Category Archives: QRM!
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”.
Seems that conditions are quite unstable right now. Yesterday evening the A-index raised to 24 and the mediumwave band was very quiet. Signal-wise, that is. Not QRM-wise, unfortunately. I was monitoring 1548 KHz between 1700-1815 UTC in hope for ABC Emerald to show up, but nothing from Australia this evening. Instead, Deutsche Welle / Trinconmalee, Sri Lanka was the dominant station on the frequency with programming in german until 1800 UTC. Co-channel Radio Sawa was surprinsingly weak the whole evening. Well, we’ll see what happens with the band tonight… If nothing interesting is to be heard, I will continue my “file work” and upload a few more audio-recordings.
Just ordered a bunch of clip-on ferrites. Going to make a really serious effort to cancel all noise/EMC when I’m coming back here again in October.
…and beleive it or not, it was the computer making noise, while radiating in such a way that it affected the MFJ-1026 ability to phase my loops correctly! I suddenly got the idea that I should try to connect my ICF-2001D to the phasing unit, and remove the SDR-IQ, computer and USB-hubs and voilá! Noise gone! Why in H*ll didn´t I think of doing that before? Tunnel-sight??
Tomorrow I will try to re-arrange the SDR-IQ setup in such a way that the computer and accessories doesn´t affect the phasing unit.
Right now listening with the ICF-2001D connected and it’s a true pleasure!
Yesterday afternoon and evening didn’t offer anything new for me on the MW-band. Just the usual strong stations from the Middle East (Radio Payam, Tehran was HUGE on 1188 KHz), China and Taiwan. Contitions in general, was very poor and a check on the 60- and 49-meter bands verified this, as a couple of very strong african stations was noted during late afternoon and evening. Since conditions didn’t offer anything “interesting”, I decided to have another try to find a solution of my QRM-problem, and it seems that adding a third, dedicated noise cancelling wire, did the trick. I have now managed to get rid of most of the noise pollution by phasing each of the loops against the “noise wire” instead of phasing one loop against the other.
If conditions doesn’t improve, I think I’ll spend the evening with writing a few reception reports. Haven’t done that for several years, hi!
Well, still got bad QRM on frequencys above 1100 KHz and also below this frequency from time to time. Very strange. On saturday there was no QRM at all, but on sunday afternoon the noise suddenly appeared. My efforts to improve the feeding of the two phased loops has not been successful – but today I will try to separate the loops a bit more, to see if this improves the phasers performance between 1100 and 3500 KHz.
Anyway; India seems to be the thing right now. Yesterday afternoon between 1700-1730 UTC, AIR Jabalpur in Madhya Pradesh was logged on 801 KHz. Not a good signal, as it went up and down in the noise, but yet audible on my mismatched loops. I’m quite eager to receive the HDLA loop-amplifiers/matching units, as I suspect they will improve the situation quite a bit!
On 1098 KHz, CBS/RTI in Taipei showed up with a booming signal around 2130 UTC, transmitting the CBS Variety Network. Guess that there is a lot more to hear, especially on lower frequencys, so I will continue tonight.
Another fun thing: Today I gained experience of what it’s like to be the one in the receiving end of a reception report. A utility-DX:er from New Zealand has sent a reception report of a shortwave Navtex transmission from Vardø Radio / LGV, the coastal radio station that I’m the manager of. The reception report is 100% correct, so it will be a pleasure to actually send a QSL for once, hi!
Yesterday, June 30, the mediumwave transmitter on Vigra island was shut down. Since 1934 the 100 KW transmitter has fulfilled an important service for the fishing fleets and other mariners along the coast, carrying the the NRK 1 and NRK Møre og Romsdal programmes. Now it’s silent, which means that there are possibilities to hear weaker signals on 630 KHz. I was listening for a while yesterday evening here in Biri, and the dominating station was (not surprislingly) Romania Actualitate. There was also an arabic speaking station, carrying recitation from the Holy Qu’ran, which I at first guessed was Kuwait. However, co-DX:er Bengt Ericsson in Växjö has ID:ed the station as RTT Tunisia. Thanks, Bengt!
630 KHz will be a very interesting, and among DXers, also a very busy frequency when the mediumwave season 2011/12 starts up. Lot’s of interesting DX here, and maybe I (after some 25 years) will get BBC Radio Cornwall in the log?