Transponder reported intermittent

[greg51]

ATC has reported my King KT 76A as intermittent. I had my mechanic check all connections and all good. Any advice on what is wrong. I read that if you check Flight Aware and  your whole track is there it is ATC problem.

Does anybody have a working one they will sell me cheap? I am  not ready to do ADSB upgrade yet

[gsengle]

I wouldn't take one report as needing a replacement yet especially if it checks out... Your avionics shop can check it and it's signal...

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[greg51]

I was trying to avoid taking to my avionics shop (not at my home field) I took a trip from KLHZ to KCRE IFR and had no trouble till Myrtle beach approach told me they never saw my Transponder. When leaving they saw it after take off but then said they lost it. When they handed me off there were no issues with any other ATC 

[gsengle]

I wouldn't do anything yet...

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[takair]

You will want to be sure it is the entire transponder and not just mode C.  If it happens again, be sure to ask if they lost the altitude and the code.  Unfortunately, the KT-76s are getting up there in age.  They have a cavity that starts to go bad.  Your shop may be able to tune it and get it back to working order, but extensive repairs can be more expense then they are worth.  You technically need to go to the avionics shop even if you replace it, since only a repair station can certify it, so it might be worth the trip.  You may also want to look at one of the Garmin transponders that are on the used market due to ADS-B upgrade.  Used KT-76 may not be much better than yours...

[ArtVandelay]

I have one if you decide to go that route, leftover from a panel upgrade.

[Piloto]

Try cleaning the tray and transponder contacts with contact cleaner. Also clean the antenna connector contacts. Most intermittent problems are due to oxidized contacts. If using a rod antenna clean the rod too.

José

[Steveolyo]

I agree with Piloto. My transponder was reporting erroneous information to ATC. After pulling the contacts and cleaning them and carefully plugging them back in the transponder became accurate again.

[greg51]

Steve, thanks for telling me your experience. I will try that first

 

Piloto, thanks also, I am going to do that first. can I get contact cleaner at auto parts store?

 

teejay, I will contact you if cleaning doesn't work

Thanks all

[N201MKTurbo]

I had a KT-76A that was intermittent. I had it bench checked 3 times. I finally changed it out for a KT-76C. While I was rewiring it I found that the encoder wires were chafing on the SS fuel pressure hose and had worn away the insulation and were shorting out. This was the root cause of the intermittent transponder.

I still have the KT-76A and it still has some cert time left. By law you will have to get it checked after installation.

[bradp]

My antenna is mounted in the worlds most prime real estate for collection of grease, oil and dirt.   

[N201MKTurbo]

4 minutes ago, bradp said:

My antenna is mounted in the worlds most prime real estate for collection of grease, oil and dirt.   

A well lubricated antenna is a happy antenna. I think I'll have another drink.

[jclemens]

The Trig TT31 is a slide in replacement for the old King KT76A.  A simple wiring addition from your WAAS GPS will give you ADS-B out too.

[Bob - S50]

23 hours ago, greg51 said:

I was trying to avoid taking to my avionics shop (not at my home field) I took a trip from KLHZ to KCRE IFR and had no trouble till Myrtle beach approach told me they never saw my Transponder. When leaving they saw it after take off but then said they lost it. When they handed me off there were no issues with any other ATC 

If everybody saw you except Myrtle Beach, it's probably a problem with the Myrtle Beach ATC.

[Marauder]

Greg -- last year I was receiving reports from Philly approach that I was reporting 200' off. They were the only one reporting my "off" altitude. The rest Harrisburg, Potomac, NY Tracon, Elmira approach all said I was on altitude. So, the possibility of it being a facility is pretty high. I would do more verification and also look at your FlightAware altitudes if you file or use VFR flight following (I think if they enter your destination, it shows up).

[gsengle]

Thread drift, but I almost never have flight aware pick up my VFR flights anymore... I flew down to Florida and back not long ago all with radar advisories, over 2000 miles and nothing...

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[bradp]

6 minutes ago, gsengle said:

Thread drift, but I almost never have flight aware pick up my VFR flights anymore... I flew down to Florida and back not long ago all with radar advisories, over 2000 miles and nothing...

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If you file on foreflight you can submit your flight plan filing as a VFR DC SFRA.   From what I understand, on the back end, this method submits your plan as a domestic IFR plan, but the altitude box has "VFR/045".  The "VFR/" part will tag you as such on the controllers' screens - so you are not actually filing IFR in any way.  This allows for the plan to be propagated to the appropriate ATC facilities.  As a result you'll get two benefits.  One is you can pull your flight up on flight aware.  Another is that you won't have as many "radar services terminated, squawk VFR, frequency change approved, try (next facility) on xxx.xx" calls.  The next facility will be expecting you and the handoff.  The local approach control facility (Johnstown) controller thought it was cool and useful that she got a strip for me.  Same with Lynchburg, VA local tower controllers.  I don't think this in any way goes against the FARs or confuses Potomac Approach (I asked them about it during a facility tour), but if anyone has info to the contrary, please do share.

You can do the same thing with by entering "VFR/XXX" on Duats or fltplan.com if you use that to file VFR plans.   I don't know how this works on Garmin Pilot.  I have never tried to "activate" a VFR flight plan using this method (not much use where I fly as I always go with FF and am in radar coverage the entire way). 

YMMV of course. 

[greg51]

Marauder, My flt aware was right on with no gaps except for a short spike in alt which I see a lot on other a/c. I just pulled my Transponder and found the contacts to be very dirty. I cleaned them and the antenna and will fly test with ATC on monday

[LANCECASPER]

The KT-74 might be a good choice - you might get something back for your KT-76A.

I like the King better than the Trig since you have the direct enter number buttons for your squawk code. $2575 at gca.aero

http://www.bendixking.com/Trade-Up/Qualifying-Products#intro

[DXB]

7 hours ago, LANCECASPER said:

The KT-74 might be a good choice - you might get something back for your KT-76A.

I like the King better than the Trig since you have the direct enter number buttons for your squawk code. $2575 at gca.aero

http://www.bendixking.com/Trade-Up/Qualifying-Products#intro

Yeah I did this- KT74 is actually made by Trig with the same innards, and it's plug and play with the KT76A - plus a single connection to your panel mount GPS to get ADS-b out.    Got $300 back from King  for my KT76A.   Assuming you have the J-bar, you'll also need an airspeed switch install for ads-b out - I think with electric gear it plugs into the squat switch.   I'm very happy with it.