RTS AND DTR are not opposite. All RS232 Lines are the same polarity when
asserted.
> -----Original Message-----
> From: writelog-admin@contesting.com
> [mailto:writelog-admin@contesting.com]On Behalf Of K4SB
> Sent: Saturday, November 09, 2002 11:32 AM
> To: writelog@contesting.com
> Subject: Re: [WriteLog] ptt line resistance?
>
>
> > > Be certain the Transistor is a PNP if Positive
> > > keying.
> > > Be certain the correct polarity is used from the
> > > RTS.
>
> Probably just a typpo on the "PNP", but you cannot use RTS on a NPN
> circuit. RTS is normally about -12 v at idle while DTR is the
> opposite. RTS of course, will go to +12 when keyed which will cause
> the collector emitter ( emitter to ground of course ) junction to go
> to near 0 ohms.
>
> If you attempted such, you would immediatly key the rig.
>
> 73
> Ed
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