I have found this very cheap transverter with built in antenna that might be suitable for S-band.
Inside there is a 7.1796 Mhz crystal divided by 256 to make a 1838Mhz LO. Then there is a microstrip mixer, filtering with hairpin filter (obviously hand tunned), and a few LNA.
There is also RF absorbing foam in the enclosure.
My measurement shows that the frequency range is higher than advertised, so we could use it for S-band. The main problem will be the LO drift. Maybe it’s wise to use an external clock or GPSDO.
It would enable us to have very cheap S-band GS on the network.
Of course it still need some work to have good obs.
The LO leak