Be sure to change your circuit according to the diagram!!

As it is now, the grid is pulled up directly to the positive via R56,

clearly it doesn't work as it should

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Best 73 (HB9HPZ)

Franz

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Von: [email protected] <[email protected]> Im Auftrag von Floyd - K8AC
Gesendet: Donnerstag, 21. M?rz 2024 18:44
An: [email protected]
Betreff: [HallicraftersRadios] HT-44 Mic audio problem

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Yesterday, the mic audio circuit was operating just fine and developed a new problem today.? In CW mode, the mic amp is disabled by applying bias to the grid of V2 (pin7) of the 12AX7 first and second audio amp.? That is happening as it should with -159V on the grid.? In AM and SSB modes, the bias is removed through contacts on the Function switch.? I'm getting no audio through the audio strip and find that the grid of the 12AX7 (pin 7) is at a -49V level.? Should be around -0.7V according to Walt's Repair Manual.? Haven't been able to figure out the source of that voltage yet.? I have found that the wiring of that grid circuit differs from the schematic in the Repair Manual and the one in the Operating and Service Instructions manual.? In my unit, R56 is wired between pin7 and R58 with R58 connected directly to C78.? Ideas?

73, Floyd - K8AC