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February 20, 2021 at 5:31 am #1739MaksimParticipant
Hello. I have an RSP2pro receiver, the antenna is a 20m long wire. The antenna is connected via a ferrite transformer 9:1. The receiver is located in an apartment in the city center. From the very beginning of operation of the receiver, spurs are observed on the waterfall spectrum, starting from the frequency of 12 megahertz. I took the following measures: I grounded the receiver, changed the balun, connected it to the matching antenna tuner, shielded the USB, and used ferrite latches. Nothing has changed. I attach screenshots. Please advise what can be done, why do these stakes appear? In the screenshots, they are indicated by arrows.
Attachments:February 20, 2021 at 5:36 am #1741MaksimParticipant
the Waterfall SpectrumFebruary 20, 2021 at 5:43 am #1742MaksimParticipant
The Waterfall Spectrum.
Attachments:February 20, 2021 at 11:04 am #1745Andy2Participant
I think HDSDR has a ‘balance IQ’ setting somewhere in the menus. Fine adjustment of this should get rid of these images. There are a number of discussions about this on the net, for instance http://www.sdrplay.com/community/viewtopic.php?t=82
February 20, 2021 at 12:08 pm #1747Andy2Participant
- This reply was modified 1 week, 5 days ago by .
Just a quick follow up. I no longer use HDSDR, but in SDRUno there is an ‘IQ channel skew’ adjustment which can be manually adjusted or set to auto. Below are two screenshots, one with the auto off and one with it on. As you can see the unwanted response at 26.5 MHz disappears.
Attachments:February 20, 2021 at 12:27 pm #1750MaksimParticipant
Yes, unfortunately in HDSDR it is not possible to delete the response. Tomorrow I will install the SDRU application, and try to achieve the result. I will write about the results. Thank you for your advice, thank you.February 21, 2021 at 11:48 pm #1758MaksimParticipant
Unfortunately, these “stakes” are not eliminated by correcting the amplitude and phase. I adjusted the amplitude and phase, both in the SDRU and in the HDSDR. This problem remained at 20-17-15m and above. I guess it could be the” affected ” frequencies. However, the receiver works very well.
Attachments:February 22, 2021 at 1:58 pm #1760Andy2Participant
Ah, those are not ‘spurs’, they are real signals getting into your system from the antenna. They seem to be spaced about 50 kHz apart, so my guess is they are harmonics from some equipment like a power supply, TV set or computer. Do they go away if you unplug the antenna?February 24, 2021 at 12:12 am #1765MaksimParticipant
Hello. That’s right, these stakes disappear when you turn off the antenna. It’s very simple, I didn’t check this idea. Thank you Andy2. This signal comes from the ether. I put together an additional low-pass filter for the receiver. It is used to suppress frequencies above 30 MHz. I don’t use VHF anyway. The spectrum has become cleaner. Since next to me are 5 powerful VHF radio broadcast transmitters. This filter is required.
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