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[Bob Faulkner]

What am I missing... (long story short)

I'm measuring the phantom power voltage (pins 1+3, and 1+2) on some random mic channels on a Presonus 16.4.2 and an analog Mackie.

Results:
    ~18 V using a Fluke 113 True RMS meter
    ~51 V using a Southwire 10030S meter

Tested the phantom power on a Mackie 12 channel analog:
    - Same results as above

Both meters show accurate results testing a 9V battery and a 120V receptacle.

How/why is the Fluke meter reading so low on a 48V reading?  The meter range of the Fluke was set high enough to accommodate ~48V.  I'm hoping this issue is a lapse of "thought" on my end and not something else.

[Ike Zimbel]

What am I missing... (long story short)

I'm measuring the phantom power voltage (pins 1+3, and 1+2) on some random mic channels on a Presonus 16.4.2 and an analog Mackie.

Results:
    ~18 V using a Fluke 113 True RMS meter
    ~51 V using a Southwire 10030S meter

Tested the phantom power on a Mackie 12 channel analog:
    - Same results as above

Both meters show accurate results testing a 9V battery and a 120V receptacle.

How/why is the Fluke meter reading so low on a 48V reading?  The meter range of the Fluke was set high enough to accommodate ~48V.  I'm hoping this issue is a lapse of "thought" on my end and not something else.

Start with the obvious: Make sure the battery in the Fluke is ok. Most mystery meter reading issues that I have encountered have come down to a low battery in the meter.

[Steve-White]

^^^ It's either a low battery or the auto-ranging circuitry is hosed up in the Fluke.

[Bob Faulkner]

Thanks for the responses.

The battery is in good condition.  I took it out and tested it (~8.9v) using the Southwire.

I've had this meter for awhile, and use it mostly to test for 120V and any continuity...   no issues; in other words, the results from the meter are within range of what I would expect for what I was testing.

Fluke shows this for the model of tester I'm using:
"LoZ low impedance measurement function to test for either AC or DC voltage, or show continuity if voltage is not detected."

I don't think the "low impedance" would be skewing results.

[Bob Taylor]

If you look up the specs on this meter, in the Auto Range it only has 3k input impedance. that will load the Phantom Power resisters in the circuit and cause these low readings.

Flukes are designed for Electricians, and having the low impedance will help them determine  if the circuit is off in the presence of Inter Electrode Capacitance from other wires in the same conduit etc. Good for them, BAD for all us electronic tech's.

Bob T

[Bob Faulkner]

If you look up the specs on this meter, in the Auto Range it only has 3k input impedance. that will load the Phantom Power resisters in the circuit and cause these low readings.

Flukes are designed for Electricians, and having the low impedance will help them determine  if the circuit is off in the presence of Inter Electrode Capacitance from other wires in the same conduit etc. Good for them, BAD for all us electronic tech's.

Bob T

Well damn...!  Looks like mystery solved!  Thank you Bob.


 

[Bob Faulkner]

Well, I fell off the horse.

What's embarrassing, was the meter (Fluke 113 model) says "Low Impedance" directly on it!!  I completely looked passed it, thinking it was irrelevant to what I was testing.  Had not considered a low impedance issue; anything I needed to test was AC or low DC voltages (testing batteries, etc... ), ohms, and continuity. 

...back on the horse.

[ProSoundWeb Community]