Alrighty, PCB's were ordered, soldering iron was warmed up and I made some boards.
I took a stab at the connector through-hole pad to ground plane clearance and used the Saturn PCB toolkit software, treating the through hole as a via for the calculations.
It gave a clearance that seemed reasonable so I rolled with it.
I have tested one board so far, and it looks good enough for me to call it done for now.
In the attached graph, the blue line is the minimum signal strength required for the instrument to get a stable lock on the signal, and anything in the white area meets or exceeds HP spec on their original design.
Test setup was:
Function gen feeding into a 11667A splitter, one side to an N8482A power sensor connected to an E4418B Power Meter, the other side connected directly to the counter input (with attenuators added to provide lower signal levels than the power sensor could measure where needed).
Performance at the top end isn't as sensitive as I'd like, but without more knowledge or design help, I'm done for now, it works well enough for my purposes (maybe swapping from coplanar waveguide to a microstrip would reduce parasitic capacitance and help improve sensitivity?)
I'll release design files etc once I have it all sorted out and tidied up.
Jared.
Jared Cabot