The Indira Gandhi National Centre for the Arts (IGNCA) maintains a digital Vedic Heritage portal.
Copy and paste this into your search engine: yajurveda trikala sandhyavandanam pdf sanskrit install
"yajurveda trikala sandhyavandanam" filetype:pdf "sanskrit"The Indira Gandhi National Centre for the Arts
Warning: Avoid PDFs that combine Rigveda and Yajurveda styles. Look for specific mantras like "Om Bhu" (Bhur, Bhuva, Suvah) which is standard for Yajurveda Gayatri. "yajurveda trikala sandhyavandanam" filetype:pdf "sanskrit"
When searching for your PDF, you need to know the exact terminology. Use the following long-tail keywords in Google or your favorite Vedic text repository:
Usually 3 rounds of Pranayama mantra: "Om Bhur Bhuvah Suvah..." – The Yajurveda specific formula.