I'll try out your suggestions tonight when I get home, Darrel - thanks.

Just to confirm: you used code like this?

Code:
DEFINE OSC 20            ' Set oscillator 20Mhz

#CONFIG
       __config _CONFIG1, _FOSC_HS & _WDTE_ON & _PWRTE_ON & _MCLRE_OFF & _CP_OFF & _CPD_OFF
       __config _CONFIG2, _PLLEN_OFF & _STVREN_ON & _BORV_LO & _LVP_OFF
#ENDCONFIG

ANSELA   = %00000000     ' Digital only (PortA)
ANSELC   = %00000000     ' Digital only (PortC)
ADCON1   = $0F
TRISA    = %00000000     ' Make all pins on PortA output
TRISC    = %00000000     ' Make all pins on PortC output


' Set CCP modules to PWM mode
CCP3CON = %00001100 ' Mode select = PWM

HPWM 3, 127, 20000

lblLoop:
    Pause 1

    GoTo lblLoop

End