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KLN94 -> GTX330 (GND/ALT switching)

Hi,

I have the above setup. The KLN94 also drives a KMD550; the connection between the two uses the "enhanced" RS232 data stream so the KMD550 displays the KLN94 flight plan.

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.

The avionics shop that did it a couple of weeks ago has offered to fix it at no charge but they are a long way away and I am trying to fix it myself if I can. I have the maintenance manuals for the KLN94 and the GTX330.

The avionics shop has connected the GTX330 to the same KLN94 RS232 output that's used to feed the KMD550, so the "enhanced" data is going to the GTX330's RS232 #1 input which is set to "GPS" input mode. But the 330 isn't showing any input.

One possibility is that the additional info in the data stream is causing the 330 to reject it.

One solution offered would be to set the KLN94 output from "enhanced" to "standard" but then I lose my KMD550 functionality, which is no good at all. The avionics place suggested using a different KLN94 RS232 output and setting that output (only) to "standard" but the 94 has only ONE output anyway.

Can anyone shed any light on how this might be made to work? Any info much appreciated.

A solution might involve a converter which strips out the extra data, but that is way too much work.

Peter.

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Reply to
Peter
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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

Reply to
Bill Chernoff

The GTX330 has that option but the cost of this is four figures here in the UK :)

I have the GTX330 installation manual; that's all. A copy can also be found at this URL:

formatting link

Sounds very useful! Especially if it can be linked to the intercom, with voice recognition while a button is pressed :)

I've often wondered about having a simple numeric keypad, with a display showing the current entry, a CLEAR button, and with some "load this number" buttons next to it marked

COM1 COM2 NAV1 NAV2 DME ADF XP

Self explanatory! Would speed up entry massively. I've seen such panels at exhibitions, apparently for bizjets and not practically certifiable for GA.

Then all you've got left is loading of flight plans into the GPS, presently done by twiddling two knobs. That one has been fixed higher up the market, too :)

Peter.

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Reply to
Peter

Bill,

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

--
Thomas Borchert (EDDH)
Reply to
Thomas Borchert

About US$2000 here in the UK, and most of that is paperwork. Even on an N-reg; in fact N-reg usually costs more due to the need for stuff like DER approvals which the U.S. based DER charges out at US$800 per item :)

I've emailed Garmin to ask whether they need a KLN94 set to emit the "standard" data rather than the "enhanced" data. I think that's the key. It would be amazing if I get an intelligent reply to such an obscure question.

Peter.

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Reply to
Peter

Peter,

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

--
Thomas Borchert (EDDH)
Reply to
Thomas Borchert

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.

Reply to
Charles Oppermann

I agree 2000%.

For the record, I have just got this piece of info

direct from somebody who knows the products intimately. So, instead of using the KLN94's pin 2 (standard RS232 output) one has to use pin 6 (spare RS232 output).

I haven't tested this yet; the trip to the avionics shop and back involves 2 days' travelling :) But if I don't report further, it worked.

Peter.

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Reply to
Peter

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