The cheap Chinese copies of the Kenwood TCXO boards are rubbish, I bought and installed a superb TCXO from Mark Goldberg, W7MLG. The results are fantastic, my TS-590SG is now spot on
TS-590SGデジタルモード設定 - 日下部ラヂヲ商會
Second Hand Kenwood TS-590SG HF Transceiver - Radioworld UK 01922 414796
I no longer have a new amplifier but I do have a new radio. | QSO365