[Boatanchors] HX-50

[Bill and Liz McHugh]

An HX-50 arrived here with a problem.  It works well on 80 and 40 but is dead on 20, 15 and 10.  Tests reveal that the heterodyne oscillator is not working on any band above 40M.  The 13 and 16 mhz crystals for these two bands are obviously fine, but I can't believe that the other four are not.

The circuit of the 6AW8 triode section oscillator is completely different from that shown in the schematic.  The cathode resistor and the feedback cap from cathode to grid have both been removed and the cathode grounded.  Is it possible that these "mods" have resulted in the stage not oscillating with the higher frequency crystals (23, 30, 37, 38 mhz), assuming these are good?  I'm wondering why this mod would have been made....increased drive on the lower two bands, better stability????

Anyone who has worked on an HX-50 ever run across this sort of mod and might have any documentation for it, or might be able to comment on the liklihood of blown crystals on the higher frequencies? 


Right now I am about to "un-install" the mods and restore the circuit to what is shown on the schematic to see if I can get these other crystals to work.

Bill VE3NH