more pp2b mod
Some additional measurements on the pp2b mod
I fired up the HP651B to measure the signal loss caused by bridging the unconnected NT4 transformer over the input.
This is the scenario where you would not use the transformer output but the transformer would obviously still be connected and present a load on the microphone.
I measured the voltage drop in dB when connected to the pp2b relative to the open circuit voltage of the generator. Measured with a source impedance of 50 Ohm and 150 Ohm.
The loss in minimal, I would not loose any sleep over this.
I fired up the HP651B to measure the signal loss caused by bridging the unconnected NT4 transformer over the input.
This is the scenario where you would not use the transformer output but the transformer would obviously still be connected and present a load on the microphone.
I measured the voltage drop in dB when connected to the pp2b relative to the open circuit voltage of the generator. Measured with a source impedance of 50 Ohm and 150 Ohm.
The loss in minimal, I would not loose any sleep over this.
| loss in dB | ||
| 100mV signal | 50 Ohm | 150 Ohm |
| 100Hz | 0.21 | 0.54 |
| 1K | 0.11 | 0.28 |
| 10K | 0.08 | 0.18 |
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