Hello Tony:
There is no "Standard Gain" for
a 10 element Yagi.
The gain of a Yagi depends
on it's impedance, design bandwidth,
and construction.
If the antenna is well built and well designed,
the gain
will be about 12 dBd.
Build
as a cross Yagi, and a 90 deg phase harnass, then
the antenna will have about 12 dBdc or 12 dB
Circular Polarized gain.
Mounting a Cross
Yagi is also difficult.
A metal cross boom can
detune the Yagi Elements.
It is best if the
antenna is end mounted.
But with VHF Cross Yagi's
you can use a metal mast if
the antenna is mounted
X fashion, and the mounting boom
is vertical
or horizontal.
Good luck Kent
WA5VJB@FLASH.NET