DC Pass, DC Block Lightning Arrestors? 1

Lightning strikes (and related phenomenon such as 'leaders') obviously have a very large DC component - think about it: they originate from a type of 'static' electricity in the clouds. (They also have some AC (RF) components when striking, which is why you can hear them crashing on an AM radio.)

Inside a lightning arrester is a parallel element triggered by high voltage and intended to bypass as much current as it can to ground. But there will be a residual voltage across this device; either from the inherent voltage drop of its internal physics (perhaps a gap, or a little gas tube); or I*R voltage drop from its internal series resistance. In the event of a strike (or similar), there would be a moderate voltage presented across the radio side of the protection device.

So if your system doesn't need DC continuity through the protection, then you might as well use a DC Blocking device with its internal series capacitor. It'll help (maybe) with protecting the radio (or whatever) from lightning.

Note: If the coaxial cable is also being used to provide power to the LNA within the antenna (e.g. GPS), then you normally can't use a DC-Block in the antenna circuit.

Complete protection requires a Systems Design approach. It can get complicated.

VE1BLL many thanks for advice.