No, char was 8 bits on the PDP-11, which was a 16-bit little-endian machine. (not middle-endian unless you count the typical compiler being weird with 32-bit values on the 16-bit little-endian hardware)
C didn't run on the PDP-7.
Being either 7-bit or 9-bit would be a choice for 36-bit hardware. Wikipedia's list of 36-bit hardware is: MIT Lincoln Laboratory TX-2, the IBM 701/704/709/7090/7094, the UNIVAC 1103/1103A/1105 and 1100/2200 series, the General Electric GE-600/Honeywell 6000, the Digital Equipment Corporation PDP-6/PDP-10 (as used in the DECsystem-10/DECSYSTEM-20), and the Symbolics 3600 series.
C didn't run on the PDP-7.
Being either 7-bit or 9-bit would be a choice for 36-bit hardware. Wikipedia's list of 36-bit hardware is: MIT Lincoln Laboratory TX-2, the IBM 701/704/709/7090/7094, the UNIVAC 1103/1103A/1105 and 1100/2200 series, the General Electric GE-600/Honeywell 6000, the Digital Equipment Corporation PDP-6/PDP-10 (as used in the DECsystem-10/DECSYSTEM-20), and the Symbolics 3600 series.