[Elecraft] External keyer question...

[Don Wilhelm]

All,
In light of the schematic details the Rich provided, it looks like that
keyer does not source any voltage, but is an open collector output.  In
which case, the circuit I described in my prior post would not be necessary
and indeed would not work since there is no voltage provided to turn on the
added keying transistor.

73,
Don Wilhelm  - Wake Forest, NC   W3FPR home page: http://www.qsl.net/w3fpr/
  QRP-L # 485   K2  SN 0020   mailto: w3fpr@arrl.net


----- Original Message -----
>
> My review of the schematic indicates that the center of the + jack goes to
> the collector of a NPN transistor, and the center of the - jack goes to
the
> collector of a PNP transistor, with no source of voltage other than the
> voltage on the base of the switching transistor when keyed either +5 or -
3
> MAX (at the base of the switching transistor.)  Each jack also has a .001
Mf
> cap, for RF protection, and a Diode across the jack to minimize the chance
> of destroying the switching transistor in the keyer.  Any voltage on the
> collector of the switching transistor would come from the keyed circuit.
>