10GHz Testing, HB100 and LNB.

Today I got my first test gear for 10GHz up and running.

I have a spectrum analyzer (SA) covering up to 1.5 or 1.7GHz. Not much to see on 10GHz with that one. So, as a test I fed the SA with the down converted signal from a PLL LNB.
I chose the cheapest one I have, a Goobay that I discarded for use with OSCAR 100, because it has more local oscillator phase noise/jitter than I like. For this purpose, and for experiments with wide band FM (WBFN) it was expected to work nicely. It certainly does for the test equipment.

So how to test the system. I have a pile of HB100, cheap ($5 or so) Doppler radar modules. Some with a tuning screw, some without. 5V to the HB100, and a nice signal appears on the screen with the LNB about a meter or two away. The system clearly works. Increasing gain of the spectrum analyzer (well, reducing attenuation) shows the noise floor of the LNB, and some spurious outputs of the DRO, some 40 - 50dB under the main carrier.
A thought: This spurious response could be due to the PLL local oscillator of the LNB, and probably not from the DRO of the HB100 module. I consider this the most likely explanation. Maybe I should try with another PLL LNB, or maybe with an older DRO controlled LNB. More to try out.

Next step was creating some signal sources. What to use? HB100 modules, of course. I tested the tuning range of the modules, and found that some of them went down to 10275MHz without any problems. So, now I have some wideband signal generators covering 10275MHz - 10500MHz in 25MHz steps. Further i tuned one for 10368 (narrow band segment) and one for 10489MHz (The transponder downlink for QO-100.

What are the limitations of this, you may ask. The stability of the DRO and the rather critical setting of the tuning screw makes it difficult to adjust within less than +/- 2MHz of the wanted frequency. This makes the test system more suited to wideband system tests,  but a crude spectrum analysis of narrow band equipment is feasible.
All this with some low cost accessories for the existing test equipment that I have.
The LNB should also be useable as a converter for a frequency counter, this will have to be tested later

This does not mean that I do not want a bit more 10GHz test equipment. I am thinking of making a narrow band signal generator for somewhere around 10368MHz, either with a 24MHz crystal oscillator and a series of multipliers, or with a ADF4350/4351 synthesizer and a tripler. This will have to be later.

I think that the next step in test equipment should be a MMDS down converter with the bandpass filter removed, so I can see signals around 2400MHz. Using the LNB for 10GHz provided me with a proof of concept for the idea.