I'll check the divider to see what the voltages are, but at the moment it works
with 12 V on the PTT-in and not with +5 from DTR.

Thanks,
AF4PM



--- In kgksdr@yahoogroups.com, "g8voip" <g8voi.reeves59@...> wrote:
>
> Hi there,
>
> The PTT input for the v6.1 TX/RX has a divider of 2 x 10k resistors driving
the base of Q7. With the DTR line input at +5V, should be more than enough to
fully turn Q1 on. When DTR goes to -5V, Q1 is turned off.
>
> It is a long time since I wired up and used my v6.1 TX/RX, but I did not have
any problems either on a laptop or my main PC RS232 port.
>
> 73, Bob G8VOI
>
>
>
>
> --- In kgksdr@yahoogroups.com, "AF4PM" <skinow@> wrote:
> >
> > When connecting the SR to the computer the diagram shows using DTR and GND
connected to the PTT-In and GND input on the board. The difficulty is that the
RS-232 input levels are +/- 5.5V and not the +/- 10V that the diagram indicates.
While differentially there is enough to trigger the amplifier section the
single-ended output of the DTR line is not sufficient. Is there a standard fix
for the level shift or do I just need to build an interface to switch 12 V with
the RS-232 signal lines?
> >
> > Thanks,
> > AF4PM
> >
>