Being new to the TADX scene I notice that a lot of the US shows are either the same content (similar to the likes of the GOLD network in the UK) or carry each others programs for sports etc. This can make a positive ID a challenge - top of the hour helps if they break for news but then again the indents’ can be "Talk Radio Sport AM" or similar. Not very helpful!

I've read about and used myself online radio players for checking DX in the past and have found that the CBS radio player at http://www.cbsradio.com/streaming/index.html a fantastic resource.

There are many AM and FM stations listed by US county and it makes comparing content a pretty simple task of matching the frequency you're on with the ones listed. It is not 100% as some will be using affiliate audio - but it helps with narrowing down just who "Talk Radio Sport AM" really is.

The various streams seem pretty reliable as well as fast and a few checks this evening on some of the early TADX stations to appear here shows that 660 KHz is the same as the WFAM web stream. :-) The pop up player even allows you to add stations to your own presets list; making it quicker to jump between them whilst checking those Perseus files!

73

QRM, a nasty three letter word to anyone with a radio.

Ever since I moved to somewhere a little quieter (read not a suburban housing estate) I noticed that even with the loop between 250 KHz and around 600 KHz there was always this mush, no matter what I did or how I worked the antenna feeds or what options I choose as for feed line this mush was omnipresent. At times it would be evident higher up in frequency at other times nothing about 2 MHz at all. So having a little of the TADX bug inside me I decided it was time to swat this pesky noise once and for all! Armed with my Perseus (which is great for spotting noise) and a UPS I went for the big switch!

A recording of the the noise 390Khz_QRN.mp3 (469.39 kb)

Killing my own mains power removed the noise completely, A Ha! It was my QTH that housed the problem, in some ways great in others not so great! If it was somewhere else I could call on OFCOM and its team of QRM investigators to find it and cure it! However being my noise it was my problem, darn! So back to the QRM DFing, now I knew it was me I could turn on the houses’ electrical outlets one by one and see when it appeared, sure enough I discovered that once the lower floors “mains” was restored the noise returned.

I was glad it was not the central heating or anything like that! This now left me with basically the downstairs and the items plugged in or hard wired – not much really to “check”. Grabbing my trusty Yupiteru and tuning to where the noise was strongest 390 KHz I began to wonder around the house (-pretty glad my YL was not about as she always looks upon this hobby with some suspicion!) each time I got anywhere near anything electrical the noise would peak, so if I moved near a light switch, wall outlet or where the wiring runs in the walls the noise would appear. Which at least shows it was the house wiring that was radiating!

This meant it was findable … moving from item to item the kitchen appliances seemed to radiate the most – well! Now I was getting somewhere. The three items that had displays were the fridge, cooker and microwave; in turn I switched them off – voila! Switch the microwave off and the noise is gone! Switch it back on and a swish and the noise returns. Hmmm now this is not some relic from the 80’s this is a state of the art combo microwave from Panasonic, nothing cheap about it, metal cabinet, screwed together and with a bloody decent screen on the back of the unit, but even with all this as noisy as a junk yard dog on a good day!

Even moving the unit to other mains outlets did nothing, boy did this throw some junk up the house wiring. There is no local radiation as running it from a UPS there is only noise (the same noise) within a few inches of the mains lead and the back area where the PSU is located, so it is not the “item” that radiates but it is throwing QRM up the mains lead into the house wiring.

Anyway I have fired off an email to Panasonic detailing what I have found and I am awaiting a reply. Hopefully something will come of this, in the mean time I just leave it switched off until I need it.

Probably a good thing as I have read some reviews on web sites and someone noted that on standby they consume 75 watts! What the hell for, the front display? If it needed 75 watts to display the clock I would be able to see if from another town it would be that bright! Below are some screenshots of the noise so you get the idea of what it looked like on the Perseus spectrum and waterfall displays.

Narrowed in on the center where it was strongest.

A view of the lower part of the spectrum with the peak.

Zoomed in to see the noise in all its glory.

A waterfall view of the same spectrum

The audio component of the QRM from the microwave.

73

Having some late starts has its advantages when it comes to LF DXing. This morning I was not needed in the office until 9am which meant some time having a look around the MW band for some US and Canadian stations. Don’t get me wrong I am up with the birds so if there is DX about at 6am then I am there to catch it! The sprogs do not as yet understand what a laying means …

I normally like to check 1010 KHz and 1050 KHz as both are pretty strong to me on the loop, well I was rewarded well this morning, Perseus was showing very strong carriers on all the 10 KHz channels across the MW band.

CFRB and WWZN were like locals to me. Pretty amazing to think that the 1.1 meter ALA330S loop was working that well! It’s not designed for MW DXing as the gain falls off below 2 MHz but even so – the recordings I’ve made this morning show that even at 8.45am they were still very audible. Much more so that the inverted L that I have up which is swamped by locals the moment the sun rises all trace of TADX more or less vanishes, whereas the loop is still going strong. That is one area that the wideband antenna and the Perseus are made for each other – showing the 2 MHz of the LF end of the spectrum at one time in waterfall mode allows you to spot the TADX a mile off.

With this in mind and what it seems a new aspect to my Perseus listening I have decided that father Christmas is bringing me something better for TADX – the ALA100 – this large aperture loop looks ideal for my QTH and would allow some lower frequencies to be DX’ed a little better. The ALA330S is great for UTEs higher up and to some extent the LF bands and the inverted L works very well all over, but the reviews of the ALA100 make it very tempting. I know what I will be doing on the 25th December this year! With the turkey in the oven cooking away I will be running some more RG58/U down the bottom of the garden to my new toy.

The TADX mp3 recordings are below; they were made at 8.43am and 8.45am. Most remarkable from my modest setup considering it was pretty much daylight by then.

CFRB-WINS1010.mp3 (4.58 mb)

WWZN_AM.mp3 (942.49 kb)

73

When looking at running a random wire of any length the question of if to use a balun or not always comes up. Since they appeared in the early 90’s people have raved that feeding a random wire with a balun and coax is much better than bringing the feed line into the house where the QRM is much higher. Remembering back in the 90’s when there was not that many noisy plasma TVs or switched mode laptop PSUs or even the dreaded PLT using a random wire and bringing it into the shack via the window frame never seemed an issue. Fast forward to 2009 and with all the noise generated in a modern shack means that a coax fed antenna does have many advantages.  I am not going to enter into the variable resistance of random wires across HF and is 4:1 better than 9:1 – there are many sites on Google that cover this subject with much greater flair in technical depth that I could ever hope to.

Going back 15 years I was at a rally where the RF systems HF balun was for sale – and after reading some “spin” about the product and then seeing that in the very noisy hall signals were in fact not so masked by noise as at other stands where the antennas were directly fed into the radio. This stand was using a balun and a direct feed side by side where you could switch between them. Most interesting to me at the time! I had my first HOKA Code30 and a PC and a very nice (at the time) 17” screen – all which generated a larger amount of QRM than I really wanted. Enter the RF systems balun. A quick £40.00 later and I was the owner of a very small round item that would cure my shack noise on HF, wonderful!

A quick change in antenna layout at the QTH meant now my 40meter wire was fed with the balun and at the time some pretty decent double screened RG58. Quick tests showed that it was better, and yes the noises that splattered about HF were in fact gone! Well worth that hard earned £40.00. And has ever since then worked very well from QTH to QTH my trusty balun has always fed the random wire into the shack. 

This brings about today’s thinking - is my RF systems balun the best there is? Are there better baluns? Could I change it and notice a difference? Well they are some very good questions I asked myself! And you too should be asking yourself! Could my balun be good but could it be better?

A Google for baluns and peoples comments led me to have a look at the Wellbrook UMB. Now these are just a little more money than the RF systems balun but and it is a big but. I am so impressed with my Wellbrook ALA330S that I was already convinced that if they can make a loop that good surely they could make a better balun?

A quick search on eBay and volia! I was the proud owner of a Wellbrook UMB. Comparing the two physically the RF systems balun has an SO239 one end and a twisty on pole/stud the other end for the antenna, the UMB has a BNC (ugggh) coax connector and two twisty pole/studs for earth and the antenna.

Swapping the first balun out for the other was easy, I already had an earth running up to the body of the SO239 on the RF systems balun which was unwound from the coax and then connected to one pole of the UMB and the antenna swapped over to the other connector. The coax was terminated with a PL259 and not wishing to unsolder this I used a SO239 to BNC adaptor – I know not ideal but it was a test ok!

Before the change over I took three screenshots from Perseus with a spread of signals around LF and MF which I always find are a good test. I’ve added the screenshots in order which are before and after. Have a look and see what you think. I’ll do some more tests later on with the HF bands when there are actually some signals to test against. QRM wise I am pretty lucky that a quick sweep of HF shows they are more or less identical in the reduction of the local noises I have here.

Medium wave 1.6Mhz spread RF systems balun. (fullsize in the gallery)

Medium wave 1.6Mhz spread Wellbrook balun. (fullsize in the gallery)

If you check the qallery you'll see the rest of the screenshots taken this morning.

73

A great source of information for all shortwave DXers is the ITU website. This has been updated with new monitoring reports. Visit http://www.itu.int/ITU-R/terrestrial/monitoring/index.html and pick your format you wish to view either a zipped DBF database or a PDF summary.

SUMMARY (ZIP DBF format) SUMMARY (PDF format) Monitoring Period Date of last update

323                                     323                               01.07.09 - 30.09.09 18.08.2009
322                                     322                               01.04.09 - 30.06.09 18.08.2009
321                                     321                               01.01.09 - 31.03.09 18.08.2009

Enjoy.

The receiver test data table located at Sherwoods website has been updated to include some new figures for the Perseus. The figures are very impresive considering that the Perseus SDR is around $1000 to purchase! Have a look at the current table here.