Erdas Imagine 8.7: exporting to DTED 2

Dear all,

Currently, i've been involved in exporting img files to DTED 2 file
format;
however the operation results in Dted files with unwanted large
extentions.
This leads me to excess file size. Namely, 550kb img file ends up with
25MB dted file;
plus the area of interest remains in the middle of a large extension
with no information.
I've tried many ways to export it but did not get any results. Do you
have any suggestions
or any other software that can overcome my problems.

regards,

CY