Lightning Protection

Arrestor Photo
click for larger image (60KB)

At the entry point of the equipment cabinet, a quarter-wave stub style surge arrestor is installed. The arrestor is an Andrew APP-12-3. This rugged component was surplussed from paging service. I haven't been able to find any data sheets on this particular device, as it is no longer manufactured by Andrew (assembled in 1996). I assume the performance is similar to the currently manufactured parts:
APT-NFNM-XX Installation Instructions

Arrestor Plot
click for larger image (20KB)

Not having a real data sheet for the part, I decided to check its performance on the network analyzer.

The newer spec. quotes insertion loss at less than .07 dB and return loss of -26.4. The plots indicate even better performance: < .03 db insertion loss and better than -28 db return loss.
I don't think I have to worry much about performance degradation due to the arrestor!

Arrestor Internal Photo
click for larger image (52KB)

This is a photo that Dave (WA6CGR) took after we decided to inspect the inside of one of these arrestors. The construction of the device is quite impressive. The main cavity is a sealed, silver plated, machined housing. The quarter wave stub is clearly visible and is actually tunable for optimum performance.

Return to Repeater Home Page