According to Insight on the Scriptures Volume 2, page 5 under the heading, 'Jehovah' the following is stated:
"Correct Pronunciation of the Divine Name. “Jehovah” is the best known English pronunciation of the divine name, although “Yahweh” is favored by most Hebrew scholars. The oldest Hebrew manuscripts present the name in the form of four consonants, commonly called the Tetragrammaton (from Greek te•tra-, meaning “four,” and gram'ma, “letter”). These four letters (written from right to left) are ???? and may be transliterated into English as YHWH (or, JHVH)."
The Divine Name brochure on page 7 under ‘God’s Name – It’s Meaning and Pronunciation’ makes the following statements:
“How Is God’s Name Pronounced? The truth is, nobody knows for sure how the name of God was originally pronounced. Why not? Well, the first language used in writing the Bible was Hebrew, and when the Hebrew language was written down, the writers wrote only consonants—not vowels. Hence, when the inspired writers wrote God’s name, they naturally did the same thing and wrote only the consonants."
According to the Encyclopedia Britannica, (1991) under the heading 'Yahweh', here is how this name came into being:
"The Masoretes, who from about the 6th to the 10th century worked to reproduce the original text of the Hebrew Bible, replaced the vowels of the name YHWH with the vowel signs of the Hebrew word Adonai or Elohim. Thus the artificial name Jehovah (YeHoWaH) came into being."
Despite the name Jehovah being nonexistent in the original Hebrew scriptures, it really started to become mainstream around 1270 A.D. due to the work of a Roman Catholic Spanish Monk, named Raymundus Martini. There is no J or V in the Hebrew alphabet. 'Jehovah' is a Latinized or anglicized transliteration. It is not an accurate one.