Re: KLN94 -> GTX330 (GND/ALT switching)

[Bill Chernoff]

I have a GTX327, and it has a squat switch which is used to switch from
ground to air modes. Maybe your 330 has the same. You may not need the GPS
connected to the 330... I am no expert, I am reading this out of the manual.

By the way, I am interested in making a remote switch for entering
transponder codes. Any info you have on the data protocol in/out of the 330
would be of interest. There are other garmin products that can "tell" the
327 what code to enter, but Garmin is coy with the data protocols.

Bill

[Thomas Borchert]

Bill,

> Maybe your 330 has the same. You may not need the GPS
> connected to the 330..
>

A squat switch is WAY more expensive than the GPS data transfer.

--
Thomas Borchert (EDDH)

[Thomas Borchert]

Peter,

Sorry I can't help. We have a 430/330 combo. Works.

--
Thomas Borchert (EDDH)

[Charles Oppermann]

> The GTX330 transponder is the recent addition. The 330 works but the
> auto ground/air mode switching (based on GPS ground speed) doesn't
> work.

According to the GTX330 Pilot's Guide, the only thing that GND mode does is
turn off transponder replies.

It's my understanding that it is no longer neccessary to turn off or put the
transponder into standby after landing and before departure because with
modern ATC equipment, ground clutter at airports is automatically removed
from radar displays.

Can ATC folks confirm this? I believe I've seen this in various
rec.aviation groups for years now. A quick search of Google Groups confirms
that. Personally, I leave my transponder in ALT mode all the time and have
never had a controller ask me to confirm that it was on.

If the only functionality provided affected by the GND/ALT mode switch is
whether or not the transponder replies to interrogations, then I'd say
forget about trying to get it to read the RS-232 info.

The KMD550 will be much more useful with the enhanced data that the KLN94
sends out. I don't think turning off the enhanced data stream for just the
GND/ALT mode switch is worth it.