[Milsurplus] Airplane question, but radio related

[Jack Antonio]

Question about aircraft registrations, but it is radio related.

What nation uses PT to begin a registration number? If it follows
radio call sign allocations it would be Brazil, just wondering if
aircraft registrations follow the same pattern.

Reason I ask, is I have an aircraft radio which is  marked
with what looks like a registration beginning with PT.

Thanks in advance.

Jack Antonio
WA7DIA