[AMRadio] Hammar HX50 balanced mod

[CL in NC]

Has anyone experienced a failure of the balance modulator band pass filter in regards to shifting freq?  The carrier osc crystals are only a couple hundred cycles off what the specified freqs should be as noted on the side of the filter, LSB is fine, but USB is leaking carrier and now thinking the actual band pass has moved down and is letting the USB carrier osc leak through.  Also the HX50 I have and the HX50 I have the schematic for are a bit different.  Both HX50 and 50A show a 7pf mica on one side of the carrier null pot, and there was none in my rig.  From the schematic I can see that several parts, including that 7pf, were added, and the schematic updated with symbols and lines that are thinner, so perhaps this rig is an early run.  The addendum pages I have do not mention that cap, or another pot that is supposed to set both carrier crystals such that the beat note is the same when you switch between USB and LSB.

Charlie in NC