Houston, we have an issue with the SDR setup

11-19-2014 11-58-04 AM

So in general i am happy with my SDR setup. I cannot imagine going back to use my radio “in the blind” without being able to see what is happening on the band. Most of the stations i work are stations that haven’t been spotted on the cluster yet. SDR helps me to discover those stations and work them before the pile-up caused by the clusters starts.

I have spent my time mostly on 10m. I am very surprised that this band is so active the last months. I don’t know why that is. I was always under the impression that 20m was the most active band, but when i look at my bandscope i see much more stations on 10m than on 20m. And it’s not my antenna setup that is deaf on 20m because when i look at the cluster stats i also see roughly twice the amount of 10m spots compared to 20m spots. Anyway, band perculiarities set aside. Houston, we have a problem with the SDR setup.

As i mentioned in previous articles when i was building the SDR solution, i pick my IF signal from CN303 which is on the RX-2 path. Why? Because the IF sits on 73.095MHz which is a frequency i can “hear” with my RTL-SDR adapter. The IF on RX-1 sits on 11.374MHz and the RTL-SDR doesn’t go that low. Because i have almost solely been working on 10m i haven’t noticed anything wrong with my SDR setup. After all, everything between 21.5 and 30.0MHz goes through the RX-2 path.

Yesterday i wanted to work a few stations on 20m and i noticed that my SDR doesn’t receive anything unless i set my RX filter wider than 2700Hz, then suddenly CN303 gives me a signal again. In the image above you can see how it looks on the band scope. It’s either nothing (filter narrower than 2700Hz) or the normal bandscope as i am used to see (filter wider than 2700Hz).

In the Service Manual i found a table that shows which RX path is chosen when and as you can see in this table there are quite a few moments where i need to open the filter to be able to hear anything at all. Most significant (to me) are the 15m band and the 20m band. Below 20m there is nothing for me to do anyway because of antenna conditions.

Thinking about it it’s not a huge problem (so Houston, you can get back to work again), but merely an inconvenience. Now that i get used to the TS-590 i started to play with the RX filter and equalizer settings and i found that i get the most out of the radio with the filter set appx 1600-1800Hz wide (300-400 Low and 2000-2200 High) and the RX equalizer to one of the two High Boost settings (HB1 or HB2). Now i need to get used to use a much wider filter setting and change the RX equalizer setting for 14 and 21MHz if i want to continue to use the bandscope to help me find stations that were not spotted yet.

Reading it back, what does this article actually tell you? Not much, really. Many times i just start writing to get my thoughts and priorities straight and fixing this SDR “problem” is now, after writing this article, not a priority anymore.

The final setup (or DXLab Suite, HDSDR, RTL-SDR, TS-590 How-To)


So this is my current setup. Step by step:

  1. Hook up CN303 of the TS-590 to the antenna input of the RTL-SDR.
  2. Hook up the TS-590 to the laptop for CAT control. In my case i am using COM3.
  3. Configure DXLabSuite to use COM3 for CAT control.
  4. Install VSP Manager and configure a COM pair. These are two virtual COM ports connected to each other. I use COM4 and COM5.
  5. Configure DXLabSuite to use COM4 as second CAT interface using the Kenwood protocol.
  6. Install Omni-Rig and configure Rig1 to use COM5 (remember that this is the one connected to DXLab) for the TS-590.
  7. Install HDSDR and add the correct RTL-SDR drivers. How-to can be found on the HDSDR website.
  8. Configure HDSDR to use the RTL-SDR USB.
  9. Configure HDSDR to use Omni-Rig and select Rig1.
  10. Switch everything on and enjoy.


SDR puzzle

20-Oct-14 11-10-15 AM

Just starting with SDR, so forgive my ignorance. Here is a HDSDR puzzle:

I installed HDSDR and hooked the RTL-SDR adapter up to my TS-590 on the tune connector CN303 (1st IF on RX-2, 73.095MHz). Cable is a normal coax cable with on the center a 100pF cap (don’t know what it’s for, but they told me to put that in). Final objective is to use HDSDR to see the spectrum and to tune the radio.

At first i thought things were not working because i didn’t hear anything on the SDR. Then i tuned in between 70 and 75MHz. Turns out that i hear my TS-590 when i tune the SDR on or around 75.550MHz. First question, why is that? Why is it not 73.095MHz?

Ok, so now i hear my radio. Let’s tune to a frequency where i have good reception and where there is always traffic, 28.120MHz, the PSK31 frequency on 10 meters. Nothing. I do hear my PLC, so i suspect that the frequency i am listening to is far below 28.120MHz. Dialing up i hear truckers on 28.230MHz. They tend to be on the CB band, so that confirms my suspicion that i am listening to 1Mhz below what my radio tells me.

I looked for a strong station on the 10m band and noted down frequencies. This is what i found:

  • Real frequency where station is transmitting: 28.465MHz
  • Frequency displayed on the radio: 31.350MHz
  • HDSDR LO is set to 75.550MHz
  • HDSDR Tuned frequency is 75.1275MHz

Now i need to understand what is happening and calculate the various offsets you can set in HDSDR.

To be continued…



Don’t know what i did, but i seems to have it working.

Here are the settings:

20-Oct-14 3-22-02 PM


And then this is what it looks like: