RTL SDR LNAs

Hello All

This is the first time I have posted on this list, sorry if I have done it wrong

I would like to use a line powered "cheap and nasty" LNA with an RTL dongle.

E.g. http://www.amazon.co.uk/Satellite-Signal-Amplifier-Booster-electrosmart%C2%A...

This may seem a like stupid question (I will ask it anyway) but will the dongle need protecting from the 18V going down the antenna line. I have seen some diagrams with protection and some without.

If protection is required, has anyone got any suggestions on how I should do it???

Many thanks

Jonathan, M0ZJO