I have followed the ¡±saga¡± about S meter deflection and noticed that cabinet radiation has not been covered.
I you have removed the buttom plate of the transceiver it will received signals even if antenna input is not connected.
You have confirmed that when TinySA output is disabled the S-meter goes to 0.
When noting connected to the RX antenna input and the TinySA output enabled does the S.Meter deflect to maximum ?
If yes then the TynySA is sending the selected frequency diredtly out as a cabinet radiation as the case is plastic and the signal generation on the PC is highlevel and coupling capacitively via air into the wide open electronics of your receiver.
I yes remove all DVM,s and mount he button plate such that the Drake is in normal condition, then repeat point ?3 and 4
If still deflection then move the TinySA so S meter deflection is 0. It might be several meters. Now you may connect all attennuators directly to RX input and not at output of the TinySA
There is more to this story but let us hear what you experience
just a remark: manual indicates that the rf gain must be clockwiseI have set full clocwise and the S-meter is totally deflected (negative going) and voltmeter readig is 1, 7 volts lowering the rf gain to a lecture in S-meter of 1, the voltmeter reading is 1,1 v. Tweaking the coils there is no movement neither in the S-meter nor in voltmeter.