Spectrum Analyzer Extender Using the HB100 Module as Down Converter.

Tonight I made a test of using the HB100 module as a down converter, so I should be able to "see" 10GHz band signals on my (low-cost) Tiny SA spectrum analyzer.

I have a few of the modules, so here goes:

With a previous test I had used a LNB with a more expensive spectrum analyzer I had access to. I tuned some HB100 modules to different frequencies, so I had some simple signal sources on frequencies from 10300 up to 10500MHz in 25MHz steps. I also made one for 10368MHz (narrow band) and for 10489MHz (QO100 segment).

Today I wanted to test how the HB100 module did as a simple dowm converter. Because it has been used with (broadcast) FM band receivers I am aware that it can be used as a general down converter, and sure enough, using a 10450MHz HB100 and a 10375MHz module, connecting the spectrum analyzer to the IF output of the module produced a 75MHz IF output. It does work as I expected.

However, I do not know the RF or IF) bandwidth of the module, so I have not checked that.

The base bandwidth of the Tiny SA is 350MHz, so I tested with a 10300 module and a 10600 module, and got a nice 300MHz signal. Using the modules is a bit tricky because the apparent output varies a lot when tuning.

Using a 10600MHz module should make "seeing" 10300 - 10900MHz with a small gap around 10600 (zero IF). Not too bad for a $5 module. For the putpose I also made a 10500MHz module (10200 - 10800MHz coverage) a 10300MHz module can be added for coverage all the way down to the 10000MHz band edge (10000 - 10600MHz)

I am well aware that I do not have any image rejection, but as long as I can calculate expected frequencies I should be able to estimate the spectrum of an oscillator or a transmitter.

The Tiny SA has a base bandwidth of 350MHz (LOW input), but also has an extended coverage up to 960MHz, so it should be possible to see more than 1800MHz with a single module. The question is how much IF bandwidth the module can provide. 

SM6WHY estimates on his blog that the IF bandwidth of the HB100 might be up to 2GHz. I have my doubts, but if that is the case I might try using my Chinese 35 - 4400MHz (primitive) spectrum analyzer which uses direct conversion to sweep the band. If I recall correctly, only 350MHz can be displayed at a time, but the 10500MHz version then might be able to cover 8500 - 12500MHz with a small gap around 10500.

Even if this is far from calibrated, it is much better than not being able to see anything.

For the initial test I just used the modules lying on the desk, with the antennas there. I do think that removing/disconnecting the antenna(s) and adding connectors, and put the module in a stable casing will improve the set-up considerably, both with respect to stability and reliability.

What do you think? a spectrum analyzer extender to the 10GHz band for about $5? Not bad.