Quick test gear project.
I blew up my RF power meter a few months ago. Not sure exactly how it happened but I suspect as it was a bare PCB it was static or mishandling that caused it. So industrial grade replacement time. Objective here was to spend £0 as I have crates of crap around. Two parts were from that old HP 1707B I bought for parts so some recycling took place
. 9V battery inside the unit tied to cable tie bases for power as this is quite sensitive so needs to be away from bench supplies etc.
Completed item. Usual AD8307 circuit with a buffer amplifier on it basically. Running short on AD8307's now so probably need to get some more.
Was calibrated across the range with the DG811 attenuator at 10MHz for now. Relative calibration is 16.31 multiplier stored in the C register of the HP35s.
And finally we're testing a 10dB "homebrew" attenuator. Any signal source within the dynamic range of it is attached and the value noted. Then the DUT is inserted and the value noted again. The difference of the two values is taken and multiplied by the C register contents. Output = 10.02dB which is pretty good
Absolute calibration in dBm is similar and it's flat between +20dBm and -60dBm. I will do a chart in GNUplot with the calibration curve so it can be looked up off the device front panel as well. But that is for tomorrow.
Really need a step attenuator now...