In article ,
N7155A wrote:
I'm thinking of buying and installing one of these in our 150 to do
some CFI-I work.

http://www.valavionics.com/ins_422.htm

I wouldn't try to train a student using one of those things. It might
be a nice backup for your own plane, but think of all the ways you
teach an instrument student to use the OBS to work out intercept courses.

Looking at eBay suggests you can get a used KX-155 w/GS and indicator
for about the same price as that standalone unit. You get another COM,
with flipflop, nav with flipflop and a real indicator.

There are lots of ways to get 3LMB (eg RST's kit) including a new audio
panel.

--
Ben Jackson

http://www.ben.com/