Creating PTT output for Kenwood TS-711
last revised on 29/09/2006
Kenwood's TS-711 (in Europe TS-711E) is a nice compact 2m all mode rig for the casual VHF contester and DXer (like me). I was stunned when I realized it has no PTT output, only PTT input. The radio has lots of room inside and the ACC-2 connector has several NC pins which can be used for PTT output.
The radio is switched to transmitting with the TX9V signal, which surprisingly provides 9V when the radio goes to TX. The circuit below was built right into the connector using small components. The minimal but more than sufficient filtering is provided by the series L. The diodes serves for protection, although the one on the output is not really needed - the IRF-840 FET has it built in.
The IRF-840 is an N-channel PowerMESH MOSFET capable of switching 500V or 8A. The reason why I like it so much for TX switching that its DS can be fully open, well below 1 ohm, and it is enough even for the FT-1000MP.
The goal was to make this vy fast so the PTT output is pulled to ground before RF appears. This circuit perfectly fulfills thsi requirement.
Many thanks to Peter HA1TNX who - to compensate my lazyness - did the mod to me! :)
