Kerry Wong Tears Down a Cel-Fi Go X Cell Signal Booster As He Looks to Improve Cell Coverage
Looking to boost cellphone coverage in his house, Wong picked up a commercial booster — then, naturally, took it to bits.
Engineer Kerry D. Wong has completed another teardown, this time looking into the inner workings of a Cel-Fi Go X cellular network signal booster — claimed by the company to offer coverage up to 15,000 square feet.
"In the area where I live," Wong explains, "the cell phone reception is spotty at the best. Even though I am only a couple of miles from a nearest tower, I barely get any cell signal at all let along usable 4G coverage. Since nowadays everyone is working from home, I thought it would be a good investment for a cell signal booster so that in the event I lose my network connection I can continue working tethered to my phone. After some extensive research, I settled on Nextivity’s Cel-Fi Go X signal booster."
"The unit is passively cooled and enclosed in a beautiful extruded aluminum case. It is NEMA 4 rated and thus is suitable for outdoor use. It is powered by an external 15V 1.6A power adapter with a sealed twist-on type connector. The kit comes with an outdoor LPDA (Log Periodic Dipole Array) wide-band high gain directional antenna. Don’t confuse this with an Yagi antenna, which has a relatively a narrow bandwidth. The main difference between these two types of antenna is that in an LPDA all elements are actively driven and its wide bandwidth is attributed to the different lengths and spacing of the dipole arrays. Whereas for a typical Yagi, there is only a single driven element and all the directors and reflectors are passive elements."
After analyzing the supplied antennas, Wong moved on to the main booster body. "The top cover is made of plastic. It cannot be fully shielded," Wong surmises, "since the Cel-Fi Go X uses Bluetooth to communicate with an cell phone application for controlling and monitoring the device. Both the uplink and downlink side of the circuitry are shielded."
"I could find very little information on the components used here. The SAWNICS module looks like a duplexer as cell phone boosters operate in duplex mode. The smaller module to the right marked with “CTS” could be a RF filter. And the smaller 6-pined SMD chip might be a SAW filter perhaps? The black SMD could be a variable gain low noise amplifier given its location but it is hard to tell without an logical diagram. You can also see some soldering pads structures covering a large area. This might be for the added heat sinking capability for the power devices mounted on the other side of the board."
After reassembling the device, Wong gave it a road test: "I am quite impressed with the performance of this signal booster," he writes, "as after installation I am have 4 bar 4G signal through out the house, even in my basement."
The full teardown is available on Wong's website.