6m FT8 RX

Well, I am glad I stayed on 6m FT8 RX last night! In the end 19 USA, Canadian and Caribbean stations  were spotted from Puerto Rico to Nova Scotia. This was just on my V2000 vertical omni fed with CB coax. No doubt better equipped stations will have spotted or worked far more.

This morning I am on 6m FT8 RX. So far, just EU and North Africa spotted.

UPDATE 1018z: So far 42 different stations in 17 countries spotted on 6m FT8 RX this morning.

UPDATE 1552z: 152 different stations spotted so far today on 6m FT8 RX.

UPDATE 1906z:  Currently 217 different stations spotted in just the last day on 6m FT8 RX. 59 different DXCC countries spotted on 6m FT8 RX since Friday lunchtime. Not bad for a simple RX antenna (V2000 omni vertical) fed with CB coax.

Simple pleasures - NOT amateur radio

This was my granddaughter at the Norfolk seaside last week. If it's hot, simple pleasures please.

10m WSPR TX (500mW)

As is usual, I am on 10m WSPR TX again. Best DX spot so far this morning is SQ3XZ (1113km). This is clearly Es.

UPDATE 1550z: 62 spots today by 7 different stations on 10m WSPR so far today.

LF transmissions with ferrite rod TX antenna

A week ago a unique LF test took place in Germany by Marcus, DF6NM.

This morning I attempted to transmit from a small ferrite antenna. It consists of a number of 9 mm diameter ferrite rods, with 7 bundled in parallel. The bundles were stacked with overlap to ~ 35 cm total length, and n=47 turns of litz wire were wound around the middle. Total ferrite cross section is a=4.45 cm^2 and volume V=156 cm^3, weighing 0.77 kg (including the coil). The coil was resonated and matched by several 1 nF high-Q ceramic capacitors.

Under small signal conditions (-17 dBm), the electric parameters at 137.5 kHz were
 L = 0.50 mH, R = 0.62 ohm, Q = 690.

Applying about half a watt significantly increased inductance and losses, and the tuning became sharply hysteretic ("jumpy"). For fine tuning, a small rod was placed at a variable distance beside the antenna.

Then I connected my PA and drove about 25 Watts into the antenna. Losses and inductance increased further:
 I = 1.3 A, U = 867 V (rms), L = 0.77 mH, R = 14.8 ohmn, Q = 45,
with the Q-factor now so low that tuning jumps disappeared again. The central part under the coil became quite hot, so a tiny fan was added which held the steady-state temperature at ~55 °C.

From the induced voltage we can calculate the flux density in the middle of the rod as
 B = U / n / a / omega = 48 mT (rms),
decreasing approximately linearly toward the ends (similar to a small electric dipole). The average Bav=24 mT then results in a dipole moment of
 iA = V Bav / µ0 = 156 cm^3 * 24 mT / µ0 = 3.0 Am^2
which results in a radiated power
 EMRP = 62.34 kohm * iA^2 / lambda^4 = 25 nW.
Thus the efficiency of this transmit antenna is only 1 ppb !

Anyway I attempted to detect the tiny signal on the DL0AO LF grabber, 48 km from here:
https://lf.u01.de
Transmitting on 137.780 kHz (6:29 to 8:22 UT) indeed produced a detectable trace in the QRSS-60 window (below the Slonim Loran line on 137781.25 Hz). Then I attempted to send a 4-character EbNaut transmission on 137.510 KHz, which was successfully decoded with some margin.

Now if that's not QRP... anyway fascinating, considering that the small ferrite antenna might be carried in a handbag, buried in the ground or taken to a cave.

Best 73,
Markus (DF6NM)

Echolink QSO

Just had a very FB QSO with a USA station via a New Jersey repeater using Echolink. This was a chat. He even managed to understand my poor voice!

VLF DX tests with earth-electrode antennas

Stefan DK7FC is transmitting 75W into an earth-electrode "antenna" and seeing if he leaves a trace on the RX at Todmorden in the UK.

"Hi VLF,

I'm sitting in my car while writing this email. I'm in JN39WI96GX and i transmit on 8270.000 Hz with a GPS locked signal generator into an about 450 m long earth antenna using two guide rails as the earth electrodes on both ends. On each end there are 16 (18) massive T-T poles holding the guide rail, providing a super good earth coupling. I measured that they are connected to each other.
The transmitter is on the air since 9:08 UTC running 550 mA with just 75 W DC inout power into my hand warm lossy linear mode VLF PA!

I'm amazed about the low losses! At DC i got 447 mA at 50.9 V. The wire is 0.4 mm diameter so it has 63 Ohm. That means the ground loss is just 50 Ohm !!!! Amazing! And i have no efforts to build up a ground connection here, i just need to connect the wire. Since the wire losses are higher than the ground losses, i can get maybe 2 dB more signal when buying some better wire. I already found a source that offers 0.75 mm^2 100 m loudspeaker cable (i.e. 200m wire)for just 13 EUR....

BTW i even have an ugly old scope here which is battery powered. I can see that the phase of voltage and current is slightly inductive, maybe 30 deg or so. So i could series resonate the antenna with some C. This is for the next experiment...

The signal becomes visible on my grabber now, in 424 uHz and also some bright pixels in the 3.8 mHz window.

I'm going to stop the carrier at 10:08 UTC, after 1 hour. Then i'll continue on 5.17 kHz!
BTW the antenna , if it works like a real loop, is beaming directly to Paul Nicholson ;-)

73, Stefan"

WSJT-X version 2.0 coming

Amateur Radio Weekly points out that there will be some significant changes to FT8 and MSK144 when v2.0 is released, probably around the end of the year. Beta testing has still to be done. This news first appeared on the ARRL site.

UPDATE 1302z July 31st: Title changed. I had it wrong!

See http://www.arrl.org/news/view/significant-changes-in-store-for-ft8-and-msk144-with-wsjt-x-version-2-0?utm_source=amateur-radio-weekly&utm_medium=email&utm_campaign=newsletter

Bob G3WKW has pointed me to the original source http://physics.princeton.edu/pulsar/k1jt/wsjt-x_v2.0.txt

80m WSPR using HAARP antennas and 80kW

Southgate News has a piece about 80m WSPR tests using the massive HAARP antennas and huge powers up in Alaska. This may well be worth looking for.

At one time this was a US government facility, I believe, and the centre of all sorts of conspiracy theories!

See http://southgatearc.org/news/2018/july/listen-out-for-haarp-wspr-80m-transmissions.htm#.W1xyh_ZFzIU

10m WSPR TX

Yet again, I am on 10m WSPR TX (500mW) as the antenna is free. No spots yet.

UPDATE 1340z: 23 spots so far today, all Denmark and Germany.

UPDATE 1834z: FY5KE (7110km) spotted my 10m WSPR beacon at teatime. This is my best DX today.

UPDATE 2010z: 14 different stations have spotted me today. Time to go QRT.

Granddaughter and strawberries - NOT amateur radio

We spent a week in north Norfolk last week on holiday. The picture shows our granddaughter enjoying strawberries with her mum and French grandma. We ate outside most days.