Here is some info about my X-band stuff:
I started using a helical feed, Miteq LNA and/or an ex-military LNA/filter, mixer, DRO as shown in the 1st picture. That worked OK but was not very convenient.
The current systems:
The feeds are based on 28mm plumbing for 8.4GHz and 35mm for 7.5GHz (as in teh post above). Whilst the 28mm works at 7GHz, it is a bit close to cut off for my liking. I started off with squashed pipe polarisers but switched to a more professional one for DSN from uhf-satcom. The LNA is a single CE3512K2-C1 GaAsFET from CEL which has an NF around 0.8dB (should be better). That's followed by a Miteq AFS3-08500960 from Ebay. That's got a NF of about 1.1dB. The overall system NF is about 1dB on 8.4 and 1.2dB on 7.5GHz.
The pipe reducers are not exactly right but work OK for offset feeds. I made Chaparral type feeds for PF dishes.
The down converter comprises: An isolator to improve the match, a Wessex surplus 2 stage amp with all fets replaced by MGF 4949, 3dB splitter to feed an analyser, surplus filter, WJ M14A mixer, 2250MHz LPF & an IF amp. The LO is uses a synth from a Gilat band B Ka LNB with external reference fed from a signal generator. Initially it used the original crystal giving an LO of 9125MHz. I swap the isolators and filters to switch between bands.
For the back-end I use SDRs (Airspy, Pluto etc), a spectrum analyser and/or a TBS6983 card. For DSN it is essential to have a very stable frequency source. I use a 10MHz GPS locked rubidium clock but many people seem to use this:
http://www.leobodnar.com/shop/…cPath=107&products_id=234
Here are a few links that I find useful:
https://uhf-satcom.com/ (8.4GHz polarisers & much more)
https://www.qsl.net/ct1dmk/mw_low.html (PF feed calculator & polarisers)
https://ssd.jpl.nasa.gov/horizons.cgi#results (Tracking data for DSN)
https://eyes.nasa.gov/dsn/dsn.html (live NASA activity)
http://estracknow.esa.int/ (live ESA activity)