Testing Ham It Up upconverter with HDSDR - Page 1
Forum section: electronics / rf-microwave

author: Sredni
author_rank: Frequent Contributor
timestamp: January 15, 2020, 02:01:40 pm
content: Well, I got a Nooelec NESDR SMArt XTR HF bundle for xmas, the kind that is advertised to span 300Hz-2.3GHz (with a hole at around 1.1 GHz - it's based on the E4000). It did not start well, since the usb dongle was fried, but support was quick enough to send me a working replacement. And the stick alone seems to work in HDSDR (meaning: with the telescopic antenna I can listen to FM radio).I have to bump sample rate to 192000 to receive FM, which is what I am using for now as a test signal - I know it's there and I know how it should sound.But when I hooked up the up-converter (with usb power, antenna in on one side, exit into the RF dongle, not in pass-through), and after selecting Options - RF front-end configuration - SDR hardware on up-down converter and selecting the LO frequency as 125000000 Hz (there is no sign, and I cannot set it even if I wanted) I do not seem to receive anything on the FM frequencies. While I hope this is just me being noob - I really would like to RTFM, but I am having a hard time finding it... - there is something that makes me think something could be wrong and maybe the up-converter came in as fried as the dongle was.Attached is a screenshot of what happens when I switch from pass-through to up-converting. See the white line? Is that normal? It stayed there in the middle of the screen no matter how I scrolled through the frequency. Is that a known software bug?Also, should I expect to receive the FM radio on the same frequencies once the up-converter is on and the options for LO are set to 125 MHz?What is a surefire way to test the up-converter, considering that my scope is only 100 MHz? This little guy has the RF noise generator inside (and if I had a spectrum analyzer I could feed it into itself to assess the band, but I haven't got one).PSWhy did I get one? It was the easiest way to elude "What should we get you for xmas?" question, and I wanted to see what signals inhabit the ether around me. Also I know antennas are of paramount importance, but for the time being, let's focus on FM with the FM antenna.

author: vk4ffab
author_rank: Frequent Contributor
timestamp: January 15, 2020, 09:26:09 pm
content: Quote from: Sredni on January 15, 2020, 02:01:40 pmWell, that is the scopes -3db bandwidth, it will still measure out to many 100's of megahertz, its just that the measurements will not be accurate. It should be good enough to check the that the LO is working the mixer IF output is there to ensure its all working. All you want to see is that there is a LO signal.Also, the point of the up converter is to receive HF, connect a large outdoors antenna and look for signals in the lower HF bands like AM SW Broadcast WWV time singal on 10mhz etc. If I remember right, the up converter has a 30Mhz Low Pass Filter on it, so you should not hear anything in VHF and up anyway.

author: radiolistener
author_rank: Super Contributor
timestamp: January 16, 2020, 06:50:53 am
content: Quote from: Sredni on January 15, 2020, 02:01:40 pmFirst disable up-down converter settings in HDSDR and test if it works. For example tune HDSDR to expected frequency + 125 MHz and check if it works well. If it does, then you can start to configure up-down converter settings.If it doesn't works, check your up/down converter bandpass filters and if your test frequency fits into bandpass filter range.Quote from: Sredni on January 15, 2020, 02:01:40 pmit depends on your up converter bandpass filters and working range. If your're using short wave up converter, you will not be able to hear FM stations (unless it have extreme high level), because it will be filtered with bandpass filter.

author: Sredni
author_rank: Frequent Contributor
timestamp: January 16, 2020, 10:08:27 pm
content: Ok, so my plan to use FM to test the gear is doomed from the start.If the upconverter has a low-pass filter (which I believe would be >65 MHz, since this XTR dongle goes from 65 MHz to 2.3GHz - at least on paper, but probably less than 88MHz) I cannot use FM radio stations to test it.I attach a picture of the transition from {upconverter on, software frequency shift on} to {upconverter off, software frequency shift on} and then back to {upconverter on, software frequency shift on} - and it shows that there are changes, but I am alarmed by the fact that when I turn back on the upconverter the waterfall seems significantly different. Is that normal?As for testing with HF:I tried to hook up a poor man's antenna to the 1:9 balun with two pieces of wire about 2meters long (indoor!), but was unable to receive anything 'listenable'. I saw a lot of red and yellow lines in the waterfall around 20-30 MHz, though but nothing I could listen to. All signals are well below -80, -100 dB almost surely due to grossly inadequate antenna skills.I can get whistles in CW, or noise in all other modes. I also used the "Frequency Manager" of HDSDR to let it set the parameters, but no luck. I still hope this is due to my extreme noobiness in this field, and to a lousy antenna, but... I've seen youtube videos of people receiving ham radio with the antennas given in the bundle...As for testing the upconverter with the oscilloscope:Before hooking up the noise source or a signal generator (I figured, if I put say 10MHz signal in, I should see it at 135 MHz out, even if attenuated by the scope bandwidth), I'd rather ask for some more advice. Like: what signal level should I put at the RF input of the upconverter? 1mv? I guess a resistive attenuator would do, right?The noise generator output is 4Vpp, which I believe is a bit too much? I would hate to fry the hamitup.Also, in the attached scopeshots (03, 04, 05, 06) of the noise generator, you can see it has pauses in it. Is this to be expected?Thanks for the patience, I am just trying to find if this thing is fried before is too late to send it back with no hassles.As for my noobiness, I just discovered that the 19KHz spike in FM transmission is not a glitch.

author: vk4ffab
author_rank: Frequent Contributor
timestamp: January 17, 2020, 02:04:06 pm
content: Go lower, 3mhz to 14mhz is where the action is at during this period in the sun cycle. 7.000 to 7.3000 is the 40m ham band, start there, lots of strong signals to be found late afternoon early morning.

author: radiolistener
author_rank: Super Contributor
timestamp: January 18, 2020, 05:10:03 am
content: noise generator is a bad choice for up converter testing purpose. You're needs sine generator, or at least square wave.

author: Sredni
author_rank: Frequent Contributor
timestamp: January 20, 2020, 12:15:41 am
content: (I had just typed in my post and my clumsy fingers must have hit some magic keyboard combination that made everything disappear).I'll be short.I cannot get anything outside of FM out of the dongle or the dongle + upconverter.The upconverter seems to work, I can see signals at the low MHz, for example in the 7 MHz as suggested. I also seem to be seeing AM signals in the hundreds of kHz. But I cannot get anything out of that. All signal all under 110-120 dB and all I can get is whistles no matter what the settings (I get hints out of the frequency manager to choose parameters).Could it be the dongle? I am in the same position as this guy herehttps://www.rtl-sdr.com/forum/viewtopic.php?t=2288Quotewho received this alarming answerQuoteAnyone in here has the same dongle as me? It's the silver one in squarish casehttps://www.amazon.com/NooElec-NESDR-Smart-XTR-SDR/dp/B06Y1HKLHYThe antenna (or lack thereof) is certainly playing a BIG part in all this. So, is there a way to concoct a poor man's antenna in one's kitchen with paperclips and scotch tape, McGyver style, just to put a few words out of the HF world? On youtube it seems people can do it using the antennas in the kit.My two pieces of wire attached to the balun did not work.I am open to suggestions.As a side note: attached is the FFT of the noise source (as far as a Rigol DS1054z can do it): it seems to have a 250 MHz bandwidth. Still puzzled about the 'duty cycle'...

author: vk4ffab
author_rank: Frequent Contributor
timestamp: January 21, 2020, 04:40:11 am
content: Put the software in i an q mode, i th8nk thats the issue

author: james_s
author_rank: Super Contributor
timestamp: January 21, 2020, 07:03:05 am
content: Build a little CW beacon.https://aa7ee.wordpress.com/2018/05/07/the-boris-beacon-a-1mw-solar-powered-hifer-beacon/You should be able to receive that easily with just a small bit of wire.

author: Sredni
author_rank: Frequent Contributor
timestamp: January 21, 2020, 07:09:55 pm
content: Quote from: vk4ffab on January 21, 2020, 04:40:11 amFirst of all, thanks for your patience.The software is already in I/Q mode by default.Still no luck outside the FM band (I have for the first time received a noncommercial radio on the FM band, just below 80 MHz), if I make the exception of a veeeeeery faint and unintelligible transmission (in a language I could not make out, maybe polish or slavic) in USB in the 20 meters (if I recall correctly).I use the options sets by the frequency manager in HDSDR but it is possible I am using the wrong settings. I played a bit setting random values, but to no avail. I am atotalnoob in this field, and I planned to build - sometime in the future - a long dipole in the attic of even in the backyard (I have space to play with) but right now I am abusing your patience to find out if this thing (the ham it up that came with the fried dongle) is fried.If you could bear with me a little longer...Attached is the spectrum I can see with the Ham it up in the 3MHz neighborhood. There seems to be activity but I all I can here is whistles. Loud and clear whistles. At least there is sign that something is being received.The bandwidth parameter are shown (and I guess I took the picture after randomly playing around).What are the values I should set (not necessarily in this band, I can see 'peaks' around 7 MHz as well, let's focus on the easiest one).What really worries me is that I do not receive AM radio at all. And there are some pretty strong stations to be received. And even there, with the parameters set by HDSDR, all I hear is noise. Shouldn't AM radio be the easiest to receive, even with a dipole made of two pieces of wire?(And yes, I have reverted multiple times back to default settings in HDSDR in order to undo all the random setting I had tried)