Dick Green wrote:
> Jim,
> If you are using an NPN transistor interface, then Writelog must be using
> postive logic, not negative logic. Right? Anyway, in addition to signal
> inversion, there are several good reasons to use a transistor interface.
-------
You cannot use LPT keying to the FSK jack with an Omni because of the
reasons Dick mentioned..
And since the OMNI has its own TTL circuits, you cannot use the
regular NPN circuit to the FSK jack, or it will key "upside down".
But, you can use the identical circuit with a NPN if you drive the
Emitter and GROUND the base. Or, the most simple of all is use DTR ( I
think pin 3 on a DB9 ) and insert about a 10K resister in series and
go direct to the FSK jack. That way, you can use the same port for
PTT.
Works great with WL, MTTY and others.
73
Ed
W9OL's suggestion to "turn the rig upside down" is not worth
considering since then the
RX logic is reversed. ):>
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