Surge arrester array
This is a simple surge arrester array that I made in my free time. Built using readily available components, the array provides effective shielding against lightning-induced surges and static discharges that can damage sensitive transmitting and receiving systems.
The primary goal of this project was to create a robust, low-loss surge protection unit that can handle multiple RF lines simultaneously. By integrating gas-discharge based lightning arresters with a solid grounding infrastructure, the array ensures that transient over-voltages are safely diverted to ground without affecting normal signal transmission.
The core of this project relies on a few key components:
At the heart of the design are eight BL-2000 Lightning Arresters, each incorporating a GDT (Gas Discharge Tube). These units are designed to conduct high-voltage transients from the coaxial line directly to ground within microseconds of a surge event. The BL-2000 series is available in several barrel configurations; for this build, PL259 female-to-female models were selected for compatibility with standard coaxial systems.
Each arrester is rated for 50Ω impedance and 400 W power handling, supporting a frequency range from DC to 1000 MHz, making it suitable for most HF to UHF amateur radio applications.
Technical specification of the BL-2000 is listed below (copied from supplied datasheet):
Frequency range: DC ~ 1000MHz
VSWR: 1.1 or less
Loss: Below 0.2dB
Rated power: 400W PEP
Minimum discharge voltage: DC230V ±15%
Discharge voltage: 1000V
Maximum discharge current: 6000A
Repeated discharge capability: DC230V ±20%
Insulation resistance: 10000MΩ and above
External dimensions: 77×41×21 (W×H×D) mm
Weight: 114g
Two 2.5 mm-thick copper bus bars are used as the main conductive path of the array. These copper strips - commonly used in electrical distribution and lightning protection systems—provide a low-impedance route for surge currents. The arresters are mounted such that their metal bodies are both mechanically and electrically bonded to the bus bars using 12mm stainless steel M6 screws. To minimize corrosion and ensure long-term conductivity, a battery terminal protection compound is applied to all connection points.
The entire assembly is mounted on a galvanized metal or aluminum plate, which serves both as a mechanical support and as an additional conductive surface. In this setup, the mounting plate from a panel board enclosure was repurposed to provide structural stability and grounding continuity.
A 7/1.70 gauge grounding conductor connects the copper bus assembly directly to a dedicated earth ground. This ensures that surge energy is rapidly and safely dissipated into the earth during a lightning or static discharge event.
During normal operation, the GDTs inside the BL-2000 arresters remain in a non-conductive state, maintaining the integrity of the RF signal path. However, when a surge or high-voltage transient occurs, the GDTs ionize instantly, creating a conductive path that shunts the voltage spike from the coaxial center conductor to the arrester body. The surge current is then conducted through the copper bus and grounding wire into the earth, effectively bypassing and protecting the connected transceivers and receivers.
The array was tested with several HF transceivers across multiple frequency bands. No measurable change in S.W.R. was observed, indicating minimal signal loss and excellent impedance matching.