开云体育

Bypass/Tune question

g4edg #985 Hi After successfully repairing an ATU-100 I find that although the tuner works well, it tends to switch from auto mode to bypass mode when more than about 75-80watts is used. Has anyone else noticed this or found a reason....or am I just expecting too much from this device! 73 Steve G4EDG ?
Onno PA1AP All Messages By This Member #986 Sounds like the processor detects overload condition which would trigger the bypass mode? Does the display show overload?? What did you fix on the tuner to make it work again?? Best regards Onno pa1ap Op wo 8 dec. 2021 12:28 schreef g4edg via <G4edg=[email protected]>: toggle quoted message Show quoted text Hi After successfully repairing an ATU-100 I find that although the tuner works well, it tends to switch from auto mode to bypass mode when more than about 75-80watts is used. Has anyone else noticed this or found a reason....or am I just expecting too much from this device! 73 Steve G4EDG ?
David Fainitski All Messages By This Member #987 Hi, Steve Most likely that is RF interferences to buttons wires. Auto and Bypass lines should be grounded with 0.1uF 0603 SMT capacitor on the board close to PIC processor nodes. Those are optional buttons and the board does not have needed components.
g4edg #991 Thank you David and Onno I have decoupled both Bypass and Tune buttons with 22nf (the only SMD caps I have) caps as close to the processor pins as possible and the tuner copes very well at 100w now. Tuner faults were: 3 faulty caps (47, 470 and 1000pf) 2 faulty relay driver fets (affecting selection of the 1000pf cap and 0.05uH inductor) 1 faulty plated through hole Open circuit on one of the bridge sense windings Faulty or inadequate caps decoupling the bridge sense winding outputs (replaced with 22nf) For a brand new ready constructed unit....pretty poor! 73 Steve G4EDG

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