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Tach generator


afrooster
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obviously the tach generator is self powered, but does it generate an AC current to power the dial or does it possibly use DC. My pubs don't really address it. The brush plate interaction on the pickup is normally a DC characteristic, but i can't help but say it's AC. thanks for any help.

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3.6.3 Voltage output. The output voltages shall be 21 ± 0.5 when operated at a drive shaft speed of 4,200 rpm and connected to a load consisting of three 40-ohm, Y-connected resistances. None of the output voltages shall be less than 3.5 when operated at a drive shaft speed of 1,000 rpm and connected to a load consisting of three 20-ohm, Y connected

resistances.

Frequency is directly proportional to turning speed.

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3.6.3 Voltage output. The output voltages shall be 21 ± 0.5 when operated at a drive shaft speed of 4,200 rpm and connected to a load consisting of three 40-ohm, Y-connected resistances. None of the output voltages shall be less than 3.5 when operated at a drive shaft speed of 1,000 rpm and connected to a load consisting of three 20-ohm, Y connected

resistances.

Frequency is directly proportional to turning speed.

That's some handy info--and info that we can't get hold of any more on the line. Do you have something like this for TIT or Fuel Flow? I remember on C-141's, we had a synchro tester that we could use to check out fuel flow and another tester that we could use for EGT. Just a matter of putting in the right settings.

On the 130, we have to do an engine run to op check them.

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Engine generator frequency is determined as follows:

T56 series III engine generator speed = 5,965 RPM

Engine generator poles = 8

The constant 60 is used to convert RPM to revolutions per second (RPS) and each pole has two ends (60 x 2).

(No. of poles x rpm) / (60 x 2) = Frequency

(8 x 5,965) / 120 = 397.66 Frequency

This should let you know what happened to the other 2 hertz. I have a hard time seeing 2 hertz on that meter.

Vic OAE

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