Homebrew paddles “Serrafusta”

Today i gave it a shot to build my own CW key. I still have the intention to learn CW one day and i thought having a key could be handy.

First step is to find the materials for the paddles. Looking around in my shed i found the almost perfect paddles.

WP_20150421_001Yes, it is what it looks like. I just took a hacksaw blade (serra in catalan) and broke them in two. The advantage of the blades is that they are conductive (at least when you remove the paint, that is) and they are just sturdy enough to bend with a fair resistance. The nuts and bolts at the end will be used to connect the dash and dot wires.


WP_20150421_002Next is the base. I created the base out of wood (fusta in catalan). The elevated part is where the paddles will be fixed, the ground connection will be made to a big bolt i screwed in the centre of the base.  On the base of the that elevated part i created a small cable guide.


WP_20150421_003The cable i am going to use is an old cable i found in the shed as well. I found out that it’s pretty difficult to find a cable with a stereo jack and some decent wire connected to it. This is a cable with one side a 3,5″ stereo jack and the other side a serial connector. Don’t ask me what this cable was for.


WP_20150421_004Here is where i connected the ground connection to the centre bolt. This image also shows the use of the small cable guide i mentioned before.




The paddles are now fixed to the base. I use a connecting bridge which puts enough pressure on the paddles to keep the firmly in place. As you can see the gap between the paddles and the nut is pretty small. You can adjust the gap by turning the bolt.


WP_20150421_006Here is a view from the back side of the paddles so you can see the bridge more clearly. The dash and dot cables are connected to the paddles now.



This is the finalised key connected to the radio. You can see that the key is pretty small. I found out that the base is way too light to work with one hand, so eventually the key needs to be fixed to the table with sucking naps, velcro or whatever. But in any case it was a fun thing to build, cost $0 and works fairly well. Now it’s time to start morse lessons!!

Moving to a Mac: Starting from scratch again

Due to circumstances i have to move from a Windows PC to a Mac. For me that means exporting my log to an ADIF file and start looking for an alternative to the great setup i had before on my Windows PC.

First the logging part: There are plenty of logging programs out there for logging and i have tried quite a few of them. Nothing comes close to MacLoggerDX from Dog Park Software. Don Agro VE3VRW has put a great amount of effort in building a program that is built by a radio amateur for a radio amateur. It has all of the features DXLab Suite had except for digital modes. So for this i still need to look for a decent program that is easy to use and integrates with MacLoggerDX.

Screen Shot 2015-04-20 at 14.08.14

Second the SDR part: There are not so many SDR programs for OS X out there. When people talk about SDR for Mac mostly you end up with GQRX which is basically a gnuradio application packaged as an executable. I have tried GQRX and i don’t like it. It needs the complete gnuradio backend to function which makes it a huge app to run. Also i didn’t find it stable enough. So what about gnuradio itself then? Yes, that’s probably the best solution, but i’m not proficient on gnuradio yet so that’s still in the freeze for later.

Screen Shot 2015-04-20 at 14.38.20

I compiled SDR# on the Mac with Mono, cross-compiling a .Net application makes it terribly slow. Too slow to work with.

I spent some time with linrad as well. Linrad seems to be the de-facto technical cross-platform SDR solution out there. I managed to compile it on OS X, but i am not impressed (yet). Usability is under par and that probably hinders adoption. I will continue to work on getting to know linrad, maybe in the future i will switch.

Screen Shot 2015-04-20 at 14.41.28

Then i found CubicSDR. CubicSDR is a new program on the market. The initial commit on GitHub was done on Oct 26, 2014 but in the 5 month that the author is working on the app, the app has come a long way. It’s still very basic, but it is very stable and very fast.Screen Shot 2015-04-20 at 14.05.55

All these SDR programs have one big disadvantage: they are not built to be used as panadapter. which means that they listen on the frequency the SDR receiver is set to and don’t interact in any way whatsoever with the radio. Also there are no interfaces like Omni-Rig which i used in my HDSDR setup. So at the moment i set my SDR fixed to the IF frequency of the radio (73.095MHz) and y just sing the VFO on the radio to change the frequency. I can live with that.

Digital modes: DXLab Suite also had a program to work with digital modes, so i needed to find an alternative for that as well. Two programs came to my mind, fldigi and cocoamodem. I haven’t decided yet what i want to use. Both programs integrate with MacLoggerDX using AppleScript, both programs do what i need them to do. Cocoamodem seems to be more a Mac program, but is not being developed anymore, fldigi is multi-platform and therefor less optimised for OS X.





I still need to figure this one out. I will let you know in a next post.

Noise canceling with RTL-SDR adapters

Yesterday someone pointed me to this video where G7CNF Nige uses two receivers and the Diversity feature in PowerSDR to phase out noise from the receiving signal. Now, cross-phasing has caught my interest when i came back to the radio almost two years ago because of the PLC noise i have in my shack. Nige is using the two receivers in his ANAN-100D, i don’t have a device like that. Also i think it’s much “cooler” to try to do this with RTL-SDR adapters.

PowerSDR is made for the Flex receivers, but there is an OpenHPSDR version of PowerSDR. Then N1GP wrote a bridge from SDR_RTL to the HPSDR platform. So using this bridge i should be able to access my RTL-SDR adapters using PowerSDR. Let’s see if that works.

  1. Get a separate Linux machine to run the bridge on.
  2. Get your dependencies installed to compile the bridge. In my case (fresh Ubuntu 12.04) i needed to install build-essential, git, cmake, libusb-1.0-0-dev, libasound-dev
  3. Clone the sources for the bridge. Do not use the branch mentioned above, if you read the README there you see that you need to use:
    #git clone https://github.com/n1gp/librtlsdr.git
  4. Then:
    #mkdir build
    #cd build
    #cmake ..
    #sudo make install
  5. You should now get something like this:
    rtl_adsb rtl_eeprom rtl_fm rtl_hpsdr rtl_power rtl_sdr rtl_tcp rtl_test

    rtl_hpsdr is the one you want!

  6. Connect your RTL adapters to the computer and test rtl_hpsdr:
    Found 2 RTL device(s), using 2.
    RTL base sample rate: 1536000 hz
    Global settings:
    config file: none
    ip address:
    length of fir: 32
    number of rcvrs: 2
    hpsdr output rate: 48000 hz
    sound device: none
    Rcvr 1 (ordered as 1) settings...
    freq offset 0 hz
    signal multiplier 1
    Found Rafael Micro R820T tuner
    tuner gain auto
    Disabled direct sampling mode
    direct sampling off
    agc mode off
    Rcvr 2 (ordered as 2) settings...
    freq offset 0 hz
    signal multiplier 1
    Found Rafael Micro R820T tuner
    tuner gain auto
    Disabled direct sampling mode
    direct sampling off
    agc mode off
    Revealing myself as a Hermes version 2.6 rcvr.
    My IP Address:
    My MAC Address: 00:00:00:00:00:00

    Nice, rtl_hpsdr is running and we found two RTL devices. Notice the last lines, they are important. “Revealing myself as a Hermes version 2.6 receiver” and the IP and MAC address of the server. Remember those two.

  7. We are almost done on the server side. The only thing that is left if to start rtl_hpsdr listening on an IP address that we can access from outside. We use the -i option for this. I suggest you enter at least once “rtl_hpsdr -h” to understand which options there are and what they do.
    #rtl_hpsdr -i
  8. We are done on the server side. Now let’s install PowerSDR on your Windows workstation. Download PowerSDR from http://openhpsdr.org/download.php and install it. Nothing special, just a standard Next, next, Finish.
  9. Remember that rtl_hpsdr told you it presented itself as a Hermes receiver? So in PowerSDR make sure that you select the Hermes receiver. Leave the Connection type to Hermes and Full Network Discovery.

04-05-2015 11.36.31 AM

Now you are ready to start PowerSDR and connect to the Hermes/RTL-SDR server. When you are connected the IP address of the server should be displayed in the Hardware config screen.



There are a couple more things to take care of. The Hermes transceiver board covers a frequency range of 50kHz-55MHz. The RTL adapter covers, without up-converter, 24-1800MHz. So the only usable frequency range with this combination is 24MHz (lower side of the adapter) till 55MHz (upper side of the Hermes). You can extend that range a bit by using the HPSDR cinfig panel, but more than 150MHz it will not do.

04-05-2015 11.47.35 AM






If all is working fine you should see someting like this on your console:

04-05-2015 12.09.49 PM




You can now activate the second receiver as well by clicking on the RX2 button next to the power button and then select the Diversity menu item.

04-05-2015 12.19.42-2 PM

Personally i found PowerSDR highly unreliable. I don’t know if it’s my PC, the communication between the PC and the server or the quality of the server, but in my install PowerSDR locked up every time i wanted to use it. It’s partner software cuSDR turned out to be more reliable, better looking as a panadapter, but lacks the Diversity function.

Let me know what you think of this article and let me know if you have more success than me setting this up.