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Building MPP REV E - Need Help
Hi I am trying to build MPP REV E step by step. It seems okay to me until I reached step 8.
Step 1: Check U3 pin 4 for -5V
Step 2: Check TP7 for +5V
Step 3: Tx driver pulse
I adjusted pulse period to 1 ms (1KHz) and pulse width to 100 us approximately.
Step 4: Tx circuit
Due to the damping resistor value(~150 ohms now) It can reach almost 200V. I think I should change the damping resistor value to obtain greater flyback voltage.
Step 5&6: Rx pre amplifier & sample pulses
At TP3 (Red CH) the RX preamplifier output can be seen, I think there is no problem with it excluding noises.
At TP6 (Blue CH) there is the main sample pulse in first picture and EFE sample pulse in second picture. Sample pulses have 10us width.
Step 7: Sampling integrator
TP4 when no target in first picture and when there is a target near in second picture.
Everyting seems tolerable to me If I did not miss anything. At step 8 I connected the 220k audio pot and when I check the TP1 while changing the pot value, TP1 is swinging between -200mV and 100mV.
It is expected to swing around -4V to 4V approximately due to building manual. I could not figure it out. Could you please help me to solve this?
And here is my board below:
Step 1: Check U3 pin 4 for -5V
Step 2: Check TP7 for +5V
Step 3: Tx driver pulse
I adjusted pulse period to 1 ms (1KHz) and pulse width to 100 us approximately.
Step 4: Tx circuit
Due to the damping resistor value(~150 ohms now) It can reach almost 200V. I think I should change the damping resistor value to obtain greater flyback voltage.
Step 5&6: Rx pre amplifier & sample pulses
At TP3 (Red CH) the RX preamplifier output can be seen, I think there is no problem with it excluding noises.
At TP6 (Blue CH) there is the main sample pulse in first picture and EFE sample pulse in second picture. Sample pulses have 10us width.
Step 7: Sampling integrator
TP4 when no target in first picture and when there is a target near in second picture.
Everyting seems tolerable to me If I did not miss anything. At step 8 I connected the 220k audio pot and when I check the TP1 while changing the pot value, TP1 is swinging between -200mV and 100mV.
It is expected to swing around -4V to 4V approximately due to building manual. I could not figure it out. Could you please help me to solve this?
And here is my board below:
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