Bruce,
The most cost-effective way to get your basic VHF nav capability would be to sell the MK12D and install the KNS-80, RNAV approved or not. Use the extra money to buy a ControlVision ATC or Garmin 396/496 handheld GPS.
A smaller and slicker setup would be to sell both the MK-12D and the KNS-80 and get a KN-53 with GS. That would give you the functions you need in two nice small packages and you'd still be money ahead. And you'd have rack space to add another com if you want.
Or you could sell the MK12D and KNS80 and buy a GS-capable navcom, like a MK12D with GS. Then you'd have dual coms and VOR/LOC/GS, and it might still be a wash financially. To do that with a KX155 would cost more than what you could get for the -12 and -80.
I would definitely have a GS. George is right about human nature, but I always cancel flights that involve extensive IMC and low approaches. At least, it's worked like that for 20 years. So while that means I probably won't ever need the GS, I like to have it for times I'm vectored to final on an ILS runway in MVFR or dark conditions, or for whatever reason I want some vertical guidance. Also, because I don't fly any other airplanes, I'll be doing all my instrument proficiency and logbook currency in the 170. It would be nice to have something other than a VOR approach to practice on.
I know you didn't ask this, but if money were no object, I'd sell everything you have and install a single Garmin SL-30 navcom. It's as good a radio as could ever be designed. Unfortunately it costs about $5500 with the indicator, but I used to have one and will never really be happy with any other radio. The audio is perfection, it has the brilliantly conceived "monitor" com function, the GS/LOC splitter is built in, the nav is quiet and stable, and there's a whole slew of front panel programmable settings, like sidetone level. It makes me weep just to think about that jewel.
If you ever find a good deal on one, grab it.
But for all this talk about VHF nav, what we really want is GPS. One box will do it all, from enroute RNAV to approaches, and those approaches are perfect for the flying we do in 170s. GPS is the future, with lots of new approaches being approved all the time. Trouble is, the GPSs are so expensive that we install obsolete VHF equipment to be "legal" while we navigate with handhelds!
Good luck. I'm still not sure what I'm going to do...
Dave
Here's what I used back in the '80s. The KX-170B and KI-214 were good but the KX-145 was worthless, so I had essentially a single navcom with GS, an occasionally functional ADF, and an audio panel I built from a kit (that worked flawlessly). That's why I think Bruce would do ok to go with "option 3 minus": one com, one nav with GS, and his handheld GPS.
. I want to again thank everyone for their input and their time. I'm talking to a few avionics shops I know well and will have a game plan by the end of the month. We'll keep you posted!
