It has never been simpler to put together a sensitive and yet low-cost 10GHz receive set-up. I say put together rather than construct, because most of the complicated technical stuff is already done for you. The starting point of the receiver is an Octagon Optima Phase Locked Loop (PLL) Low Noise Block (LNB) satellite receive converter. This is similar to the LNB that will be in use on your average Sky dish, but a whole lot more stable and suitable for receiving even CW and SSB. It has plenty of gain on our 10GHz amateur band. You can then fit this to an old Sky dish, but don’t forget you will need to point it down by about 30 degrees, as satellites are up in the sky. If you are interested in the gubbins, there is a detailed description and pictures of the innards here:
PLL LNBs used to be (and still can be ) horrendously expensive (I saw one listed at nearly £1000!), but German company Octagon have produced this one, the OTLSO, which you can get on eBay for between £16 and £30 depending on whether it is in stock in the UK.
It is important to get the OTLSO PLL one as Octagon also produce quite a few similar ones with the traditional but considerably less stable Dielectric Resonator Oscillator (DRO).
The original version has two independent boards and uses a 27MHz crystal and a fractional-N synthesiser to produce a stable downconverter which we can use on 10GHz.
The latest version has a completely redesigned single PCB with a 25MHz reference crystal and band-pass filtering. On first inspection it appears to be a little less sensitive than the original, but still perfectly usable.
We have found an Icecrypt badged version for less than half the price of the Octagon unit.
ebay id: 372144545727
The local oscillator is 9750MHz so to receive 10368MHz or 10.368GHz if you prefer, the IF output will be 618MHz, which we can receive on a Software Defined Radio (SDR) receiver. This we can make cheaply by repurposing an RTL R820T (Realtek RTL2832U chipset) TV receiver dongle, which again you can get on the Internet for under £9.
If you don’t mind waiting a few weeks longer for delivery, you can get it from Asia for even less.
The USB dongle plugs into your laptop, or via a USB on-the-go (OTG) host cable into your tablet and some smartphones. You then run an SDR program such as SDRSharp or SDR Touch with a suitable driver installed.
The last bit is a 12 volt power inserter for the LNB and an attenuator into the RTL dongle. The gain of the LNB is huge as it is designed to receive signals from satellites roughly 22,500 miles away, so you need to reduce the level of the output to save the front end of the RTL dongle.
The DC inserter can be found ready-built on eBay for £13, although I should point out that it consists of only a DC blocking capacitor and an inductor if you fancy building it yourself.
You can get a cheaper one from CPC, but you need to be careful with inserting it the right way round:
The attenuator is only three resistors, but again you can get that on eBay or from CPC if you choose not to build it yourself.