You will need a multi pole relay and the required annunciators for IFR
approach.
Usually a 165 and a GPS drive one indicator. If you have a 155 you need
a converter.
Michelle

N523RV wrote:

I have acquired a KX-155, KLN-89B and a 209A indicator. The 209A has a
built-in relay to switch between the GPS and NAV. I'm trying to figure
out what 'annunciation' is _required_ for this setup. The MD41
annunciator is about $950. I can get the control head only for about
$700.

The real question is do I have to have this? $700 seems like a lot for
a couple of switches and some lights! Can I not have a simple toggle
switch on the panel to switch between NAV/GPS and let the 89B do all
the annunciation?

Matthew