You may need to reevaluate what you are trying to do here...
Just in very rough figures, for a one mhz split at 150 mhz, you will want
about 85 dB of isolation between your two frequencies.( just as a starting
point)
That would be around a thousand feet of horizontal separation of antennas,
and more than a hundred vertical.
That's probably why you are seeing info on the little notch duplexer not
being able to work at that freq split.
They are usually good at 5 mhz or at least 3.5 mhz.
You will likely have to use both a notch duplexer and separate antennas, and
even at that suffer some desense.
Again, these are VERY general figures.
What you are trying to do is not impossible at VHF, but it will be difficult.
Run the numbers, and work out a solution before you try to make something
that won't work well enuf.
Some combination of duplexer (actually Tx and Rx filters) and separate
antennas may work.
