Before applying power I measured the resistance of the power lines and some other important points to ensure there are no nasty shorts hiding somewhere.
The big moment applying power.
Nothing except a short blink of the lcd back light happened .
Soon I figured out there is a very nice software power switch implemented.
You need to press the ok button to switch the unit on.
Very nice, I will implement that logic in my own designs too.
Power switches are so outdated.
So the unit works. As a first test I measured the power and frequency of an fm test generator.
Without calibration the frequency part worked ok but the power measurement was of by 3 db.
To calibrate the unit I need access to the university test lab, which I don't have until September.
First impressions, pros and cons of the unit:
Very nice power on design
Usage of qfn components I lover to solder fine pitched smd devices
Open source software for the microchip and the cpld
A usb port to export data is missing
The displayed frequency is always drifting
No gate time setting
Silk screen of pcb is horrible , very fuzzy and partly unreadable (the manufacturer promised to take care of this problem though)
In the end I am unfortunately disappointed of the unit.
On the other hand it still will be a help in the spectrum analyzer build process.
I am also thinking about implementing an serial output.
To log the data in a computer could be a big help. You could for example plot the frequency versus power output of a device and visualize the stability of the power in a given range.
|Finally the counter in action (Please excuse the flare on the lcd)|
3 Ghz counter and power detector build Part I
3 Ghz counter and power detector build Part II
3 Ghz counter and power detector build Part III
Elektor project page