Jeff,

I'm about to get this unit installed into my PA28-140. To be legal for IFR
approaches, you'll need (as others have said):

- An external CDI. I happen to be using the GI-106 (more on that
below).
- An external annunciator/switch which: a) lets you share the head
between the GPS and a NAV radio; b) gives you course deviation while flying
an approach; and c) tells you when the approach is active and armed.
- A flight manual suplement. Your avionics tech should be providing
this as part of the install. If not, then you're not legal.

You'll also need to keep your GPS database up to date (unless you're not
using it for approaches then, technically, you can fly with an out of date
DB). Jeppesen charges around $300 for a year of updates. As one poster
mentioned, you can use an MD-41 (MidContinent?) which combines the CDI and
annunciator into one unit. That'll save you some bucks. With a 430 you
only need the CDI, the annunciator is built into the box. One last,
probably inconsequential note: the 300XL isn't certified for WAAS approaches
and probably never will be. Neither is the 430 although Garmin says they
plan to add it "soon".

I'm replacing a crusty old NAV/COMM/CDI and an ADF which means either the
300XL or the 430 (i.e. a pure GPS unit like a KLN90 would leave me with only
one COMM).. Many of the used 430s are 28v units which my avionics guru
advised me against (apparently, the voltage converter needed to step down to
14v is not terribly reliable). Compared to a new 430, a cheaper overhauled
300XL is an acceptable tradeoff for my steed. My second NAV/COMM only had
the localizer head, so I opted for the GI-106 which will give me a
glideslope needle when I need it.

You can get an overhauled 300XL on ebay for about $2400. A company called
JA Incorporated periodically buys up all the overhauled Garmin units so they
almost always have them in stock. If you want to skip ebay, go to
avionicsgps.com, where they advertise the 300XL for $2600.

Best of luck....

mark

"Jeff P" wrote in message
om...
Anyone have any experience with the GNC-300XL IFR GPS/COM?

Does it work well? Do you like the user interface? How is the
screen?

I want to have GPS IFR capability in my 172. What else will I have to
install to get IFR cert for this unit?

Thanks,

Jeff