Simple 136kHz beacon TX

Francis F6HSI very kindly sent me a "divide by 26" module based on a small micro-controller. With this I've built a small beacon transmitter for 136kHz (QRSS3 or 10wpm CW) by dividing down from 3560kHz, the QRP calling frequency on 80m. At the moment it only puts out 250mW and, with the earth electrode "antenna" used, the ERP probably considerably below 1uW.


Using my 20m spaced earth electrode "antenna" on TX and with a PA0RDT designed active antenna with a 19 inch whip antenna feeding into the (deaf) FT817 I could copy the 10wpm CW at 0.4km across the fields.

New VLF DX record today: 5.6km on 838Hz earth mode

Today I resumed my VLF earth mode tests using 4W into 20m spaced earth electrodes. The aim of the test today was to determine the absolute maximum range possible by utilities assisted earth mode. Best result was 5.6km along Commissioner's Fen to the west of Burwell. Signals were just copied at this distance using the 80cm 30 turn loop and preamp into the PC running Spectran. A test a 6km resulted in no detectable signal.

An amateur solar plane "satellite"?

Recently, Qinetic managed to keep a solar power plane aloft for 7 days using its onboard navigation to keep it over a fixed location and using solar cells to top up batteries to keep it flying at night. Could such solar powered flying devices could be used as "satellites" flying a few miles above the earth to support amateur VHF/UHF repeaters and experiments i.e. a more sophisticated version of balloon experiments?  See http://www.bbc.co.uk/news/science-environment-10664362 .

More 8.97kHz operation from Germany

Just seen this post on the LF reflector from Horst DO1KHS/DI2AN :

"As you know I am planning tests on Dreamers Band from 24. July 2010 on our fieldday at Erpeler Ley, JO30ON.  I will install a 800m earth base. Possibly there is a chance for me to leave the near field. So watch out for my signal.  Beside that there is much space for near field test. So I can compare my vertical antenna with the tv transformer to the big earth base. I will be online there via UMTS so I can give you the details here in the reflector."

So, some further 8.97kHz operation from Germany next week. More details of power, mode etc expected next week but he is expecting to run 100W with QRSS600 and plain carrier.

70MHz, Icom and Yaesu

There are now approaching 40 DXCC countries granting access to the 70MHz (4m) band and further countries are granting access every few months it appears. See  http://www.70mhz.org/bands.htm.  I do hope that some of the commercial "big boys" such as Yaesu and Icom start to make VHF multimode rigs that include 4m in future. It can't be too difficult to add this band. Apart from the latest ChineseWouxun FM handportables (see  www.wouxun.co.uk) and ex-PMR units, only the FT847 has 70MHz coverage. Imagine how operation on 4m SSB/CW would take off if Yaesu's FT817 successor has 4m coverage as well.

Technology Page

The Tech the Future page has an interesting mix of articles on new technology and is worth a read from time to time. See http://www.techthefuture.com/

6m northern Es opening

Just took a look on 6m this evening and heard several northern beacons (GB3RMK, GB3LER, OY6BEC) and worked GM8IEM in IO78 square way up on the north of Scotland followed by GM4DZX in IO88 on CW.  Nothing else about, but this sort of opening to more northern areas is common at this time in the Es season.

Fabulous noctilucent cloud image

Check out this image of a noctilucent cloud formation. See http://www.spaceweather.com/swpod2010/10jul10/CROISIER-Alexandre1.jpg

Soundcard based VLF receiver

SM6LKM has a very neat sound card based VLF receiver ideal for listening to sub-9kHz ham signals and SAQ on 17.2kHz. On his website you can download the files and instructions.

Noctilucent Cloud storm

Recent nights have been good for these high altitude night-time visible mesospheric clouds which return strong microwave echoes, so should be good for 10GHz super-DX. See www.spaceweather.com

NOCTILUCENT STORM: Last night, sky watchers in Europe witnessed the finest display of noctilucent clouds (NLCs) so far this year. Electric-blue tendrils spread as far south as France:"I could see the NLCs from my window," says photographer Alexandre Croisier of Brittany, France. "So I rushed down to the beach to take this picture--a 6 second exposure with my Canon 350D.  

In England, the same display stretched from horizon to horizon. "There was quite a lot of detail visible, including swirls and tiger stripes," reports Mark Jones of Leamington Spa, UK. Even city lights did not overwhelm the NLCs. "I had no trouble seeing them from southwest London," says onlooker Maurice Gavin.

July is often the best month of the year to see these mysterious clouds. High-latitude sky watchers should be alert for electric blue in the nights ahead.

iPhone electronics toolbox app

http://www.iphone.roskosch.de/electronictoolbox.php has a useful app for the iPhone (and Touch?) which allows you to carry out lots of useful electronics calculations.

Tour de France - live action

On our way through Burgundy today we got diverted because of a roadblock at St Fargeau which turned out to be because the Tour de France was coming through. We were able to watch the whole "circus" coming through over about 2 hours and took some great pictures and video clips from about 10m from the  racing cycles. I'd no idea that, before the riders came through, there are loads of vehicles throwing goodies to the waiting crowds. I managed to catch a Frisbee that my grandson will have when he next comes to stay. Great fun and an opportunity to be part of the real French experience, purely by chance.

French food

Being in France currently it gives me a chance to try some good, and inexpensive food. This evening we've enjoyed a first class 4 course meal with wine that was superb. Carpaccio (marinated raw beef with a pear sorbet - tastes wonderful) followed by Loire fish, cheeses, and a delicious sorbet and tart and good coffee to follow. Tomorrow there are a few more chateau visits. I can recommend Logis de France as good value places to stay and eat.

Miracle Whip Yahoo group

Many years ago now I started a Yahoo group for people interested in the Miracle Whip and similar antennas. Amazingly the group now has over 1200 members.  Opinions vary about the effectiveness of the MW - in my opinion it is a compromise antenna that is inferior to many simple whip antennas - but it is easy to tune and with a counterpoise or reasonable ground does allow DX contacts on all modes when conditions are decent. See http://groups.yahoo.com/group/miraclewhip/ .

French wedding

These last few days we've been enjoying our son's wedding in Brittany, France where the weather, company, food and wine have been great. Unlike an English wedding, this one has taken 3 days to get through! Great fun though with a day dedicated to eating crepes (pancakes) yesterday followed by a siesta in a meadow under the oak trees!

Solar flux levels

We're now months into cycle 24, yet the solar flux levels are showing little signs of rising much: they're still in the mid 70s only and the sunspot count is below 20. Recent predictions have suggested it's going to be a very weak cycle and events so far confirm this. However, the sun throws surprises and in 6 months time the picture may be better. We can only hope. See http://www.solen.info/solar/

300m long kite antenna for VLF transmission

Stefan DK7FC has now received permission from the German authorities to use a 300m long kite antenna in daylight to transmit below 9kHz. With this antenna, 200m longer than his previous one, he should be able to run up to 16mW ERP which is 10dB more than when he lasted tested on 8.97kHz. A stronger signal should allow more stations to copy his signal.

GQRP Limerick Sudden kit

The GQRP club (subs £6 per year - excellent value) is now selling the Limerick Sudden kit. This is an improved version of the classic Sudden direct conversion receiver for various single HF bands. The cost includes everything you need including battery , knobs and case. See http://www.gqrp.com/sales.htm. Members Price - only £34.00 (Non members £40)

Supporting MS research by skydiving

A young friend of ours, Josie, has multiple sclerosis (MS) very badly and it has devastated her life in many ways. Undaunted, yesterday Josie did a skydive to raise money for the MS Society charity. So far she has raised over £1500. She is so plucky. If you care to give something please visit http://www.justgiving.com/Jo-Hardiman. Two others in our family have had MS, one of whom died a few years ago. It really is a most awful condition that robs, mainly young people, of their hope and future. Josie's uncle was Len G4IRZ.

Not quite QRP - the Haiku Omega VLF transmitter

Jim M0BMU has posted a link on the LF reflector to a site showing the Omega beacon antennas and transmitter at Haiku Valley in Hawaii. This very accurate beacon system operating just above 10kHz. It has now closed being largely replaced by GPS. My house and entire garden would fit twice in the room shown as "the dummy load room".

VHF NFD next weekend

Next weekend it is VHF NFD so there will be a good opportunity for some QRP DXing on the VHF bands. In past contests I've managed to work way up to Scotland from here with just a small halo and 5W. This sort of DXing sometimes requires going on to CW to complete contacts though. Best times, ignoring conditions, are usually early Sunday morning as the sun is rising, when tropo conditions are good, or late in the contest when stations are looking for new stations to work.

Kanga Products kits

The well known range of QRP kits from Kanga are now available again in the UK. These include the FOXX3 transceiver and the Sudden receiver. See the Kanga Products UK website.

Live 8.97kHz transmission from Germany

DK7FC is transmitting now (0800-1100z) on 8.97KHz. His signals are visible on his 8.97kHz grabber . Stefan is testing further improvements to his earth electrode antenna. The message is very clearly "73" sent in DFCW 600.

Nuclear submarines + UK Trident nuclear deterrent

There's a programme on BBC TV tomorrow about the design and building of the UK's latest nuclear submarine. The preview said that each costs 1 billion UK pounds to build!! Couple this with the 100 billion pounds we are likely to spend on upgrading Trident nuclear weapons and we are talking about a huge amount of money.  I find these sums on such weaponry obscene and plain wrong. If similar amounts were invested in the search for sustainable energy sources I'd be much happier.

More 500kHz WSPRing with the earth electrodes "antenna"

This evening I've again been running my 500kHz QRP transverter into the earth electrodes separated by 20m of wire at about 1.5m above ground only. Reports from M0BMU (69km) and G0KTN (210km) confirm that this is only 6-8dB worse than my spiral top loaded 5m long vertical (i.e. ERP is now between 50-100uW). At the moment the only antennas I have up are a disconnected V2000 VHF/UHF vertical and this earth electrode antenna also used on 838Hz VLF, so the signal is definitely just what's coming from the loop formed in the ground.

German VLF earth mode test: 5.2 km on 8.97 kHz

Stefan DK7FC has been doing some experiments with around 50W to a 300m spaced grounded earth electrode "antenna"  in a remote location in Germany. Today his experiments were successful with his transmission of 30 minutes clearly received on his E-field probe receiver and grabber located in the city some 5.2km away.  See the report on his experiments at  http://www.iup.uni-heidelberg.de/schaefer_vlf/VLF_5km_with_an_earth_antenna.pdf . Stefan can improve the electrode arrangement and increase current into the ground as well as run up to 500W. He's hoping to see the signal on the DF6NM VLF grabber located 174km away. If successful, this would be the first reported amateur radiated VLF DX using earth electrode antennas.

VLF Earth Mode: 5.25km DX today with 4W

This evening I repeated my visit out in the fens with my loop seeing how far I could copy my 4W 838Hz beacon. After getting good QRSS3 copy at the same location 5.1km out as 2 evenings ago, I then tried going further out along the same fenland drove road. Although I managed to copy the signal at 5.25km this evening, no copy was achieved at any greater range despite travelling along several different lanes in many different directions. I'd like to know what it is in the roads that is helping - I assume water pipes, but it could be gas pipes or buried cables. What is clear now is that without these, the signal is absent more than 0.5km from home. This time I tried looking for the signal in far more places about 4-6km to the north of the village, but there was no trace of signal in this direction. Best directions are west (fenland peat) and south (chalk uplands). I've still to test to the east.

Another future test will be to try receiving the signal with a second pair of earth electrodes instead of the loop at some distance from home as one might expect stronger signals. This test will have to wait until the weekend though. If similar to results close to home, the 50Hz noise will be much worse though and this may prevent reception unless very quiet spots can be found.

Another beautiful QRP transceiver from AA1TJ

Menos es MAS is another fine QRP transceiver design from Mike Rainey AA1TJ. This really is about as simple as an HF transceiver gets with reasonable performance and QSOs in his log to prove it.  I like Mike's technique of using a development board to knock circuits together. This approach is fine for lower HF bands.

Earth Mode DX map

This map shows the places round and about my QTH in Burwell (JO02DG) where I was, or was not, able to receive my 4W 838Hz earth mode signal in tests on June 21 and 22nd. Red dots here show attempts that failed, i.e. no signals detected, and green dots show where signals were successfully received and recorded. Best DX was 5.1km, but further is certainly achievable on QRRS3 with "utilities assisted" earth mode i.e. where ground coupling is enhanced by buried pipes and cables. Best DX with 4W into the 20m spaced earth electrodes using purely induction seems to be around 0.5km.

136kHz using the earth electrode "antenna"

This evening I was able to copy G3XIZ on 136.5kHz CW at 559 using my deaf (at 136kHz) FT817 fed from my 20m base earth electrode "antenna" used on VLF. I've made a recording and emailed it to Chris who is 46km away from me. Later this year I hope to transmit QRSS or CW on 136kHz, but the antenna needs some thought as I don't have much space.

Earth mode VLF DX now 5.1kms

Today I managed to copy my 4W earth mode 838Hz signal at a range of 5.1km. QRSS signals were so strong that I was able to copy by ear my 10wpm CW beacon too! To copy the 10wpm signal I needed Spectran running with narrow bandpass filters. Without the filtering, all that could be copied was 50Hz noise.  At this range the signal level is definitely being helped by conduction through pipes in the roads and the main propagation is not by induction. Lots more information as well as screen shots and recordings on my sub-9kHz webpage.

VLF Earth Mode: 3.6km DX today with 4W

My earth mode VLF DX increased to 3.6km today using QRSS3 and a PC running Spectran. TX was 4W into 20m separated electrodes in the ground. TX frequency was 838Hz. The 80cm loop and preamp receiver were set up in several places well out of the village in several directions and results well exceeded my expectations. Lots of information on my earth mode webpage including screen shots and sound recordings made using Spectran when out in the field.

This screenshot was from the roadside 2.5km south of the QTH. Signals were so strong (30dB S/N) that the signal was audible when Spectran's BPF in circuit (lots of 50Hz hum without).

More 500kHz weirdness

Today I experimented some more with 500kHz WSPR using earth electrode pair arrangements rather than conventional antennas. In the end I was still getting reports from 210km away when using around 100uW ERP (maybe less) from a loop consisting of an earth rod outside the back door connected to about 7m of wire back to the bedroom with the other connection going to the central heating radiator. Why this works I have no idea! My latest theory is that this small loop is acting as a coupling loop to local overhead phone wires. I can't see otherwise how this "non-antenna" can otherwise work.

Stable audio frequency tone generation (for VLF QRSS)

Next week I want to try QRSS3 with my earth mode VLF system to extend the range. As in the test this week,  Spectran software will be used my PC to filter and decode it. For a stable source I'll use a crystal and divide this down to sub-9kHz. Looking around for a suitable simple circuit I found G4HCL's very simple 1750Hz toneburst circuit which uses a 455kHz ceramic resonator (pulled slightly) and a 4060 IC as a divide by 256. With a crystal instead of the ceramic oscillator this should be perfect if followed by some filtering to produce a decent sine wave output. See M1GUR's page for more details.

Earth electrode loop effective area at 500kHz

From some measurements of my earth electrode "antenna" this evening and some estimates of the ERP calculated from received field strengths 69km away, I've received an estimate of my effective loop area including that part that is within the ground. This was calculated by Rik Strobbe OR7T as 70m^2 in total, suggesting some 20m^2 of the loop was within the ground. These were Rik's calculations:

"Assuming

- 50uW ERP

- antenna is traded as a loop (gain = -0.4dBd)

Due to the negative gain (-0.4dB versus dipole) a loop antenna must "radiate" 55uW to get 50uW ERP.

Since the antenna feeding current is 0.15A the radiation resistance is 2.44 milliOhm (R= P/I^2)

The radiation resistance of a small loop is : Ra = 320xPi^4*A^2/L^4

where A = loop area (m^2) and L = wavelength (m)

For 500kHz Ra = 5*10^(-7)*A^2 or A = 1416*sqrt(Ra)

If Ra = 0.00244 Ohm then effective the loop area is 70m^2"

Diagram of my earth electrode antenna for 500kHz and sub-9kHz

This is a hand drawn diagram of my earth electrode antenna for 500kHz and sub-9kHz. On 500kHz WSPR this has managed to TX a signal as far as G0KTN who is 210kms away when using my 5W QRP transverter. Sub 9kHz my 4W TX is audible by ear at 0.5km range on an 80cm loop.  This is a totally "stealth" antenna that is not visible at all to anyone looking at the property.

Balloon SSTV from 30kms

From the Southgate News page:

Ed M0TEK and James M6JCX bring news of an amateur radio Slow Scan TV transmission on 434.075MHz USB that'll take place from a high altitude balloon at 30km on Thursday, June 17.
In addition to the 434.075MHz USB SSTV transmissions there's another telemetry beacon on 434.650MHz USB.
At high altitude the balloon may be receiveable by stations up to 300 kilometers away.
Ed and James write:
Just to announce that there is going to be a balloon launch Thursday, June 17, from Churchill, Cambridge at ~ 11:00BST. Onboard will be Nova 18 consisting of the CUSF Ferret tracker and a school experiment and also there will be Pegasus VII a SSTV payload. Normal flight profile is expect, burst altitude just over 30km landing just South West of Milton Keynes.

Screengrab of 1.8kHz earthmode transmission today

Today I modified my VLF TX so it could send either a 10 wpm or QRSS3 beacon signal. I also went out into the fields with my loop/preamp and a PC with Spectran to receive it. For the first attempt with a PC I went 0.3km away from home where the 4W signal from the earth electrode "antenna" could clearly be received by ear. With Spectran I could read the 10wpm CW signal with 20dB S/N in a 12Hz bandwidth, if my understanding of the Spectran settings is right. There is an audio recording here so you can judge the S/N yourselves. This suggests that with QRSS3 and really screwing the bandwidth down I should be able to do much better. My problem is knowing how to calibrate the soundcard etc and clearly I need a more stable source than my free running twin-tee audio oscillator.

500kHz WSPR - without an antenna!

Well, I'm amazed. This evening I connected my 500kHz transverter straight to the two connections of my sub-9kHz grounded electrodes and TXed WSPR. No attempt was made to match anything on the assumption that the two electrodes system looked not too far from 50 ohms resistive as measured between 1-9kHz.. Pout from the IRF510 is around 5W. What happened?

Three people copied me - M0BMU, G7NKS and M0JXM with reports between -21 and -28dB S/N. The wire to the furtherest ground rod is at most 20m long and most of the way it is 1.5m above ground. Once again, this must be acting as a pretty effective loop mostly within the ground.  Screen grab of the WSPR log attached.

So, if you live on clunchy chalk soils like me then don't worry too much about big antennas, :-)

Grounded electrode antenna on 500kHz

This evening I tried listening on 500kHz WSPR using the 20m spaced grounded electrode pair "antenna" in the back garden (earth rods 20m apart). To my surprise I decoded G3ZJO and G7NKS. Both stations were using just 1-2mW ERP. I'm tempted to try this "antenna" (actually a loop formed in the earth) on TX to see if anyone can decode me on 500kHz.