Mixed result on 8.9775kHz today

Earth-mode test results. Distance to "best DX" location 6km NW of TX

Today I tried a few new things:

(a) A larger coil for RX: 12 turns on a loop with a diameter of approximately 3m, that could be placed on the ground.
(b) Transmitting a callsign in 10wpm CW followed by a 60 second carrier.
(c) Trying to pick up the signal at new locations.

Results were mixed:

The larger coil is really no better than the 80cm 30t coil placed on the ground. I was hoping it might be better. Failure!

Although I tried several locations in a new direction (SW) I only managed to copy my beacon signal at one new test location 4.4km away in the village of Swaffham Bulbeck. Tests at a closer location in that direction gave no copy at all. Also tests at 3 more distant locations (max 7.5km) were complete failures with not the slightest hint of anything there.

Much weaker signal copied at 4.4km SW today (nowhere near strong enough for QRSS3)

The trick of sending 10wpm CW followed by a long carrier worked: when the signal was weak it could be copied on Spectrum Lab in narrower bandwidths than I use for QRSS3 as the dash is 20 times longer. This helped me positively ID the signal in Swaffham Bulbeck. On QRSS3 the signal would have been lost in the noise. Best signals appear to be out in the Fens to the NW and to the south (on the chalk hills). I have still to try NE with sensitive kit.

I am still totally puzzled by how the signal propagates through the ground. Placing the loop right over water pipes in the road failed to detect anything where I expected copy at about 4km SW, and the one successful location at 4.4km  SW was on a corner of a road close to some overhead (11kV?) lines but not near water pipes as far as I know. So, I tried other places close to these overhead cables and copied nothing! There must be something that is common to all successful places that is not there helping the signal at other places. I am still trying to think how to find what this is!

I am extremely doubtful of success on these DX tests we are running over the next 24 hours judging by the mixed bag of result very locally. Certainly it will require the very narrow bandwidths to see anything at all from the miniscule radiated component.

KX3 in stock at Waters and Stanton

I read that W&S now has the Elecraft KX3 in stock for immediate delivery. This is a far cry from the 8 month lead-time when deliveries first started.  The supplier is  taking a profit from selling the units, but at least you know the price. My experience when importing kits and parts from the USA into the UK is that the import duty and VAT and Parcel Force "handling charge" (a rip off!) can add a significant amount to the final price, and a degree of uncertainty.

I am still tempted by the KX3. It is many years since I last bought a commercial rig and this one, although expensive, does tick all the boxes: small, 10W, excellent SDR receiver, coverage to 6m (soon 2m), auto ATU, speech processor., etc.

Maybe?

Workmans Broadcast Radio

When I had my kitchen refitted recently, the workmen had one of these radios on the go all the time. I guess they are designed to be rugged and stand a lot of abuse. Theirs was covered in plaster and dried on dust but it still managed to work! They are not cheap and not that small, but I guess it is "horses for courses" as they say.  Any readers used one of these?

Makita BMR-101 Job Site Radio with DAB + AC Power Adaptor (Blue) (Google Affiliate Ad)

32km test on 8.9775kHz VLF

Tomorrow evening, Oct 16th, at 1700z I'm starting a 24 hour continuous carrier transmission on 8.9775kHz using my earth-mode system and 5W beacon TX. The carrier will be dropped for a few hours at some time (not previously disclosed) during the transmission to help later ID.

Chris G3WCD, who is 32km west of me, is trying to see if anything at all is detectable from my earth-mode set-up at that distance. We both do not realistically expect success, but with the ability to look in uHz bandwidths using Spectrum Lab it is worth a go.

If there is anyone else closer to Burwell, Cambs JO02DG85VD who wants to try looking as well, please let me know ASAP. Ideally stations in the 10-20km range.

MF WSPR activity at an all-time high

MF WSPR activity this evening

This evening the 472 and 500kHz bands are humming with WSPR signals and those monitoring for them. At the last count there were 40 stations either on RX or TX WSPR. No great DX so far this evening here with the best report being from an SWL F59706 who is 560km south of me.

Best DX yet on 8.97kHz earth-mode: 6km QRSS3

Today I went out to my usual test sites to check the performance of my latest VLF earth-mode system. For the first time, my RX loop and preamp could be optimally tuned in the field. At 1.6km the 8.978kHz QRSS3 beacon signal was rock solid (see first image).

5W 8.978kHz QRSS3 earth-mode signal at 1.6km (STRONG)

5W 8.978kHz QRSS3 earth-mode signal at 6.0km (10dB S/N in 0.67Hz BW)

I then moved on to a number of other locations eventually arriving at a spot 6km from the 5W TX where previously I'd only ever managed copy with a constant carrier or QRSS30 (30 second dot CW). This time the signal was about 10dB over noise in 0.67Hz bandwidth on QRSS3, my best ever result at this range (second image).

In the coming week I'll be looking for a new RX test location around 7km or further from the home QTH in the hope of increasing my through-the-ground DX record.

500kHz WSPR Spots

Conditions on HF appear to be very disturbed (according to the propagation forecasts) yet I'm getting plenty of WSPR spots on 500kHz. It will be much better when we all get access to 472-479kHz as, currently, activity on MF is split between this band and 500kHz.

SAQ (17.2kHz) transmission Oct 24th

SAQ, the historic alternator transmitter on 17.2kHz CW VLF will be making a special transmission on United Nations Day next Wednesday Oct 24th 2012 starting at 1010 UTC with the message being sent at 1030 UTC.   Reports from this transmission will not be confirmed by QSL card (some test transmissions are  QSLed).  The transmission is a part of the celebration of the United Nations Day in Grimeton, see http://undayorg.files.wordpress.com/2012/09/unday-english1.pdf.

IC7100 for 1 penny??

Amused to see the Nevada advert for the Icom IC7100 on their website. At this price I would expect this high end mobile/home station multimode to be sold out!

Nice price for the IC7100 !

Earth-mode VLF RX kit updated

Today I've been updating my VLF receiving kit ahead of doing some further field tests, probably on Monday. I've now changed my RX loop so that the resonance can be adjusted in the field using a capacitance switch box to bring it to resonance.  The capacitance to bring it to resonance is around 240nF. The loop was about 1kHz off-tune so that the signal was around 4-6dB weaker than it should have been. Now I can tune the loop for maximum S/N in the field and can adjust the loop to a variety of test frequencies.  I've also peaked the 8.97kHz tuned circuit on my earth-electrode receiver input and fixed a faulty connection cable.

Whether these changes will allow me to get any further through the ground remains to be seen.