So having mended the IF amp, remaining deafness hard to trace without an SA which covers 2-3GHz. Thanks to a kind loan, the deafness traced to one of the stripline 2.046GHz bandpass filter sections which is an approximately 60db attenuator. Careful inspection shows one section of stripline has no gold so no great surprise and I should have noticed sooner! For the moment I have put in a piece of 50ohm semi-rigid coax to bypass this section and with this bodge I can get it to calibrate.
I vaguely recollect doing the J-admittance inverter calculations to design one of these filters for a Chebychev response and I have a quick response measurement from the other so that shouldn't be so hard although this looks like an Alumina substrate around 0.72mm thick ... don't think the cheap Chinese PCB people do Alumina, or Rogers 3010! And I also seem to remember some iterative length adjustment was needed to the lines....
