Jensen JT-44K-DX MC Step-up loading doubt

[merlin el mago]

To simulate my MC of an output voltage of 0.3mV, the voltage divider to reduce the output voltage of generator of 3.3V using 14 ohms to simulate my cartridge output imepdance have to be 140 ohms in place of 100K, it's OK?

 

[merlin el mago]

Nobody?

 

[merlin el mago]

Please help.

 

[merlin el mago]

 

[hego]

Felipe,

I used a squared BF generator very attenuated in the primary and looking for the minimal overshot-ringing at HF. The zobel for my mic trafo JK-115 (SUT use) is about a 18K + 50 pF.The final load is @ 12K and the cart reflected load @ 200 ohm.Is very different in the Jensen info.

I think is also important the Miller effect in the input grid (12ax7- 6n2p). No caps, only the 47k gid resistor . The capacity from the cables and connectors are enough.

Salut company.

Chris

 

[SY]

Please help.

You got step by step directions. I'd recommend following them and see what happens.

 

[merlin el mago]

The scope at the output shows a very small signal, I can't very well the square wave.

 

[merlin el mago]

I can't see very well the square wave.

 

[SY]

Then increase the input signal.

 

[merlin el mago]

The output voltage is set at maximum 3.3V

 

[SY]

Output voltage of what? Perhaps a drawing of exactly what your test setup is right now could clarify.

 

[merlin el mago]

The signal generator.

 

[merlin el mago]

Felipe,

I used a squared BF generator very attenuated in the primary and looking for the minimal overshot-ringing at HF. The zobel for my mic trafo JK-115 (SUT use) is about a 18K + 50 pF.The final load is @ 12K and the cart reflected load @ 200 ohm.Is very different in the Jensen info.

I think is also important the Miller effect in the input grid (12ax7- 6n2p). No caps, only the 47k gid resistor . The capacity from the cables and connectors are enough.

Salut company.

Chris

Chris,

What's the output voltage of your signal generator and what attenuation are you using?

The input grid of Valve Itch have 60pF http://www.diyaudio.com/forums/analogue-source/140635-valve-itch-phono-243.html#post4718334

Gracies company on vius?
Thank you where you live?

Felipe

 

[SY]

The signal generator.

Then reduce the series resistor. Remember, it should be about 1000x the shunt. The 200k value was suitable for your higher resistance cartridge.

 

[merlin el mago]

For 14 ohms 14K, attached pic signal generator set max., scope probes connected primary MC step up after shunt 14 ohms / 14K.

 

[merlin el mago]

Attached pic, scope probes connected to secondary, RC 6K8 / 200p as Jensen suggest for transformer, as we can see there is a peak at the left corner of the square wave.

 

[merlin el mago]

Both pics scope set 5mV/cm 0.5ms

 

[merlin el mago]

If I take off the 200p capacitor the peak dissapear.

 

[merlin el mago]

The scope shows an output signal aprox. of 5mVpp when the input is aprox. 1mVpp is OK for the ratio 1:10?

 

[merlin el mago]

What do you think?