Frank:
Does anyone else have a problem with ATC losing their Mode C? It seems that when the ATC station is directly in front of me they lose my Mode C for a time. Since I’m in and around Class B often, I get nervous about being violated. I’m wondering if I’m getting interference from the nose gear? My xponder antenna is in the centerline of the underside, about even with the rear of the wing. Xponder is a King KT76; and bi-annual xponder tests, etc. are OK.
Editor:
Some ATC radar locations seem to have problems with the old KT76, even when a shop has just checked it out. The area around Savannah, FL is a good example. I saw a technical explanation of the reason, once upon a time, but I remember none of the details. I would not spend much repair money on this old unit. The KT76A is better, and the KT78 is better yet. But with products like the Garmin 320 and 327 on the market, including available used units, putting repair money in the 76 series probably won’t make much sense. They are money pits at this point in time, with their old cavity tubes.
If they have cleared you into the airspace with a working transponder, then they encounter intermittent replies, they will usually just alert you. If they have a congestion problem, they may route you out of the airspace. I have not heard of anyone being violated unless they entered the airspace without clearance. At worst, they’ll mail you a letter that requires a response confirming “repair” or a check-out. Not normally an issue.