Tuesday, 22 August 2017

6T9 (promoting JT9)

Henk PA2S has mentioned it at the start of this year. The JT65 frequencies are going to be overcrowded. Strangely enough I still see few on the even more sensitive mode JT9. Did you know for instance that it is possible to receive JT65 and JT9 on the same frequency, especially important because there is no JT9 allocation on 60m and 6m. Besides that, on 60m, british stations are not allowed above 1000Hz in the waterfall and do call/listen with JT9.

Hopefully this post will contribute to the migration from JT65 to JT9. Henk PA2S and Steve GM0HUU contributed with the invention of 6T9. Henk wrote a nice article about it and posted a 6T9 logo on his site. You are free to use this logo anywhere you want to promote JT65 to JT9.

Now, with the new mode FT8 this all sounds a little silly. However, don't forget that FT8 would only decode till -20dB. It is not nearly as sensitive as JT9. When propagation is really bad JT9 can still save your QSO.

If you like to be more active on JT9 an finally meet more stations there as activity has been lower since the introduction of FT8, you can spend next weekend in the JT9 activity days. See for more info on the website of the Russian Digital Radio Club (RDRC):


Sunday, 20 August 2017

LOFAR antennas

Remember this post from 2009? Probabely not! But of course I remembered my old post as I wrote it myself ;-). Something I wanted to do for a long time is to visit and investigate this LOFAR remote site myself. I think not many people here do know about this receive station site in their village Roodeschool. With the help of google maps though it is easy to find (if you know were to look for). And so this morning I went on my bicycle to make my "tourist" sightseeing. This LOFAR RS509 site is one of many to make a array of antennas forming a radio telescope. My main interest is not what they can do with it but what the construction of the antennas is made of. I found detailed information in this PDF document.

More info about LOFAR can be found on: https://www.astron.nl/general/lofar/lofar

LBA Low Band Antenna contains a LNA Low Noise Amplifier in the top cap. Dipole arms are from 1,38m long thin insulated copperwire as far as I could observe. Resonance frequency is 52 MHz. The groundplate is made from simple concrete mesh you can also buy at he DIY.

HBA High Band Antenna are made from alu. It consists of 4x4 dual lineair polarization dipoles housed in a polystyrene structure covered by polypropylene sheets also known as agricultural plastic sheet. Of course I could not take a look under the sheet so exact construction will remain a secret to me.

I observed another antenna at top of the first server housing. It is pointed to the nearby road. I guess it is a WiFi antenna so any maintance read out can be done from the road? Not shure why it is done like this as the whole site is connected to high speed internet via a optical fibre cable.

The whole site is situated about a kilometer from my home. And although the antennas are mainly pointed upwards I would still have doubts about interference from nearby amateur radio stations like me. Although I'm not transmitting signals 24/7 on the 6m band of course.

Saturday, 19 August 2017

Summertime updating

I realize I haven't been updating my blog for a while. I've so many ideas and so many projects I want to share. I really should get it out of my mind spending time for this radiohobby in summer. Too many things that happen in and around the house and familywise this time of the year. So instead I publish some nice summer photos from our garden to look at...

Garden July-August 2017