Ammeter, Marked As 15 Amps "RF Line Current" For Other Uses

[Honduras]

An ammeter is an an ammeter, pretty much.

My impression of this antique Simpson is that external circuitry made the scale match the requirement.

Any input?

 

[MikeMl]

Did you mean to post a picture?

True RF ammeters are a special breed. Too useful to a RF guy to cannibalize for just the meter movement. If you need a DC meter movement for a project, maybe we could make a trade...

 

[gary350]

The Simpson 260 meter circuit shows the meter as 50 ua, 100 mv, 2000 ohms.

The circuit shows the meter will test 10 Amps. If you put 10 amps directly across that meter it would smoke the meter. The circuit makes it possible for the meter to test 10 amps.

 

[debe]

This is a true RF ammeter using an internal thermocouple. Picked it up many years ago from a military surplace store.

 

[dr pepper]

Not all ammeters are ammeters, you'd have to look inside, some even have 2 coils.

 

[ronsimpson]

This is a true RF ammeter using an internal thermocouple. Picked it up many years ago from a military surplace store.View attachment 90733

The meter will not measure below 0.4A. It might not respond to DC at all. It is for AC-RF. There is a diode in side to turn the AC to DC and that is why the scale will not go to zero.
That is a special meter don't go alter it to do a different job.

 

[Honduras]

The Simpson 260 meter circuit shows the meter as 50 ua, 100 mv, 2000 ohms.

The circuit shows the meter will test 10 Amps. If you put 10 amps directly across that meter it would smoke the meter. The circuit makes it possible for the meter to test 10 amps.

I suspected as much.

To cloud the issue farther, the meter is a Simpson, who usually marks their equipment properly, and marked in Amperes, not Amperes RF. Also the scale goes all the way to 0, but it is a logarithmic type scale.

If it really is an RF meter I would be more than happy to trade it.

I would really rather not take it apart.