29 Nov 2008

3X5A (Guinea) worked on 10m QRP

There were few 10m CW stations audible today (Nov 29) in the CQWW contest but among the few was the DXpedition to 3X5A in Guinea, West Africa.

I called them around lunchtime but at first they struggled to hear me but a few minutes later they were stronger and a solid QSO followed. This was a new country for me on 10m QRP. This is a picture of their QSL card from last year (from their website). See the Voodoo Contest Group website.

26 Nov 2008

160m good tonight

Although I do not do that much on 160m I took a listen this evening and conditions were very good. Heard were UA6MF, EY8MM and 3X5A all on CW. If conditions are similar next weekend there should be some good DX around for the CQWW CW contest.

23 Nov 2008

SK6RUD on 500kHz and "cross pond" LF reception

SK6RUD was a good signal on 500kHz again this evening around 2000z on my basic set-up here.

The better equipped stations in Europe are currently receiving some of the experimental 500kHz stations from the USA during the night hours and some have even managed to detect some of the Lowfer stations operating between 160-190kHz running less than 1W DC input. This is amazing when you think they are being received in the midst of the high power broadcast stations on this side of the pond.

21 Nov 2008

Late Swallow - faulty GPS?

Had a change from ham radio today when I went birdwatching on the Wash in North Norfolk with our University of the Third Age group in Cambridge. Conditions were good but the wind very strong. Some decent birds about on the tidal mudflats and lagoons including black tailed godwits, mergansers, goldeneye, golden plovers and thousands of shelduck. No snow buntings seen although there were a few about. Apparently there was still a swallow up there last week, which is very late for the UK. Someone suggested it had a faulty GPS so didn't know which way to fly!

See http://www.rspb.org.uk/reserves/guide/s/snettisham/ .

19 Nov 2008

Backscatter - microwave compendium

Last week G4BAO showed me a copy of a new book running to nearly 400 pages called "Backscatter" which has been created from articles previously published in the microwave newsletter "Scatterpoint". The book is available for £14 and, if you are into microwaves from 1.3GHz upwards this is a very useful reference book.

It was fascinating to read about something called rainscatter which allows 10GHz stations to work each other by scattering signals off rain clouds/drops up to distances of 600-700kms. This mode allows narrowband uWave stations to work great distances, even from less than perfect home locations. Small 45cm dishes and about 1W RF seems all that is required at 10GHz to use this mode, which works even with NBFM. Signals sound like aurora as they get spread by the scattering process.

I can't see myself getting on 10GHz in a hurry but I can understand the fascination with such intriguing propagation modes to be explored.

Another sked with the FETer rig (unsuccessful)

Tried a sked on 3560 this morning with Richard G4ICP in Braintree when using the FETer micro-transceiver with 18mW and the single FET RX. Although he was quite a reasonable signal with me, as was G3LUB in Aylesbury, Richard could not hear me. This all suggests that for the 1 FET transceiver to be more useful it needs more power on TX. Probably 500mW is needed to stand a reasonable chance of random QSOs - I need to experiment some more to get the TX power up.

I am still keen to do further local tests to see what the limit of daylight range is. At night there will be too much activity on 3560 to stand a chance.

17 Nov 2008

Miracle Whip Yahoo Group

Back in 2002 I started the Miracle Whip Yahoo group for those interested in the Miracle Whip antenna and similar homebrew versions. Today the membership topped 1000 people for the first time making it one of the largest Yahoo ham groups. If you are interested in this and similar compact multi-band portable antennas feel free to join. Sometimes the topics can get quite heated.

15 Nov 2008

Talk at the Huntingdonshire Club

This week I was fortunate to be asked along to the Huntingdonshire Amateur Radio Society to give my talk on Kitchen Sink Minimalist Radio. The club was excellent with lots of people attending and a real sense of "buzz" about the place. If you live in the Cambridge, Huntingdon, Ely or Peterborough area I'm sure you'll receive as warm a welcome as I did.

For those who attended and wanted copies of the presentation slides, they're now on my main www.g3xbm.co.uk website.

PS I've noticed I put up not quite the final version- I will change to the correct version when I get access to my WinXP PC.
Publish Post

9 Nov 2008

uu80b micro-transceiver now on main website

www.g3xbm.co.uk now has the information on the 12 parts only micro-transceiver for 80m. I have also corrected the link to the DX cluster's new URL.

8 Nov 2008

uu80b 80m Micro-transceiver - measured performance figures

Following a 2-way QSO this evening with M0BXT 2 miles away using the uu80b micro-transceiver on 3.560MHz CW I went across to his shack to measure the performance figures on a decent calibrated signal generator and spectrum analyser.

These are the results:

MDS -93dBm (comfortably copy 10uV signal)
TX Power out +28dBm (>600mW)
TX harmonics 2nd -6dBc, 3rd -15dBc i.e. poor without LPF!
TX/RX offset 400Hz (without 22pF cap fitted)

Overall, not bad for something this ultra simple.

However, it needs more TX/RX offset and needs a low pass filter. The RX is also too insensitive for serious use as it would not hear weak QRP stations on the same frequency. Nonetheless, it will allow some QSOs over very decent distances to stations >10uV in level. This evening it was copying stations in PA0, DL, YL, F and G without too much effort.

7 Nov 2008

Even simpler 80m micro-transceiver!

Just finishing off breadboarding a 12 parts QRP transceiver (plus hi-Z earpiece, xtal and key) for 80m CW. The name is the uu80b.

It is crystal controlled on both RX and TX and the inspiration was the Curumim rig from PY2OHH (see earlier post). TX output is 450mW. The xtal controlled regen RX seems to be quite sensitive too. Unlike my FETer, this rig is full break-in and needs no multi-way TX/RX switching. I have already seen and heard the TX part on the on-line Twente University SDR which is 150 miles away from here in Holland. The rig uses just two 2N3904 transistors and a handful of standard parts.

Currently it is on 3.579MHz but this will be moved to 3.560 as soon as I get another crystal next week. Skeds welcomed!

Isn't ultra-simple QRP construction
magic!

6 Nov 2008

500kHz - OR7T in Belgium

OR7T was a new country for my SWLing on 500kHz this evening. He was calling CQ and was called by G3KEV but no QSO resulted (that I heard). Also heard tonight was M0FMT. All stations were on normal speed CW.

5 Nov 2008

Is this the world's simplest transceiver?

My attention has been drawn to this circuit which is, as far as I am aware, the simplest transceiver I have ever seen that is likely to be capable of serious use. It looks like an even simpler version of the well known Pixie circuit but replacing the oscillator and PA with just an oscillator used as the TX and the mixer in a direct conversion RX.

For more information visit PY2OHH's website:
http://py2ohh.w2c.com.br/trx/curumim/curumim.htm

Sunspots are GO

At last there are really clear signs that cycle 24 is on its way at last. It may be a few months before the rising sunspot count and flux levels start to be noticed in significantly better conditions on 10,12 and 15m but this time NEXT year the HF bands will be real fun again. CQWW contest in 2009 is likely to be a very different contest on 10m.

See http://www.dxlc.com/solar/images/solar.gif

29 Oct 2008

OK0EMW beacon on 505kHz

The OK0EMW beacon on 505kHz was audible last night just slightly LF of the DI2AM beacon and visible as a QRSS trace on a waterfall display. This is the first time I have positively identified this signal which is a new country for me on 500kHz listening.

Work on my 500kHz QRP TX has now started, so I hope to have a few mW ERP on the band within a few weeks.

27 Oct 2008

M0KHW was 579 on 502kHz

Ken, M0KHW in Luton was a solid 579 on CW this evening at 1735 when calling CQ on 502.4kHz with 90mW ERP. I did not hear him get any replies though.

26 Oct 2008

G3XIZ on 502kHz RTTY

Using my old pocket PC next to the IC703's LS with Pocket Digi software running I am getting very good copy of G3XIZ over in Biggleswade on 502kHz RTTY. He is only running 250mW to an inverted L antenna. Currently he's sending a list of NoV holders.

25 Oct 2008

CQWW SSB contest - 10m poor so far

Listening on 10m this morning in the CQWW DX contest it sounds a bit marginal with just weakish stations from across Europe audible plus a few Russians and 4X4s. Worked with my QRP EC7AKV, 9A5D, G2F, G0AEV (in Wiltshire by groundwave). Conditions on 10m were even worse after lunch so I called it a day and went out instead. SUNDAY UPDATE - sounds pretty dead on 10m so far apart from G stations plus tropo to ON, PA and MS pings from further Europeans.

These have been the poorest CQWW SSB contest conditions for many years. Next October just has to be better, HI.

23 Oct 2008

Main G3XBM webpages updated

http://www.g3xbm.co.uk has been updated tonight to include the FETer 14 parts 80m QRP rig and to add information about my start on 500kHz transmitting.

SAQ 17.2kHz VLF - testing Oct 24th

There is to be a transmission with the VLF Alexanderson alternator transmitter in Sweden on United Nations Day (Oct 24th 2008) at 09:30 UTC. Start up and tuning from about 09:00 UTC.

This is a good opportunity to try out VLF converters.

22 Oct 2008

500kHz band - my plans

As I've a very small garden and don't like antenna "monsters" which upset neighbours, I'd like to see what results can be achieved on 500kHz with my 15m long wire and a few watts of RF applied to it. So, my next project is a VFO controlled 500kHz TX running a few watts and a simple 500kHz ATU. If I can work 30 miles or so I'd be thrilled to bits.

21 Oct 2008

500kHz band QRP QSO tonight

This evening I made my very first QSO transmitting on 502kHz with my NoV. My TX was unusual: an old Farnell LFM4 audio/LF generator tuned to 502kHz putting out just 20mW with a morse key in the RF output lead then crudely matched with a ferrite rod matching network to my 15m long end-fed wire and central heating ground.

Only a few microwatts would have been radiated but 2 miles away the signal was copied weakly, but solidly, by M0BXT. My signal was slightly chirpy. Listening to the signal on our 50.55MHz talkback link it sounded a decent, solid, signal.

CONCLUSION
A small 501kHz 1W output transmitter simply matched (i.e. no huge low loss coils wound on dustbins!) to even a short length of wire inconspicuously strung down the garden is likely to give quite solid contacts on normal speed CW out to several miles. Using modes like QRSS there is no doubt that such a (low tech) station and antenna would be able to span much greater distances.

Incidentally, the SK6RUD beacon on 500.3kHz was a good signal this evening.

Best DX yet with the FETer 14 parts transceiver

This morning managed a QSO with Dom M1KTA at 18kms on 80m with the FETer ultra-simple transceiver (1 FET - 18mW and regen RX). Dom was perfect copy on the regen RX when running 500mW to his FT817. Another 10dB lower would have been OK. Dom is no CW expert and I am grateful for his perseverance. See Dom's blog at http://www.m1kta-qrp.blogspot.com/

A sked last night with Richard G3CWI "up north" failed though: Richard was a good signal on the regen RX but could not hear my 18mW.

So far, there are 4 two-way QSOs with 3 different stations in the log now with the ultra-simple FETer transceiver (see http://g3xbm-qrp.blogspot.com/2008/10/2nd-qso-with-feter-80m-micro-rig.html)

20 Oct 2008

2-way QSO - "1 active device transceiver" at each end!

M0BXT's 1 valve transceiver (see left)

Last night M0BXT and I had a nice two-way QSO with a difference.

Andrew used his 1 valve 300mW transceiver (see http://tetrode.co.uk/ ) and I was using the FETer 1 FET transceiver. Reports both ways were good over the two mile path.

With the help of Andrew's RF test gear I was able to accurately measure the sensitivity of the FETer rig and its power output. Sensitivity is better than -100dBm (around 2uV) for a reasonably comfortable level in the crystal earpiece. Signals could be detected (just) at around -105dBm sensitivity. The TX has a bit more power than I was able to measure crudely - around 18mW output with a 12V supply. These figures are really quite remarkable for the few parts used.

Next aim is to work some further distances with the FETer. I am sure this will be possible.

19 Oct 2008

Our grandson



Here are a couple pictures of our little grandson, taken in Paris late last week. He is a real character who has given us so much joy and happiness. This is the first time he's seen and enjoyed the autumn leaves.

18 Oct 2008

Heard of the FLEA yet? (Ultra simple rig)

http://ea3fxf.googlepages.com/flea has details of the superbly elegant rig from EA3FXF. Basically this is a simple QRP TX converted into a neat transceiver. The link has lots of information on this rig including a PCB layout and a SPICE (electronic simulation) file. There is also a Google Group on this little beauty although the correspondance is in Spanish. A full article on the FLEA is available at http://ea3fxf.googlepages.com/SPRAT-FLEA.doc . I think Eduardo and Joan must have prepared a SPRAT (G-QRP club mag) article.

Excellent stuff Eduardo, EA3GHS, and Joan, EA3FXF - a wonderful addition to the "ultra simple transceiver" line!

14 Oct 2008

2nd QSO with FETer 80m micro transceiver

This morning I had a second QSO with the FETer 80m CW "micro rig" which uses just 14 parts in total plus earpiece and morse key. The QSO was with M0DRK in the village and the report again S9 suggesting contacts at further distances are certainly possible. I would welcome skeds with stations between 10-30 miles from my QTH (JO02DG in East Cambs) to check daytime range.

This is SUCH fun and proves that solid, reliable contacts can be made with next to nothing. In all, the parts cost about £5.

13 Oct 2008

1 FET transceiver .....QSO No 1

Managed a solid RST598 (yes 8 - a little chirp) QSO on 3.579MHz with M0BXT tonight when I was running just my 14 component MPF102 FET transceiver tonight.

The regen RX in this works extremely well and is pulling in loads of 80m CW and SSB stations at good volume in the crystal earpiece. The TX uses only 4 parts including the crystal!

Now THIS is real ham radio - solid contacts with a tiny, simple, rig that can be built, with brand new parts for about £5.

12 Oct 2008

Cycle 24 ....starting at last??

http://www.dxlc.com/solar/

If you look at the solar flux and sunspot count I do believe, at long last, there are real signs of a climb out of the long sunspot minimum. There have been several false dawns already, but I think this is really it.

LATER: more spots have appeared!

Early "through ground" communications experimenter


http://earlyradiohistory.us/1902stu.htm has some details of Nathan Stubblefield's early (late 19th/early 20th century) experiments with conduction (earth mode) telephony communications through the ground.

Sometime soon I want to try some more experiments with this mode using QRSS or PSK31 at frequencies below 10kHz.

1 FET transceiver built


Today I built a single FET transceiver for 80m using just a handful of components (see pictures)

Currently it puts out 10mW on 3.579MHz (will be changed to 3.560MHz when I get another xtal) and uses the same single MPF102 FET in a tunable regen RX covering 3.50-3.62MHz. On RX it is picking up plenty of CW stations on the FISTS net so must be reasonably sensitive. The first QSO should be tomorrow on a sked with a local station a few miles away. If you want to try to work me using this rig please let me know via email at rogerlapthorn(at)gmail.com.

7 Oct 2008

VLF/LF converter

The VLF up-converter on my website (used to receive SAQ last year) has a new box and had a tidy-up! It works well and is sensitive from around 2kHz up to 200kHz. It should be useful on 137kHz receive. The actual circuit is built ugly style on a small piece of copper clad PCB material and this is about half the size of the 9V battery used to power the converter. The circuit uses a "back to front" SBL1 mixer with a 2N3904 oscillator and post mixer buffer.

The original lash-up received SAQ at RS58 and a QSL card was received for this historic 17.2kHz CW transmission from Grimeton in Sweden.

The various time signals (on 50, 60, 75 and 77.5kHz) are audible as are the Russian Alpha beacons below 15kHz. There are various unidentified data transmissions from 17kHz to around 80kHz audible but not identified.

3 Oct 2008

New UHF/SHF super-DX mode?


The ARRL Propagation report (link on my website) today reports some interesting findings about very high altitude noctilucent clouds reflecting radar signals, raising the possibility that extreme, INTERCONTINENTAL, UHF/SHF DX might be possible using reflections from such clouds. See
http://www.sciencedaily.com/releases/2008/09/080925144806.htm

"...the clouds contain ice coated with sodium and iron from micro-meteors and sit at about 53 miles (85 km) altitude, mostly between 50-70 degrees latitude, and sometimes as far south (or north, in the southern hemisphere) as 40 degrees latitude or less.

The clouds are highly reflective of radar signals, and instead of diffraction as we see in ionospheric propagation, ripples in the clouds seem to reflect in unison, reinforcing each other.

Noctilucent clouds are sometimes visible at night, because their altitude is so high that they reflect sunlight into areas of darkness. They are also known as polar mesospheric clouds, and appear most often at twilight during the summer."

Imagine working many thousands of miles on 10GHz QRP by a mesospheric
reflection mode. Now that would be something REALLY different!

GI4DPE on 501kHz

501kHz was in a reasonable state a couple of evenings back with Finbar GI4DPE being a steady signal down here on CW in East Anglia. I must get some QRSS software as there have been a few stations on which I have not been able to decode. QRSS "by ear" is not easy!

30 Sept 2008

HF AM excursion - all 9 bands!

M0BXT and I usually have a natter on 144.55MHz vertical AM on Mondays at 8pm. We were on last night but got distracted doing some tests on all 9 HF bands using QRP AM.....

Starting on 10m and working down to 160m we very briefly exchanged reports at 4W and then with some 10-20dB less to see how signals compared across each band on our end-fed antennas tuned via an auto-ATU at each end.

I have to confess to a brief AM QSO on 30m (shame, disgrace!!) but only for 20 seconds at most so no harm was done to the planet.

We managed solid QSOs at over S9 over our 2 mile path on all bands apart from 24MHz where signals were weaker, maybe because our wires had deep holes in radiation on this band. The best band was 80m where signals were 59 + 50dB or so. 160m was also pretty good.

M0BXT and I hope to have our first two-way single valve or single transistor transceiver QSO in the next few weeks on 80m but this will be CW.

19 Sept 2008

Decent DX around despite the sunspots

This last week has seen some decent DX around despite the zero sunspot number. V51YJ is booming in on 20m CW this evening. VK3PA was audible on 80m SSB a few nights back at sunset and YB6INU a decent copy on 40m SSB.

On 501kHz (600m) the SM6BHZ and DI2AM beacons have been reasonable signals in the evening this week.

14 Sept 2008

40m in good shape

Listening on 40m tonight in the contest there was plenty of decent DX around on SSB including PJ4NX, ZW5B, K5ZD (who "QRZ? ed" me with 10w and short endfed), W1UE and others at decent strength.

5 Sept 2008

Icom IC7000S

Anyone know if this version of the IC7000 series (10W low power I think) is available in the UK? This would make a nice QRP radio for many.

Interesting solar fact

August 2008 was the first calendar month with no sunspots since 1913 according to the ARRL propagation report this evening. They also note that cycle 19 (the biggest on record) was preceded by long periods without spots. You never know, cycle 24 might turn out to be a whopper and we'll all work the world on 70MHz with milliwatts.