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echoUAT with no (old) transponder?

FinnFlyer

Well Known Member
If I read the documentation correctly, the echoUAT can either get squawk code, altitude and Ident by sniffing power to old transponder or from a modern EFIS unit.

Also says to keep its antenna at least one meter from any existing transponder antenna.

This makes me wonder if either of these are possible:
1) Put a dummy load on my GTX 320A and replace its antenna with the one supplied with the echoUAT.
2) Remove the GTX 320A and its AK-350 altitude encoder and make my own control head (simulating a modern EFIS). (I have altitude info from Dynon D-10A.)

Am I missing something? Do you still need a Mode C transponder in addition to the UAT transmitter?

Why?

Two different frequencies?

Finn
 
To fly in "rule" airspace (inside mode C veil, class B, C, above 10,000 ft etc) you must have both a mode C (or S) transponder AND ADSB-out. Now, if you are asking, may you have ADSB-out in airspace where no transponder is required, and where you don't have one? I think the answer is yes but I can't say for sure. It'd be unusual, certainly. I imagine that if my transponder failed, I could continue without it as long as I avoided 'transponder required' airspace. I wouldn't turn my UAT off. So I think the answer is yes.
Edit: part of the "why" is that airlines use a transponder based collision avoidance system, and the FAA wants to keep that working as a backup.
Two frequencies? Depends on whether you use a UAT or a mode S-ES for ads-out.
 
Thanks Bob.

So the only way to have only one transponder antenna is to have an 1090ES with ADS-B Out like the Stratus 1090ESG. Sucks!

I wonder how far the UAT antenna really have to be from the Mode C transponder. 1 meter or 3 feet is quite the distance considering length of the antennas are only a few inches.

Finn
 
Thanks Bob.

So the only way to have only one transponder antenna is to have an 1090ES with ADS-B Out like the Stratus 1090ESG. Sucks!

I wonder how far the UAT antenna really have to be from the Mode C transponder. 1 meter or 3 feet is quite the distance considering length of the antennas are only a few inches.

Finn

Well, Garmin does make a one antenna UAT-transponder system that uses an electronic box to keep from sending 200 watts of transponder signal into the UAT. Like most things Garmin it?s not cheap.
If your 320 was getting long in the tooth, cheapest 1090S-ES system I know of is a Trig TT22, with one of several $500 approved gps boxes to drive it. ADSB-in not included (nor required).
One reason for the antenna separation is that your transponder is blasting out a 200 watt signal on a frequency close to where your ADSB-in is listening. You don?t want to overload that poor receiver.
Other: keep in mind that you must use the same altitude encoder source for both your transponder and ADSB-out. You may not drive one from your ACK350 and the other from your Dynon?s encoder.
 
Supposedly Sandia's STX-360 is an all-in-one Mode C and UAT Out box. I haven't actually seen it for sale and in stock anywhere. Bu I would mch prefer to use 978 on a new build airframe.
 
OK, so I'm back to the echoUAT/FSKYFYX-EXT bundle as the least expensive solution for me (and includes ADS-B in).

Just have to live with two antennas.

Finn
 
IMHO you should think of the whole "system". In no particular order:
1. Any plans to fly at or above FL180? Then you need 1090 S-ES. Mexico or Canada? Check out their plans and/or current requirements (Mexico may require 1090S_ES, I'm not sure).
2. Do you want "all new"? Are you planning on a TSO 144/145 ("IFR") GPS? If so 1090SES may be the less expensive option, since you need a transponder either way.
3. Willing to buy used? Garmin 327 transponders can be had for $400 (people trading them in for 1090SES units have flooded the market).
4. Want ADSB-in? How will you display the data? Tablet, EFIS?
Figure out a whole package that will work for you, get you what you want.
 
Just trying to make my RV-3B ADSB-Out legal.
No plans to go above 18,000'

I'm considering the RV-4 I'm building to be my cruise or trip plane.

Considering I don't need ADSB-Out for local flights where I live, maybe I should postpone ADSB-Out until/if I'm ready to sell the RV-3B.

Finn
 
So the only way to have only one transponder antenna is to have an 1090ES with ADS-B Out like the Stratus 1090ESG. Sucks!

Finn

Finn,

Nope. The GDL 82 uses the existing belly transponder antenna and existing Mode C transponder. No additional antenna on the belly. It can be had for about $1,675.00. And gives you anonymous mode to boot.

Many folks such as me prefer UAT out over 1090ES for cost and privacy issues. And we prefer a seperate "in" device that can change over time and easily without being married to a specific Kool-Aid maker. For no additional transponder-type antenna the GDL 82 fits that bill.

I installed an Echo in my RV-3B just forward of the battery between the pilot's feet and put it's transponder type ball and stick antenna right under it on the belly behid the firewall. My Mode C transponder fin type antenna is farther back on the belly under the baggage area. I will take some photos tomorrow as I have the boot cowl off. One of the niceties of the EchoUAT is it also gives you dual in while selling for something on the order of $1300+.

Jim
 
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