Panadapter, the continuing story

So recently i got a new toy in the shack. I wanted to make a small step up from the RTL-SDR adapter and got myself an SDRplay. I first tried out the SDRplay using it as a plain SDR device and i must say that the guys at SDRplay did a great job. The radio is so much more sensitive than the RTL adapters (yes, also more expensive, i know) and this increased sensitivity really makes a difference. Also i can see 8MHz of band where the RTL adapter only (ONLY?) can see 3.2MHz. The SDRplay shows less spikes, less images, etc, etc. All in all simply a better radio.

Next step is to use the SDRplay as a panadapter for my TS-590. Since i have built the RTL-based panadapter described here i have been reading up a lot on where to connect the SDRplay. As you know the RTL adapter is connected to the first IF and that solution has a couple of issues:

  • I can only listen to the adapter on the IF frequency. This is not an issue when using Windows, i can use omni-rig to sync the SDR with the radio, but it is on the Mac. There is no omni-rig on the Mac.
  • I can only listen to the frequency the TS-590 is set to plus or minus 1 Mhz (something around there, i’m not sure how much bandwidth the IF shows).


Reading up on the web and looking at several different panadapter setups i found out that the IF solution i chose is not the most common one. The most common places to pick the signal for the panadapter is at the end of the RX path. CN101 and CN201 are the places where people pick their RX signal from where CN101 is before the BPF and CN201 is after. So i decided to use CN101. I created a jumper cable from an old Wifi antenna cable and hooked it up to an old jumper i had lying around. The shield of the cable i connected to ground exactly as shown on the image here. In fact, i took the idea from the website linked by the image.

Good things i found out:

  • I can really see 8 Mhz of spectrum now.  Quite impressive although for HAM radio use i normally set the SDRplay to 1,5 MHz which usually covers the band i work at that moment.
  • I can use the SDR even with the radio switched off. Basically the SDR is now directly connected to the antenna and the antenna works whether the radio is switched on or not.
  • I can see other bands than the band i am working on. So i can work one band using the RTL adapter and in the mean time monitor the propagation on other bands to see if i need to move.

Bad things: The SDRplay ONLY supports Windows!! And that sucks big time!! On the SDRplay website it’s the longest thread is about Mac support for the SDRplay. There is mention of an API and a library for OsmoSDR, but i haven’t found anyone who got that to work yet. I managed to compile SDRplay support into gr-osmosdr and use the SDRplay in gnuradio and the radio works, but the audio is horrible. I am complaining about this to the SDRplay guys every week hoping that they improve the OsmoSDR library. In the mean time I hope that the developer of CubicSDR, my favourite Mac SDR software, moves away from OsmoSDR support in CubicSDR and builds native support for the SDRplay.

Until then i have a separate Windows laptop with HDSDR running on the SDRplay to see the bands and use CubicSDR with the RTL-SDR on my Mac to do my regular DX-ing.

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.