PA1SDB on VLF

PA1ASB has been active recently on VLF and on his site he has a grabber showing what signals he has/is copying around 8.270kHz  which is the new favoured spot. This is below 8.3kHz and so falls in the unallocated part of the spectrum as 8.970kHz is now within the  spectrum reserved for sferics research.  Most amateur VLF TX stations are now operating around 8.270kHz. Here in the UK I believe it is legal for ANYONE to TX below 8.300kHz  as long as no harmful interference is caused to allocated services above 8.300kHz. This is my view, not a legal statement. I have asked OFCOM to clarify.

Also of note on these pages are the .SDR configuration files for Spectrum Lab software. It is ESSENTIAL to use Spectrun Lab or very similar software to detect anything at any range. See http://www.qsl.net/pa1sdb/index.htm . I suggest that, if you want to build a VLF amateur RX, to base your configuration files on those given on these pages.

My own experience is that 420uHz or less bandwidth is essential to see any trace of amateur VLF signals integrated over many hours. 42uHz is better. In both cases you have to lock to a VLF MSK signal, Russian Alpha beacons or GPS for excellent stability. This is all sorted out with the .SDR file automatically. You may be surprised  how stable a RX you can make very simply.

More VLF activity from Germany

DJ8WX has been experimenting with a new GPS locked frequency source and is trying to put a signal out on 8.9700000kHz.  The signal has been received strongly by several stations including Paul Nicholson in Todmorden and at PA1SDB. This is the signal at PA1SDB over the last few days. Note the timescale on Peter's grabber covers several DAYS. Such is the world of amateur VLF!

Signal from DJ8WX now on 8.970000kHz (was 8.970022kHz)