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maco 300


i have put too many watts in my maco 300 and now it want key up please how do i fix it

maco_300b_sch.jpg


Trace back the circuit from the Radio connector,
you will find a 10 pf capacitor ties to a 47 ohm resistor, at the bottom of the 47 ohm resistor, you have 22 uf inductor, a 33 pf cap and, a 1N914 Diode which is connected at the SSB delay switch.

1. The 1N914 diode could be bad (blown open).

2. At the point of the diode, you will find a 470 ohm resistor (and some other components) that is connected to the base of a NPN Transistor; that transistor controls your keying relay.

There is high voltage running around in there so, make sure that you know what you are doing or, you will hurt yourself.

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