Bell System Techical Journal now online

The complete Bell System Technical Journal from 1922-1983 is available on line and searchable. See
http://www.alcatel-lucent.com/bstj/ .

G3XIZ testing on VLF overnight tonight

Chris G3XIZ will be active on VLF again this evening and overnight on 8.9766616kHz although the start time is not yet known. My VLF on-line grabber is already on in readiness, as is the grabber at G3ZJO. Chris has recently been improving the match to his VLF loading coil and antenna and is working on a new variometer.

Optical Comms DX

The latest RSGB news reports that G8CYW and G8KPD have set up a new UK record for optical DX over a distance of just under 90km in NE England using SSB and FM with a design that appeared in a recent RadCom.

10m WSPR

10m WSPR reports (5W to a halo)

Another good morning on 28MHz (10m) today with WSPR reports from 4 different Australian stations plus RA9 and G's by tropo (I assume at 250km).  I was also copying VQ9JD on WSPR.

Transequatorial 70MHz QSO

SV2DCD and ZS6WAB have had the first ever 70MHz transequatorial (TEP) QSO on 70 MHz. It has also been announced that Namibia now has access to the band. Watch the video.

Earth mode VLF tests with E-field probe RX on car

As an experiment today I rigged up an E-field probe on the car to try to do something similar to LA3EQ's earth mode tests of the last few days. Instead of WSPR I used QRSS3 on 8.76kHz putting my usual 5W into the earth electrodes (one connection to the copper pipe ground and one at the bottom of the garden 20m away). The E-field probe consisted of my 1.5m long whip into an MPF102 source follower feeding a 2N3904 emitter follower with roughly the same arrangement as the PA0RDT E-field probe. The probe was attached at the top of a 2m long PVC pipe poking out of the rear window vertically. The actual E-field probe was powered by an internal 9V battery and was mounted about 1m above the car roof.

With the laptop PC running Spectran on the front passenger seat I was able to drive around and glance at the screen whilst moving. In the village there was a reasonable copy of the signal but outside of the village I only managed to get a couple of places 1km apart where the signal was strong enough to copy. One was at 2km and another at 2.1km. Compared with a loop on the ground at the same spots last year the signal was at least 10-20dB weaker. Although I am getting reasonable copy of the 11905Hz Alpha beacon the signal level is around 10dB down on the level on the 80m sq loop at home. So, maybe the E-field probe can be improved still.

In summary, with utilities assisted earth mode, for that is what the propagation is, the car mounted E-field probe is, as yet, nothing like as effective as a loop for RX.

I'd like to rig up some way of driving along with a horizontal loop attached to the rear of the car about 0.5m above the ground. This way I could drive around the local area and log where copy is possible. Presently I have to get out of the car with the loop to take a measurement when doing earth mode tests.

So, a useful test even though the results were not outstanding, or even good :-)

WSPR at VLF

Seeing Jan LA3EQ's recent 4km earth mode tests with WSPR at VLF I must pass on something I'd forgotten about.

WSPR software is able to transmit a WSPR signal at least to 22kHz just by selecting the TX frequency to the chosen frequency. For example, if you want to send WSPR at 8.970kHz just select the band as "other", set the dial frequency to 0.000kHz and set TX frequency to 0.00897kHz. Listening to the tone it definitely is at the frequency stated.

What I haven't determined yet is how high the WSPR software will decode at. When I tried WSPR some time ago on 8.97kHz I used my up-converter and FT817 as the receiver. When I tried to decode directly at 8.97kHz today (setting the RX PC's dial frequency to 7.470kHz) it did not decode.

Bank bonuses - direct action Dutch style

Being really VERY annoyed with the size of totally unjustified bank bonuses in the UK, I was amused to read this article which proves that peaceful and non-violent "people power" can work. No need to spray paint on banks (pointless and unhelpful), just threaten, en mass to withdraw your money.

http://www.guardian.co.uk/business/2011/mar/27/dutch-bankers-bonuses-axed-by-people-power

A 100W PA for VLF use

BK Electronics in the UK make a range of MOSFET PA units with built-in toroidal power supplies. They have a 100W unit for £53, which is very reasonable for a built and tested unit. I believe these units work to 137kHz with a small modification and they would be ideal for 8.97kHz VLF use. There are versions up to 1kW, but these are quite expensive.

See http://www.bkelec.com/Modules/Amplifiers.htm

Easy mistakes

On Monday night I was looking for Uwe DJ8WX again on 8.97022kHz.  To my great surprise I copied nothing when G3ZJO and M0BMU were getting good copy. I'd copied Uwe several times before. After suspecting my PC sound card was faulty, I found out why I copied nothing tonight: on Sunday I'd retuned my loop ATU to copy M0BMU on 500kHz and I'd forgotten to retune it back to 8.97kHz. Although Spectrum Lab locked onto GBZ OK, the sensitivity was about 20dB down! We learn by our mistakes.