Custom Made Transformer from AC Mains Rated Inductor

Hi All,

The main problem is I cannot find a line transformer that satisfies following requirement:

1) One set of primary windings rated at 250VAC and 2 sets of secondary windings rated at 11V/0.25A,0.05A each.
2) The component footprint small enough to fit within the existing PCB constraint not bigger than 30mm (L) x 25mm (W) x 13mm (H)

I have zeroed on another possibility which to use flyback transformer for the power supply since the smaller component footprints are readily available, which leaves me with the problem of selecting suitable transformer with 1 set of primary winding rated at AC mains voltage and 1 set of secondary winding rated at 11V, 0.05 to 0.25A for signal coupling to power line. But even 1 such component (power line signal coupler by BEL, P/N: 0557-7700-25) form factor is still too large.

Which leaves me with no choice but to explore possibility of customizing/hand made my own transformer to have a transformer form factor that's small enough and yet meets my electrical spec for the secondary winding above. So my proposal is to select an miniature (preferably magetically shielded) toroidal coil with calculated inductance which is rated for AC mains, dismantled the metal shield, manually wound a wire gauge (made for transformer coil wiring) of suitable diameter around/over exsiting primary coil windings, attached both ends of manually wounded secondary coil to suitable pins (preferably extra unused pins provided with the original component or made my own terminals). And finally mount the custom made transformer for power line signal coupling onto my PCB.

I have no knowledge of what type of wire gauge diameter to select for the transformer coil and how many turns to made for the secondary winding to meet my electrical specs for transmit/receive signal. And also what type of inductor coil to select for the coupling trasnformer (ferrite core vs. iron core or toroidal core etc?).

Anyone with the know-how please advise.

Or does anyone has any contacts from suppliers or factories who does customise design to standard inductor component (similar to above), please let me know.

Your help would be greatly appreciated.
Thanks and regards

CW