DOes anyone know if its possible to use a IDME 891 with a GNS430 as the primary indicator to display both VOR/ ILS and/or GPS data when selected?
No it’s not possible to use the IDME891 for a fully-functional interface to a GNS430. The IDME does not use a conventional resolver synchro so won’t work for VOR (or GPS in OBS mode). It will display ILS LOC and GS or raw GPS L-R.
@wigglyamp, does the CDI have to have the “NAV/GPS” flag as well?
Or is it optional for the GNS installation?
There are probably converters, but whether you can get one cheap enough to make this worth doing, is another matter.
The CDI doesn’t require internal source annunciators for Nav/GPS so an external light can be used. In fact in some situations they’re not required at all (see GNS-W LPV STC or Garmin’s GTN STC – depends on whether the navigator is in the Normal field of view).
Here is the installation manual picture of the resolver – it uses a sin-cos potentiometer instead of a resolver synchro – uniquely Narco I believe. I’m not aware of any converters.
I spoke to someone who said they had used one but it had some sort of converter in the wiring harness. I was going to buy it but someone beat me to it. What sort of converter would be required?
A sin/cos potentiometer to X/Y/400Hz conversion is simple (I am working on a board which could do it) but if it doesn’t exist already, nobody will do it because there is no market for it. It will be cheaper to buy a King-interfaced HSI.
I presume the sin/cos pot output is from the course pointer position. The heading bug is normally just a voltage +/- of “straight-ahead”.
Over the years, all kinds of converters have existed. A quick google finds a lot of close stuff but not exactly this. In the old days, before microcontroller solutions, people worked out all sorts of cunning ways to do this stuff. Nowadays it is about a week’s work, to do X/Y/400Hz (X/Y/Z) to “various analog” or ARINC429, assuming you have the hardware well sorted. But also almost nobody will touch an uncertified box with a bargepole.
Peter wrote:
sin/cos potentiometer to X/Y/400Hz
Most GA Nav radios use a 30Hz resolver, not 400Hz. You find 400Hz resolvers in some KingAirs, Bizjets and upwards.
thanks all for the help. In my pile of stuff i found a KNI-520 which is compatible with the GNS-430 (i couldnt believe it either, for a indicator designed for the original kx170s…) So ill just use that instead and scrap the DME idea.
Most GA Nav radios use a 30Hz resolver, not 400Hz
The principle would be the same, but I must be thinking of something else. For example I had to fit an MD26 (400Hz source) to make everything work because the KG102A didn’t have enough power on its 400Hz output to drive the KI525 HSI and the KI225 RMI. These were driven from a KX155A/KX165A. All that stuff is now gone, replaced by the Sandel kit, but still running 400Hz.
I have an extensive private site with avionics manuals but can’t find anything called KNI520 or similar.
