01-13-2013, 04:29 PM
Sounds like you need better bypassing of the RF stage. Double check the screen and plate bypass caps (maybe bad new ones) Also the lead dressing. Lead placement may be critical on this set. You can up the value of the bypass cap too to see if that helps. If your set uses metal tubes make sure that pin 1 is grounded at the socket.
GL
Terry
GL
Terry