A Ku band sdr device

Henrybond158 · 2018-01-17T01:25:52.178Z

Is there an rtl sdr device that goes up to 10-12Ghz or are there down converters that exist?
If so, what are they called?
Thanks in advance.

Konrad_Roeder · 2018-01-17T06:38:47.273Z

@Henrybond158

No, I don’t know of any Ku-band SDRs. However, down-converters do exist. They’re called LNBs (Low-Noise Block down-converters).

The DC3 project will be based on a Maverick MK1-PLL. The LNBs are powered through the same coax that the L-Band signal comes down on. I bought mine from E-Bay. They also sell them on Amazon.

I use a Bias Tee to inject the DC voltage to the LNB. It wants 13 or 18 V depending on the polarity you select. The bias tee blocks DC from going towards the receiver.

[RTL-SDR]===RF===[Bias Tee]===RF+DC===[LNB]

I bought my Minicircuits Bias tee from E-Bay. I also made one. I can show you pictures and a schematic if you are interested. I power my bias tee with my lab supply.

The DC-3 project will include the Bias-Tee as part of its circuitry.

–Konrad, WA4OSH

Nate · 2018-01-17T10:03:59.220Z

@Konrad_Roeder

I’d be interested in pictures and schematics. What frequencies would a mk1-pll bring ku band down to?

– Nate, KE0PFS

Konrad_Roeder · 2018-01-17T14:29:55.966Z

RF in is 11.7 to 12.2 GHz
IF out is 950 to 1450 MHz
LO is 10.750 GHz

I will take some pictures of things and draw up some schematics.

–Konrad, WA4OSH

Henrybond158 · 2018-01-17T18:27:07.939Z

So when tuning with a LNB. You just need to know by what factor.

I have a few rtl sdrs a few of them have bias tees. Although I think this voltage is to high for any of them .

So shopping list. Ku band antenna, bias tee, lnb.

Am I missing anything?

Konrad_Roeder · 2018-01-17T19:23:29.275Z

The factor (?) that you are referring to is the LO of the LNB. So if you tune to 950 MHz on the RTL-SDR, you are actually tuning at 950+10750 = 11,700 MHz.

No, your RTL-SDR may have a bias tee, but it can’s supply the right voltage to the LNB. It needs to supply 13 / 18v depending on the polarization. You will need a separate Bias Tee and maybe a lab supply. The voltages are used to change the polarity of the LNB - Vertical or Horizontal.

Be sure to buy an LNB with PLL frequency stabilization. The Maverick MK1-pll has been vetted by @Syed.

–Konrad, WA4OSH.

Konrad_Roeder · 2018-01-17T19:41:52.184Z

@Nate

Here is my bias tee and schematic:

BiasTee.JPG807×583 46.4 KB

Surface-mount parts are really not that hard to work with. I took a small piece of two-sided FR4 circuit board and carved out the needed lines with an exacto knife. The back is solid copper. I ground the back with bare wire that connect front to back.

–Konrad, WA4OSH

kb2sdrjay · 2018-01-18T13:35:59.165Z

Looks good,
What’s the inductance of the coil?

73
Jason
KB2SDR

Konrad_Roeder · 2018-01-18T16:40:45.359Z

@Jason,
You caught me! (seriously, it was an omission on my part). I took a 100K Ohm resistor and wound some magnet wire on it that was in the junk box 30 ga? about 20 turns. I did not measure it. Typical values are around 1 nH. I don’t think it matters a whole lot.

I put it on a VNA and looked at the 21 (through) and 12 (reflected) and it looked ok. At VHF, UHF, and L-Band.

Here’s a Bias tee calculator that might be interesting to get better values.

–Konrad, WA4OSH

Konrad_Roeder · 2018-01-18T17:16:00.400Z

This Chinese one uses a tiny surface mount inductor L1 C1, C2 and C3 are similar. D1 looks like it’s for reverse voltage protection. It shorts out your power supply instead reverse-powering your LNA or LNB. I suppose R1 is a bleed-off resistor? Nice screw-on connector. The whole thing costs less than the SMA connectors on my board.

jpg_640x640

The point is that you can throw something together out of things in your junk box. I work with 1208 Surface Mount Devices because I can still see them and solder them onto home made boards by hand. I bought a grab bag of SMD devices for $5 at my friendly electronic store – Vetco

–Konrad, WA4OSH

Henrybond158 · 2018-01-19T13:28:14.740Z

Bias tee calc is what I need. Thanks!

I reckon I can cobble one together from pieces around my apartment.
So if I understand correctly, it’s a way of powering the antenna and removing the DC leaving only the RF from the output?

Time to dig out a bread board!

Syed · 2018-01-19T13:43:23.132Z

Switching from 13V to 18V won’t be necessary for the Outernet signal. Just twist (skew adjustment) once and you’ll be set.

Nate · 2018-01-19T22:16:02.711Z

@Konrad_Roeder Thanks! I’ve been meaning to pick up a selection of surface mount components, anyhow. I just need to remember not to go overboard on caffeine before soldering. rolls eyes

Seasalt · 2018-01-20T05:57:55.267Z

Syed:

Just twist (skew adjustment) once and you’ll be set.

So this service as oposed to the L-Band service would be impossible to use with a fixed antenna on a vehicle as the polarity would keep changing as the vehicle turned.

pe1chl · 2018-01-20T12:20:37.124Z

The polarity does not change so much, the direction does. The polarity only changes a little when you move a large distance east or west (hundreds of km). Probably not even a problem in practice.

Syed · 2018-01-20T14:02:16.502Z

We are working on a circularly polarized antenna, as well. There will be a 3dB hit, but that would allow for no skew adjustment at all.

ac8dg · 2018-01-23T13:27:20.300Z

I have my lnbf - mk-1, and a spare 90 cm off-set dish if needed, the feedline bias-tee,and an airspy.

Now… does anyone have a screen shot of what an SPSC or VSAT signal looks like? I have HDSDR and SDR# Sharp, I have found several continuous carriers in the 11.740 to 12.120GHz and a couple of wider double sideband waveforms as I point at various satellites like Galaxy 19.

Konrad_Roeder · 2018-01-23T15:44:07.312Z

I have an MK1-PLL, a modified 45 cm dish, a splitter that has DC pass on one side and DC block on the other. I have a dish pointing tool and a Freesat V8 satfinder. I also have a variety of RTL-SDRs including an airspy. My dish may be too small for me to lock onto a satellite yet, or I may not quite understand my setup.

Is the normal position for an MK1-PLL with the F-connnector facing down or to one side?

Which satellites are you looking at? Of course what I can see from Seattle may be just a bit different from where you are. Let’s go SCPC hunting.

–Konrad, WA4OSH

donde · 2018-01-23T16:21:57.528Z

What’s the Frequency Kenneth? (Syed)

A song by the American alternative rock band R.E.M.

Screenshot - 01232018 - 11:39:00 AM

I’m ready to receive!

ac8dg · 2018-01-23T16:36:29.083Z

Using my Freesat v8 satfinder, no splitter since it is providing the 13v, with the F oriented down and feedhorn pointing at the dish (got nothing w/o the reflector) I get signal ~75% but quality is tough to achieve. after programming in the transponders… I finally got a “blind” scan TV and radio channels at the 97W. So I disconnected the satfinder, hookup the “directTV” injector, and my NOOELEC rtl-sdr ( the one in the metal enclosure), then guessing at a frequency of 1,000Mhz after applying a 10.750G offset… I’m off to the races…

Edit: Now that I think about it, The directTV injector is supplying 21vdc vs the 13 v that the Freesat finder is injecting. So I may be comparing apples and oranges - or different polarities.