Happy days are here again - LimeSDR lives in HF!

Going to pick up some food, While my other PC is apart… I’m using my old PC core 2 duo, GT730 Nvidia, with SDR console from simon… Without fiddling with any settings, I can pick up the 15 MHz WWV broadcast… woohoo!!!

ETA: I’m using my 2 Meter vertical. Original Ringo with ground plane.

Again, Haven’t messed with the settings, but the signal is there and legible.

Second photo is N0UN on 14.225. His antenna is pointed towards Asia at the moment. I’m east of him.

@Jman87,

If you want, increase the PGA gain to something like 13 or 15…you’ll notice a sizable difference…

73 de Marty, KN0CK

1 Like

I made a mod (removed MN18). Seen an improvement but it’s still deaf (comparing to HackRF). Then I started to test balun circuit with ohmmeter and found that something is completely wrong with my balun. Alex, if you also removed that coil, can you check with ohmmeter your board if balun circuit is connected as in schematics?

@LY2SS I hope somebody else can do this for you because I’m very busy and I don’t want to spend anymore time on this until I get my v1.4 board. Sorry.

@LY2SS,

Are you using Linux or Windows to check your LimeSDR? If you’re using Linux with GQRX I’m I’m not going to be able to be much help because even my Linux setup is not working that right with GQRX at the moment. The BIG tip-off if you have GQRX configured with a LimeSDR is the ability to switch to the right antenna port (should be RX1_L). If you don’t have that ability to configure an antenna port, then there’s your issue - LimeSDR isn’t configured with GQRX. Also, LNA, TIA, and PGA gain settings will also be critical to adjust to get enough gain to listen to HF.

If you have a Windows 7 to 10 PC, please install the USB 3.0 drivers and SDRConsole V4.0 to be able to use your LimeSDR on a Windows PC.

Check all that and then get back with us - thanks,

73 de Marty, KN0CK

Dear Marty,
A big hello,
Can you make a Screenshot from 50 KHz in reception from home.
We in Europe, the range from 20 KHz is already enormously alive.
Thank you in advance for your help
Bernard

20 KHz to 550 KHz with SDR ELAD FDM-S2 with
Antenna Long Wire,
Length 160 m of wire aluminum, wire diameter 2.5 mm to 10 m high and 9:1 transformer

1 Like

@Bernard,

I will do my best to provide you with a picture this evening of the LimeSDR operating from 20 kHz to 300 kHz off the newly modified (for HF) Wideband Port (RX1_W) such that you can see the spectra - - I will also take a couple of pictures from the RX1_L Port, too. One caveat: My antenna, even though it’s a 6 Band Trapped Vertical (Hustler 6BTV) with the 80m resonator coil on it, it will not be very well matched to my setup for VLF (50 kHz to 500 kHz) and I have no way to run a longwire on my property because of the chain link fence that I have around by property and no real mature trees to hang it from. So the only antenna I have will be this 6BVT, but I will send you the results you’re looking for. VLF is not very active in the US and I’m pretty far from each coastline being in the middle of Iowa. But there are some VLF beacons around and there will be chances that some low-frequency transmissions may propagate from Europe and may be heard over here - a lot of that will depend on conditions. Today, it’s clear and not overcast here in Iowa - so there’s a chance that no cloud cover will not hamper reception on all bands, and sunspots have not been too good lately for HF (and VLF) - I’ll just have to see what it bears and send you what I have. Again, reception in VLF will be affected because my antenna is not optimal for VLF work - but, again, let’s see what happens.

More to follow later today - stay tuned, Bernard,

73 de Marty, KN0CK

I have Linux/pybombs environment. I have selected correct input.
Initially, after removing MN18 coil I saw significant improvement in S/N @ 14MHz. I thought - wow that was simple! But waited until dark… Almost no stations in 1-5 MHz region. Then I decided to test T3 balun circuit with ohmmeter. What’s puzzled me is that primary coil shows short connect with secondary. This should be the case because looking in schematics both are grounded (2,4 pins). (MN18 is removed already) But! There’s no short connection between 4-6 pins of balun on my board. Instead 6th pin shows short to 1pin. I will probably change the balun with home made one when time permits. Sorry for this long explanation.

Best regards/73

1 Like

@LY2SS,

You shouldn’t have to change the balun on the board because it’s flexible down below 160m - receives fine there. Just make sure there are no solder bridges when you removed the MN18 coil from the board…I had that happen to me before I powered it, and I corrected it.

I’ve been noticing, as there are others too, that there is an issue where the receive below 8 MHz is weak for some reason in GQRX, yet when I run by LimeSDR on SDRConsole over the entire band the receive is fine - perfectly normal. There was a thread I was trying to look up where another LimeSDR user was seeing the same thing but I cannot find it immediately - so bear with me on that.

@csete: LY2SS has an issue where his receive is fine on GQRX at 20m, but when he runs it down to 1 - 5 MHz the receive isn’t that great. He’s performed the MN18 mod on the board and is still seeing this issue. I, too, have seen the receive fall off below 8 MHz on GQRX. Not sure what to do on this, but keep us advised.

73 de Marty, KN0CK

Marty,

Bandwidth - use a lower bandwidth with GQRX?

1 Like

For folks who are afraid of taking a soldering iron to their board to remove MN18. I found that using my ESD safe SMD tweezers I was able to to remove MN18 simply by twisting the component off the pad. The trick is to support the part along the long length with the tweezers and gently twist it back and forth. I find that pick-n-place assembly tends to use a minimum of solder making it easy to remove components without damaging pads.

Don’t use a pair of needle nose pliers or like tools if you want to preserve the part. They have a tendency to crush the part and/or dislodge adjacent components.

I doubt Lime Microsystems would recommend this method, so take my suggestion with a fair grain of caution. The usual warnings about using your own judgement apply.

-Freeman, N5FPP

1 Like

@SimonG4ELI,

Worth a try…Lemme give that a whirl tonight amongst other things (like PiHPSDR with LimeSDR on Pi3)…

73 de Marty, KN0CK

Ok guys, I got it, but there is nothing I can fix in gqrx regarding this matter. Hardware specific issues are handled by gr-osmosdr and soapysdr so it is @joshblum you have to poke :wink:

Apparently LimeSDR PDF schematics and baluns used in LimeSDR have very different drawings ( different balun types) That’s what confused me. Sorry for the noise.
I am still thinking about replacing that T3 with another version to get acceptable sensitivity on HF.

OK going to install SDRConsole in Win7. Thanks!

Simon, can you give us a few examples of which bandwidths you use in SDRConsole? I tried the ones listed in the datasheet but most of them give errors, so I suspect something is still not quite OK in soapysdr.

Sorry, I don’t understand. If you have errors in my software please report them here.

No, Simon, the problem is with Gqrx, which uses soapysdr library to interface to the limesdr. I just wanted to try the sample rate/bandwidth settings that are used by SDRConsole to make sure I use settings that are known to work using different software.

Well,

I’m sure a kind Windows user will oblige :slight_smile: .