Should I trust the Hartmann & Braun or the Fluke 🙂

[dsk]

I have this old Hartmann & Braun meter, but I do not know much about it. Its probably made around WWi
The logo was usesd between 1901 and 1933.

Are you able to tell me about my old Voltmeter 0-6V & 0-150V DC.

[HowardPgh]

The voltage ranges shown look appropriate for tube radio work. 6 volt range for the filament A battery, 150 volt range for the plate B battery. Also for the bias C battery.

[tubaman]

I got slightly confused as the article you've put next to your picture says it's for testing torch (flashlight) batteries, but then I saw that is a different version with a 0-2V and 0-6V range.
I agree with @HowardPugh that the version you have would be suitable for valve (tube) radio work. This is assuming it has a reasonable ohms/volt specification of course.

In answer to your post title "Should I trust the Hartmann & Braun or the Fluke", and given that your Hartmann & Braun meter appears to have been dropped at some time, I think I'd trust the Fluke. 

[dsk]

By some reason I did not get this picture enclosed (Now I have resized it to smaller photo)

It is a readable difference, and that may be because the instrument was laying and not "standing"

When I am holding it up right, the needel is as clos as I may see to the mddle beteen 3.9 and 4 volts. :-)

[countryman]

IIRC an instrument like this uses a permanent magnet, much like a telephone receiver. If the magnet should have lost strength over the decades it might also cause a deviation. Even better if it still is precise in the supposed reading position!
I wonder what the digital meter is reading in the year 2122 

[HowardPgh]

The difference in the readings is because of the load put on the voltage source by the watchcase meter versus the load put on by the Fluke. Watchcase meter is a battery tester only, so it puts some load on the battery to get a true reading of the battery output. The Fluke is for testing voltages and current in circuit so it should theoretically put no load on the voltage source for a true reading. Usually a multimeter is 20,000 ohms/volt, where as the watchcase meter maybe 200 ohms/volt or less.  Older and cheaper multimeters were usually 1000 ohms/volt. A VTVM could be rated in the millions of ohms/volt. VTVM= Vacuum tube voltmeter. The higher ohms/volt the less load the meter puts on the circuit.

[countryman]

All correct, but with both meters hooked in parallel they should in fact read the same voltage.