This is corrected post after several messurment on different resistors.
Here are the measurements for the 22ohms, 120 ohms, 1k, 10k, 22k, 100k and 1M ohms resistor as well as the Theta angel. See attachment. These measurments are done on Hntel 1832c just with the software modification mentioned in this forum, no hardware intervention.
The Theta angle is interesting, the value should remain 0,but i noticed three groups. First group measured between 8-120ohms, maybe more i didn't have other resistors, the 50-100Khz band remain with same Thetha angle, the second group is 1K to 10K, and the third group is 22k and 1M oms resistors. Are these the calibration models that the device is building, probably.
These measured values are very close to the measured value of djQUAN, after changing C66 and C67 capacitors, maybe some of them are better??. He wrote at page 3 "And the result with the 10k resistor test is more sensible but the reading has a slight rolloff. 9.66k from 100Hz to 40k then 9.57k @50khz, 9.52k @ 75kHz, 9.45k @100khz."
Maybe this confirms that the problem is in the firmware, not the hardware? But how so, when it is the same firmware for both devices. It would be nice if someone with the Hantek 1833c measures just for comparison the 10k resistor, and what the device will say.