Transponder upgrade - Interference issues

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Charles
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Transponder upgrade - Interference issues

Post by Charles »

We recently replaced the GTX 327 transponder for a GTX 335 for ADS-B Out compliance. Nothing else changed. With the new transponder, a crackling noise can be heard from the audio panel. The noise goes away when the transponder is turned off.

The transponder was tested with a connection to another antenna and the noise is not heard, which points to the antenna or cabling being the source of the interference.

My avionics tech is baffled. Has anyone experienced the same issue?
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Diamond_Dan
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Re: Transponder upgrade - Interference issues

Post by Diamond_Dan »

Would be interested in feedback on this one. Our audio made a crackling noise with the old GTX 33 AND the new GTX 345. The problem will disappear when the transponder breaker is pulled. One shop replacing our audio panel advised us not to bother tracking it down. Says it's "typical". A different shop that installed the 345 checked the wiring and antenna and couldn't find anything wrong. Honestly, I don't notice it after a few minutes.
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TimS
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Re: Transponder upgrade - Interference issues

Post by TimS »

Is the crackle noise constant? Or intermittent? e.g. does it occur when the transponder receives or broadcasts or just powered on?

Tim
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