Thank you for the info SpectrumAnalyzer. I do know for sure that the 'blades' (Sinclair Excalibur Series) have an O ring around the RF connector and Sinclair does not include any other gaskets in the box with the antenna other than the O ring. But outside of Sinclair, General Electric installs flat gasket material under the antenna when they install them on their new locomotives. So I would say that if you have seen 'blades' with a gasket under them then its probably the installer doing it on their own perhaps for personal preference. I would think that there needs to be an electrical connection between the antenna and the ground plain other than just the mounting bolts but I may be wrong about that. I'm not sure how the former Motorola and Antenna Specialist ASP series firecracker antennas where mounted. Now that I see PC Tel is in the game after the two former mfg.'s quit making them I will contact PC Tel to find out more about the gasket situation and installation process and what their opinion is. Oh, if any railfans are thinking about buying a new ASP16, they are $300 each. The 1/4 wave NMO antenna works just as good for less than $50. If it's not going on a real locomotive, save your money!
