Did you turn it to FM(PPM) mode?
From the 3PJS manual page 30
The 3PJ SUPER transmitter output signal format can
be changed to match the type of receiver. Check if the
modulation mode is set to match the receiver used.
When using an FM receiver (e.g., R113F), the modulation
mode must be set to PPM. When using a PCM receiver
(e.g., R113iP), the modulation mode must be set
to PCM. If this setting is incorrect, change it with the
Mode Select (page 93) function.
The 3PJ transmitters are nearly identical on the exterior to the 3PJS.
Download and follow the 3PJ Super manual for use with your older 3PJ radio system:
3PJS manual (2,862K)