kontiki wrote:
I'm thinking seriously now about upgrading the avionics in my
Comanche. An HSI would be a nice thing to have too (once you've flown
something with one you become a believer) so I'm thinking of
combining the effort and putting one of them in too. Maybe a GNS 430
and keeping the 155 as my second NavCom. Currently I have a King
stack... 155s and an ADF. I don't want to go broke doing this so what
are you guys thinking along those lines?

The KX155 is a good radio, though it has been proven to cause harmful
interference with certain GPSs when tuned to certain frequencies. For
what it's worth, I'm familiar with two 155/430 installations that seem
to work well. The KX165 doesn't have that problem, but it comes in 28V
only, and the power converters aren't worth the money.

If you must have an HSI, I would generally avoid spending the money on a
traditional analog HSI head. They're just not worth the money based on
what an EHSI can give you. My philosophy in these situations is "In for
a penny..."

The only EHSI worth considering right now is this:

http://www.avionicswest.com/archive/sn3500.htm#2004

You may be tempted to buy its predecessor (SN3308), but it's not very
readable off axis or under full sun. To top it off, the bulb must be
replaced at regular intervals and pulling it out of the panel each time
can be a pain in the ass.

Personally, if I had $10-15K to spend on an HSI, I'd sooner drop the
money into an Avidyne EX500 moving map display with terrain, chartview
and XM satellite weather subscription. Lot more useful if you do "real"
IFR. An autopilot using GPS steering (like the STEC55 or new Chelton
unit) don't need a fancy rotating card to fly.

As far as the 430 is concerned, at about $10.5K installed with a new
GI106 CDI, it's probably the biggest bang for the buck on the market
right now. Some might argue that the CNX80/GNS480 takes that crown, but
that depends on the kind of flying you do and whether $3K extra is a lot
to you. The only thing I really miss with the 430 is support for
airways. It really stinks having to enter every waypoint along a route,
but then again, it forces one to review the entire route before
departure...and that's not a bad thing. And then there are the
OUTSTANDING ergonomics and user interface of the 430. I've used the 480
enough to know I don't like the interface nearly as much.

As far as the ADF is concerned, unless it's the KR87 or some other
slimline unit that doesn't take up precious panel space, and in fine
working order, my advice would be to dump it. GPS can substitute for
it, and you should consider the cost of maintaining it over the long haul.

You may also want to consider a Garmin GTX330 Mode S transponder.
Thanks to the masters of paranoia over at the Transportation Stupidity
Agency, a working transponder is a critical asset. The 330 adds traffic
information services, which coincidentally can be displayed on both the
430 and the Avidyne EX500.

I've written a couple articles on avionics updates over the last couple
years. They're on my website...click through

Aviation-Articles-Maintenance

For some realistic prices on the equipment I've mentioned, check out the
shop I use:

http://www.pennavionics.com/

HTH,

-Doug

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Doug Vetter, CFIMEIA

http://www.dvcfi.com
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