Autek va1 calibration generator#
Autek va1 calibration software#
Autek va1 calibration Pc#

Fortunately, because of the modular approach for the overall product design, this will be a plug-replacement for the DDS card. That all said, we are indeed actively pursuing design changes to improve the performance above 30 MHz. There have also been a few off-mark approaches (e.g., that neglect the phase relationship on the reflected channel), that we let pass by. There have been a few good ideas that would've required some redesign (such to use a log amp or frequency-dependent Wheatstone bridge equations), but we decided to stay the course and try to flesh out our original design approach for the reflectometer. In the past we have had protracted discussions with some of the same guys still here on the reflector concerning the approach to the reflectometer design and computations. So as one can see for the Analysis/Calculator worksheets with the raw data produced in Debug Mode, the numbers are well within the limitations of the computing engine. Further, I've carefully studied the internal registers and intermediate numbers being generated from the computations, and recently increased the precision of the registers to properly handle the extreme cases of numeric computation.

Autek va1 calibration software#

As someone recently noted, it's the same software and algorithm that is being used throughout the frequency range, so it's not a software bug that is specific to VHF.

Which again leads to the belief that the layout introduces various 'internal reactances' at varying/differing areas of the reflectometer circuitry at VHF.

It's still a mystery to me how the system can indeed be calibrated and work very well below 30 MHz, but that same software not calibrate as well above. They indeed worked well for improving accuracy below 30 MHz, but curiously not so above that mark. We thought that the improved, multi-point calibration techniques would work out well across the entire frequency range. but with some unexpected caveats, as we are now seeing. When the Micro908 was initially designed, we didn't think that we'd be seeing operation that high, but with the advent of the DDS-60 Daughtercard we saw that we could indeed reach up higher than 30 MHz. In a nutshell, Joe and I think this is due to the layout of the reflectometer circuit, whereby the trace runs and component layout introduces some unexpected impedances as we aproach VHF freqs. However as many of us have noted, the measurement accuracy falls off when you start getting into the >30 MHz VHF ranges.

One just cannot beat the feature/performance of the Micro908 in the HF frequency range.

Autek va1 calibration generator#

Overall, performance below 30 MHz has been fairly good ('outstanding' would be my actual description, but I'm trying to be objective), which was in the days when we were usuing the DDS-30 signal generator card within, and even recently when using the DDS-30 card (while keeping the operating frequency below 30 MHz). It is, however, a scalar-based instrument in the same class as the MFJ and Autek products, which also have issues at higher frequencies (some different, some the same, and *lots* less flexibility compared to the Micro908).

Autek va1 calibration Pc#

Nor is it a vector-based instrument such as the TAPR VNA (which also requires a $1500 PC for it to work). it's not a $10,000 lab-grade measurement device from HP that is spec'd to 0.1% accuracy with several DSPs and a Pentium-grade processor. Something I'd like everyone to keep in mind is that the Micro908 is a $200 hobbyist instrument with an 8-bit processor for the computing engine.