"Dear LF/VLF group and further VLF watchers :-)
After another very successful, exciting and fascinating /p VLF experiment i want, as usual, thank all the many (>=24) receiving stations who took the time to arrange a suitable antenna/receiver, PC and to watch the experiment and take some interesting captures. The transmissions took place on 2 VLF bands, 33km (8970 Hz) and 58km (5170 Hz).
So, thanks to TF3HZ, SQ5BPF, G4WGT, G3KEV, Daniele Tincani, G3WCD, G3XDV,M0BMU, G3XBM, OK2BVG, OE3GHB, G4AYT, IK1QFK, DL3ZID, F4DTL, OE5ODL, PA3CPM, PA3FNY, DL4YHF, DF6NM, DJ2LF, DD7PC (bold = 1st positive reception on VLF).
Special thanks to Halldor/TF3HZ who wasn't member of this group before but set up a very sensitive VLF receiver and even a most intersting grabber just by my email request. This is the first VLF detection between DL and TF. My signal appeared at up to 15 dB SNR in 4.5 mHz in 2404 km. This helps a bit to get some imagination how far a transatlantic detection is away.
Sorry to those who tried without success this time, like 4X1RF. The next experiment will come soon, maybe in about one month.
So, see you in the 11th experiment. :-)
Vy 73, Stefan/DK7FC'
9 Feb 2011
DK7FC's report on his 10th VLF test
This is an extract of the note from Stefan to the LF-reflector about his tests last weekend:
8 Feb 2011
HamSphere internet ham radio system
How HamSphere works |
User interface is via a simulated HF transceiver presented on the computer screen. The "feel" of the transceiver is remarkably good. Of course, being an internet based virtual amateur radio system, no amateur radio equipment is needed and no RF is radiated, yet the experience is very close to that of operating a real HF radio on the HF bands. For those unable to operate real radios because of planning restrictions or other problems, this system offers some of the fun of amateur radio again. It is like CQ100, but in my opinion better.
The transceiver uses Java technology and simulates all amateur radio bands from 160 to 6 meters. The software, plus a lot more information about this service, is available from http://www.hamsphere.com/ . The software works in Windows, Mac and Linux.
Using the system I just had a QSO with ZS4CCM in South Africa. It felt like a real "on air" HF QSO. It's no substitute for the real thing, but fun to use on occasions and when HF conditions are appalling.
6 Feb 2011
DK7FC copied well here on 8.97kHz
After a few false starts and faulty kit, I managed good copy of Stefan DK7FC's signals on 8.97kHz this afternoon with my loop in the garden and this simple preamp into Spectrum Lab running on the PC. S/N was around 5-7dB in a 4.52mHz bandwidth. He was also copied in Iceland at over 2400kms.
5 Feb 2011
JT65A on HF
Having seen the article on how to do this in the latest edition of Practical Wireless, I have installed the software and taken a listen/look. Main issue seems to be that the AGC in the FT817 is fierce and with close-by PSK31 signals it kills the gain of weak JT65A signals nearby. Anyway, it looks a useful mode. For HF use, download the HF tailored version at http://jt65-hf.sourceforge.net/. Not yet had a 2-way QSO but will soon when I've got the hang of this.
DK7FC/P active on VLF this Sunday
Stefan plans to be out with his kite antenna and around 100mW ERP on the VLF bands this weekend from 0700-1630utc transmitting on 3 frequencies starting with 8.970000kHz. Progress can be monitored on his grabber located 40km from the /P location. I am hoping to copy Stefan on 8.97kHz again as I managed it back in December.
These grabbers will show when he is active:
8.97kHz http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber.html .
6.47kHz/5.17kHz http://www.iup.uni-heidelberg. de/schaefer_vlf/DK7FC_VLF_ Grabber2.html
These grabbers will show when he is active:
8.97kHz http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber.html .
6.47kHz/5.17kHz http://www.iup.uni-heidelberg.
4 Feb 2011
4m transverter - stage 1
4m converter breadboard (2N3904 oscillator and NE602) |
Next stage is to breadboard the TX mixer and buffer stages.
Labels:
4m
E-field probe test on 8.76kHz away from home
G3XBM E-field probe for 8-9kHz |
1 Feb 2011
VLF earth-mode success: G6ALB copied at 3km on 8.76kHz
Spectran trace of G6ALB on 8.76kHz at 3km |
This is the first time I've received another amateur by earth-mode (conduction). The result suggests much further is possible. Experiments continue!
Labels:
8.76khz,
earth mode
PA1B analyses my 137kHz WSPR results
Bert PA1B has done some interesting "reverse analysis" of the WSPR reports I've given people. Working back from these you can estimate the lowest levels (in mW) that they could have used and still been copyable with me. This also gives a good guide to the likelihood of these stations receiving my weak signal. It is clear that M0BMU should be able to copy my 50uW ERP signal frequently (which he does) but that I'd need a lot more ERP to be able to get reports from the PA stations or SM6BHZ. See attached table from Bert.
29 Jan 2011
137kHz transverter update
Breadboarded 137kHz 8W transverter (ERP 50uW from antenna) |
Simple 137kHz QRP transverter - click for larger image |
Labels:
136khz,
137khz,
transverter,
wspr
28 Jan 2011
DRM - a waste of money?
Does anyone know how much the cash-strapped BBC is spending on DRM transmissions on shortwave ? Also, does anyone actually use a proper SW receiver equipped to receive this mode? Surely this mode is a total waste of money.
Labels:
Drm
27 Jan 2011
4m transverter paper design
Today I have been gathering data and information for my 4m QRP transverter and started on an "on paper" design around an NE602 RX mixer, 2N3904 3rd overtone oscillator, 2N3904 driver(s) and a 2N3866 PA. It is surprising how much can be done on paper before you start by referring to datasheets and on-line RF calculators. I'm wondering if my T50-6 toroids will just stretch to 4m.
Labels:
4m
26 Jan 2011
500kHz WSPR - a good evening
A decent set of reports this evening with my 1mW ERP WSPR beacon on 500kHz. Best DX DF4PV's report at 597km. Also I copied Gerhard DI2AF's WSPR beacon (just over 800km) higher up the band on 505.13kHz.
25 Jan 2011
FT817 antenna pin: getting a DC voltage on the inner when on TX.
The FT817 does not have a DC voltage change between RX and TX on the antenna connector, unlike the old IC202. This voltage was very useful to switch PAs and transverters. I now know how to modify the FT817 to add this feature thanks to Chris GM4YLN who sent the link http://www.kolumbus.fi/oh5iy/ HW/Yaesu.html showing one way to make the mod.. Note in this link the FT817 is wrongly called the FT718. An easier to implement link is shown at http://www.bergtag.de/ download/ft817.pdf . Thanks again to Chris for this one too.
Labels:
ft817
4m Chinese Multimode rig and a FT817 successor from China?
There are rumours, apparently with some substance, that a Chinese mulitmode transceiver for 4m may be being designed. This would not be too surprising, although expect some delay between "being designed" and being available in the shops.
Of course, with several Chinese FM handhelds and mobiles now available at competitive prices from 4m - 70cm it can only be a matter of time before a Chinese equivalent to the FT817's successor (yes we are still waiting, waiting, waiting Yaesu!) will hit the streets, and at a knock-out price. It would not surprise me one bit if such a rig appeared before the end of 2011. Once the Chinese realise they have a ready market for quality ham gear then look out Icom, Yaesu and Kenwood as your days may be numbered, seriously.
Of course, with several Chinese FM handhelds and mobiles now available at competitive prices from 4m - 70cm it can only be a matter of time before a Chinese equivalent to the FT817's successor (yes we are still waiting, waiting, waiting Yaesu!) will hit the streets, and at a knock-out price. It would not surprise me one bit if such a rig appeared before the end of 2011. Once the Chinese realise they have a ready market for quality ham gear then look out Icom, Yaesu and Kenwood as your days may be numbered, seriously.
Labels:
4m,
china,
chinese,
ft817 successor
Poland soon on 4m
70.1 - 70.3 MHz will soon be available to the Polish radio amateur service on secondary basis. The maximum power will be 20W EIRP. Date of release still not known yet.
24 Jan 2011
4m transverter
It is almost certain now that my next project will be a 5W transverter for 4m. This is a band I have never used under my own call and for which I have no gear yet. The design should be straightforward transverting to 10m with the FT817 as the driver. I have started a 4m QRP transverter page on my website to track progress of this build.
Labels:
4m
22 Jan 2011
No luck with OE3GHB and G3XIZ on 8.97kHz today
Despite having my antenna and receiver system well optimised and running a Spectrum Lab configuration file allowing very sensitive detection (DFCW6000), nothing (so far) was identified from either Gerhard OE3GHB or Chris G3XIZ on 8.97kHz today. So far, the only station I have "seen" on VLF is DK7FC/P back in December. Since then I've improved the set-up. G3XIZ didn't have his "balloon extended" antenna in place, so he could be several dB stronger the next time he tries again.
21 Jan 2011
Austrian VLF tests this weekend
Gerhard OE3GHB hopes to be transmitting on VLF this Saturday (Jan 22nd) on 8.96995kHz (+/- 0.03Hz) starting between 0800-0900z. Although the chances of copying him are low, I will be monitoring and uploading what I see (or do not see) to my VLF grabber which will be active as long as possible this Saturday.
Labels:
dreamers band,
oe3ghb,
vlf
20 Jan 2011
Optical DXing at around 460THz
Until I read the webpage below I didn't know that the record for optical morse DX goes back to 1896 and was an astounding distance of 183 miles using a Heliograph between Colorado and Utah in the USA. This link about the heliograph makes fascinating reading. The heliograph is essentially a keyed mirror that reflects sunlight and uses it to send morse code over long distances. Modern versions of heliograph mirrors are available on eBay for emergency communications. See for example eBay item 250681260168. A good article about heliographs is on Wikipedia, see http://en.wikipedia.org/wiki/Heliograph.
Modern amateur optical DXing uses either lasers or high intensity LEDs. There is a piece about this on p51-52 of the Feb 2011 RSGB RadCom in Sam Jewell's "GHz Bands" column with further links including http://www.lasercomms.org.uk/index.htm which looks like a useful resource. There was also a funny article in the RSGB Bulletin of April 1962 called "Getting Going on Bottom Band".
Modern amateur optical DXing uses either lasers or high intensity LEDs. There is a piece about this on p51-52 of the Feb 2011 RSGB RadCom in Sam Jewell's "GHz Bands" column with further links including http://www.lasercomms.org.uk/index.htm which looks like a useful resource. There was also a funny article in the RSGB Bulletin of April 1962 called "Getting Going on Bottom Band".
Labels:
heliograph,
laser,
LED,
optical
Dreamer's Band activity around 8.97kHz
In the last few days OE3GHB and OE5ODL have been testing close to 8.97kHz with their signals (from home QTHs) being received at considerable distances across Western Europe. DK7FC was planning his 10th kite VLF test this weekend but has had to postpone this until Jan 29/30 because of the weather. My grabber is currently looking around 8.97kHz and seeing a strong signal, although I suspect this is a locally generated interferer. See http://dl.dropbox.com/u/15047843/xbm_grab.jpg for the grabber as it updates. This is not on all the time, just when I am testing or listening.
Labels:
8.97khz,
dreamers band,
vlf
Corporate Greed
I don't usually get political on my blog, but something has incensed me this week. Goldman Sachs, the huge multi-national finance company, has declared huge bonuses for its staff. In the press yesterday it was reported that their staff now have an average salary+bonus package of $430000 a year! At the same time I've read that they've slashed their corporate charity giving by a large amount. If these figures are correct, then I believe them to be obscene and a prime example of the corporate greed of some big financial institutions. I am not sure how to respond, but want to email their CEO, but haven't managed to find his email address on the swish corporate website! In the end, such greed cannot be acceptable. This is the sort of behaviour that festered revolutions a century ago: the seeds are there for it to happen again within 10 years when the ordinary man says, "no more".
Labels:
banks,
goldman sachs,
quakers
19 Jan 2011
5mW on 80m - best DX 1310km
80m WSPR with 5mW output |
FT817 lowest power setting at 500mW
Do you know, I've only just realised something about my FT817 having owned it for almost 10 years: as someone pointed out to me, the lowest setting on the FT817 is always 500mW whether on an external supply or internal batteries. For some reason I had believed "1 dash" on the display was 500mW on batteries and 1W on a mains PSU. I just checked and it really is 500mW out.
So, my recent WSPR DX spots with 10mW and 1mW were actually at 5mW and 500uW!
So, my recent WSPR DX spots with 10mW and 1mW were actually at 5mW and 500uW!
Labels:
ft817
Reverse Beacon Network
Thanks to Mike Rainey AA1TJ for putting me on to this. The Reverse Beacon Network is a revolutionary new idea. Instead of beacons actively transmitting signals, the RBN is a network of stations listening to the bands and reporting what stations they hear, when and how well. It works by using skimmers to check activity and then uploading spots to an internet database much like WSPRnet for WSPR spots. Using it you can see if your signals are making it to a given spotting location.
Labels:
reverse beacon network
18 Jan 2011
1mW DXing on 40m
Today I reduced the power from my 40m WSPR beacon TX from 10mW down to just 1mW. The FT817 is run at minimum power setting (1W) then via a 20dB attenuator within a few cm of the antenna connector and then into a 10dB stepped attenuator. My antenna is the 5m coax feeder (inner and outer strapped together) up to my 10m halo and tuned via the Elecraft T1 auto-ATU. The first report received at 1436 today was from DC4FS at 523km (-28dB S/N).
VLF earth-mode tests legal without NoV
Today I received a letter from OFCOM, which clarifies the legality of operating so called "earth mode" (conduction/induction via the ground) experiments at frequencies below 9kHz in the UK. In it, the official from OFCOM stated, "We would not normally issue NoVs for communications using non-wireless telegraphy apparatus/stations i.e. where you rely only on conducted emissions and where there are no intentional radiated emissions.".
Wanting to check earth mode propagation behaviour at a series of frequencies below 9kHz to see how results compared (earlier tests at 0.838kHz seemed around 10dB better than at 8.76kHz), I asked OFCOM if I needed an NoV extension to be legal. One could reasonably also argue that such through the ground conduction tests at frequencies above 9kHz would also be legal as long as they don't cause any "Undue Interference to any wireless telegraphy" and one was not intending to radiate.
This sounds a wholly pragmatic answer from a government body.
Wanting to check earth mode propagation behaviour at a series of frequencies below 9kHz to see how results compared (earlier tests at 0.838kHz seemed around 10dB better than at 8.76kHz), I asked OFCOM if I needed an NoV extension to be legal. One could reasonably also argue that such through the ground conduction tests at frequencies above 9kHz would also be legal as long as they don't cause any "Undue Interference to any wireless telegraphy" and one was not intending to radiate.
This sounds a wholly pragmatic answer from a government body.
Labels:
earth mode,
nov,
ofcom
17 Jan 2011
PA1B's QRPp website
Whilst looking at the links on PC4T's blog I noticed Bert PA1B's excellent website all about QRPp operating with lots of tips on how to produce mW power levels and have real fun on the HF bands.
This has encouraged me to have a go, so I am currently WSPR beaconing on various HF bands using 10mW out from the FT817 via a 20dB attenuator right next to the rig.These were the results from 40m late this afternoon and into the early evening. Encouraging!
This has encouraged me to have a go, so I am currently WSPR beaconing on various HF bands using 10mW out from the FT817 via a 20dB attenuator right next to the rig.These were the results from 40m late this afternoon and into the early evening. Encouraging!
Best DX 983km with 10mW in just a few hours! |
15 Jan 2011
136kHz RX activity
In the last few weeks I've received 136kHz signals from several different countries and stations:
DK7FC/P CW/QRSS
DF6NM QRSS
G8IMR WSPR
M0BMU WSPR
PA0A WSPR
SM6BHZ WSPR
Certainly my receiving system is now up with the best since adding the tuned preamp. My main drawback is the TX/RX loop's directionality which reduces signal levels in a N-S direction. We just need a lot more stations active on the band, especially on WSPR.
DK7FC/P CW/QRSS
DF6NM QRSS
G8IMR WSPR
M0BMU WSPR
PA0A WSPR
SM6BHZ WSPR
Certainly my receiving system is now up with the best since adding the tuned preamp. My main drawback is the TX/RX loop's directionality which reduces signal levels in a N-S direction. We just need a lot more stations active on the band, especially on WSPR.
Labels:
136khz
13 Jan 2011
Further 8.76kHz VLF test transmissions today
8.76kHz earth mode tests - best DX 5.1km and 4.75km |
Labels:
8.76khz,
earth mode,
vlf
A 4th UK station with VLF NoV
Just received this from Gary G4WGT:
"Today I received my SRP from Ofcom to carry out research and experiments on the 9kHz band. The NoV is effective immediately and expires on 10th January 2012. The allocated frequency, power and additional conditions are the same as for other UK 9kHz operators, ie. 8.700kHz to 9.100 kHz with a maximum of 100mW (-10dBW) e.i.r.p. I am not ready to transmit a signal yet but it will be quite soon. I will make an announcement through the usual channels.
73 Gary - G4WGT"
Labels:
8.97khz,
dreamers band,
vlf
12 Jan 2011
What next at G3XBM?
With my recent semi-successful WSPR transmissions on 136kHz and a few outings on 500kHz I feel I'm at a crossroads now: do I go on with the LF experiments or do I have a change and do something completely different? My original aim on the LF bands was to see what could be done "simply" i.e. without large antennas and with real 5W or less QRP power from the PA. Already I have the measure of this and I doubt I'll prove much more to myself by striving further.
Next challenge? Ideas please.
Next challenge? Ideas please.
On-line CW training
If, like me, your CW is not as good as it could be, then you may want to visit http://lcwo.net/ where you can both train yourself and test yourself. On plain callsigns I could read 22-23wpm on average, but I still made mistakes at much slower speeds. 30 minutes a day on this site and anyone's speed would rapidly improve.
Labels:
cw
Short Marconi vertical on 136kHz - forget it!
ATU for 136kHz. Antenna connected to top of ferrite rod |
My conclusions are that an ultra-simple QRP approach to 136kHz TX is just not possible if one is to achieve useful results consistently.
11 Jan 2011
ERP with the loop on 136kHz
Today I did a recalculation of my 136kHz ERP using the loop antenna with my WSPR transverter. I have a small RF ammeter in series with the loop wire and I measured the current as 1.3A.
For 136kHz the ERP of a loop is = (I^2 * A^2) / (205 * 10^6)
where I = loop current and A = loop area (see "LF Today" RSGB book p101)
Putting in the numbers ERP = 1.3^2 * 80^2 (205 * 10^6)
So my ERP = 52uW on 136kHz.
A further 3dB could be obtained by thickening up the wire used in the loop taking the ERP up to around 100uW. Other improvements could come from increasing the TX power output from the present 5W. Later today I will work on a small ATU to resonate my 5m feeder to the 28MHz halo as a Marconi vertical. First I will work out the antenna current needed to beat the ERP of the loop. At least a Marconi will not be directional, which is a drawback of the loop.
For 136kHz the ERP of a loop is = (I^2 * A^2) / (205 * 10^6)
where I = loop current and A = loop area (see "LF Today" RSGB book p101)
Putting in the numbers ERP = 1.3^2 * 80^2 (205 * 10^6)
So my ERP = 52uW on 136kHz.
A further 3dB could be obtained by thickening up the wire used in the loop taking the ERP up to around 100uW. Other improvements could come from increasing the TX power output from the present 5W. Later today I will work on a small ATU to resonate my 5m feeder to the 28MHz halo as a Marconi vertical. First I will work out the antenna current needed to beat the ERP of the loop. At least a Marconi will not be directional, which is a drawback of the loop.
9 Jan 2011
Reports on 137.5kHz WSPR and QRSS3
In the last couple of days I have managed to get a couple of reports on 136/137kHz. Yesterday G3UUT copied my QRSS3 beacon and today G3XIZ copied the WSPR beacon. Neither represent any great distance - G3XIZ is 46km and G3UUT about 18km - but these are my first reports since getting back on the band after a few months of absence. ERP was about 10-20uW. G3XIZ was getting me at about -22dB S/N suggesting that around 100km may be possible on WSPR with the current kit (I did get a few spots from G3YXM at 148km last autumn with the same set-up), so I hope a few more stations in range can manage to detect me. I really must increase the ERP by 10dB: I have been saying this for too long and not doing anything about it!
8 Jan 2011
DK7FC/P on 136.8kHz normal CW
DK7FC/P very strong on 136.8kHz CW today |
6 Jan 2011
Improved E-field probe for VLF
Today I made an improved version of my VLF E-field probe. The first hi-Z FET input stage now an amplifier with an 8-9kHz tuned circuit in the drain. Sensitivity is now much better than before with strong Alpha beacon reception. It works well with the 80cm loop too and with the large TX loop in the garden via a step-up transformer. I'm looking forward to further tests by DK7FC and G3XIZ on 8.97kHz as my sensitivity is now better. I hope to test this out in the field with my 8.76kHz transmitter over the weekend.
Labels:
8.97khz,
e-field probe,
vlf
5 Jan 2011
136kHz WSPR DX reception
Today there were several stations active on 136kHz WSPR with best DX heard the 50mW ERP beacon of SM6BHZ. Also copied PA0A and G8IMR. So far this evening no-one has heard my own modest (10-20uW ERP) WSPR beacon on 137.5kHz though. I'll keep trying.....
4 Jan 2011
SAQ Jan 3rd
SAQ was audible well last night around 2330z tuning up for a transmission on 17.2kHz CW at midnight. The signal was about 20dB above noise using the 20m spaced earth electrodes as an antenna.
Labels:
saq
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