Laut Datenblatt:

f = fo +-5%
delta f (-3dB) = fo/10

TSOP1730 30 kHz
TSOP1733 33 kHz
TSOP1736 36 kHz
TSOP1737 36.7 kHz
TSOP1738 38 kHz
TSOP1740 40 kHz
TSOP1756 56 kHz