A common guideline is that you'll need the turning level on the crystal to get 10°C bigger than the higher operating temperature with the OCXO oscillator circuit. Other than the direct temperature variation, thermal and temperature gradients in TCXOs have an affect on the stable Procedure by producing irregular heating https://tcxooscillators48260.tokka-blog.com/31214529/tcxo-manufacturer-things-to-know-before-you-buy