Tuesday, December 25, 2012

Simple Elecraft KX3 and PowerSDR configuration

I have played with HDSDR and Elecraft KX3 for a while.  While  HDSDR is an excellent piece of software I am more familiar with PowerSDR as I have used it over 2 years.  I wanted to see how KX3  would work with my Flex3000 / PowerSDR  setup.  This turned out to be a fairly simple configuration - in fact you can run multiple instances of PowerSDR connected to different radios simultaneously.  Note that I am using PowerSDR version v2.4.4 on Windows 7.

The first step was to connect the Elecraft KX3  RX I/Q  interface to a sound card in the computer.  A quick visit to Radio Shack was required as I did not have a 2.5 mm to 3.5 mm stereo Y-adapter (part 274-945).  Using a normal male-to-male  3.5 stereo audio cord I connected KX3 to my home brew computer  Line Interface  (Light Blue connector in ASUS P8Z68-V PRO/GEN3 motherboard as shown in the ASUS P8Z68 Manual ).  See fig 1. below  - don't use the pink microphone input jack.

Fig 1.  ASUS P8Z68-V  audio connectors

Next step was to configure PowerSDR  properly.   When you start PowerSDR  without turning Flex3000 on first it will pop up a window - note the button "Add Legacy Radios" below.

Fig 2. PowerSDR Radio Interfaces

You can add SoftRock 40 legacy radio - no need to add anything on Serial Number field.

Fig 3.  Adding Legacy Radios

You will get back to Fig 2. window  and select  "Use" button on the right. Main window of PowerSDR software should come up.  

Next step is to select  Setup menu from the top and General / Hardware Config.  You can setup the Center Frequency here - see Fig 4. below.

Fig 4.   Set Center Frequency

Next you configure the Audio / Primary settings.  In my case I am using the built-in sound card of the ASUS motherboard which is not on the supported sound cards list. There I selected "Unsupported Card" as shown in Fig 5. below.  Also,  I configured Sample Rate to 192,000 to get maximum frequency coverage from KX3  RX I/Q signals.  I also used "MME" Driver of Windows 7  and selected Input  and Mixer to "Line In High Definition Audio"   and selected Output to my video monitor "EQ276W DP-1 (NVIDIA...)".
Fig 5. Audio Hardware Configuration
Time to  press the "Start" button on  PowerSDR.  You should see some signals on panadapter if evrrything is configured correctly. 

Fig 6.  PowerSDR showing 96 Khz of signal coming from Elecraft KX3

Note that PowerSDR expects the center frequency be at 14.200 MHz   (see Fig 4. above) and
to get the frequency display correct you need to tune KX3  at that frequency.   You can also see that PowerSDR covers approximately  96 kHz  bandwidth centered around 14.2 MHz.  Of course you can change that by just going to Setup menu.  

Fig 7. Elecraft KX3  tuned at 14.200 Mhz

I was running Flex3000 and KX3   in parallel listening some stations while switching the antenna between KX3 and Flex3000.   I did not do any scientific A/B comparison study  but just by  using two instances of the same PowerSDR version connected to different radios I could not really tell much difference between these two radios.  Both picked up the faint  DX stations equally well.  The only difference was really the few kHz noise band around the KX3 center frequency  - outside of that the sensitivity and sound quality was very similar in both of these radios. 

I was also playing with the CAT interface of PowerSDR  - however, it does not recognize Elecraft as an option so I did not spend much time on that.  In comparison HDSDR uses Omnirig  CAT interface which has more choices, including Elecraft K3  that works well with KX3.    If you can figure out a way to get KX3  CAT interface working also with PowerSDR please let me know.

In conclusion I wanted to test if I can make PowerSDR software to use Elecraft KX3  as a receiver.  As you can see above this was a quick and painless configuration effort.

Mauri   AG1LE


  1. Curious if you've tried to connect your KX3 to PowerSDR via a KXUSB cable. I had to download the 64 bit driver to even get the PC to communicate with the KX3, but finally did. Haven't tried to do anything except test communications per the instructions. 73 de n2gj

  2. I have my KX3 connected to PowerSDR via the RX I/O connector and via the CAT connection and also have them synchronized with Ham Radio Deluxe Version 6, HRD Log and HRD Digital (formerly DM780).

    Essentially I followed the instructions posted in a PDF file on the KX3 interest group on Yahoogroups by VE5KC. This got me as far as successfully connecting the RX I/O and the CAT interface between the KX3 and PowerSDR.

    In order to sychronize the KX3 and PowerSDR with HRD, HRD Log, and HRD Digital I downloaded and used com0com to install a virtual com port between HRD and Power SDR and downloaded and used Virtual Audio Cable to provide the audio connection between PowerSDR and HRD Digital (formerly DM780) and to install an audio repeater (MME) to route the audio to a speaker.

    Note, if you are using a 32 bit computer and Windows XP you can use the virtual com port in HRD and do not need to download and use com0com, but I was unable to make it work in 64 bit system running under Windows 7 therefore I downloaded the 64 bit version of com0com.

    Changing band, frequency or mode with PowerSDR will change the band, frequency, or mode of the KX3 however I have not been able to get it to work in the other direction as the CAT control does not seem to flow from the radio to Power SDR. Since PowerSDR was developed for Flex Radios that do no have knobs and dials maybe bidirectional CAT control was not included in the software.

    I am using HDSDR because the CAT control tracks and synchronizes HDSDR, HRD, and the KX3 from either direction.

    If someone gets CAT synchronizing in both directions between PowerSDR and the KX3 I'd like to know how they accomplish it.

    73 Hugh W4VAB

    1. There is a way to synchronize the CAT control and have bidirectional frequency control between between the KX3, PowerSDR, and HDR.

      The solution is to use the modified version of PowerSDR developed by WU2X. You can read about it then download it from his Website http://www.wu2x.com/sdr.html.

      It works fine.


      Hugh W4VAB

  3. Mauri,

    I have a limited budget and have to choose between the Flex3000 and the KX3. This blog seems to me to say get the KX3 because it can do everything the Flex3000 can do and then some (portability). Except for the lower power (10w vs 100w) what else am I really losing if I get the KX3? What combination do you prefer to operate (Flex3000/PowerSDR or KX3/PowerSDR)?

    Thanks and 73,

    1. Hi Dan

      KX3 is an excellent QRP transceiver but it does not have all the same capabilities as Flex-3000. The purpose of this experiment was to demonstrate that KX3 receiver provides I/Q output that you can connect to PowerSDR. I did not try to get CAT control working so when you change the bands in PowerSDR the KX3 is not following. However, see comment from Hugh W4VAB above - it looks like there is a workaround available. KX3 is a self contained transceiver that does not need a PC to operate.

      Flex-3000 does not work without a powerful PC. I have a Thinkpad T60 laptop that is underpowered to run PowerSDR and other programs - therefore I built a pretty powerful desktop machine to get the maximum out of Flex-3000.

      I am using both of these radios for a little bit different purpose. I travel quite a lot and do take KX3 with me on trips. It is very portable and fits into my backpack easily. It can also run on batteries and from a small portable power supply.

      For my home station I use mostly Flex-3000. It has more power and features, has a very good receiver and 100W output drives my amplifier to full 700W. I can receive two frequencies simultaneously and shows 192 KHz slice of the HF band on the panadapter. This is very useful when working with DX stations on split. You can see and hear what station the DX is working right now and can anticipate where to make your call.

      I have carried Flex-3000 also with me to places like St Croix, USVI but I did purchase KX3 as it is much more convenient radio to take with you on the trips.

      I hope this clarifies how I use these two radios. It is never easy to make a choice so you need to decide what you want to do with the radio. Both have many good features and they are excellent products.

      Mauri AG1LE

  4. Is it possible to use the Tracking Notch Filter within PowerSDR while attached to the KX3 or K3?

    Norm KL7RS

  5. No responses to the possibility of using the Tracking Notch Filter within PowerSDR and K3?

    Norm KL7RS

  6. Hi Norm

    TNF feature can be enabled but probably does not work like you would expect. Since PowerSDR CAT control does not work with KX3 the TNF allows you to set a notch filter but it does not do tracking as you change frequency on KX3. I assume that this is what you wanted to accomplish, right?

    I have not tried the modified PowerSDR version that Hugh W4VAB is talking about in the first comment (see http://www.wu2x.com/sdr.html). You may also want to post this question to Yahoo KX3 Group mailing list - there are several people who have tested various SDR software with KX3.

    Mauri AG1LE

  7. See also this thread in eham.net -


    NaP3 has integration with Elecraft KX3 CAT - see instructions here:

    Mauri AG1LE


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