Transponder / Encoder testing

I have an RV6A based at Gwinnett LZU and was interested in knowing if anyone in the area might know of an avionics tech that does transponder, encoder and static testing/inspection in this area at a resonable price and can do the work on site without having to remove the equipment from the plane? I have a calibration problem of about 300' or so. Thanks in advance for any assistance that you all might be able to provide to me.

We took ours to Lowes Aviation in Macon. Not the cheapest but close to you.

Talk w/ Avionics West at RYY. I've always been happy with them.

I'm based at LZU too. Georgia avionics over at WDR will hook you up. They work with RVs all the time. Give them a call. I'm assuming your calibration error is with your mode C? If so, just don't turn it on. You don't need your mode C if you head east directly out of LZU. We are *just barely* outside of the mode c veil.