Last weekend and this coming weekend was the AWA Bruce Kelly 1929 QSO Party. For this event only transmitters of 1929 (or earlier) design/technology are allowed. I try to participate every year. See http://w0vlz.blogspot.com/search/label/AWA%201929%20CW%20Contest .
This year I again started out trying to get my Hull Hartley to sound reasonable on 80 and 40. See http://w0vlz.blogspot.com/2009/10/more-1928-hartley_21.html Somehow since 2009 something has changed giving my Hartley a raw AC buzz and some signal drift. Swapping out parts/tubes and cleaning all of the contacts did not help. As a final effort I moved the entire station away from the shack outside wall (nearest the antenna). It still drifted and had a T7 to T8 tone...it went back on the shelf and down came my trusty TNT.