31 Dec 2008

Best wishes for 2009

My very best wishes for 2009. For a change, I'd like to quote an extract from the last of T.S.Eliot's Four Quartets poems which is called Little Gidding. It reminds me that every year is part of our never ending exploration and journey.

"With the drawing of this Love and the voice of this

We shall not cease from exploration
And the end of all our exploring
Will be to arrive where we started
And know the place for the first time.
Through the unknown, unremembered gate
When the last of earth left to discover
Is that which was the beginning;
At the source of the longest river
The voice of the hidden waterfall
And the children in the apple-tree
Not known, because not looked for
But heard, half-heard, in the stillness
Between two waves of the sea.
Quick now, here, now, always—
A condition of complete simplicity
(Costing not less than everything)
And all shall be well and
All manner of thing shall be well
When the tongues of flame are in-folded
Into the crowned knot of fire
And the fire and the rose are one."

Go quietly on your journey in 2009 and may it be a very fulfilling and joyful one.

30 Dec 2008

70cms good conditions tonight

Just worked GW0LJW in Gwent and G3VEH/M via a 70cms repeater in Somerset tonight when running 5W (actually about 1.5W into the antenna after the coax run) into the vertical colinear. Conditions are definitely up in that direction as the distance is about 250kms.

29 Dec 2008

Dutch on-line SDR testing new bands

The on-line software defined radio (SDR) in Twente, Holland http://websdr.ewi.utwente.nl:8901/ (very useful when testing 80m QRP rigs) temporarily added the 0-150kHz, 1.8MHz and 10MHz bands to the ranges with wider band coverage than before on 20 and 80m over the Christmas period. This SDR is now back to its usual 80,40 and 20m coverage (as of Dec 30th).

28 Dec 2008

The South Hams and G5BY on 6m

A slight aside from ham radio, I just want to give a plug for the most beautiful part of England where I lived until leaving for university - the beautiful part of southernmost Devon known as the South Hams. Our family has lived here from at least 1428, the earliest date in our family history records when one of my ancestors owned one fee of land in the time of King Henry VI. You can understand why I still regard this as my spiritual home even though we enjoy living in East Anglia. We still make regular pilgrimages back to "the promised land" as my dear old dad called it. Indeed it is.

There is a new book of walks in this area called The South Hams Coast by Gerry Miles (see www.devonpaint.nl/ and also available from www.amazon.co.uk). The book is beautifully illustrated with coastal walks covering many of the high spots from where some great VHF DX has been worked. These include Bolberry Down from where G5BY worked the USA on 6m back in the 1940s when the band was briefly available. Today his QTH (see old picture) is "The Port Light Hotel" a delightful place to drink a pint or have a crab sandwich on a long sunny cliff top walk.

27 Dec 2008

G4IRZ Silent key sale - items now sold

On behalf of his widow, the kit belonging to the late Len Winnert G4IRZ was sold today, as one lot, to a private buyer in East Anglia.

25 Dec 2008

Radio Nature

A very happy Christmas everyone. One of my presents was the book called "Radio Nature" by Renato Romero which is a very good introduction to the weird and wonderful world of ELF/VLF natural emissions such as whistlers and tweeks. The book, available from the RSGB on-line bookstore, is an excellent read.

See also his excellent webpages at http://www.vlf.it/ .

24 Dec 2008

Tunnel Diodes rigs

Way back in the 1960s I recall making a simple tunnel diode oscillator as part of a lab project and being excited to see such a circuit used to span 160 miles on 80m by a ZL station despite the power being microwatts only. These days tunnel diodes are almost unheard of.

Recently I spotted a similar tunnel diode TX and RX on AA1TJ's excellent webpages on which you can find more data and links to off-air records made at DX distances.

23 Dec 2008

G3XBM is 60 today

Well, another milestone passed - I have reached the age of 60 and get a free bus pass for local English buses nationwide as well as a winter fuel allowance. At least there are some perks for getting older.

21 Dec 2008

Elecraft K1

This morning I fired up my Elecraft K1 CW transceiver not having used it for some time. It is such a good little rig. Mine has the 4 band unit and internal ATU option and covers 40, 30, 20 and 15m. The filtering is excellent and the user interface good as long as you can remember the menu system, which I forget often when I don't use the rig for a time.

Within a few minutes of connecting the end-fed wire about 15m long into the back of the rig I had 5 QSOs in the log on 40 and 15m. It is such a perfect CW rig.

More details see the Elecraft website http://www.elecraft.com

£500 silent key sale - a REAL bargain!

Some weeks ago I mentioned that I had been asked by a niece of G4IRZ to help with disposal of his (silent key) radio gear which included an Alinco DX70 HF transceiver in original packing and an FT767GX, FP707 PSU and lots of other ATUs, SWR bridges, BC221, GDO, etc. Several requested the list, but no-one has put an offer in.

The whole lot is yours for £500, buyer collects from Cambridgeshire.

I believe the actual value of the kit FAR exceeds this amount but I am not in a position to spend time disposing of the items individually. If someone is willing to buy the lot from his niece she would be pleased (as would Len's XYL) and the buyer is likely to make a decent profit if the items are then resold separately. It would also make an excellent complete ham shack for anyone starting out.

Remember, £500 buys a huge LOT of decent gear for Christmas.

Dec 27th: Now all sold.

Solar data page - new URL

The Solar Data page has a new URL weblink. If you have this saved as a bookmark in your web browser the new link is now http://www.solen.info/solar/

19 Dec 2008

29MHz FM

Just after 7pm tonight (Friday) I hope to do some tests with G4NUA in Cambridge around 29.6MHz FM. We will both be HORIZONTALLY polarised (Homebase-10 wire halos) running around 10W FM. If there are others in the mid-Anglia area who would like to join us then please do call in.

At one time there was a lot of activity on 29MHz FM but there is much less these days or is it just around here?

1930hrs update: successfully heard G4NUA at RS56 but he could only just detect my FM carrier (no modulation) his end. Surprised that we were unable to work each other at this distance with a pair of horizontal halos. On 2m he was 59++ and on 70cms 56. Ted was using the FT8900 4 band 50/35W FM rig covering 10m, 6m, 2m and 70cms - nice radio.

15 Dec 2008

Useful on-line distance calculator


Type in the 2 callsigns to get the QSL addresses and the distance, (in miles or kilometers), between them plus miles/watt. Thanks to KD0FNR for finding this one.

The distance of my 2007 6m QRP QSO with K1TOL works out at 5083kms.

10 Dec 2008

UK price rises - Yaesu and Icom rigs

Have you noticed that prices of the Yaesu FT817 and Icom IC703 have been significantly increased by at least one of the big UK suppliers in the last few days?

With the falling pound I can understand margins being squeezed more than before but surely, with a VAT reduction and with Christmas coming, this must be the most stupid piece of marketing yet.

Later comment: Several people have explained to me that the yen/pound exchange has significantly worsened so there is probably little the dealers could do but pass on a major part of their price increase on goods from Japan. I also see that most dealers are now holding the old prices on goods in stock as well as offering some good trade-in deals.

8 Dec 2008

SM6BHZ on 504.5kHz - strong

The 3W ERP beacon of SM6BHZ on 504.5kHz is coming in well tonight at 2215z in slow CW and QRSS3. QSB rate is slow with peak to trough being around 1 minute with me.

4 Dec 2008

Ham gear for sale (silent key G4IRZ)

Recently I have been asked to help sell a large amount of ham radio equipment from an ex Royal Signals ham who is now a silent key - Len Winnart G4IRZ. This includes a FT767DX (base mains powered multi-mode rig), a DX70 multi-mode HF/6m transceiver still in its packing, FP707 PSU, a GDO, various ATUs and SWR bridges and lots more. If anyone is interested in seeing the list please email me at rogerlapthorn (at) gmail.com and I will send you the full list of items.

In particular, if anyone is prepared to make an reasonable offer for the whole lot I'd be happy to discuss. All I am trying to do is dispose of the equipment to someone who would make use of it at a fair price for his XYL.

Please contact me ASAP if you have an interest in this kit.

2 Dec 2008

Argo plot of OK0EMW tonight on 505kHz

This is the Argo waterfall plot showing the Czech 505kHz beacon OK0EMW on QRSS3 (slow CW, 3 sec dots) coming in well tonight at 1700z. It was not audible by ear though. Note the QSB in the middle when the number 0 was being sent.

1 Dec 2008

VO-52 satellite reception

Not listened for amateur satellites for some time so took a quick listen on 2m SSB around 145.9 this evening. Managed to catch a couple of VO-52 satellite passes and logged IK1SOW, EB2FJN, SP4BY and HB9XJ on SSB. I have printed out the passes for the next few days so will see what else I can receive on the FT817 and the vertical colinear antenna.

The first place to check for first-time satellite SWLs is the AMSAT page which has lots of helpful info on satellites, frequencies and passes.

WSPR beacons on the 500kHz band

There are now some stations appearing on the 500kHz band using WSPR mode which is a clever digital beaconing system allowing reception to be monitored and mapped/listed using PC software attached to a suitable transceiver and the internet. In effect you can set a transmitter running then check for reception reports from similarly equipped stations via an internet reporting page. See http://www.physics.princeton.edu/pulsar/K1JT/ for more information. K1JT designs some mighty impressive ham software! When I get a WindowsXP machine that is reliable again I will try this mode I think.

A family picture

One of our greatest joys this past year has been our first grandson, Lucien. He is now 1 year old and looking more like a little boy every day that passes. His mum, Jo, is French and his dad Tim is English, so he is likely to grow up speaking both languages. This is a nice picture of my wife Lis, our elder son Tim and little Lucien taken a few days ago. Our other son Chris and his wife Lauren - an Australian - are expecting their first grandchild next March. Whether either will be interested in ham radio remains to be seen.

30 Nov 2008

SAQ (17.2kHz) active on Dec 6th

There will be an extra SAQ VLF transmission this month on Dec 6th at 1045UTC on 17.2kHz. No reports are being requested and no QSL cards will be sent out this time.

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

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:

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.

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??


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

"...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 Sep 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 Sep 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 Sep 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 Sep 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.

25 Aug 2008

Simple 432MHz operation webpage

Just added a new 70cms web page to my site at http://www.g3xbm.co.uk .

19 Aug 2008

501kHz tonight

Heard G3KEV calling CQ on 501kHz CW tonight and listening for crossband QSOs on 3533kHz. Although I called him a few times on 80m he did not hear me. Also heard (for the first time) was G3DXZ also on CW. Both stations were RST549 on the FT817 and random 15m endfed wire.

17 Aug 2008

6m and 10m lively today

Both 6m and 10m were lively in Europe today with quite a few QRP QSOs made on both bands via sporadic-E. Nothing heard much beyond Europe though apart from 6V7L being called by many on 10m.

16 Aug 2008

Home Base 10 - webpage link fixed

The link to the Home Base 10 (10m halo antenna) on my webpage http://www.g3xbm.co.uk went AWOL last week. This has now been fixed. The antenna is fully described in September 2008 edition of Practical Wireless p38-40.

6 Aug 2008

Good 6m opening tonight

What an evening! Only worked one EA station on 6m QRP but heard some amazing DX. Firstly D4C Cape Verde Is (working piles of Europeans on CW) who was audible on the vertical colinear on the side of the house at 539 at best. Also heard was Lefty K1TOL in Maine, USA who was peaking 569 on the same vertical antenna. Really thought I had a chance of working him again with 6m QRP but was not so lucky this season.

Home-base 10 antenna - QSO with USA

10m opened up to the USA this evening and I managed to get RS53 from N2MM in New Jersey with QRP SSB to the Home-base 10 10m halo. This antenna is really working very well indeed. There is an article showing how to build this antenna in Sept 2008 edition of Practical Wireless.

5 Aug 2008

G3XBM website updated

My website at http://www.g3xbm.co.uk was updated today with a page on the Moxon 70cms antenna including a diagram and a few pictures.

3 Aug 2008

70cms Moxon results

Well, the 2el Moxon made from my wife's coat hanger was tested in the 432MHz low power contest today and it worked very well considering how tiny it is and how it was made! Best DX was F8BRK at 326kms who gave me a 519 report. In all 10 QSOs were made in a few hours of operation with 5W from the FT817. A total of 8 QTH locator squares were worked in very dismal conditions and rain.

2 Aug 2008

70cms Moxon 2el yagi

There is a 432MHz low power contest this Sunday, so I have made a small 2el Moxon yagi to use /P with the FT817 in the contest. I have no idea if I will work anyone with it. It was built using one of my wife's coat hangers. If you hear G3XBM/P be sure to give me a call. I shall be operating from JO02CC or JO02DD square in East Cambridgeshire. Both have clear take-offs to the north round to the west, but not so good to the east.

26 Jul 2008

DSB10 - more progress

I have now breadboarded the 10m DC receiver for this rig using a single balanced mixer with 2 diodes followed by two stages of audio. It works well and was pulling in plenty of stations in the IOTA contest this weekend on both SSB and CW without any sign of AM breakthrough. I think the secret is plenty of LO injection to switch the well balanced diodes hard.

21 Jul 2008

10m DSB Rig - started at last

For some time I have been toying with the idea of building a simple but effective 1-2W DSB transceiver for 28MHz. Well, this weekend I made a start by breadboarding the transmitter up to, but not yet including the final PA stage. The 2N3904 has been used throughout plus a couple of 1N4148 diodes (which seemed well matched) for the TX balanced mixer. Output from the balanced mixer was sub milliwatt so a couple of linear stages lift the output to around 50-100mW pep. With a single 2N3866 PA stage this should take me up to the 1-2W pep level.

Next stage to breadboard is a mixer-VFO. I am thinking of a 20MHz xtal oscillator (because I have a crystal) and an 8MHz VFO. Ideally I'd like a higher xtal oscillator so the VFO is lower in frequency and more stable.

The RX was breadboarded last week and uses a single balanced diode mixer followed by 2 stages of audio. This works really well with no sign of AM breakthrough at all.

15 Jul 2008

Pipit20 rig on air

This last week I have been building again. Not much, just another DC transceiver built ugly style. The rig covers 14048-14070 VXO controlled and puts out about 500mW using the OXO design. It uses an SBL1 mixer on RX followed by 3 stages of AF gain. Only station worked so far is M0BXT but hoping for some Europeans maybe at the weekend. It suffers a bit from AM breakthrough and the 2N3904 transistors used in the AF sections are too noisy really. This is really not a perfect radio, more a work in progress.

Why the name? The Pipit was a similar (better!) radio design I put in SPRAT many years back for 15m.

2 Jul 2008

Micro80 4-transistor transceiver QSO

After some time without use, I resurrected the little Micro80 4 transistor transceiver for 80m last weekend. To increase the power a bit I've now got provision to run it from an external gell cell battery at 12v, so giving me about 2dB more RF out compared with the 9V internal pack. Using it with the bench PSU was impossible because of 50Hz hum pick-up. I also managed to improve the AM breakthrough by around 10dB at least by putting a 4n7 cap across the base-emitter junction of the first stage of the darlington in the RX AF. This makes it a usable radio on 80m at night now as it is not obliterated by the BC stations around 4MHz. Success soon followed with a solid QSO with G3XIZ in Biggleswade around 30 miles away late Sunday afternoon.

24 Jun 2008

Wet square on 6m

Just beat the pile-up to work UT1FG/MM on 6m SSB in IN38 square out in the Atlantic. Obviously I have not worked this square ever before!

501kHz listening

Having re-erected my end-fed wire antenna I am able to listen to 501kHz again. First station heard recently was G3XIZ on CW at 579. I have an NoV to transmit on the band so really must make an effort to get some sort of TX together.

22 Jun 2008

6m DX QSL card from K1TOL

This is the QSL card confirming the June 25th 2007 6m QSO with Lefty, K1TOL. I was using 2.5w ERP at the time to a small vertical! Magic band? You bet!

Lefty has a big 6m antenna farm and runs 1kW, but I much appreciated him hearing my tiny signal and giving me the RST519 report that night. It was one of the best contacts I have ever had in 40 years on the bands.

20 Jun 2008

Real 6m DX at last

Earlier this week 6m bucked up a bit allowing W5OZI in EM00 square to be heard hear at around 8000kms! Also heard were N3DB, 4X4DK and 4Z5LA. This was a few days ago now and I've not heard any further "super" DX since when I have listened. It is amazing what can be heard on just a small vertical antenna fed to the FT817 via about 40 feet of RG58 coax!

Also this week I received the QSL card from K1TOL for our 6m transatlantic QSO last summer - my best ever 6m QSO with just 2.5w ERP.

11 Jun 2008

Canary Is and Cape Verde Is on 6m

6m opened up nicely this evening allowing two QRP SSB contacts into EA8 (EA8YT and EA8CQW) both in IL18 square. Also heard the D4C/B beacon in Cape Verde Is for the first time just hovering at the noise level for me at best.

10 Jun 2008

Still below average on 6m

Just one EA worked on 6m QRP yesterday and still no further transatlantic stations heard. Conditions definitely not up to last season.

5 Jun 2008

6m not as good as 2007?

Do others agree that 6m conditions have not been as good as in the 2007 season so far? This year I've only heard one transatlantic station (HI3TEJ) so far, and he was only just audible. At this point last year I'd heard several Caribbeans and USA/Canada.

1 Jun 2008

Photo of Homebase10 10m antenna

This is a picture of the "Homebase10", a horizontal 10m antenna mounted on its pole above my roof. It is a wire halo which very effectively covers around 600kHz of 10m with a low SWR. It has allowed me to work plenty of stations running QRP with some contacts with just 50mW (see earlier blog post).

Homebase 10 (10m halo antenna)

This antenna is appearing in PW shortly. There is a page about it on my website. http://www.g3xbm.co.uk

26 May 2008

Online SDR

http://websdr.ewi.utwente.nl:8901/ is an online software defined radio which up to 50 people can use at the same time. It covers parts of 80, 40 and 20m and works really well on my little Asus EEE PC. You need both Java and JavaScript enabled for this page to work properly. Unfortunately it does not quite tune down far enough to cover the QRP calling frequencies.

Ukraine worked on 6m QRP

UR5WD in KO20NC was the best QSO on 6m QRP (5w CW on the small vertical) yesterday. He was quite weak with me on CW and I was surprised to work him, but got a 559 report. The band was open most of the day to somewhere in Europe although the opening favoured the east for me.

25 May 2008

50mW 10m QSOs today

WPX CW contest today and 10m in great shape allowing 4 QSOs just now with just 50mW into the recently built Homebase10 wire halo antenna. These stations would have been workable at 5mW or less I believe, but I could not find a larger RF attenuator!

Worked with 50mW: DL7BY (599), DH8BQA (599), DG4R (599), EH3MM (599)

24 May 2008

New 6m country worked

Although not super DX, I worked 9H1 this evening with 5W CW on 6m. The band was in good shape with stations from all over Europe audible and even hints of transatlantic stations (8P9 worked by a CU3 and calling CQ DX Eu).

21 May 2008

6m and 10m lively this afternoon

10m was in good shape at 3-4pm today with plenty of EUs workable including a new country for me on the band in the form of LX1AX who gave me 55. He was running 1kW to a 9el yagi - rather out-doing my QRP and a halo! Still, a new 10m DXCC country is in the log.

6m was also open managing to work IK0FTA with 5W SSB and the vertical.

20 May 2008

Some life on 10m tonight

10m was open earlier this evening to ZD7X. I was unable to hear him when I got on but did work EA and EA6 on QRP SSB.

19 May 2008

Inter-G 10m DXing

Some years ago the RSGB arranged some evening 10m activity periods during a quiet part of the sunspot cycle. It was fascinating to see how far one could work on 10m around the country even with QRP SSB/CW. Contacts from here in East Cambridgeshire regularly extended to as far away as Yorkshire even with just a sloping wire dipole or CB half-wave antenna only. Contacts were often right on the edge and CW helped. I would be happy to try skeds with others in the UK on any mode on 10m although I can only run 10w maximum. I have long thought the 10m band is much under-used for local and semi-local QSOs. It is a pity there is now less 10FM activity around 29.6MHz apart from when the band is open for DX.

Through the ground communications?

Anyone experimented with "through the ground" (earthmode) communications using audio amplifiers and grounded electrodes? I have done this in the past with limited success but never used more than a few watts at 1kHz. These days with ultra-narrowband digital modes like QRSS, PSK31 ad PSK16 coupled with waterfall displays ranges should be quite respectable. My best DX was 0.3kms but I imagine this could be at least doubled using modern DSP techniques. There is some info on this on my website http://www.g3xbm.co.uk

Publicising the blog

Just announced this blog on http://groups.yahoo.com/group/GQRP/ so it will be interesting to see if anyone now reads it.

The simplest possible QRP transceiver?

What do you think is the simplest possible QRP transceiver? The Pixie or Micro80? Have you built a functional transceiver with even fewer parts than these famous QRP radios? If so, post a link. I believe it should be possible to make a transceiver with fewer than 20 parts in total.,

Elecraft K3

Have you seen the new K3 from Elecraft yet? All review comments are very favorable and it is certain to be a hit for those wanting a top of the class rig at a relatively modest outlay for a radio in its class. Although I wouldn't mind one, it is not top of my own shopping list though.

If you have used one of these rigs please let us know how you found it by posting a reply on the blog.

Fredbox 2m AM mini-rig

There have been a few recent posts on the VHFam Yahoo group from people building versions of my Fredbox 2m AM rig. This rig was first designed back in the 1970s and rebuilt a couple of years ago.

Best DX worked was 160kms across the channel to Brittany from South Devon using just a whip antenna - not bad for 10mW. A proposal for a Fredbox 2 is shown in the files section of the VHFam group. This is a DSB version based on the NE/SE602 double balanced mixer.

10m and 6m summer conditions

So far I have been disappointed by this summer's sporadic-E conditions, which have not been as good as last year. OK, it is still early days in the season and things may improve. Traditionally, early June is a good time for super DX across the Atlantic to start.

On 10m I am testing my new Homebase10 antenna. This is a wire halo antenna based loosely on the cobwebb and the GM3VLB antennas. It is called the Homebase 10 as most of the bits can be bought from the local Homebase or B&Q stores.