VLF beacon transmitter schematic

G3XBM's VLF 5W Earth Mode Beacon

This is the schematic of my TDA2003 5W ULF/VLF beacon transmitter used in recent earth mode tests. The frequency is derived from a 4.48MHz crystal that is divided down to either 8.760 or 1.095kHz using a 4060 IC. This is keyed in either 10wpm CW, QRSS3 or QRSS30 with a K1EL beacon keyer IC. The output of the TDA2003 is matched to the resistance presented by two earth electrodes using a tapped toroid transformer. Best DX is now 6km across the fenland near me.

Braintree LF/VLF talk slides

The slides from my LF/VLF talk at the Braintree and District Amateur Radio Society on Monday August 1st 2011 are now available on-line. BADARS is a small but active radio club in Essex and I was given a very warm welcome by the members.

10m tropo

Weak signal modes never cease to amaze me. This evening I've been exchanging 5W WSPR reports with G4CUI 173km away near Sheffield on 10m by what I presume is tropo. Running WSPR for hours on end certainly shows unexpected paths popping up from time to time. Even 5W is enough with this mode, and I assume modes like JT65.

If properly exploited by using weak signal modes like JT65 and WSPR 10m could be a great inter-G band even with QRP and small antennas. I wonder who will be the first G station to Work All Britain on 10m JT65 with QRP?

Very accurate QTH locator data

Today I found that my very accurate full QTH locator is JO02DG85VD by looking at http://no.nonsense.ee/qthmap/?qth, zooming in and reading out the 10 digit alphanumeric code. You may want to try and find yours too if you want to know distances from another station very accurately.

IC7000 versus FT450D?

As a keen QRPer I'm usually quite happy with 5W (sometimes 10W) but I'm considering upgrading my IC703 to a newer radio as it is now many years since I've done so.  My main (non-LF/VLF) interest remains 10m and 6m although I quite fancy doing more on 2m and 70cm SSB. With HF conditions unlikely to be great in the coming years (even with cycle 24 peaking soon) maybe a little more power would be useful at times. Also, improved filtering and DSP functionality could be helpful as the HF bands get noisier.

The favourites on my shortlist are either an FT450D or an IC7000 as www.eham.net reviews give both radios good scores and these are feature-rich small radios.  The IC7000 is quite a bit more expensive but adds 2m and 70cms.  I'm wondering if readers can make any recommendations please based on personal experience? The other option is to wait another 6-9 months until the Elecraft KX3 appears.

Finally, in the UK, what is the best deal on these radios? I want a supplier who is likely to be around in 3 years time, a long warranty and the best price!

Goats, rabbits and pigs

Amateur radio activity has been on hold this week as our younger grandson has been here to stay. Today we went to Wimpole Home Farm and he enjoyed making friends with the goats, rabbits and pigs. Here he is trying to get friendly with some very tame goats.

Braintree LF/VLF talk next week

Next Monday, August 1st, I've been invited to share my interest in LF/VLF with members of the Braintree Radio Club in Essex. The talk starts around 8pm and will cover my (dead simple) approach to MF, LF and VLF as well as giving some insight into the recent work in Europe by VLF enthusiasts with both earth-mode and radiated DXing. I'm looking forward to this.

40th Wedding Anniversary

40th Wedding Anniversary Guests

This weekend my wife Lis and I have been celebrating our 40th wedding anniversary with our friends and family. It seems only yesterday we were married! Time flies so make the most of every moment. This group photo shows everyone who attended our afternoon party.

G4ILO's brain tumour

Several readers of my blog also read Julian G4ILO's interesting blog. You may, or may not, be aware that Julian has recently been diagnosed with an incurable brain tumour known as Glioblastoma Multiforme Grade 4 and he is just about to start treatment to slow down its progress. A complete cure is unlikely but modern treatments can certainly help to slow the tumour growth. I'm sure you all join me in wishing Julian every success in beating this. Julian and his wife Olga have a new blog tracking his treatment progress called One Foot In the Grave which I commend to you.

6km DX by VLF earth-mode today

8.7605kHz earth-mode reception at 6km across the fens

My personal DX record for VLF earth-mode (through ground conduction/induction) at 8.7605kHz has been pushed up to 6km today using a long carrier transmission with periodic ID breaks and Spectrum Laboratory software with bandwidth of 11mHz on receive. Transmit power was 5W from a TDA2003 transmitter.

See https://sites.google.com/site/sub9khz/earthmode/vlf-xbm-blog