I just aquired a Drake R4B which is in quite good
condition. I've found one problem which I am hoping may be
familiar to someone, namely hum when using AVC-Off. This is
appearent on CW signals or the calibrator. There is no hum
when using the AVC. This _should_ be easy to track down but
the schematics in the BAMA handbooks have such poor
resolution that its difficult to see where the connections
go. I may have to buy a handbook but I would like some
assistance, if possible, before I have to do that. Its
probably a tired capacitor somewhere, but _where_?
Also, does any one know of a freebee handbook that is
better than the one at BAMA?

Join the Drake Yahoo group- there' are guys up there that have worked on
hundreds of the 4 line and know the problems and circuits by heart.

Dale W4OP