Used to have a KNS-81 and a KN-53 direct the VOR needle on a KI-229 RMI over a switch.
KN-53 is still installed and is connected through a VOR COMPOSITE + ILS ENERGIZE signal (at least thats what i have found measuring the pins)
Replaced the KNS-81 with a GTN-650. Installation manual lists a wiring with OBI to the KI-229.
The Pin Out of the GTN also have VOR/LOC COMPOSITE OUT.
Is it possible to include the GTN signal to run the RMI for needle over the switch. Either by using the COMPOSITE signal to the switch(will it be able to drive the needle?), or somehow switch between the KN53 COMPOSITE and the GTN OBI signal??
You can not switch the VOR composite signal only. The ILS energize signal determins the sensitivity of the instrument.
The certified connection is using the OBI function.
Based on your questions I would highly recommend you to get in touch with a local avionics guy who can help you with these questions, and who can measure the setup.
If the installation is on an certified EASA aircraft you should have a received a form from the installer with all settings and interconnects, as well as a minor change approval which is needed to approve the configuration used for your particulair aircraft.
Its a N-regged aircraft.
Jesse, you are the local avionics guy :)
Is it possible to use the GTN Composite and ILS ENERGIZE signal to run the RMI like the KN-53 does?
The composite output and the ils energize signal are equal for the KN-53 and the GTN-650. Therefore it should work. You should switch both and use good shielding practices, it should work. However it won’t be according the STC manual (not for EASA nor for FAA). I would also recommend you to test this as well.
Thanks.
There is a lot of these new vs old avionics issues. Looking into the GAD43e setup for a future upgrade, another issue is the DME tuning. The GTN is listed with King Serial in the STC. However the KN53 only have 2×5. And you have to decide for 1 type of protocol. The GTN do however have all the required outputs. But wiring these in parallel will be a lot more work than the King serial. But if I want DME from NAV 1(GTN) and NAV2 displayed on the G500, thats how it needs to be.
Are you sure using a different output than what is listed in the diagrams is violating the STC?
I mean the outputs are there for a reason, but I guess it would be a massive task for Garmin to make diagrams for all possible connections
Some options are approved if previously approved, or when seperate approval is received. The installation manual gives information on this
I had a similar KI229 issue on my TB20.
Initially the job was completed (by Air Touring) with the KI229 not working; they never tested it.
Later they got it working but refused to give me the wiring, saying it is their “intellectual property”. Welcome to the UK 
Years after they went bust, the administrator sent me a wad of papers (without stamps on the parcel) with some info, which I will try to dig out tomorrow.
The KI229 needs composite plus the ILS energise signal. The GTN must be able to output these… But the 400Hz output from the KG102A cannot feed too many loads so sometimes a KI229 installation needs a MD26 inverter also.
This is all standard practice IAW various installation manuals for the non-Garmin kit.
The KI229 needs composite plus the ILS energise signal.
Yes or the OBI signal, Garmin AML STC refers to the OBI installation. The composite plus ILS energize should also work as this is standarized.
the 400Hz output from the KG102A cannot feed too many loads so sometimes a KI229 installation needs a MD26 inverter also.
The KG-102 loading doesn’t matter in this case, it doesn’t change as the KI-229 is already installed.
This is all standard practice IAW various installation manuals for the non-Garmin kit.
True, however this combination will not be mentioned in the KI-229 installation manual, neither in the Garmin GTN installation manual. While some senseable people would say you can do this, some others will not approve installation of anything that is not published in wiring diagrams by manufacturers, like this solution.
The KG-102 loading doesn’t matter in this case, it doesn’t change as the KI-229 is already installed
I guess I was thinking that it may already be working marginally…
I know that in my TB20, where (prior to all this being ripped out for the SG102 AHRS, etc) the XYZ output of the KG102A was driving the KI525 HSI, the WX500 stormscope, and the KI229 RMI, the KI229 installation needed, strictly speaking, the MD26. Without that (and yes, of course, Air Touring did it without it initially, true to form) the RMI bearing ring worked intermittently.
Specifically I think it is the “Z” output (which is just a 400Hz “sinewave”) is the limiting factor, and that is where you need to use the external inverter.
some others will not approve installation of anything that is not published in wiring diagrams by manufacturers, like this solution.
True. But I would not go anywhere near an avionics shop that does that. Fortunately I have not come across any as yet. Installing non-STCd solutions which work isn’t the biggest problem here in the UK… they tend to specialise in installing STCd solutions that don’t work 
It is a (seriously) interesting point of view that anything not in the STC IM is banned. I know many people hold that view. It is similar to the view (held by some I know) that any aircraft subassembly cannot be legally serviced unless a CMM (component maintenance manual) exists for it (and that is for an N-reg, too, laughably). It’s like saying that anything not permitted by the law is illegal. So if e.g. the Garmin GTN650 IM shows the Composite Out going to (say) 3 different things, only those 3 things can be legally connected. That principle would make nearly all mods to aircraft illegal… e.g. installing a power output connector to a PA28 (the connector obviously not on the 1965 TC) would be illegal unless the connector comes with an STC (which obviously it doesn’t). It also makes AC43-13 (a generic repair manual) void, which is plain silly. This is all a huge grey area and a lack of specific prohibiting regulation must mean that it is permitted.
Jesse
It may all be in the Garmin manuals but they tell their dealers not to release the manuals to anyone.
Only ones that have been pirated are avalable.
