Marco wrote:
Why not try a !good! amateur dual band 2m/70cm antenna, a lot
cheaper, less obtrusive, and IMHO a lot better.

This may not really be a good idea.
The aircraft band is a long way from the 2m bands and you will be using the
antenna well outside its designed frequency band. Depending on the precise
construction of the antenna, it may receive no better than a damp piece of
string. My own 2m/70cms co-linear (well sited, outside) actually receives
less than a discone in the loft on airband. No contest on 2m or 70cms
though, the co-linear is far better.

--
Laurie