[600MRG] U3S with T/R relay

[Steve Flood]

I plan to use an Ultimate 3S for WSPR operation.  I will be using it to
drive an external Class D amplifier (using the square-wave output from the
U3S synth chip with its own PA disabled).

 

I am having trouble figuring out how to activate the output T/R antenna
relay prior to RF transmission.  Likewise I need to key the driver stage of
the external amp.  This all needs to be automated for unattended WSPR TX/RX
sessions.

 

I was hoping to use the +5v "KEY" output from the U3S to activate the relay
and driver, but Hans tells me that it is essentially simultaneous to the RF
output.  I am trying to avoid hot-switching the T/R antenna relay or causing
a load fault shutdown.

 

Any ideas?   How have others used the U3S with a T/R antenna relay?

 

Thanks,

Steve KK7UV/WH2XNV

 



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