Saw your post on the cheap approach certified gps. i am thinking about the
same either at kln89b or m3. What is the cost of the mid-continent
cdi/announciator unit? i have been looking at ebay but cant find any.

Endre


(Snowbird) wrote in message . com...
(Martin Kosina) wrote in message . com...
I am toying with the idea of installing a "cheap" IFR GPS in my '76
Cardinal. Being admittedly a bottom-feeder in this area, my choices
are basically limited to a used KLN89B, or the Northstar M3 Approach,
something like a $1500 setup total.

Martin,

We have an Apollo 2001 in our plane, which might be another
alternative for you to consider. It's installed exactly as
you suggest -- coupled to a Midcontinent integrated obs/
annunciator unit. Ours is also coupled to an Apollo 360
moving map which sits right in the primary scan area and
is very very useful.

I'm not as familiar with the M3, but I believe all of the
IFR GPS of that era required baro-aiding. This may mean a
serializer cable for your altitude encoder.

I would be doing the work myself with an IA's assistance & signoff

I could be mistaken, but I don't think an IA can sign off
the installation of an IFR-certified GPS. It has to have a
337 field mod approval signed off *in that airplane*, which
includes some frequency testing and so forth and so on.

What I suggest is that you start with the FSDO. Ask what's
involved -- who can do it etc -- and for some names in your
local area. Also talk to your IA. If you luck out (we did)
the FSDO person you talk to will bend the rules a bit to suggest
a couple of names you can talk to. Then talk to them and find
out what they're willing to do to work with you. If they're
willing to let you do most of the install under their supe, and
do the frequency and flight testing, you can probably do OK
on the price.

Thanks for any comments, particularly from current M3 owners or
someone who has rolled their own (any brand). I think I have a pretty
good understanding about all the things required to have the rig
IFR-blessed (encoder interface, CDI, annunciators, COM interference
testing, AFM supplement, etc.), so I am looking for war stories about
the certification process itself when avionics shop wasn't involved.

I could be mistaken, but I really think you need a certified avionics
repairman to bless the installation. We found someone who was willing
to work with us. I would start with the FSDO and ask there -- if they
tell you an IA is fine, Nevah Mind.

Good luck! IMHO, the older IFR units are amoung the best values
today. What did someone else here say? "the cutting edge of yesterday's
technology"?

Sydney