I'm making progress with this year's 1929 QSO party station. The SW5 works OK but I wonder if the grounding may have gone bad over the years. Nothing in the 1930's SW-5 literature hints at the sort of microphonics and feedback that I'm experiencing. I've tested the bypass caps by substitution and tightened all of the nuts/bolts I find with no change. Running it with an untuned RF stage seems to be the biggest help. Next is powering up my 1928 Hartley.
Pictured is my SW5 at the operating position and Hull Hartley on the window ledge. My Hartley tends to be microphonic because of the tank circuit construction. It can't sit on the operating table because just pounding on the key will be transferred to the transmitter causing the signal to wobble. The window ledge sits on the cinder block house foundation. it shouldn't be going anywhere. I'm using a National 5880-AB power supply (recapped, fused and cord replaced) with the SW5. The regulated power supply is for the Hartley...anything to make the signal as stable as possible. Also part of the station is my Elecraft KX3. The BK recommended operating windows are only 25 KCs wide, just a couple of dial divisions on both the SW5 and the Hartley. The KX3 will be my frequency meter and backup receiver.