Something to note is that Tyndale was influenced by Martin Luther, who was German.
German words beginning with ‘H’ and ‘J’ sounded like ‘Y’ in German and vice versa. Coincidently, it was about this time that we begin to see the ‘J’ used for the ‘Y’ sound in the Bible. ‘Y’ sound is the Hebraic sound, YHWH, Yehoshua, Yehuda etc. They were translated into ‘J’ words in the Tyndale Bible. Although Luther himself never used Jehovah which is a rendering of YHVH, he used LORD instead in his translation.
Just in case you did not know, JeHoVaH is YHVH with vowels in the Tyndale Bible. Suspicious, if you ask me, considering the proper pronunciation of YHVH which was only used by the Hebrew priest in Temple services once a year is lost. However, Tyndale took it upon himself to pronounce YHVH as JeHoVaH.
Although, Tyndale introduced us to the letter ‘J’ but not the ‘J’ sound. The ‘J’ sound was already in the English language.