Mezzanine experiment PCBs. Add-on for WSPR-TX_LP1

Add-on cards for the WSPR-TX_LP1 transmitter.
This kit contains two PCBs, ten hex M3 studs, 10 nuts and a pin header.
Put this on top of the WSPR-TX_LP1 as an exprimentation surface, use the drilled PCB or the flat PCB with a ground plane.
The 11mm high studs give room below the Mezzanine card to have a low-pass filter made with T37 cores. 
Examples of use:
 
Power amplifier, bring in 12V or use the 5V and boost the power up to a few watts.
I2C sensors  etc, perhaps transform it to a Hell or PSK beacon transmitter, lots of code example on the net as WSPR-TX uses the popular Si5351 oscillator.
TX Disable button, for fast antenna switching, throw the switch and it stops transmitting so you can change the antenna quicly if you are doing A/B comparisons.
OLED display and rotary encoder to view and change info like call-sign, TX frequency, output power and duty cycle.
Recevie disable, put a relay on that is controlled from TX line and disable RX when TX is on.  
etc