LW NDB Beacons

It has been raining much of the week and I have spent the last few days with a heavy cold, so as going out wasn't going to be an option, I spent the time building a loop antenna for long wave. I used an old MW prototype and simply extended the wire from 13 turns to about 25. In order to cover both the LF broadcast band and the NDB beacon band, I needed to add a switch that kicked in an extra 940pF of capacitance to reach right down to 153 khz and allow me to receive Deutschlandfunk and France Inter, the latter being a station I am growing to really like.

 The MRV aero NDB at Merville (Calonne), France

which I have logged several times from my QTH

here in Torquay.

My first few hours of beacon experimenting were disappointing and I was barely able to receive the "EX" NDB here at Exeter airport (only 19 miles away!). But I soon realized that despite the DX394 being VERY sensitive on the LW broadcast band and both the MW broadcast and marine bands, it is all but useless on the bit inbetween ie from 250khz to 500khz. As soon as I swapped over to my Sony SW7600GR things improved enormously. I inductively coupled the Sony with the loop by simply sitting the 7600GR inside the loop with no direct connection to the radio, and this is working wonderfully.

I have logged dozens of beacons from as far afield as Belgium and Northern France, with my best "DX" so far being the Mackel NDB (MAK) near Ghent at a daytime distance of 311 miles. Considering these beacons are low power in the 25 watt range, I think this is great.

I am too tired to post a photo of the loop tonight, but when and if the sun comes out I shall try and take a nice shot of it now that I have spent the afternoon tidying it up and revamping it a bit. At first I simply added the extra turns needed for the LW band over the top of the windings already on it for MW. But after I unwound that mess and did it properly the capacitance dropped significantly requiring more turns and yet still extending the coverage significantly. It now tunes 150-200khz with the extra  940pF switched in, and 230 to 860khz with it switched out.

In order to make use of the gear I already had in the shack and not buy new stuff, I tune both sections with both an AM radio capacitor salvaged from an old radio, and a vintage radio capacitor brought for 20p from the Wooton Bassett Vintage Radio Rally last year.

So altogether the loop cost me, ahhh let me see, 20p!!