Markmp Posted September 25, 2017 Report Share Posted September 25, 2017 In receiving quotes from a few avionics shops for a GPS+ADS-B upgrade, I've noticed some shops say I need a separate altitude encoder, specifically the GAE-12 to work with the proposed Garmin GTX345. Other shops say I should get the ACK A.30 encoder. Some shops say I don't need either with the GTX but I can install if I want to. Can someone shed some light on whether I need a separate encoder or not, and which one is appropriate? (and why?). Assume a GTX345+GTN650 setup. Thanks! Quote Link to comment Share on other sites More sharing options...
Bob - S50 Posted September 25, 2017 Report Share Posted September 25, 2017 We did not need to buy a new encoder when we had our GTX345 installed. The one we had worked just fine. However, if I was going to buy one, I'd probably get the one that Garmin makes (GAE-12) just because it is small, light weight, and easy to install. Quote Link to comment Share on other sites More sharing options...
Andy95W Posted September 25, 2017 Report Share Posted September 25, 2017 The GTX needs altitude encoder input. Most modern avionics use RS-232 which is fairly simple to connect, but older avionics used a 10-wire system called Gilham or grey code. Your old encoder may only output grey code, and the Avionics shop wants to install the more modern (and easier) RS-232. IMO, if your encoder really is that old, get a new one. They really aren't that expensive and you could be avoiding problems down the road. Quote Link to comment Share on other sites More sharing options...
Cruiser Posted September 25, 2017 Report Share Posted September 25, 2017 The GTX 345 requires external uncorrected pressure altitude input. If multiple sources are available the GTX 345 will use the following priority for input ARINC 429 data RS-232 data GAE module Gray Code 1 Quote Link to comment Share on other sites More sharing options...
jetdriven Posted September 25, 2017 Report Share Posted September 25, 2017 I Put in the garmin encoder. It was only like 250$ and low installation cost. It snaps into the gtx backplate. Quote Link to comment Share on other sites More sharing options...
nsrrlearjet Posted September 27, 2017 Report Share Posted September 27, 2017 I just put in a GTX 345 & GTN 650 a few months ago. So far so good.Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
bradp Posted September 29, 2017 Report Share Posted September 29, 2017 Garmin unit is tucked away and small. Price is in line with a blind encoder Cruiser has it right - 345 has multiple sources in an order of priority for pressure altitude. Quote Link to comment Share on other sites More sharing options...
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