Hi!
I have an ETL and watched the video from "The Signal Path" about the FSL frontend board. The hardware is very comparable. The ETL has the TG equipped and a few other components that were missing on the FSL version. It also does have different type numbers, but my board may be even an older revision too.
Unfortunately, the video only roughly covers the different parts on the board and jumps quickly from the frontend input to the unlocked PLL. In addition the FSL board seems to have only one VCO, while the ETL board, even a nearly identical layout, has a few more VCOs installed. At least three more in the region between the Analyzer In and the TG Out port.
R&S seems to upconvert the signal as the three VCOs cover 6,6 to 10.15GHz while the ETL works up to 3GHz. There are a lot of supply voltage filters and such, which I all measured good, but it would really help to have sort of a comparison chart for the supply voltages. I.e. I can only see that there are caps and 1R resistors and SMD filters that route 3V3 and 5V0 and some are 0V. But I am not sure if the 0V are correct or a missing supply line. In some places 0V seems logical as the chips have GND or Vss pins on the pads, but in some places, it might be a fault as the chips support positive and negative voltages instead of ground.
On the right side of the board are two ICs which might be mixers, labeled 624 but I cannot find them. These have obviously two supply lines, each decoupled via a filter and a 1R resistor. But only one line has 5V the other is almost GND.
Is that GND filtering to keep the chips' supply symmetrical or is there a missing voltage? As I said, the chip is not an HMC624 as it has less pins.
There are a few other chips, like the ATMEL ATRRS02 for which I could not find any datasheet as well.
Thanks for any ideas on how to get a clue of the board. I will try to follow the way in the video and borrowed some RF probes from the company over the weekend. But my equipment ends at 7GHz so I am not sure if I can trace out the 10GHz part on the front of the PCB.
Astralix