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Old 02-05-2018, 03:52 AM
chris mitchell chris mitchell is offline
Join Date: Jul 2006
Location: near Harrogate, England
Posts: 376
Default KLN-89B for ADS-B OUT?

I have just replaced an old KT76A transponder with a Trig TT-31, to provide a mode S device. It occurs to me that I could also enable ADS-B by connecting the TT31 to a suitable GPS.

The aircraft has both a Flymap L and a KLN89B. The Flymap can be used but would need more software (about USD400).

So I wondered about the KLN89B. It has RS232 ports in and out. What I don't know is whether it will output data in a format that the Trig can use?

The alternatives are:

Do nothing until its mandated; - impact on safety;
Get another GPS to replace the KLN89 B (which is rather old); - cost;
Stump up the cash for the software update on the Flymap; - cost;
Wait for the Trig TN72 (a standalone GPS unit specifically to provide the ADSB function); - cost (probably around 5-600USD);

So - if the KLN89B can do the job, for the cost of 2 feet of wire and a few connectors, its my preferred solution. If any knows or better still has actually done it, I'd be grateful for details.

Many thanks

Chris Mitchell

Repeat offender;
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Old 02-05-2018, 06:08 AM
Thermos's Avatar
Thermos Thermos is offline
Join Date: Jan 2005
Location: KASH
Posts: 414

Hi Chris,

The KLN-89B isn't WAAS-capable so it's virtually certain that it won't meet the GPS accuracy and integrity requirements for ADS-B Out. As far as I know, Honeywell doesn't have an upgrade path to add WAAS to the 89B so you might want to look at other options.

Hope this helps,

Dave Setser
RV-7 skin, bones, muscle and heart complete, nervous system in progress
Nashua, NH (KASH)
Putting the "slow" in slow-build since 2004!
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Old 02-05-2018, 06:17 AM
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BCP Boys BCP Boys is offline
Join Date: Oct 2011
Location: Kennesaw, Ga
Posts: 669

Hi Chris,
Dave is correct. The important part is that your GPS or position source must be WAAS capable. Its one of the reasons why folks are getting rid of their GNS 430's (non-WAAS) and opting to go with another solution. Your other option would be to use something like the Garmin GDL 82 that will give you WAAS positioning (for ADSB purposes only) and will work with your existing transponder for ADSB out. If you are just looking for WAAS GPS position source only, you will need something like the GPS 20A (these are just some of the Garmin products that I know, I'm sure there are many other companies that provide similar solutions).
RV-7 QB - N174WM
Supporting VAF since the first visit
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Old 02-05-2018, 11:25 AM
BobTurner BobTurner is offline
Join Date: Dec 2011
Location: Livermore, CA
Posts: 5,662

You’ll notice that we are all quoting US rules. In the UK they may be different, so you’ll need to do some research. For example, in the US the GRT ‘2020’ GPS is an approved position source for the TT31 and ADSB-out ($500 USD). But the approval is thru GRT and ‘meets the performance standards’. It does not carry a TSO. Is that okay in the UK? I don’t know.
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