Narco AT150 Transponder Question

[MooneyFlyer]

Hi, just had the transponder check and it passed. In flight, the unit has power, the reply light blinks, it tests correctly. I cleaned off the antennae, I pulled it out and reseated it, BUT still no ATC sees me! No reply on the ground at all....any suggestions? Replace the antennae? have the wiring replaced? other? (It's an older aircraft, and replacing it with a $5k Garmin isn't really an option).

 

[cgrab]

Contact cleaner spray always seems to fix my comm problems. A little bronze brushing of the contacts may help if it is real bad.

 

[murphey]

Check the encoder, too.

 

[unsafervguy]

when they did the check did they do a power check or just the FAR required check? could be putting out enough power to receive a signal on the test set, but not really transmitting enough power to get anywhere. its an old design and not really supported, your only real options are a used serviceable unit, or replace with a modern unit. personally, (and since i have an at50 in one of my airplanes im in the same boat) i would replace it with a modern unit. as much as I hate garmin, i will probably go that way soon.

bob

 

[bnt83]

when they did the check did they do a power check or just the FAR required check? could be putting out enough power to receive a signal on the test set, but not really transmitting enough power to get anywhere. its an old design and not really supported, your only real options are a used serviceable unit, or replace with a modern unit. personally, (and since i have an at50 in one of my airplanes im in the same boat) i would replace it with a modern unit. as much as I hate garmin, i will probably go that way soon.

bob

Did you know that the FAR test requires measuring power output?

https://www.ecfr.gov/cgi-bin/text-i...363ea95&mc=true&node=ap14.1.43_117.f&rgn=div9

(1) Verify that the transponder RF output power is within specifications for the class of transponder. Use the same conditions as described in (c)(1)(i), (ii), and (iii) above.

(i) For Class 1A and 2A ATCRBS transponders, verify that the minimum RF peak output power is at least 21.0 dbw (125 watts).

(ii) For Class 1B and 2B ATCRBS Transponders, verify that the minimum RF peak output power is at least 18.5 dbw (70 watts).

(iii) For Class 1A, 2A, 3A, and 4 and those Class 1B, 2B, and 3B Mode S transponders that include the optional high RF peak output power, verify that the minimum RF peak output power is at least 21.0 dbw (125 watts).

(iv) For Classes 1B, 2B, and 3B Mode S transponders, verify that the minimum RF peak output power is at least 18.5 dbw (70 watts).

(v) For any class of ATCRBS or any class of Mode S transponders, verify that the maximum RF peak output power does not exceed 27.0 dbw (500 watts).

 

[unsafervguy]

Yes I know it's required, but I also know it isn't always done.......

Bob

 

[d.grimm]

I've got a AT155 that I'm pretty sure uses
The same rack and wiring. Solid state,
Repaired last year. Took it out for ADSB install. How about $350?
Dave

 

[mv_myrx]

Hi, just had the transponder check and it passed. In flight, the unit has power, the reply light blinks, it tests correctly. I cleaned off the antennae, I pulled it out and reseated it, BUT still no ATC sees me! No reply on the ground at all....any suggestions? Replace the antennae? have the wiring replaced? other? (It's an older aircraft, and replacing it with a $5k Garmin isn't really an option).

The 150 was a slide in replacement for the 50. I have a 50 that I just removed a couple of weeks ago to install the appareo. If you want I will let you have it cheap you pay shipping. Say $50.