Lo-Z Probe

[Howardlong]

Buffering in the circuit is even better than FET probes.

But then again, hindsight is such a wonderful thing 

[Mosaic]

These cheaper SA's etc ike the DSA 815 from Rigol appear to have frequency varying impedance at the input. Thus unless you're using the calibrated tracking gen as the input  to your DUT you're going to get some dB variance from your true signal across the range. Thus if you have a signal generating device, VCO or whatever that you're characterizing, there's going to be an instrument accuracy issue at some frequencies.

Which leads me to the concept of a device which will provide decent calibration for  DSA's which implement correction tables.
A device/VCO/sweep CW which connects directly (no coax) to the DSA and outputs a flat amplitude (+/- 0.1dB perhaps) across the required Freq span as driven by a USB control signal from a PC/laptop.
this allows the user to implement & save the DSA correction table to get the flatness optimizations.

Such a device can also drive a DIY Lo z probe and also allow for another correction table to compensate for BOTH the probes and the DSA VSWR issues.

Interesting?

[electrolust]

These cheaper SA's etc ike the DSA 815 from Rigol appear to have frequency varying impedance at the input. Thus unless you're using the calibrated tracking gen as the input  to your DUT you're going to get some dB variance from your true signal across the range. Thus if you have a signal generating device, VCO or whatever that you're characterizing, there's going to be an instrument accuracy issue at some frequencies.

Which leads me to the concept of a device which will provide decent calibration for  DSA's which implement correction tables.
A device/VCO/sweep CW which connects directly (no coax) to the DSA and outputs a flat amplitude (+/- 0.1dB perhaps) across the required Freq span as driven by a USB control signal from a PC/laptop.
this allows the user to implement & save the DSA correction table to get the flatness optimizations.

Such a device can also drive a DIY Lo z probe and also allow for another correction table to compensate for BOTH the probes and the DSA VSWR issues.

Interesting?

Old post I know, but isn't that exactly what the DSA815 does?  I thought I saw in the Dave video that it's not that the tracking gen is calibrated to the input for a combined flat response.  I thought you applied the tracking gen (or other flat signal) and then you push a button on the SA to apply a software filter which compensates the input Z variation.

Once you've calibrated the input response, you can apply any DUT signal and WYSIWYG.