Below 30Mhz on LimeSDR Mini - Full of garbage

Maybe I don’t understand the NCO correctly. Isn’t it the freq being feed into the mixer that makes up that up converter?


(page 3 and much more…)

I guess I am to use to how RF mixer stuff works as a physical device and how I can click 1 button with my other 3 SDRs and instantly get HF stuff (lower then 30mhz)

So I manged to get it working correctly but even with filters. (FM and AM broadcast blocking filters) The limesdr mini seems deaf compared to a rtlsdr with direct sampling. No matter how high I turn the gain I can’t get any of the signals I can see on my rtlsdr to show up. (They are FT8 signals some very strong.)

Any suggestions?

I am using a dipole that is tuned for 40m and I have check both 40m and 20m with both the limesdr min and rtlsdr and the lime can’t seem to hear a thing at all.

I have also adjusted all the filter settings I could find that SDR Angle gives me to work with and nothing.

Can you try with SDR# and LimeSDR plugin!

I have tried but the plugin always just crashes. (Using the build of SDR# that comes with it installed)

This is what happens after I set it to LimeSDR then click the configuration gear.

See the end of this message for details on invoking
just-in-time (JIT) debugging instead of this dialog box.

************** Exception Text **************
System.NullReferenceException: Object reference not set to an instance of an object.
at SDRSharp.LimeSDR.LimeSDRControllerDialog.LimeSDRControllerDialog_Activated(Object sender, EventArgs e)
at System.Windows.Forms.Form.OnActivated(EventArgs e)
at System.Windows.Forms.Form.set_Active(Boolean value)
at System.Windows.Forms.Form.WmActivate(Message& m)
at System.Windows.Forms.Form.WndProc(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

When clicking play it says the source is not ready.

From where did you download SDR# and plugin? What is the version?

From the AirSpy Site.

The “Community Package with Plugins” and its version is v1.0.0.1732

And LimeSDR plugin?

It came pre-installed in the " Community Package with Plugins" version of SDR# no idea of its version.

Try from: https://github.com/GoranRadivojevic/sdrsharp-limesdr/releases/tag/0.4
You can download and select 32 or 64 bit version. It was tested with 32bit SDR# 1672 (not sure is this correct number). Also not sure about 64 bit version number.

That worked. I can now see the LimeSdr Mini in SDR# (And it works, Tested with some FM signals from my vertical antenna.)

So how do I get to HF with this? Seems to not have a way to control the NCO.

Just change freq to HF. Set sample rate to 1536, LPF to 40MHz and you can receive down to 5.5MHz. For entire HF increase sample rate and LPF (but you need to change RF input of Mini). Also, use GFIR as band filter (set to 0.4 for 20m for example).

Not seeing any difference between what I got with SDR Angle and SDR#. Seems to not hear anything no matter the gain setting. (On ANT_W)

Maybe my AM and FM filters are making the signal to weak for the LimeSDR? Even when its perfectly fine on my RTLSDR.

I just don’t know what else to try. I have had this thing for well over a year and haven’t gotten it to work for the reasons I bought it. Which was to use it as an HF ham radio for down to at least 20m.

Do you see any change in noise level when gain is changed? NCO is automatic for freq. below 30MHz but if board is not cooled properly or it is faulty local oscillator can’t lock 30MHz (as reported here on forum from HAM radio member from Czech republic). Do you see difference in band noise between 40-35-30-25MHz? What is board temperature?

The noise does change but it is all very low at -90 dbm according to SDR# Even with the gain maxed out.

Board temperature is 46.0 - 48.0 C which is what its seems to stay at even when I just plug it in for the first time in the day.

Since device is not under warranty you can open metal cover and check input circuit. Schematic is at:


Check page 5, RX1_W input is identical as LimeSDR-USB (700-900MHz) and EasyFix1 and 2 for HF is applicable. High resolution image could help to compare with working device. If you don’t have necessary skills tray with local cell phone repair guys (usually they have microscope, BGA welding tools…).

Here some tips, who knows, may be useful to someone…

Have here one LimeNET micro which was not used on primary intention.
Assuming that RF part is similar to mini consider this approach:

I was able to use on 7 MHz with Ron’s SDR Console all gain to max and LNA4ALL
but that is only Win solution and no use of on board CM3.

Therefore decided to try with Raspibian and Soapy Remote…
Managed to install all that and find out that Cubic SDR is working on remote
and SDRAngel crashing - the author reply was:
"
Soapy suppport is a workaround for devices that are not natively supported in case this may be useful. I will not make any effort concening Soapy.
"


you can notice presence of SDRPlay RSP1, that was consideration to cover
HF, work nice over CM3 USB with Soapy Remote.

So for the time can forget TX on this setup…

Later with running Cubic SDR find out that on HF even with all gains up, reception is poor or almost impossible bellow 10 MHz.
So here temporary solution till I find out something better:
ICOM PCR1000, IF out on 10.7 MHz
Again sensitivity of Lime was not enough to properly receive 10.7 IF
Let’s try solution with moRFeus in mixer mode, LO on 85 MHz - 10.7 MHz = 74.3 “zero” on IF
Good surprise - moRFeus is able to mix signal bellow 30 MHz (specification)
And this solution is working now fully remote from 100 kHz up to 1.3 GHz
I am setting PCR1000 on start of band, for example 7.000 the rest is on Lime.
Lime is properly passive cooled and temp. stay in 35 C range.

Here some CW contest on 7 MHz running now and I am able to use Ubuntu and Win10 host notebooks for RX all over the local WiFi network, bandwith up to 500 kHz

Messy setup in attic :blush:
Left PCR1000, Mid moRFeus, Right LimeNET micro /with upper case cover removed…

Done for test, 10.7 MHz IF out on PCR1000, C 10nF SMD

I’ve successfully used SoapyRemote with the server running on a LimeNET Micro and SDRangel running on an Ubuntu 18.04 laptop as client. When using packages on the LimeNET Micro, SoapySDRServer would crash as soon as the client connected. However, this was resolved by building it, SoapySDR and Lime Suite on the Pi all from source.

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Good tip, thank you, must try that again…

My client was also SDRAngel build from source on 18.04 Ubuntu,
crash is on client side on selection, either SDRPlay RSP 1 or LimeNET micro/
please see picture above. Tested Lime USB was running ok on client in direct mode.
After crash Soapy Server still running and can run CubicSDR on any client.
I used SDRPlay RPI SD image and just build from source what was missing =>
Lime Suite and Soapy for Lime.