Thursday, 15 March 2018

Solar storm mania

Northern lights in Finland last night!
Over the past years I noticed a increased number of posts on all kind of media about solar magnetic storms. Just like the media posts and news about storm forecasts. The geomagnetic storm that wil arrive today will wipe out all radiocommunication, all GPS devices will be un-usable and there might be electric power grid problems, at least.....that is what the media wants to believe us!

Well, the predicted geomagnetic activity index number this night will be Kp5 (G1). That's just a minor storm. If the Kp would be 9 (G5) it is a extreme storm and in that case things could be worse. Aurora or northern light can be rarely seen here in the Netherlands. But in Finland it is very common. You can view beautiful aurora on this webcam:

There are people that think that geomagnetic storms can influence our thoughts. The same people say that it was all predicted by the Maya's and even claim it is written in the holy bible. They also have a good solution if you don't feel well. You should take a rest and drink a lot of water to reset your body and that way you can accept higher resonance frequencies in your body and thoughts. I guess this will help if you feel dizzy after a few hours of contesting as well ;-)

Well, Dr. Tamitha Skov, who is a Ph.D. in geophysics and space plasma physics is a modern kind of geomagnetic weather forecaster, will tell you all about the upcoming magnetic storm:

Tuesday, 13 March 2018

The subject of grounding

In the past weeks I had some questions about interference on VDSL2 modems and another question  if grounding would be necessary. So I was searching in my blog archive as I have been studying the subject several times. And even after studying, I could do some things wrong. So this is a small list from my previous articles about grounding and/or a shack earth point.

And this is what happens with static electricity build up when a thunderstorm is nearby. The reason why I have a ground at my antenna entrance.

Not that I always have a clue what I am talking about, but at least I try....
Best written articles about grounding can be found at

And even I made a fault to include a knife switch in my installation which was completely unnecessary.

So what I've learned:

- A ground in your shack which is bonded to a earth electrode is for safety. It is not a RF ground.
- Use a entrance panel for your coax and other cables that is grounded well outside the house.
- If possible ground your antenna supporting mast as well
- Prevent earthloops, they are a source of much RF problems.

A good tool for measuring is a simple multimeter. If you seem to have problems anywere try to find that second or even third uneccessary ground connection and remove it. Remember that the shield of your coax is ground as well. So a extra wire for example from your radio to the entrance panel is only giving you a groundloop and so, this is not necessary at all. For grounds sake, less is better in grounds case!

Think about this: Most of the mains grounds are bonded to the case of a appliance. In our case as radioamateurs we always have a power supply which is bonded through the ground via the mains connector cable. Most computers have this ground as well on the same mains net. A extra ground wire from the computer to your ground is not necessary (ground loop again). However, if you do digital modes you have your soundcard connected to your radio, is the ground from your connectors grounded to the mains ground in the computer? You could have a problem (ground loop). In my case the ground of my mains connecting cable is also bonded to my negative pole on the 13,8V output in my Astron RS-50A power supply, I've had a lot of groundloop problems before I discovered this. That's why measuring with a simple multimeter is important! 

Ground paths in my strokes are grounded.
Above the main net supplies, 12VDC supplies, coax and ground paths in my shack. My power supply has no galavanic connection to the main electricity net. The computer does however. Nothing is connected to main net safety earth. Everything is connected to the shacks own earth electrode which is bonded to my entrance panel. There is no separate earth wire connection to the entrance panel, I trust the coax shield is my earth connection. However, if a thunderstorm is nearby I disconnect the coax from the entrance panel leaving my equipment un-earthed. But that's no problem as I always switch my mains net off in the shack (have 2 master switches for both wall outlets) in that case. The central earth point is there but is only connected to a counterpoise which is existing of strokes alu foil tape below the floor. The radio is earthed through the coax connected to the Palstar tuner.

I don't say the above writing is the truth and nothing else. It is like other posts for archive purposes as well. I might think completely different in a couple of least I've the feeling I'm safe this way.

Friday, 9 March 2018

#APRS messenger on HF 2 - MFSK-4

It seems APRS messenger gets more attention worldwide. A number of stations are active now. In my last post about the APRS weekend I had doubts about the receiving capability of the messenger program. Well, Chris G4HYG, the APRS messenger programmer has changed some things in the program and in the last version it has now MFSK-4 capability.

Here are the changes from last week:

The latest latest version 3.37 has a bug fix for a decode problem with MFSK-4. Good packets were being rejected especially if the background RF noise was high. 

Version 3.36 has a new mode option MFSK-4. This is a very slow and narrow (176 Hz) mode which is 4-5 dB more sensitive than MFSK-16 at 18 dB in a 2.4 kHz bandwidth making it comparable to FT-8. Beacons are very slow taking typically 1 minute for the shortest callsign and lat/long position packet. Messaging without acks is available for MFSK-4 but watch your message length, the shorter the better. MFSK-4 transmits 210 Hz higher that the usual frequency used for APRS Messenger messages to allow slow MFSK-4 traffic to run without blocking the "fast" channel. On the 30m frequency (10.1497 MHz) used for APRS Messenger traffic the MFSK-4 signal just fits in between the normal traffic and the band edge. Before you use it check the frequency calibration of your transceiver against WWV on 10 MHz or RWM on 9996 kHz to make sure you don't transmit out of band. A checkbox to select 9600 bd GPS receivers is added to the main window, The GPRMC sentence is used for GPS beaconing. 

Version 3.35 has a new option to stop the start-up timer on the first page, switches the beacon off during messaging, add metric level squelch for MFSK-16 and a minor bug fix and text change. 

Curious about the receiving capability now! Another weekend of testing! The idea is to add -63 to your call to show you're working with APRS Messenger. That way all stations worldwide are easy to find for instance on