I have a multimeter in series with the amplifier I am testing setup to measure current which seems to be the culprit for a large ripple.
Input: 2Vpp
Differential gain: 2
Output: 8Vpp
Load: 8Ω
Pout: 1W
When I use mini grabbers from the regulated PSU to the DUT with long cables the ripple is ~ 100mVp. When I solder short, heavy gauge wires in parallel for for each direct PSU connection (power, gound) the ripple is ~10mVp. With the multimeter in series to measure current even with the heavy gauge wire (mini grabber from multimeter to heavy gauge wire) the ripple is 300mVp.
A large ripple will wreck havok with THD+N performance. Does anyone know what the innards of a multimeter are like where it would cause a ripple on the PSU to the DUT? The multimeter is an Agilent 34401A.
I would expect long wires to have inductance to be a factor, but the multimeter makes it worse.
Input: 2Vpp
Differential gain: 2
Output: 8Vpp
Load: 8Ω
Pout: 1W
When I use mini grabbers from the regulated PSU to the DUT with long cables the ripple is ~ 100mVp. When I solder short, heavy gauge wires in parallel for for each direct PSU connection (power, gound) the ripple is ~10mVp. With the multimeter in series to measure current even with the heavy gauge wire (mini grabber from multimeter to heavy gauge wire) the ripple is 300mVp.
A large ripple will wreck havok with THD+N performance. Does anyone know what the innards of a multimeter are like where it would cause a ripple on the PSU to the DUT? The multimeter is an Agilent 34401A.
I would expect long wires to have inductance to be a factor, but the multimeter makes it worse.