Glad to hear that you're interested in learning Morse. Don't let the learning curve (for Morse or the transceiver) discourage you. Your transceiver is not broken, and the problem you have described is simple to resolve.
Your transceiver apparently has either Full
Break-in or Semi
-Break-in selected. You must deselect break-in operation to practice CW without transmitting. See page 30 of the FT-897 operating manual, where you will find the following instruction:"5. To practice your CW sending (without transmitting),
press the (BK) key to make the “Parentheses” disappear.
Now, pressing the key will cause the CW side tone
to be heard, but your radio will not be transmitting a
signal on the air."
This is typical of many modern rigs. The CW mode allows user selection of (1) Full
Break-in operation (switching from TX to RX with little to no delay, which allows the operator to hear activity on frequency between Morse characters); (2) Semi
-Break-in operation (the transceiver remains in TX for a period of time after the last character is sent - this delay period is user-adjustable); and (3) No Break-in at all
(the transceiver does not go into TX when keyed, but the side tone is heard).
Good luck with your Morse practice. Between practice sessions, why don't you check out the Straight Key Century Club (SKCC) at this site: http://www.skccgroup.com/
SKCC members offer help and encouragement to newcomers to CW operation, including real-time skeds to get you through the first-time jitters. 73