Products > Test Equipment
Picotest Injector Teardowns
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Sighound36:
Some good investigational work there chaps.

Personally if going to this detail I would rather over engineer the the whole thing using much better specifications on not just the parts but the board and box. My personal thoughts
Jay_Diddy_B:
Hi,


--- Quote from: Sighound36 on April 13, 2020, 10:44:40 am ---Some good investigational work there chaps.

Personally if going to this detail I would rather over engineer the whole thing using much better specifications on not just the parts but the board and box. My personal thoughts

--- End quote ---

I would be interested to know from users of the PicoTest  injectors which ones are really useful and what improvements are desirable.

I have built and used:

1) Injection transformer for loop measurements - many times

2) PSRR measurement device - Occasionally only with high performance LDOs

3) High Frequency Injector (AC coupled) for looking at capacitor impedance and PDN. (Very Occasionally)

I have never looked at power supply stability by looking at output impedance in the frequency domain. I have done many measurements with a stepped load current. This is really the same thing in the time domain.

Any users out there?

Regards,
Jay_Diddy_B
Sighound36:
I can see 1 and 2 being very useful for a lot of folks here.

So the J2120A and the J2130A would be my first suggestions
Wolfgang:

--- Quote from: Jay_Diddy_B on April 13, 2020, 03:32:51 am ---Hi,

Further to my last reply, the manual that can be found here:

https://www.picotest.com/support.html

On page 44 it says the maximum input voltage is DC +  AC is 5V

5V x 74mA = 375mW

This is consistent with the transistor selection and mounting method.

Regards,
Jay_Diddy_B

--- End quote ---
In my J2111A manual the *output* voltage (and its not the input voltage that counts here) is 40V. So the power is way too much.
Jay_Diddy_B:

--- Quote from: Wolfgang on April 13, 2020, 03:35:54 pm ---
--- Quote from: Jay_Diddy_B on April 13, 2020, 03:32:51 am ---Hi,

Further to my last reply, the manual that can be found here:

https://www.picotest.com/support.html

On page 44 it says the maximum input voltage is DC +  AC is 5V

5V x 74mA = 375mW

This is consistent with the transistor selection and mounting method.

Regards,
Jay_Diddy_B

--- End quote ---
In my J2111A manual the *output* voltage (and its not the input voltage that counts here) is 40V. So the power is way too much.


--- End quote ---

Wolfgang,

You are right.
It is not all that clear in the manual and the datasheet which limits apply to which connector
.

By "input" they seem to be referring to the modulation input.

By "output" they are referring to the part that connects to the device under test.

From the teardown photographs of the J2111A 40V transistors are used CZT3904 and CZT3906.

If you apply 40V output and turn on the bias, there will be nearly 1W dissipated in the transistor. If you apply a signal to the modulation input then it increases.

There is no mention of power limit at all.

I am not recommending this architecture, I am exploring its performance and limitations.

Regards,
Jay_Diddy_B
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