You don't pass '437 A A437', you pass the result of pack('N A1 A*', '437', 'A', 'A437').

use Data::Dumper qw( Dumper );

for (qw[ A066 A067 A098 A099 ]) {
   my $coded = pack('N A1 A*', substr($_, 1), substr($_, 0, 1),  $_);
   local $Data::Dumper::Useqq = 1;
   local $Data::Dumper::Terse = 1;
   print("$_: ", Dumper($coded));
}
[download]

A066: "\0\0\0BAA066"
A067: "\0\0\0CAA067"
A098: "\0\0\0bAA098"
A099: "\0\0\0cAA099"
[download]

PS - Why do you keep replying to your node?