Monthly Archives: July 2012
We’re getting there! The MW-DX season 2012/13 is getting closer for every day now. A few days ago, the sun disappeared below the horizon for an hour or so, and each night is getting a couple of minutes longer. Around November 21, the sun gets below the horizon 24/7 and we will not see it again until around january 21. Although 24 hours of daylight is bad for DX, the midnight sun is a beautyful sight, isn’t it?
Well, it doesn’t happen very often, but this aftornoon we had quite a thunderstorm approaching from the northwest and over Vardøya island. The temperatures the last few days has been pretty high (yes, over 16 degrees Celsius is considered almost “tropical” up here in the arctic clima zone). Anyway, I took a picture of it, sorry for the poor resolution – my cellphone camera doesn’t allow anything better than this – and although there isn’t any visible lightning in the picture, the sky was amazing.
By the way, at the right in the picture, one of the 60 meter high MF-transmitter towers of Vardø radio is visible. We have four of those here. Luckily enough, we only transmit during a few minutes every third hour on medium frequency, and never on the full hour, so it’s actually possible for me to erect my phased HDLA-loops here and do some serious DXing, hi!
The antenna and equipment pages on this site has been updated this evening. Have a look and say what you think! Also, I created a new page dedicated to ultralight DXing only, where you among other things will find my complete ultralight DX log from March to April this year.
Ok, so here it is. Compared to the system used last season, the two loops will have a somewhat larger curcumference. On each loop the HDLA-amplifier/matching unit will be connected in the lower apex facing the desired listening direction. In my case, I want to favour reception from northwest and northeast and everything in between. In the lower apex of each loop, facing undesired directions, a 1 KOhm terminating resistor is connected. This will (hopefully) attenuate noise from nearby buildings and unwanted signals and QRM from southwest and southeast.
As you can see, the system can be defined as two phased KAZ-loops. Both loops are mounted on the same pole, in 90 degrees angle from eachother. This is far from ideal, but due to lack of poles and real estate, I don’t have any other choice than to do it like this right now. The loops are, however, separated in height. I do have high hopes for it’s performance the upcoming MW-season. But, just like all other antenna systems – this one demands real life usage in order to prove it’s useability. In any case, I’ll keep you posted about the assembly process. Just wish them horses to leave the spot where I’m planning to erect this “thingy”.
Well, I guess that most of you people in the DX community has heard about this new SDR-receiver already. After reading about the Afedri on Arctic DX, I got inspired and decided to order one myself. The Afedri SDR-Net is offered by Alex /4Z5LV via his website, and sports a 80MHz 12 bit ADC, which in comparison with other (and much more expensive) SDR:s is representing a compromise. The Afedri doesn’t have any band pass filtering, so if you – like me – are interested in mediumwave DXing, it’s recommended that a low pass filter is added before the antenna input on the receiver. More about that further down. Anyhow, what’s making the Afedri so interesting for the MW-DXing community is the receiver’s ability to record up to 1250 KHz of IF bandwith – and this for such a low cost as US$ 249 + shipping! I paid a grand total of US$ 277 including shipping to Norway from Israel. In fact, you can afford to buy at least THREE Afedri’s for the same cost as for one high-end SDR. No wonder I’m curious about this little baby, and the upcoming MW-season will show if the Afedri SDR-Net represents the Best Bang for The Buck! I’m not going to get into any technical discussion here, instead I recommend you all to read Bjarne Mjelse’s thoughts about the radio, which is found here.
However, since the Afedri’s front/end is “wide as a barn door”, it’s recommended that the serious MW-DXer adds some kind of low pass
filtering at the antenna input, to avoid overload on the MW band from strong shortwave stations. I decided to opt for a custom made low pass filter with a cutoff frequency of 1800 KHz from Clifton Laboratories. I guess that this setup will work just fine!
In any case, the Afedri story will be continued this upcoming MW-season!
Yes! I’m still around! It’s still sort of summer up here (actually, with “summer” I mean “non-MW-season”), but we’re definetely getting closer to the next season of darkness – and DX:ing! A lot has happened since my last post here and, among other things, I’m now settled permanentely here in Vardø. Right now I’m preparing my antennas for the next season, and I will modify my phased HDLA-loops a bit – trying a pair of phased KAZ-loops, which I beleive will be able to fight local QRM a little bit better than my previous setup. As you can see in the picture, the loop wires are cut and as soon as the horses that now are populating the area where I’m planning to erect the antenna are gone – I will put the antenna up. A schematic diagram of the modified HDLA-loops will be published here within a few days.
During “pre-season”, I’m planning to update the blog two to three times per week, and when the season has started in september, my ambition is to update on an daily basis.
By the way: please note that I’m now using a new e-mail adress for DX-related correspondance: