KI209 vs KI209A CDI. How to tell

[chrisk]

I'm in the process of upgrading my avionics.   I'd consider a new garmin GNC255A nav/com, but I don't want to spend the money on a new CDI.  I'm under the impression a KI209A will work with these, but not a KI209.  Short of having the avionics shop check, how does one tell if they have a KI209A or KI209?

[1964-M20E]

Well it is probably difficult to see from under the dash. You might get a clue from the log books. If you do manage to get the model and posibly the SN from it wirte it down in your log books so you will have it later for any reason.

[OR75]

Indeed the log book or form 337 is the easiest.   If the KI was installed a while ago, it likely will be a KI-209. the non-A version would be cheaper. The A version would need a "switch" to toggle from VOR/LOA to GPS mode.

Another way of answering is : what is currently driving your indicator ? is there a reason for it to be a KI-209A ?

 

tough to tell from the front. In any case, there should be tag on the back of the indicator (under the connector) that would have the King part and serial numbers 

should not be easy to access to read although you may have to remove the front seats

One thing I found that help identifying parts is to use a small digital camera and take pictures (and hope it will point and focus to the right spot) 

[jetdriven]

The 209A has two connectors at the back, the -209 has a 9 pin connector only.

[N601RX]

The 209 has a internal converter and is for used mainly with vor type radios like the kx155 that have composite output.. The 209a has a internal relay that bypasses the converter and connects the Left+ Right+ output of the gps directly to the needle coil. This allows it to be used with most all gps's and RNAV systems.

[Schinderhannes]

•Interfaces with most CDI (w/resolver), HSI, and autopilot systems (From Garmin Webpages)  Neither the 209 nor the 209A have a resolver and will most likely not work with the GNC255.  KNI520, Collins 351, KI206 are older indicators with resolver that should work with the GNC255.  

[chrisk]

I love the internet.  I just learned what a resolver is: 

 

"It's the gizmo inside the CDI that's hooked to the OBS knob. The resolver converts the position that you set on the knob to an electrical signal that goes to the converter, telling it what course you're interested in."

 

Apparently it works by phase shifting a signal.

[N601RX]

Resolvers generally output a sine and cosine signal and the phase shift difference of the 2 gives you your angle.