6th unique WSPR reporter on 137kHz

This autumn is beginning to look a bit like last year when I was taking my first tentative steps on 500kHz WSPR: each week would land me a few new reports from more distant stations. This autumn my challenge is 137kHz WSPR and so far I've been copied by 6 different stations: G6ALB, G3XIZ, G3XVL, G3WCD, G3YXM and, this evening, M0FMT. Best DX remains G3YXM at 148km. Not bad for a true QRP station with less than 5W from the PA and less than 20uW ERP with the transverter just a breadboard on the desk and the ATU sitting on the bedroom table.

Also today I copied G8IMR, Andy Talbot's QRP beacon from Southampton on 137.530kHz.

Sub-9kHz Amateur Radio (Yahoo group) formed

This new group is for anyone interested in amateur radio communications below 9kHz in the so-called "Dreamer's Band".  See http://tech.groups.yahoo.com/group/sub9khz/

VLF DX transmission with earth electrode transmission (49.6km)

DK7FC's 8.97kHz DFCW transmission received at 49.6km

Stefan DK7FC has informed me that he has successfully transmitted the message "CU" in DFCW on 8.97kHz to Michael Oexner at a distance of 49.6km. His TX puts out 250W into a 600m spaced earth electrode pair with a current into the antenna of about 0.5A. This is definitely far field reception. Stefan's earth electrode antenna is capable of further improvement, so he is expecting more successes shortly with it.

Another source of LF/MF and HF interference

This was posted on the LF reflector: we'll have yet another source of LF/MF and HF interference in the years ahead as more people install such systems. Hugh's post got immediate replies from people who'd suffered bad interference from such systems. beware of photocell panels on neighbours' roofs!

"My neighbour informs me that she is intending to have photovoltaic panels installed on her roof, in a scheme where she gets free electricity (all subsidised by the government of course!)

My concern is the possibility of high levels of interference generated by the kW inverters needed to pump electricity back into the National Grid. I would guess that such invertors probably operate kHz and might be expected to interfere with LF and VLF reception. The wiring to all the panels on the roof might act as a
very good aerial!

It also occurs to me that any lack of RF immunity to my transmissions, in the new installation, might have dramatic consequences - I know from studying electrical engineering at college that connecting a generator to the grid with incorrect phase leads to a big bang!

Has anyone any experience of such installations? Perhaps someone has one nearby and could comment on any EMC effects.

Hugh M0WYE"

More sub-9kHz experiments

Just received this from Stefan DK7FC:

Dear LF/VLF,


Today i saw the first time a flag from Norway on my VLF Grabber (http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber.html). I would be very fascinated if my signal would be copied in LA/SM/OH  (of course, in all countries it would be very fascinating :-) ). Are there any stations, reading the reflector, from there who have the ability to receive on 8.97 kHz (or even 6.47 kHz) with a sensitive and stable RX frequency in DFCW-600 mode?
This would be one of my wishes for this period! One. ;-)
For this weekend i planned the next VLF experiment with the 200m vertical on 8.97 kHz but the wind forecast is not too promising :-( Maybe things look better tomorrow. I have to inform the air traffic control to give out a NOTAM (http://en.wikipedia.org/wiki/NOTAM), 48 hours befor i can start...
I will announce  tmw, if i will carry out the next test, if.
The signal would be once again the strongest i've ever radiated. About 50 mW ERP is the goal.
My planned tests for this year on VLF (kite antenna):
- CW QSO to DF8ZR (16 km distance) on 9 / 137 kHz
- Copying my signal on 8970/6470 Hz in Heidelberg in CW (40.0 km, audio recording and later analysis)
- Beeing visible in DFCW-120 in UK
- Beeing visible on the grabber of Renato Romero on 8970/6470 Hz
- Becoming QRV with the 300 m vertical antenna on 8970/5170 Hz, radiating 100 mW ERP at 8970 Hz
- Beeing visible in Russia and at all interested RX stations :-)
- Maybe a TA contact?
vy 73, Stefan/DK7FC *Dreaming...*

148km on 137.5kHz WSPR!

WSPR reports on 137kHz 21.09.10

Just had a report from G3YXM who gave me -24dB S/N on 137.5kHz when I was running no more than 20uW ERP.  He is now my 5th WSPR report on the band and the best DX by far. This is so thrilling! The transverter is just sat on my desk and the PA isn't even warm.

G3YXM's screen showing my weak signal on 137.471 kHz

Possible progress on a worldwide MF allocation at WARC 2012

Info on the ARRL website suggests the USA authorities are supporting an amateur allocation at MF. See Secondary Amateur Radio Allocation at 461-469 and 471-478 kHz

 

The loop works well on 500kHz TX

Unique reports on 500kHz WSPR this evening

My vertical loop of 1mm diameter wire seems to work very well on 500khz WSPR with some excellent reports this evening, indeed some of these reports are better than I ever received (I think) on the short Marconi vertical last winter. Certainly there will be some directionality, which is the downside of this antenna. Results on 500kHz are SO much easier than on 136kHz where the lower radiation resistance and electrical size make it so much less efficient.

Loop antenna on 500kHz

My vertical loop antenna (about 80sq m area) made with 1mm diameter wire (tuned with a capacitance decade box) performs quite well on 500kHz judging by reports. Yesterday I lowered the bottom wire to run along the ground, increasing the loop area from about 70 to 80sq m.  Reports from M0LMH (223km) and M0BMU (69km) are pretty good with my 1mW ERP signal at M0BMU up to -5dB S/N on WSPR, which is as good as I've ever had and he's not in the best direction for the loop. Also, PA3EGO was up to -2dB S/N on receive. Results on 500kHz are much easier to obtain than on 137kHz although this is explainable by the much lower ERP (probably 20dB less than on 500kHz).

Increasing interest in 137kHz WSPR

WSPR LF activity lunchtime Sept 19th

In the last week there seems to have been an increase in 137kHz WSPR activity. The attached image shows the stations active on 137 and 500kHz this lunchtime.  G8IMR was the call being used by Andy G4JNT for his WSPR beacon before it died.

Why NOT to use QRO on 136kHz

Andy G4JNT was testing a 600W RF WSPR beacon on 137kHz today when he noticed burning from the plastic shed used to house the ATU. When he opened the door he saw the plastic shed and shelf melting and flames everywhere which he quickly extinguished.  LF at high power can be dangerous stuff and one reason why I've restricted my activity to QRP.

New all-band SDR from Funk Amateur

SDR transceiver PCB assembly

http://www.dh1tw.de/first-pictures-of-allband-software-defined-radio-fa-sdr-trx

The German magazine Funk Amateur has a new all-band 1W SDR transceiver kit in the October edition. This will sell for around $170 US and looks a very interesting project. More details from the link above.

137.5kHz WSPR - best DX now 61km with less than 20uW ERP

137.5kHz WSPR reports so far today - with <20uW ERP!

Just got a -27dB S/N report on 137.5kHz WSPR from G3XVL near Ipswich at 61km. This is particularly good as this is more or less in the null of my TX loop antenna: in the better direction the signal could be some 6-10dB stronger!

From Michael Rainey's blog

http://aa1tj.blogspot.com/2010/09/verweile-doch-du-bist-so-schon.html

Michael Rainey AA1TJ has an excellent blog in which he covers a range of subjects. This post (see link) is about a tiny pocket watch made almost entirely from wood and other organic materials that Michael came across in a museum in Vienna.

WSPR success on 137.5kHz

G3XIZ's 137.5kHz WSPR reports today

Chris G3XIZ has successfully received my QRPp WSPR beacon this morning on 137.5kHz. ERP is around 10-20uW from the class-E PA producing around 4-5W. This brings my total number of WSPR reports on the band to two with the best DX now 46km.

Shortwave America blog

If you want to look at the quirkier side of SW radio activity check out http://www.shortwaveamerica.blogspot.com which is written by Dan KC9NCF. Most recently he's talking about pirate activity just below the 40m band.

137.5kHz WSPR 7-11pm UK time Friday

137.5kHz WSPR TX transverter

My WSPR beacon will be on-air from 7-11pm UK time Friday and any reports would be appreciated.

137.675kHz QRSS3 beacon report

The <20uW ERP 137.675kHz beacon was copied again by G3XIZ 48km to the west of me last night. I'm pleased with this report as the power from the PA was less than it was a week or so ago, yet he still managed to copy me. Work is now progressing on the class-E PA based WSPR beacon which should run about 10W from the PA (ERP around 20-50uW).

iPad case with keyboard ....but why???

http://www.senacases.com/ has a case for the Apple iPad which incorporates a Bluetooth connected full keyboard. Excuse me, but why not just buy a netbook at far less half the price in the first place? In the UK there is a range of netbooks available around £180-220 whereas the cheapest iPad is over £400.

137.675kHz QRSS3 beacon back on

This evening I restarted beaconing with my sub-20uW ERP beacon on 137.675kHz having fixed the blown FET PA. The current design is stable and seems to be working very reliably with around 4-5W from the PA. All being well the latest version of the 137.5kHz WSPR beacon will be ready and on-air this weekend. The design of this is a class-E PA and should run around 10W from the PA with an ERP of up to 50uW.

Sub 9kHz NoVs - a step nearer

The current UK applications for sub-9kHz NoVs have now been forwarded to the Met Office and I understand they have been received. With luck we may hear about the outcomes in the next few weeks. Currently there are 3 people appying for these G3XBM, G7NKS and G3XIZ. If these are successful I expect G3KEV and several others will also apply.

ULF/ELF/VLF radio technician job vacancy

If you fancy a job engineering radio instrumentation below 10kHz here is your chance. Armargh is in Northern Ireland, which is a truly beautiful part of the British Isles.

A research-technician-grade position is available at the Armagh Observatory funded by the EuroPlanet Research Infrastructure (RI) under the Seventh Framework Programme of the European Union (EU). Salary will be in the range £18,486 - £29,719 per annum, the exact figure depending on individual experience.
The primary aim of the project is the construction of a working instrument prototype able to (a) record and store, in digital form, electromagnetic (EM) radiation signals in the ULF/ELF/VLF frequency range (3Hz-30kHz) (b) pick up naturally-occurring radiation while screening/filtering out manmade interference in this frequency range (c) be optimised for the high-quality reception of radiation thought to originate from meteors in the Earth's upper atmosphere. In addition, the equipment should be capable of operating in the field and at remote sites with a high degree of autonomy.

 See http://star.arm.ac.uk/jobs/2010/vlf_job_announcement.html

A nice break from the radio

For the last few days we've been looking after our 2yr 10month old grandson and this has meant a break from radio during the period as he sleeps in the room used as the shack. During the days we've been enjoying some great things including a trip to the seaside, a visit to a farm with lots of young animals, picking blackberries and similar, simple pleasures. On Wednesday it will be back on with the 136kHz experiments, but we'll miss his company.

Heatsinks and IRF510s arrive

My heatsinks and more IRF510s have arrived in the post today. All being well I'll get these into my 136kHz QRSS3 beacon and transverter shortly and be back in business by the weekend, although operating time will be limited because my elder grandson is staying and sleeping in the shack.

Grandchildren time

After a busy few days building LF kit (and blowing it up!) it is now time again for our grandchildren. Our younger grandson came to stay last weekend and this weekend we have our elder grandson with us. The picture here is with me in the lane close to our home on his way to feed Maggie the horse, who is a favourite with both grandchildren.

Class E PA designs

Today I made a first proper attempt at a QRP class E PA design for 136kHz. Although the values in the output circuit seemed to tie up well with theory I wasn't able to realise the expected high efficiencies, possibly because of the gate drive design. In fact I managed to blow up my last IRF510 because it got very hot and this meant aborting a WSPR test (at a sensible power level).  One resource recommended to me is http://www.alan.melia.btinternet.co.uk/classepa.htm which has a E class design spreadsheet. 

I also discovered today that 16mm diameter 3C90 toroids do NOT make good LF PA output bifilar transformers: they get very hot. The larger diameter 3C90s appear to be fine.

Overall, a frustrating day!

Encouraging QRPp results on 136kHz tonight

This evening I had a good report and screenshot from Chris G3XIZ 48km away. This is my best report in terms of S/N and distance yet, with very clear images on the Argo screen.  I was going to try WSPR on 137.5kHz but had problems with the PA so QRSS3 beaconed instead. ERP was less than 20uW.

Comparing 500kHz and 136kHz WSPR over a 3km path

This evening I've been running about 5W PA output (not ERP)  from IRF510 PAs on both 136 and 500kHz WSPR and getting reports from G6ALB 3km away. I'm using the same ATU (just different capacitor settings) into the same loop antenna. On 136kHz I get-20dB S/N whereas on 500kHz +10dB S/N. This is a difference of 30dB!! 136kHz seems a heck of a lot harder than 500kHz.

LATER: Just got this from Steve Olney - VK2XV:

G'day Roger,

I read with interest your observation of the behaviour of the "in the air" loop via WSPR.

"On 136kHz the best report was about -20dB S/N whereas on 500kHz it was +10dB. This is a difference of 30dB!!"

I am not surprised at the 30dB difference as the radiation resistance varies with the 4th power of frequency for the same dimensions giving 23dB difference (i.e. 10 log ((136/500)^4)). In addition WSPR reports a S/N against in-band noise.    Atmospheric noise is inversely proportional to frequency and there is about 36dB difference (500kHz being quieter) between 2200M and 600M. This difference is effectively reduced by man-made noise which is higher wrt to atmospheric noise at 500kHz compared to 136kHz. This reduces the difference in noise levels from 36dB to about 10dB to 15dB (depending on location). Therefore I would expect about (23 + 10) = 33dB to about (23 + 15) = 38db difference between WSPR reporting for 2200M and 600M.

Your measurements are reasonably close to this - given there would be other differential effects such as ground loss.

Keep the interesting stuff coming !!!

73 Steve Olney - VK2XV

136/500kHz loop ATU

This morning I tidied up the arrangement to match my "in the air" wire loop antenna currently being used on 136kHz and 500kHz. The loop looks like a few ohms resistive when tuned so I have a 4:1 turns ratio step-down transformer wound on a 3C90 core. The loop is tuned using an old decade capacitance box and this is fine tuned with the 365pF variable capacitor. The picture shows the values needed to resonate the loop on both bands. It is simple but works fine at the QRP power levels I'm using (5W max from PAs on both bands). My report from M0BMU at 69km on 500kHz WSPR was -8/-9dB S/N which is pretty good.

A poem that moved me

Today I went to a memorial service for a local villager who died of Parkinson's Disease after years of failing health. The church was full. This poem entitled "He Is Gone" was said at the end and I found it profoundly moving.

You can shed tears that he is gone

Or you can smile because he has lived 

You can close your eyes and pray that he will come back

Or you can open your eyes and see all that he has left

Your heart can be empty because you can't see him

Or you can be full of the love that you shared

You can turn your back on tomorrow and live yesterday

Or you can be happy for tomorrow because of yesterday

You can remember him and only that he is gone

Or you can cherish his memory and let it live on

You can cry and close your mind, be empty and turn your back

Or you can do what he would want: smile, open your eyes, love and go on.

It was written in 1981 by David Harkins. See http://www.poeticexpressions.co.uk/

AM Day Sept 19th (info via João Costa, CT1FBF)

The ‘Associação de Radioamadores do Litoral Alentejano’ invites everyone to participate in a special Amplitude Modulation (AM) transmission commemoration, using the 80, 40, 20, 10 and 2m bands, on Sunday, Sept 19, 2010.
Frequencies and periods:

3.685 MHz - from 0600 to 0800 UTC
7.1 MHz - from 0800 to 1100 UTC *
14.286 MHz - from 1300 to 1400 UTC
29.075 MHz - from 1400 to 1500 UTC
144.575.0 MHz - from 1500 to 1600 UTC

*alternative frequency is 7.143 MHz

More loop experiments at 500 and 136kHz

Today I converted my earth electrode antenna with elevated feed wires into a full "in the air" loop for both 500kHz and 136kHz. As might be expected, tuning is now very sharp as there is no longer a 50 ohm earth resistance in circuit dampening the Q. At first I found matching and tuning impossible until I decided to match the loop with a step-down transformer (3.5:1 on a 3C90 core) and separately do the tuning. This works a treat and it is now a simple matter to tune the loop either for 500kHz or 136/137kHz.

First reports on 136kHz with the QRSS3 beacon suggest the signal is about 6dB stronger, which is a great result. The loop is wound with quite thin wire (1-2mm diameter), so a higher efficiency is possible with thicker wire, but with even sharper tuning.

LATER: Attracting any attention is turning out to be a serious issue with real QRP on 136kHz. Even with alerts on my blog, the LF-reflector and the GQRP Yahoo groups it's hard to get that many people taking a listen/look. With uW ERPs I'm beginning to think that I'm never going to be able to get much further than my present best DX of 62km.

Last days on 56MHz (5m) - lost recording?

Many years ago Jack Hum G5UM attended the Cambridge club and talked about VHF. During the talk he mentioned a gramaphone disc being made recording the very last night of operation on 56MHz in the London area in the 1940s. Does anyone know what happened to this most historic recording?  This would be a wonderful item of ham history if it could be located.

More results on 137kHz and a better ERP calculation

Today I managed, I believe, for the first time to accurately measure the ERP of my QRPp system on 137kHz. This is the method used:

• Using the E-field probe, FT817 (AGC off, gain backed off as far as possible and a 10dB pad between the EFP and the FT817) and Spectran I went to my usual test site 1.5km away from the QTH, 45 degrees off the main lobe of the TX loop/earth electrode antenna.
• Measured the signal level of DCF39 on 138.83kHz
• Measured the signal level of G3XBM on 137.675kHz
• Repeated this three times to reduce errors.
• Noted the difference in FS level.

Difference in signal level = 44dB . I feel pretty confident this is an accurate figure now and not effected by AGC and overload. Assuming DCF39 is 1mV/m here (info from Alan Melia)  then my FS at the test site is 6.4uV/m.  Using the formula ERP = (E*d)^2/49 where E = 6.4*10E-6 and d=1.5*10E3 gives an ERP = 1.9uW giving an antenna efficiency of -63dB using the earth electrode antenna with the elevated feed and 4W from the PA. 

The test site is about 45 degrees off the main line of fire of the antenna, so in the best direction it could be 10dB (?) stronger, i.e. 20uW ERP giving an antenna efficiency of -53dB in the best directions. Frankly I'm amazed that anyone can copy this signal at any distance, so full marks to G3XIZ (48km) and G3XDV (62km).

Mike G3XDV sent me another screenshot of my signals this morning during the tests. if you look carefully you can just make out "G3X..." in QRSS3.

Solar activity progress

See http://solarscience.msfc.nasa.gov/images/ssn_predict_l.gif

Sunspot cycle 24 does, at last, show signs of gathering some momentum. Despite the ups and downs in the sunspot count, there is an inexorable climb now towards the next maximum, probably on 2012 or 2013. This autumn we should start to get the regular 10m transatlantic openings again which, to me, are a sign that the new cycle is here and "good" for several years. In the press there's been some alarmist headlines about solar storms around the sunspot maximum knocking out swathes of the power systems and satellites around the world. Certainly the danger exists, but surely it is a manageable risk with planning and contingencies in place? See news.com.au on this subject.

LF/MF antenna change

Today I changed the earth electrode antenna by raising the height of the connecting wires to form a (part) loop in the air as well as in the ground. The loop part in the air has an area of >100 sq metres.  This should increase the effective loop area by a factor of at least 2, thereby improving the ERP. Later I'll repeat the tests with just the loop in the air only, so I have 3 different sets of results to compare. On 500kHz WSPR my signal with M0BMU (69km) was 6dB stronger than before with the earth electrode antenna. At the moment I am QRSS3 beaconing on 137.675kHz and seeking reports.

136kHz WSPR - first report received

Well, it is no great DX at 3km away in the next village, but I've now received my first WSPR report on 136kHz from G6ALB. He gave me -21dB S/N when I was running 20uW ERP from the earth electrode antenna.

WSPRing on 137.5kHz at last

136kHz TX transverter

Having got the TX part of the 136kHz transverter going today I am, for the first time, putting out a WSPR signal on 137.5kHz. Power from the PA is around 4W and the ERP from the earth electrode antenna is around 20uW. I am hopeful that Chris G3XIZ in Biggleswade may be able to decode the signal, possibly others not too far away. In the picture the transverting bit (from the 10MHz band) is on the right and the PA in the top left with low pass filter visible using the T106-2 toroid. Note the heatsink for the IRF510 - a couple of crock clips being all I could find in the junk box!

My 20uW ERP QRSS3 signal as received by G3XIZ

This was the signal G3XIZ got today 48km away on QRSS3 from me on 137.675kHz.  It is somewhat stronger than earlier in the week, confirming the few dB extra ERP.

136kHz TX transverter almost ready (5W from PA)

Today I should complete the first breadboard version of my QRP TX transverter for 136kHz. It mixes down from 10MHz in a similar arrangement to my 500kHz unit, which transverted down from 28MHz. ERP on the original 137.675kHz QRSS3 beacon has been increased by 3dB to 20uW. The ERP from the transverter into the earth electrode "antenna" will be about the same level initially. I'll run WSPR tests for the first time on 136kHz this weekend.

Another report on the 136kHz QRPp beacon

G3XIZ has sent me a nice screenshot of my 10uW ERP 136kHz beacon as received in Biggleswade, about 35km away. Chris believes I'd be perfect copy with QRSS10 (10 second dots).