Working through a repair on a Raven MBA-6 helix GPS antenna (water damage, since fixed through the component level) and need someone with actual RF test equipment to finish fault isolation. I've done what I can with a NanoVNA and continuity checks, but I think whatever's left needs a spectrum analyzer or signal generator to find. I am far beyond my skill set.
What's been done already:
Confirmed and replaced correct LNA (MACOM MAAM-12021)
Confirmed and replaced correct SAW filters (TOKO TDF2A-1575B-13 and -11)
Repaired the RF shield can
Clean continuity throughout, correct bias voltage present at the feed point
Still no signal output
If you've got a real RF bench setup and some experience with GNSS front ends, I'd like to pay for your time to look at this. Open to discussing rate.
This is partly toward learning to see where I missed, partly to have this available and partly right to repair. Also picked up a working MBA-6 and MBA-7 separately as a backup, so this isn't urgent/desperate, just want to see this particular repair through since I'm most of the way there.
Texas based, can ship anywhere in the US. Reply here or PM me.

You can use the nano vna as a signal generator in some cases. I have a Blade RF & LImemini SDR v1 which I have used to gen signals around the L1 range. I have typically used GNU-Radio but there is open code to generate real GPS signal like https://github.com/osqzss/LimeGPS. Of course they can receive also FDX but would have to deal with spitting the datastream.

Also have a friend who has a FieldFox in College Station that he has made available to several HAM operators in the area. Likely some of the radio clubs in the Houston area have microwave interested members. I suspect some in the JSC club might have lab access.

I have been out of building GPS infrastructure for several years and my home lab is more limited these days but my email is in my profile if you have questions.

Thanks for the response. I replaced a few components that showed bad via thermal heat. I've sketched out the circuit, it's fairly simple, and the electrical (continuity) is ok. Something is going off the tracks with RF, my guess. I'm happy to pay for shipping and time, and the parts I've sourced, I just need someone more knowledgeable. This project is my extent of knowledge and I am stuck. In a perfect world, I'd like this to work and I get the information of where I missed. And subsequent projects build on what I know and can do.

weekday bump?

I have a signal generator and a spectrum analyzer, but my background is big satellite antenna RF testing and electrical integration. I know nothing about GPS antennas or GNSS front ends. If you're close to Longview, you're welcome to use my equipment, but I probably won't be much help other than basic operation of the equipment.