Greetings from W-TN, My T-4XC drifts for several (like 10) hours after powering it up. On the other hand my R-4B is stable after a very short warm up (like 10 minutes). The T-4XC works fine using the R-4B to control frequency. Is there a specific component that usually causes this problem? Or do I need to start searching from scratch? Thanks for your time, Don - K4BEV