickly, this can cause a force that pulls moisture up through the cable glands and into the radio housing. If this happens enough, water can build up inside the unit and cause failure.
The vent feature (of the radio itself) was redesigned and released to production in April, 2019. It was made larger (therefore better able to cope with these temperature differentials). These external breather vents were created in order to modify those units that were built prior to this design change, to reduce the possibility of taking in moisture.
This part has been available and is noted on (or near) page 114 of the User Guide for several years. It contains instructions for installation and the part number.
This part is not necessary for any 450m units that were manufactured after April, 2019.
There have been several cases of water ingress reported on 450m (as noted in Nick’s linked thread), and there are critical installation best practices that must be followed to reduce/eliminate the possibility of this occurring:
- Use proper outdoor gel-filled cabling.
- Ensure the Surge Suppressor is installed with a proper drip loop. (We have found that if the cables are curved too aggressively, they are prone to cracking, which allows water to enter the unit through the cabling).
- Ensure all cable glands are tightened with the proper torque.
The purpose of this post was simply a training video on proper installation of these vents.
In summary, these breather vents are not necessary (therefore “optional”) for any 450m radio manufactured after April, 2019. If you have radios manufactured prior to this date, and want to obtain vents for them, please contact support and we will send them to you.
The weather condition that can exacerbate a water ingress issue is rare, but does occur. The breather vent does allow for faster equalization of pressure, so it may be beneficial to add, but is not necessary. Therefore, these parts are available for purchase for anyone that wants them.
As always, Cambium Support is standing by and ready to support our customers with any issues that may occur.