Ts4d Motorola

[timmy]

Originally Posted by dieseljeep

Did it blank out the hum? If so, the hum originates from the audio circuit.

It blanked out all as if no speaker was connected, or as if it were turned off. If the hum was gone there should have been other noise like a hiss when no antenna connected.

[jr_tech]

Originally Posted by timmy

It blanked out all as if no speaker was connected, or as if it were turned off. If the hum was gone there should have been other noise like a hiss when no antenna connected.

Since that is the last audio stage, there would not be much/any hiss when it's input (the grid) is grounded.

Another experiment... instead of grounding the disconnected grid, insert a 470 k ( or so ) resistor between the grid and either end (try both) of the 330 ohm cathode resistor.

jr

[timmy]

Originally Posted by jr_tech

Since that is the last audio stage, there would not be much/any hiss when it's input (the grid) is grounded.

Another experiment... instead of grounding the disconnected grid, insert a 470 k ( or so ) resistor between the grid and either end (try both) of the 330 ohm cathode resistor.

jr

What I did was put the grid back on pin 5 of 25l6 then jumped from the grid to either end of the said 330 ohm resistor, the grid was put back on when I did this and it blanked out so now you want me to use a 470k or so resistor from pin 5 to either end of the 330 ohm resistor while the 330 is still in place, correct? So really it's just raising the value of resistance in that area. Ok I got it, lol between grid and the 330.

[jr_tech]

Yes, but the grid should be disconnected from the couplate.

jr

[timmy]

Ok grid disconnected 470k from grid to ground side of 330 has hum to the other end of 330 blanked out, silent nothing no hiss.

[jr_tech]

Originally Posted by timmy

Ok grid disconnected 470k from grid to ground side of 330 has hum to the other end of 330 blanked out, silent nothing no hiss.

Is the hum as loud as when the grid is connected to the couplate?

jr

[timmy]

Originally Posted by jr_tech

Is the hum as loud as when the grid is connected to the couplate?

jr

Couplate on , hum, couplate off 470k to the ground end hum is Alittle less 470k to the other end of the 330 blanked out.