Liking SDRUno

[pgoelz]

Been using the RSP2 and SDRUno for several weeks now and I have to say I am rather shocked at how good SDRUno is for a "free" program. I am well versed in receivers and SDR technology and I had no trouble setting it up and using it right out of the box. The only "out of box" issue was the residual LO signal causing distortion if it coincides with the receive frequency (which it does when you first start up and recall a memory). I just click off to the side a bit and recall the memory again.

I have had several small issues with stability and screen redraw, but since I mostly use SDRUno remotely via RDP (ethernet >> router >> Wifi) it is very possible that these are stimulated by RDP and not native to SDRUno. I also saw a significant improvement after installing OpenWRT on my WNDR3700v2 router vs. the factory firmware. That said, SDRUno does not always fail gracefully if the RDP connection is interrupted.

I am hosting the RSP2 on a homebuilt PC with an i7 CPU, 8GB RAM, SSD and USB3 ports, using the graphics adapter on the MB. It loafs along at <30% CPU even at a 10MHz sample bandwidth.

I do have a few feature suggestions:

1. It would be very useful if the current waterfall zoom level was stored when you store a frequency to a memory location.

2. I use two monitors and it would also be very desirable to be able to group all active windows and move them as a unit to another display.

3. The LO distortion issue could be solved if SDRUno (and/or the RSP2) was able to simply offset the LO by, say, 10KHz if the receive frequency was less than 10KHz from the LO. Is that possible? I don't like to use "low IF" because it limits the max bandwidth to two choices.

4. I could really use a third antenna input but the HiZ input seems to have an internal high pass filter so it is not suitable for MW or 6M frequencies. It would be desirable to be able to disable the high pass filter on the HiZ input so it is at least usable MW through 30MHz. Note that I was coupling to the HiZ input with a small balun with unknown characteristics.... if there is in fact NO high pass on the HiZ input..... well..... never mind

Paul

[g1hbe]

Paul
I use the Hi-z input for all my LF, MF and HF operation and it has a very good response right down to a few kHz, much better than the two SMA inputs. In fact SDRPlay recommend the Hi-z input for these bands. I'm not sure of the response above 30 MHz but the SMA inputs work well from 30 MHz to UHF anyway.

[pgoelz]

I played around with it again yesterday and you are correct. The issue was my balun(s). I was using the little Nooelec 9:1 balun in reverse and it turns out it has a DC path from input to output that was messing with me. After I broke that AC coupled it, it worked a lot better. A second issue that I did not consider is the fact that I think the balun at the feedpoint of my fan dipole is not very good at MW frequencies. It is rated 3-30 MHz and seems to drop off rapidly below 1.5MHz. I had completely forgotten about the fact it was up there.

Above 30MHz the RSP2 will not let you activate the HiZ input so I can't compare it on 6M.

But at the end of the day, I still get more consistent results with the SMA inputs than the HiZ with my balun (or even direct without the Nooelec balun). The antenna itself is a 20-17-10M fan dipole, but I am usually using it nowhere near those frequencies and the feedpoint balun is (I think) a choke balun so the feedline may be acting as an antenna at some frequencies and accounting for the difference between the SMA and HiZ inputs.

I tried searching for a simple broadband sma 1:1 balun and was surprised that I was not able to find one unless I wanted to wind my own from a core and wire or buy an SMD part and mount it on a home made board.

Paul