Short wave DX'ing

[lightning]

l've recently acquired two short wave radios, l remember in the 1990's l had a Philips communications receiver and the shortwave bands were full of activity.

I've tried this week and the wavebands seem
empty.

l thought it was because l was using a small
portable set but even on the Racal there's not much to hear.

l found what sounded like a couple of amateur radio stations on SSB and a few
beeping noises like Morse.

Has SW gone that quiet? l couldn't find any actual radio stations at all. Maybe it's RFI that's killing it?

There's plenty of activity still on MW even on a pocket radio at night, maybe SW is better away from houses and their digital devices.

[Bazz4CQJ]

Originally Posted by lightning

l couldn't find any actual radio stations at all. Maybe it's RFI that's killing it?

There's plenty of activity still on MW even on a pocket radio at night, maybe SW is better away from houses and their digital devices.

You may well have answered your own question. I live in the country but have an S8 noise level across much of the SW spectrum. Check out "magnetic loop" aerials, one of the best known being a commercial product by Wellbrook and then there is the DIY copy called Wellgood - discussed at length on this forum.

B

[Jolly 7]

There are some shortwave stations audible right now if you tune in to the 31 m and 49 m bands. e.g. two stations on 9600 kHz and 5900 kHz are broadcasting in English.

[paulsherwin]

SW broadcasting is much quieter than it used to be. Most European broadcasters have ended their SW services, at least to Europe. Arguably it creates the opportunity to listen for genuine long distsnce transmissions now that the local blasters have closed.

There is radio China, get it everywhere, some of the programmes are quite entertaining in a weird way. Here https://www.short-wave.info/ quite up to date.

[lightning]

Well, that sounds more promising.

l will get one of the aerials recommended above, does it have to be installed on the roof?

[Jolly 7]

A simple and inexpensive longwire antenna is maybe all you need. Depending upon your radios, the longwire can either be crocodile clipped to the telescopic antenna or connected to an aerial socket via a suitable plug. The wire can be retracted when not listening to shortwave. It is easy to make one too.

[Skywave]

Yes, a longwire: as high and as long as you can get it. Try to get its downlead away from buildings as best you can and the fitment of an earth plate buried in the ground with a wire from it to the 'E' or metalwork of the radio sometimes really helps reception.

Al.

[Cruisin Marine]

I had to build a phase cancellation unit to kill all the local QRM, and now the noise is no more than s1 and SW listening is once again enjoyable. Of course you can buy them ready made like MFJ etc.

SW listening is at times quite fascinating as is MW Dxing. Patience is a true virtue though.

[Bazz4CQJ]

Originally Posted by merlinmaxwell

There is radio China, get it everywhere, some of the programmes are quite entertaining in a weird way. Here https://www.short-wave.info/ quite up to date.

IIRC, you are using a Wellbrook magloop I think? I believe they sold at something like £350 originally and I've never heard anyone say they were disappointed with them. Now that the circuit of the (potted) amplifier has been revealed, it's possible to build one (two transistors) for less than £20, depending on what your junk box has to offer, and the PCB is available from George Smart at Wellgood.

An internet search will pull in may other designs for magloops. They can be used closed to the ground (David(4EBT) has his magloop mounted on the back of his garden shed), and it you stick a rotator on, are directional. Moreover, their great advantage is that they are relatively immune to digital RFI.

B

[Radio Wrangler]

They're still directional even without a rotator, but a rotator allows you to change the direction ( Sorry, Bazz) The real value of a loop lies in planting the null on the worst interferer rather than peaking the signal. The peaks are rather blunt, while the nulls are shapr and deep. The limitation is that they work best if you only have one direction of interference (well two at 180 degrees)

Receive loops. particularly if low mounted, are within the scope of those cheapie low-duty rotators intended for FM antennae.

David

[Bazz4CQJ]

Originally Posted by Radio Wrangler

Receive loops. particularly if low mounted, are within the scope of those cheapie low-duty rotators intended for FM antennae.
David

I believe that someone on the forum was tinkering with using a radio-model servo mechanism as a cheaper than cheap rotator. I think he suspended the loop on a wire and the servo carried no weight, but simply rotated the loop. He may have had it located in his roof-space.

B

[ex seismic]

Look also at the Mini Whip, originally done by a Dutch chappie. Two transistors again so simple to make.

gmb

I believe that someone on the forum was tinkering with using a radio-model servo mechanism as a cheaper than cheap rotator.

That's me, I still owe you all a photo of the insides, I the main reason for using an RC servo is speed, easy to get notch using my on screen control. The whole thing is held up from the bottom, no strings attached.

[G6Tanuki]

The SW broadcast-bands are indeed a lot quieter than in times-past: the late-80s/earlly-90s collapse of the Communist regimes in central/eastern Europe led to a big closedown of nsome of the louder and more-intrusive SW broadcasters like Tirana/Bucharest and the sprawling tentacles of Radio Moscow [which had 'Radio Rodinya' - apparently it meant ~homeland~ and was aimed at the Russian deep-ocean fishing-fleets].

This century most remaining Western 'nation-state' SW broadcasters have gone QRT - Radio Nederland's SW service from Hilversum shut down a decade ago.

https://en.wikipedia.org/wiki/Radio_...dio_broadcasts

A few stalwarts continue: Chinese state-broadcasters are always doing their thing; I still listen to the Voice of America for a rounded version of world news, and there are a bunch of religious stations when you need some comedy. The 7.1-7.2MHz slice of the 41MHz broadcast-band in Europe has been reassigned to us radio-hams [so we no longer have to work in the gaps between multiple renditions of Radio Moscow/Radio Tirana!].

If you want some 'interesting' listening, tune from 6.1 to 6.4MHz on weekends; this is where the European free-radio types come up. Think of them as the SW equivalents of Caroline/Radio London which we remember from our childhood.

[ManxDave]

I have been tinkering with a homeade, receive only, passive magloop this last couple of weeks. Basically the main loop is 1m diameter of 10mm copper pipe withe a variable capacitor across a break in it. With about a 25cm diameter pickup loop.I am very impressed with the results on SW.
As well as having to rotate it for best performance, the other difficulty is it needs tuning for each band, hence the capacitor. At the moment I am tuning it manually but hoping to use a stepper motor in future so I can mount the loop remote from the receiver. There are designs for this all over the net including sophisticated ones using arduino etc to remember capacitor positions for each band.
As well as automating the tuning I want to try and get it working down to MW, where it is currently useless and I may try an active design but not sure I need the amplification yet.

[Dave757]

Hi Dave,

I use a similar loop for both receiving and transmitting, also made from small
bore copper tube about 10 to 12mm, also with the coupling loop a quarter of
the main loop , but just slightly less diameter at around 95 cm. My loop will
tune with a capacitance a bit less than 20pf to the top of the 29 MHz band,
but takes nearly 1000pf to resonate it to 3.5MHz. It would take a great deal
of capacitance to tune it to MW, and would not be very efficient. Of course you
could easily try it by adding additional fixed capacitors across the variable.

I have made loops which work pretty well at MW (and lower), by using
4 pair telephone cable on a 1 metre square wood frame, - 6 of the wires connected
in series with the 2 ends connected to the tuning cap, and the other 2 wires in series
connected to the feeder as a coupling loop. Of course you could just use single strand
insulated wire wrapped around the frame.

Good luck with your project.

Kind regards
Dave G0ELJ

[ManxDave]

Thanks Dave
I'll try adding much more capacitance as an experiment but it sounds like your multistrand frame is the way to go for MW. I use something similar for my pantry transmitter, removing harmonics from that will be another thread for the future.

[Bazz4CQJ]

Originally Posted by ManxDave

As well as having to rotate it for best performance, the other difficulty is it needs tuning for each band, hence the capacitor. At the moment I am tuning it manually .

I think I've seen at least one design where someone used varicap diodes to tune a loop. They sent the DC for the varicaps down a separate wire taped to the coax RF line.

B

[majoconz]

Best SW long distance is achieved in the evening from your east and in the early morning darkness from the west and on the lower frequency bands. I get some remarkable signals here in our winter on the 49 and 41 metre bands - and on the 'Gray Line' where it's sunrise in Europe and late afternoon here - huge signals from Romania then Greece and lastly Spain's International service - their transmitter if just a bit west of Madrid - which is just about my 'antipode'.