I am trying to align this radio but I have a couple questions. I'm a bit new at this so pardon my dumb questions. First, how am I supposed to connect my signal gen to the Det-Osc control grid? I don't see a contact point on the outside of the chassis. Do I just slightly unplug the 6A8 tube and connect to the tube plug itself through a cap, or do I need to pull the chassis to get to the right spot? If I do connect to the tube directly, which pin on a 6A8 tube is the control grid? The schematic does not show pin numbers.
Secondly, to measure the output at the speaker should I use an o-scope or a DVM set to AC? Thanks a bunch!
Hap

Hi Hap

Connect the signal generator to the top cap of a 6A8. That is your input grid.

It's best to measure voltage on the radio AVC line. This line goes negative with better alignment. AVC can be found on the left side of R2 (400K) in the schematic.

Norm

: I am trying to align this radio but I have a couple questions. I'm a bit new at this so pardon my dumb questions. First, how am I supposed to connect my signal gen to the Det-Osc control grid? I don't see a contact point on the outside of the chassis. Do I just slightly unplug the 6A8 tube and connect to the tube plug itself through a cap, or do I need to pull the chassis to get to the right spot? If I do connect to the tube directly, which pin on a 6A8 tube is the control grid? The schematic does not show pin numbers.
: Secondly, to measure the output at the speaker should I use an o-scope or a DVM set to AC? Thanks a bunch!
: Hap

: Connect the signal generator to the top cap of a 6A8. That is your input grid.

Ok, got it!

: It's best to measure voltage on the radio AVC line. This line goes negative with better alignment. AVC can be found on the left side of R2 (400K) in the schematic.

Do you mean R3? R2 is not a 400K, R3 is.

Hi

I was looking at Most Often Needed 1926-1938 Radio Servicing Information. They must have used different numbers.

The resistor starts under 6H6 circuit (right side) and goes to grid #1 on Det-Osc and IF Tube grids through coil and IF Transformer (left side). Can you locate the resistor? It's below 6K7 tube in my book.

Norm

: : Connect the signal generator to the top cap of a 6A8. That is your input grid.

: Ok, got it!

: : It's best to measure voltage on the radio AVC line. This line goes negative with better alignment. AVC can be found on the left side of R2 (400K) in the schematic.

: Do you mean R3? R2 is not a 400K, R3 is.

Ok, I guess that is R2. Do you think there is a way to access that part of the circuit without pulling the chassis? I don't see how I can get to it without pulling the chassis. Thanks alot for the info! It was really helpful.

Hap

Here is something to try. AVC voltage goes through the antenna coil to top cap on your 6A8. Connect the red lead of your meter to chassis. Connect the black lead through a resistor to the top cap of 6A8. Use any resistor 100K - 1 meg. This will help prevent the meter from affecting alignment.

A VTVM would be the best meter to use. A 20,000 ohms/volt meter like 630 or 260 will work. Digital meters are hard to use for alignment. Set the meter on a low DC volt scale. The meter will give higher readings as alignment is improved.

Norm

: Ok, I guess that is R2. Do you think there is a way to access that part of the circuit without pulling the chassis? I don't see how I can get to it without pulling the chassis. Thanks alot for the info! It was really helpful.

: Hap

So that would basically be the same place I connect the signal generator correct? I will give it a try. Thanks again.
Hap
: Here is something to try. AVC voltage goes through the antenna coil to top cap on your 6A8. Connect the red lead of your meter to chassis. Connect the black lead through a resistor to the top cap of 6A8. Use any resistor 100K - 1 meg. This will help prevent the meter from affecting alignment.

: A VTVM would be the best meter to use. A 20,000 ohms/volt meter like 630 or 260 will work. Digital meters are hard to use for alignment. Set the meter on a low DC volt scale. The meter will give higher readings as alignment is improved.

: Norm