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I'm looking for a schematic from an electronic one (control) parts in a given antenna tuner, which she sold after. 2000 company Holcman Hochfrequenz from Tišnov. I have a tuner diagram, but the control part is in it only “box”. And, of course, there is no control box diagram, which from a hamshack by hand, with setting memory for each band, controls tuner settings, located directly on the antenna terminals of the dipole.
Switching capacitors in front of inductance series works, the stepper motor rotates with a large tuning capacitor at the output terminals, only the inductances refuse to switch.
I'm in the tuner so far “found” M5450B7 controller and beyond 2 x ULN2803A. I can't find from the mixture of signals coming from the hamshack, what part of the tuner to control.I did “reverse engineering” and according to the reactions on the controller and on the other ICs to individual signals from the control box in the hamshack, I found a fault in the incorrect response of one of the ULN circuits. After its replacement, all relays controlling the inductance switching work.
Although digital technology is outside my field, but after a few hours of studying the literature, I gradually recognized the oscilloscope, what is happening right and what is not.
what is happening right and what is not.
