28 Nov 2009

RXing on 500kHz this evening

Although I cannot TX on 500kHz at the moment (should be back on next week), I am listening again this evening and hoping to copy G3ZJO who is testing his station on WSPR. Not heard him yet but will keep listening.

26 Nov 2009

Off 500kHz TX for a few days

Our little 2 year old grandson has come to stay for a few days, so I'm unlikely to get much operating time until Sunday evening. I have to rebuild my PA before I can get back onto 500kHz TX, so it may well be next week before I'm on the band again. I shall try to listen as and when I am able. The main information I've gathered on FET PAs (especially in class D/E) for 500kHz is to make sure the antenna is well matched (i.e. don't adjust the ATU/matching when the PA is on), don't exceed the peak voltage rating on spikes, ensure that parasitic oscillations are well suppressed and be generous with the heatsinking.

24 Nov 2009

Another oscillator calculator

Harry Lythall SM0VPO has a most interesting site full of ideas. Among the useful stuff is an oscillator calculator which allows you to work out values of L and C to make an oscillator that Harry claims always works. The circuit produces about 20mW.

This is the link http://web.telia.com/~u85920178/blocks/osc7m00.htm

23 Nov 2009

500kHz WSPR - back to 100uW ERP

Having blown my 3rd IRF510 PA because of overheating, I decided to go back to my 700mW PA based on a 2N3906/2N3904 pair until I rebuild the transverter with a decent heatsink. This PA is bullet proof!  Having made antenna improvements since I last ran this ERP, it will be interesting to see what reports I now get. So far, just M0BMU and G7NKS at -10dB on the reports when running 1-2mW, so all is as expected.

21 Nov 2009

WSPR and DXCC

The following is an extract from a posting on the LF reflector and may suggest getting QRPp DXCC may have become a whole lot easier:
"The discussion at the RSGB meeting noted the ARRL’s position that essentially if two stations make WSPR reports with each other and this is confirmed by QSL or some other approved method then there has been a two way exchange of call sign, report and other info e.g. locator and that qualifies as a QSO for DXCC purposes."
This may surprise some, and did me.

Does anyone know precisely what the ARRL has said regarding DXCC qualification and WSPR? By the definition above I "worked" VK6POP with a few watts of WSPR on 40m earlier this week.

As someone pointed out, a lot LESS data is exchanged in an HF contest, when often the callsigns are not sent (very often) and reports are meaningless. At least with WSPR you get the full calls, location and QTH locators exchanged.

20 Nov 2009

Blown my 500kHz PA ......again

My IRF510 500kHz PA has a tiny heatsink (soon to be addressed when a new heatsink arrives) and it is not very tolerant of poor antenna match. As a result it died again this evening in mid WSPR! This afternoon I managed to raise to PA output to 8W by changing values and this must have made the tiny heatsink just too small to be useable. I also need to find a better way of getting my antenna tuned to 50 ohms.  This is all a good excuse to do a proper rebuild next week.

Belgium gets 4m allocation

With immediate start all radio amateurs in Belgium holding a full licence have access to 69.950MHz (+/- 5kHz) with 10W EIRP on a non-interference basis.  If you can read French or Dutch there is more information here.

19 Nov 2009

New WSPR DX record tonight (40m)

Trying out WSPR2 on 40m this evening and just got a report from VK6POP at 14465kms, which is a new DX record for me. I was running 5W to my 500kHz antenna tuned via the Elecraft T1 ATU. It must work pretty well on 40m!

First experience with WSPR 2 (new version)

Well, it works. I deleted the old version from my PC and installed V2 tonight. Set-up was straightforward and I like the slider to set the TX percentage. Also 500kHz is now one of the default listed bands (600m). My first TX was spotted (with the new version) by I2IAL on 40m.

WSPR 2.0 now available

WSPR 2.0 introduces a number of new features including a  user-friendly setup screen with drop-down selection of audio devices and rig-control parameters, support for compound callsigns, fine selection of the fractional time for transmitting, and a Tune button.  A new Advanced setup screen offers optional CW identification and tools for frequency calibration and automated frequency corrections for your radio.  Full details are presented in the WSPR 2.0 User's Guide, which you will need to read in order to use the new features.  For the first time, a binary installation package is made available for Ubuntu Linux (versions 8.10 and later), Debian 5.03, and other Debian-based 32-bit Linux distributions.

WSPR available at http://physics.princeton.edu/pulsar/K1JT/wspr.html 

Sunspots - blimey!

Just seen the sunspot count for today - 29 - which is pretty good for where we are in the new cycle. It is very clear that sunspot cycle 24 has got into gear and next year should show considerable improvement on bands like 10m.

Birthdays

It was my elder grandson's 2nd birthday last week. We went to Paris to enjoy it with his French grandparents and had a good time. This is a picture of both grandchildren when they came to stay a few weeks ago. It is my wife's birthday next week, so I'd better get thinking. Mine, just before Christmas, is easy as I tell my XYL what I want - usually some radio books.

500kHz PA blown - my fault

My IRF510 500kHz PA just died on me as I TXed for a full WSPR slot into an open circuit (the wrong coax connected!). It won't take 5 minutes to fix tomorrow, but this evening I'll WSPR on some HF frequencies for a change.

18 Nov 2009

500kHz - USA reception this evening

The 5W ERP beacon of W17XSH (the "WSPR shortened" call of WD2XSH/17) was copied here very well just after midnight. This is my first transatlantic WSPR reception and only my second 500kHz station heard from N.America.

Overnight my 500kHz WSPR beacon was running but no new stations reporting me when I checked at 0700z.

17 Nov 2009

8th country on 500kHz WSPR

Just got my first report from Wales tonight with a huge (for me) -6dB S/N report from GW3UCJ in IO81 at 286kms away.  Also a new reporter from Belgium ON6EO. Reports are very good tonight so the WSPR beacon will run overnight.

136kHz WSPR tests (soon)

Very encouraged by my results at 500kHz, I'd like to try some "low ERP" WSPR tests on 136kHz using the same small antenna and transverter (slightly modified).  Ideally I'd need stations like M0BMU, M0FMT, G7NKS and others not too far away from JO02dg to TX and to listen out for me, as these stations get a good signal from me on 500kHz.

Please would you let me know if you'd be able to listen and upload 136kHz WSPR spots sometime in the next week or so
? As yet I am not quite ready to start, but I'll let you know when I am.

15 Nov 2009

Presentation on CW and other weak signal modes

Andy Talbot G4JNT has put an interesting presentation about weak signal modes onto his website. He gave this talk at a recent Microwave Round Table. See http://g4jnt.com/MartleSham.htm. It is exploring how we can push the boundaries further when working with very weak signals.

My first 2-way CW QSOs on 500kHz

This afternoon, just after midday, I worked Mal, G3KEV, in Scarborough for my first 2-way CW QSO on 500kHz. I gave him 569 and he gave me 529. Then at 4pm I was called by Chris G3XIZ who gave me 579. ERP at my end around 2mW.

14 Nov 2009

Report from 7th country on 500kHz

This evening I got my first report from Germany on 500kHz WSPR - DK6NI in JN59ln at 805kms. This brings my countries total to 7 now.

FT817 successor coming?

Has anyone heard any intelligence/news on what is happening at Yaesu regarding new hand-held all-band, all-mode, successor to the FT817 with new features such as internal auto-ATU, speech processor, maybe 70MHz included on EU version, LiIon battery pack, etc...

Transatlantic 500kHz reception - VX9MRC

This evening at around 2200z I heard my first ever North American ham station on 500kHz. VX9MRC, the beacon operated by VO1NA was coming through on CW (about 10wpm) on 507.77kHz in and out of the noise at about RST339 at best. On WSPR he would have been solid copy.

A 30th reporter on 500kHz

Lots of trouble getting my 500kHz antenna to match tonight, so late getting on to WSPR tonight. To my surprise (as the antenna current was lower as a result of the rain I think) I got a new report from France - F6CNI in JN19qb which is 418kms away.

Back home - on 500kHz tonight

Just been to Paris, by Eurostar, for our elder grandson's 2nd birthday. At home, the 500kHz antenna is being battered by the very stormy weather at the moment, but I hope to be on the band again tonight ..... if the antenna and roof are still there at teatime.

8 Nov 2009

Voice powered transatlantic 20m test

AA1TJ's historic attempt to span the Atlantic with just a "voice powered" TX (powered only with DC generated by rectifying audio from a LS into which he was shouting) started at 1500 UTC on Tuesday Nov 10th. Power out was about 15mW QRP from the coast of Maine, USA. They had a 2el vertical antenna aimed at Europe and a good clear sea path, but unfortunately the test was unsuccessful, although they did make contact (not voice powered though) with Europe on 160m QRP. For a report see http://www.QRPme.com .

Norway gets some new bands

Stations in Norway now have new, quite large, allocations at 500kHz, 5MHz and 70MHz as well as certain other changes. If you can read Norwegian, see http://www.lovdata.no/ltavd1/filer/sf-20091105-1340.html ).

SM6BHZ hears me on 500kHz WSPR

SM6BHZ heard me at last on 500kHz WSPR at 0556z this morning, so my best DX has now gone up to 951kms with the tiny station. He reported my WSPR signal at -26dB S/N. The distance beats my previous record on the band by almost 100kms. Gus, thank you so much for country number 6 on the band and Joe K1JT for designing the software to make this possible.











7 Nov 2009

Climate change - Copenhagen

A binding agreement in Copenhagen next month seems to be slipping away because no-one wants to make firm commitments on the reduction of harmful greenhouse gas emissions. Personally, I think it would be a tragedy if our leaders came away with just a "wishy washy" set of political statements and nothing concrete. See http://news.bbc.co.uk/1/hi/sci/tech/8345343.stm . For the sake of our children and grandchildren we need ACTION from our statesmen, not words.

500kHz improvements - summarised

The spiral top-hat on the 500kHz antenna.

Since first putting a signal out on 500kHz a few months ago, I believe the ERP has increased by about 18dB. These steps were:
  • Initial PA 500-700mW (0dB reference)
  • PA output increased to 5W (+10dB)
  • Additional grounds added (+2dB)
  • Antenna spiral top hat added (+6dB)
No further changes are planned as I am close to fulfilling my original objectives of seeing how effective a small and simple QRP 500kHz station could be. The two remaining goals are to get reports from Germany and Sweden.

After that, it will be farewell to 500kHz and welcome to the next challenge!

6 Nov 2009

ERP increased on 500kHz (6dB up)

Today I modified my 500kHz antenna introducing a spiral inductance/ top capacity hat consisting of around around 8 "spiralling in" turns in the space occupied by the original 28MHz halo. Seeing my initial reports from M0BMU I am some 5-6dB stronger than I was before, I guess because more of the antenna current is in the 6m long vertical section.

Three new 500kHz reports overnight: F4DTL, PA0AM and G4CAO. The improved antenna efficiency is definitely helping. Also my strongest report yet from GM4SLV.

5 Nov 2009

Top Band WSPR

This evening I moved from 500kHz to 160m to see if I could improve my WSPR DX on topband. At first try, GM4SLV heard me up in the Shetlands. As for 500kHz, my ERP will be considerably lower as I am only using a short 5m long vertical tuned with a ferrite rod ATU. See John's screenshot, that also shows some digital QRM on the same frequency. At 2116z John was copying me on 160m when I was running just 100mW from the TX.

3 Nov 2009

24 stations hearing me on 500kHz

This evening I received a WSPR spot report from F4EMV who is 433kms to the south of me. Yesterday I had one from F0DVZ. This brings the number of different stations reporting my signals on 500kHz to 24 (22 on the WSPR database and 2 others).

Planned 500kHz antenna changes

Before the end of the weekend I intend,weather permitting, to make changes to my small 500kHz antenna. These changes will be:
  1. The 28MHz halo and 6m long feeder will be replaced by a spiral top capacity hat and a slightly longer vertical wire. The effect should be to increase the effective height of the antenna a bit.
  2. Move my TV antenna away from the pole carrying the 500kHz wire. At the moment this is on the same pole, so is probably absorbing energy.
Taken together, I expect another 2-3dB improvement in antenna current and ERP. If these improvements work I'll give it an "on-air" test for a week or so. After this, I'm not planning any further 500kHz improvements as I'll have run out of "keep it simple" options.

More voice powered DX in the USA

Mike Rainey AA1TJ has pushed his DX up to 1329kms on 80m using his Code Talker TX (see left) which uses only the energy derived by shouting into a loudspeaker to power the transmitter - no external DC power sources at all. He worked W4OP at 0133z. Just visible is the tin can used to focus the shouts into the LS cone! I am beginning to think Mike will work some serious DXCC countries in the years to come using his "voice powered" TX. Imagine this rig into a beam on 10m when the sunspots are high.

Mike tells me he is having a go at a 20m version now.

1 Nov 2009

Optical DXing - mirages

Andy Young has an excellent page about optical mirages which is worth reading. Land has been seen hundreds of kms over the horizon as a result of this phenomenon. Indeed there is some evidence that the discovery of Greenland may have been as a result of a mirage off the coast of Iceland. I'm not aware of radio amateurs exploiting fleeting mirages for optical frequency laser DXing.

Our grandchildren

We have two lovely grandsons: Lucien who is 2 and Edward who is not yet 1. This is a picture taken last month when they both came to stay for a few days.

New 500kHz ERP calculation

Some weeks ago Jim Moritz M0BMU made an estimate of my 500kHz ERP based on received signal strength levels at his QTH 69kms away. As I've recently increased my ERP, I asked Jim if he would kindly do a recalculation. These are his latest estimates.

Well, repeating the original calculation, taking your "best" signal level as -12dB on a noise level estimated at 3uV/m in 2.5kHz, your received field strength at my QTH is 0.75uV/m. At a distance of 69km, and assuming only "geometric spreading" propagation losses (i.e. an inverse relation between FS and distance), your ERP is

ERP = (Ed)^2 / 49 , with E = 0.75u, d = 69000, ERP = 55uW

Then we have to consider what additional propagation losses exist; originally I suggested 3dB, which would increase the ERP to 110uW. However, looking at G4FGQ's grndwav4 program, and the ground resistivity around this area, the "ground type" in the program might be 6 - 8, making the ground wave propagation losses between 4.2 and 8.5dB.
This would make the ERP between about 140uW and 390uW.

Obviously there is a lot of uncertainty in this kind of estimate - the two main things are the possible variability in noise levels between when I estimated the noise level and now, and the propagation losses. Both these could contribute several dB variation, so the ERP estimate should only be regarded as "order of magnitude" accuracy.

Still, your signal is certainly much stronger now - one of my nearer-term projects is to make some more accurate FS measurements by injecting a calibration WSPR signal into the loop antenna, which should give a more direct and accurate measurement of the signal levels.

Cheers, Jim Moritz
73 de M0BMU