A friend and fellow amateur radio enthusiast, Ross GW3NWS, let me borrow one of his TCO’s, a ToyoCom 5MHz unit.
As I wanted to obtain some higher accuracy to the results, I decided to use the 9th harmonic at 45MHz. The signal was observed on a SunSDR2 Pro, that had been provided with a GPSDO 10Mhz reference signal.
The TCO-613 was powered up from cold, the following was observed, again using WSJT-X in FreqCal mode. After 12 minutes the TCO settled to around 0.43Hz high at 45MHz, an average of the last 8 minutes of delta frequency. The test was concluded after 20 minutes. No adjustment had been made and was tested as provided by Ross.