Receiver for 8.97kHz DX experiments

Jim M0BMU successfully copied signals from DK7FC on 8.97kHz VLF last weekend using a small loop antenna and preamp feeding into a Spectrum Lab soundcard VLF receiver. I've put a copy of Jim's latest preamp on my 9kHz page on my website. Others have tried voltage probe antennas.

Talk Invites

Sharing the real fun of ham radio is important to me and so I enjoy giving the occasional talk to clubs on subjects such as QRP, simple radio fun, WSPR and the like. The Chelmsford ARS has asked me to do one on 500kHz and WSPR in November. Not liking night driving, I'm hoping someone there will offer me a bed for the night.

Litter in the UK

Some parts of the UK appear to have a problem with litter on the roadside verges. In our area this is only collected once every 6 months, so bad areas can look awful after a few months. There are several initiatives to help co-ordinate local "self-help" groups where volunteers go out in groups to tidy up particularly bad patches. See http://www.thebigtidyup.org/default.aspx . I'm hoping to get involved in East Cambridgeshire where I'm sure a few of us can make a difference.

More amateur VLF DX on 8.97kHz

Since I was last at home there have been further tests from DK7FC on 8.97kHz. His signal has been received in Germany, Netherlands, Italy and the UK at better strengths than a week earlier as he managed to get the ERP up a bit more. These experiments are truly ground breaking with amateur signals being successfully received by ionospheric propagation on VLF. See http://abelian.org/vlf/9k/ for some reports from the UK station who received these signals. Jim Moritz M0BMU also received the signals last weekend using a small loop antenna at a portable location near Tring.

Back from (rainy) Devon

Got back from our week in Devon today. Although I packed my VX2 dual band mini portable it only got used to listen to BBC Radio 4 I'm afraid. All week, apart from a couple of brief breaks it rained and rained. There is an old saying, "come to sunny Devon where it rains six days out of seven". As much as I love the county where I, and my ancestors back to at least the 1400s lived, sadly the saying is true! Get good weather and there's nowhere else to beat it. Get a wet week and it's a bit bleak. This is a picture of Bolt Tail in better weather last Sunday.

QRP 2m FM

For the next few days I'm going to stay with my brother in S.Devon. I'll be taking along little ham gear, just the VX2 handportable to see what I can work out /P on the cliff tops. Usually I find activity levels down there very quiet but occasionally I manage to surprise myself by working some simplex DX. The weather forecast is normal for when I go to Devon - rain, then rain and then some more rain :-(  The VX2 is a rather good little 2m/70cms portable - very small and light - but it works better with a decent antenna such as a 1/4 wave whip on 2m, which also works pretty well as a 3/4 wave on 70cms too.

Sub-9kHz NoV application being processed

Rod Wilkinson confirmed that he's received my application today at OFCOM:

Hi Roger,

Many thanks for your email and you will be pleased to know that your application has arrived on my desk this morning, I am sure all will be in order.

As mentioned earlier my colleagues have contacted the Met Office but we are awaiting their response, I am afraid this may not be a prompt process.

I will keep you updated as we progress but if you do wish to check on the status please do contact me.

Vy 73

Rod

A WSPR first on 8.97kHz

This afternoon I set up my "earth-mode" station using a pair of electrodes about 10m apart in the garden, one near the house and one at the bottom of the garden. Using my 4W audio amp driven from the WSPR software in the PC I transmitted a WSPR signal on 8.97kHz. With a separate PC at the other side of the house and with 1m of wire as the "antenna" plugged into the mic socket of the PC I went listening for my WSPR signal.  Sure enough, there was my earth-mode transmitted signal at -15dB S/N. Distance was only about 10m but at least the TX, WSPR system and ground electrodes work, so I now can go out into the fields behind my house to look for my WSPR beacon using a decent, sensitive 8.97kHz RX next time. Strictly I need my sub-9kHz NoV to do this test, but as nothing is radiated I doubt anyone will care.

As far as I know this is the lowest frequency on which WSPR has ever been successfully used.

Sub-9kHz NoV application now with OFCOM

The application form and supporting data for my sub-9kHz NoV request are now with OFCOM. The very helpful and supportive man there, Rod Wilkinson G3TXA, says it has to go to the Met Office who need to give their approval. I'm expecting some weeks to pass before the application is, hopefully, approved. In the meantime I've started work on some equipment including a decent receiving system for 8.97kHz.

G3KEV considers 8.97kHz operation

One of the biggest signals, if not THE biggest, on 136 and 500kHz is Mal G3KEV up in Yorkshire. He has very large antennas and good equipment and has worked some very impressive DX on CW. Today Mal suggested he might also apply for an NoV to operate below 9kHz. This was his email to the LF reflector when he talked about what equipment he might use:

If I get time and a NOV for 9 kcs my proposed approach for TX would be an IC 706 on 900 kcs divided by 100/driver chip TC 4427 and a couple of FETS class D for an output of a few hundred watts, designed for 50 ohms, 50 ohm coax to antenna 200 feet away from shack as at present for 137 and 500 kcs.

Use the existing 1/4 wave inv L for 500 plus 2 additional ones same spec all in parallel and base loaded by inductor to resonate on 9 kcs, use existing ground radial system not too elaborate. Antenna height is approx 100 ft vertical and the rest to make up the 1/4 wave is horizontal.

The speculators, gamblers and dreamers might be able to guess what distance I might cover.

Let me compare your figures !!

Assume pwr to be 400 watts at base of antenna.

Using 9 kcs figure for convenience, but 8970 kcs would prob be the qrg

 I expect the experts on the LF reflector will come back with a probable range figure in QRSS100 shortly. It will be many hundreds of kilometres for sure.