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GTX330 from 2005 - any point in upgrading or changing?

I don’t think you would do that. There is no point, because a GTN can feed the 345 with its WAAS GPS position data.

Hmmm. How much work is replacing a GTX330 with a GTX345 and installing one WAAS antenna?

Actually this opens a can of worms because of antenna locations and the upper TAS605 antenna really needing to move as far forward as it can go. If there isn’t enough cable slack, it becomes a big big job.

Currently the GPS2 antenna is feeding a bluetooth GPS receiver. That location could be used for the GTX345 antenna. But really the TAS605 antenna and the GPS2 antenna should be swapped.

Administrator
Shoreham EGKA, United Kingdom

Peter wrote:

If I did that, and later put in the GTN (or 2×GTN) I would (due to not wishing to have more antennae than the GCHQ) have to disable the 345’s GPS and re-use that antenna for a GTN, and anyway the 345’s GPS would be irrelevant.

It’s not only about antenna count. Strictly speaking, using several position data sources (GPS receivers) within the avionics stack is a bad thing to do unless one also implements a full reversion capability (that is, the ability to select any given data source to feed any given data sink).

LKBU (near Prague), Czech Republic

Peter wrote:

I don’t think you would do that. There is no point, because a GTN can feed the 345 with its WAAS GPS position data.

Why would you say that? Yes I would. You need to fit a WAAS antenna anyway. You would get ADS-B in as well as out.

It is 3k vs over 1k to upgrade to ES – it is a much better deal IMHO and gives you more options with GTN devices in the future to display the ADS-B in traffic.

Last Edited by JasonC at 08 Feb 22:42
EGTK Oxford

unless one also implements a full reversion capability (that is, the ability to select any given data source to feed any given data sink).

I think if one installed a GTN650+750 then one would have an antenna for each. And each of my two Sandel EHSIs can select GPS1/GPS2. So that’s done.

The one thing which cannot be done (legally; technically it is trivial) is to drive the autopilot from either EHSI’s autopilot output, switchable with a toggle switch, because that would need a new autopilot AFMS.

So if I install a GTX345, yes, currently with the KLN94 I would need to give it its own GPS antenna, and then I would have ADS-B OUT immediately.

I could connect the TAS605’s traffic output to it, so it merges that with its received ADS-B IN data, but the GTX345 won’t drive anything I have i.e.

  • SN3500 x2 – this might work (I know the GTX345 STC “doesn’t support” the SN3500 as a display device)
  • KMD550 – this probably won’t but nobody knows (I know the GTX345 STC “doesn’t support” the KMD550 as a display device)

Then we get back to this again

If the GTX345 cannot show traffic on the SN3500, that will be a huge retrograde step for me because I will lose TCAS, and when the GTNs go in I will see traffic only on them which is nothing like seeing it on the EHSIs, right in front of me.

So clearly I need to check out the traffic data stream compatibility GTX345 → SN3500 and not bother with any of this until this is 100% checked. I have already discussed this with Sandel and didn’t get a reply which I could understand clearly. Well, they said that ADS-B traffic will not show because it is sent via a different protocol (which seems bizzare since the GTX345 is supposed to be merging them transparently!).

It is very possible that a GTX345 would work for Mode C/S and ADS-B OUT and nothing else, and ADS-B IN would have to be done using the TAS605 “A” + ADS-B IN upgrade if they ever do it. Not sure I would want to spend a few k for this.

It is 3k vs over 1k to upgrade to ES – it is a much better deal IMHO and gives you more options with GTN devices in the future to display the ADS-B in traffic.

Indeed, but not if the Sandel EHSIs cannot display ex-GTX345 traffic…

Administrator
Shoreham EGKA, United Kingdom

Peter, to your question, I already had a GTN750 so the GTX345 is getting its WAAS GPS position from there, directly. I thought about putting the GTX345 to get some redundancy but that made things more complicated.

My disappointment with the GTX is the SynVizz is which is truly useless.

EGTF, LFTF

I have asked Sandel the very specific Q of whether TAS605 → GTX345 → SN3500 displays any traffic on the SN3500.

Presumably if it works, nobody will want to talk about it, unless the IM for the GTX345 or the IM for the SN3500 shows the connection

If not, then changing the GTX330 to a GTX345 would just give me ADS-B OUT, at a cost of a few k, which almost nobody (of relevance) will see anyway, and is there any ADS-B OUT mandate for IFR below 5700kg on the horizon? There will never be one for VFR, as there will never be one for Mode C/S (in much of Europe).

Administrator
Shoreham EGKA, United Kingdom

I may be naive but I think we may get a carrot in the form of on-board weather and “TIS” traffic.

EGTF, LFTF

Jason wrote:

It is 3k vs over 1k to upgrade to ES – it is a much better deal IMHO and gives you more options with GTN devices in the future to display the ADS-B in traffic.

It’s hard to argue with that, but here goes:

1. Peter doesn’t really need ADSB-in (for now). He already has TAS, so ADSB-in would, at best, show a bit more accurately a very small percentage of the potentially conflicting traffic already displayed on his EHSI.
2. Conversely, ADSB-out might be seen by a few of the transponderless aircraft which Peter’s TAS can’t detect, but who nevertheless have PFLARM, PAW, Stratux, GDL39 or similar portable traffic detection gizmos – all of which can detect ES/ADSB-out, even with SIL=0.
3. It’s true that few light aircraft in Europe currently have ES transponders, but I don’t think that’s a good reason not to join us.
4. I upgraded my GTX330 to ES last year. There’s practically no labour involved, and I think it’s worth doing even if the 1 AMU cost will never be fully reflected in the resale value of the transponder.

Last Edited by Jacko at 11 Feb 14:34
Glenswinton, SW Scotland, United Kingdom

Conversely, ADSB-out might be seen by a few of the transponderless aircraft which Peter’s TAS can’t detect, but who nevertheless have PFLARM, PAW, Stratux, GDL39 or similar portable traffic detection gizmos – all of which can detect ES/ADSB-out, even with SIL=0.

That is possibly a good argument for implementing ADS-B OUT.

What I don’t know is how many people fly with those low cost gadgets. Reading some UK forums (which admittedly I rarely do these days) there seems to be a different gadget for every evangelical supporter of it. And I know that the highest volume posters do the least (or zero) flying.

I upgraded my GTX330 to ES last year. There’s practically no labour involved, and I think it’s worth doing even if the 1 AMU cost will never be fully reflected in the resale value of the transponder.

What does that actually do?

Administrator
Shoreham EGKA, United Kingdom

After the “ES” hardware upgrade, the transponder can be connected to a GPS and configured to transmit Mode S extended squitter (aka ADSB-out). In my case the transponder was already connected to my GTN650, but you’ll need to establish a serial connection if not already present. Then you just tweak a couple of configuration settings as detailed in the manual.

How many active pilots have some kind of electronic traffic detector? I guess about 1,000, give or take a factor of 10. But one can at least say that most of these (relatively) cheap portable gizmos can receive 1090 MHz ADSB.

Glenswinton, SW Scotland, United Kingdom
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