>I tried 2.2 Kohms and a parallel cap 100 nF but didn't work.
>The only way I got it working on two diferent PCs was with 4.7 Kohms.

Yes, the input impedance of DTR varies on different PC's.

>Any idea to leave VCC on all the time and be able to Read/Verify ?

Yes.

This is the schematic for my PIC16C84 Module (without oscillator circuit).
Programming can be done in circuit, if RB6/7 aren't connected to any high
load.
Otherwise I'm removing the module for programming.
Supply voltage must be turned on, if the connected circuitry draws power from
Vdd.

The 2k2 / 4k7 between DTR and RTS is placed inside the SUB-D case, therefore
removing the programming connector removes the load and RB6/7 will be free
for use.



 TxD --------------------------*---------------------I
                               I                     I
                              ---                    I
                              I I 2k2                I
       I-------I              I I                    I
+6.5 *-I 78L05 I-----I        ---                    I
     I I-------I     I         I                    ---
     I     I         I        ---                   I I  10k
     I     I         I        \ /                   I I
     I100n I         I        ---            47k    ---
    ---    I         I         I              --     I               _____
    ---    I         *---------*----------*--I  I----*-------------- Reset
     I     I         I         I          I   --     I
     I-----*         I +     /---         I          I
           I        ---     / / \ 5V6     I          I
           I        --- 15u   ---         I          I
           I         I         I          I 14       I 4
           I         I         I       I--I----------I---I
           I         I         I       I Vdd        Vpp  I
           I         I         I     5 I                 I
GND -------*---------*---------*-------I Gnd             I
                                       I                 I   PIC 16C84
        22k                            I                 I
        --                          12 I                 I
RTS ---I  I----------------------------I RB6             I
        --                             I                 I
        --                          13 I                 I
DTR ---I  I---*------------------------I RB7             I
        --    I                        I                 I
        2k2/  I                        I-----------------I
        4k7   I
CTS ----------I



 - Erik