Just as final follow up, a mosfet switch worked for my requirements perfectly.

73!  Chris Cox, N0UK
[email protected] or [email protected]


> On Aug 31, 2020, at 18:26, Chris Cox <[email protected]> wrote:
> 
> I’ve thought the problem through further and have decided to use a simple 
> mosfet switch in the connector shell to invert the TXInh logic sense and 
> configure the KX3 for -TXInh instead of +TXInh.
> 
> Hard switching the GPIO pin showed that to be a usable workaround.
> 
> 73!  Chris Cox, N0UK
> [email protected] or [email protected]
> 
> 
>> On Aug 31, 2020, at 12:51, Chris Cox, N0UK <[email protected]> wrote:
>> 
>> I wish to interface my KX3 to my portable 10GHz transporter system.  I have 
>> the transporter’s PTT sequencer configured to output a +ve TX Inhibit signal 
>> which I have been using to prevent my current I/F rig from transmitting 
>> until all relays have changed over to transmit.  The current rig is a Yaesu 
>> FT-817. 
>> 
>> I want to be able to simply switchover the PTT/TXInh cable between the two 
>> rigs, so that I can continue using the ‘817 as a backup in the event of some 
>> problem with the KX3, and so was intending to us the KX3’s ACC2 GPIO TX Inh 
>> +ve input just as I do the 817.
>> 
>> However, it seems that the KX3 actually has some bias applied that requires 
>> to be pulled low to enable the transmitter, rather than looking for removal 
>> of the +ve signal.  This will mean that I need more than to simple switch 
>> over the physical connectors on the umbilical cable.  Although not 
>> insurmountable, it’s not exactly ideal.
>> 
>> Anyone else done this or similar and, if so, what was your solution?
>> 
>> 73 Chris
>> 
>> 
>> Chris Cox, N0UK
>> [email protected]
>> 

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