Roger G3XBM's Amateur Radio Blog

Rail holiday in Switzerland

2013-05-20T06:24:00.000+01:00

As I am currently in Switzerland on a Great Rail Journeys rail holiday (without amateur gear), posts this week will be infrequent. Having a good time though combining rail travel with excellent scenery. Currently based in Chur for 3 nights and travelling to Arosa by train today. Later this week we travel on the Glacier Express narrow gauge line across the country towards the Zermatt area.

My blog on the holiday (adding to it each day) is at http://hb9trip.blogspot.co.uk/

28MHz BitX SSB transceiver

2013-05-15T22:11:00.001+01:00

http://www.qrpkits.com/images/bitx20acase1.jpg

The very popular BitX SSB transceiver is, to my knowledge, available in kit form (from QRP kits) for both 20 and 17m, but I haven't seen versions for other HF bands.

What would be really nice would be a version for the 10m band where 6-8W would be enough to work the world when the band is open. The IRF510s would need to be changed to a Mitsubishi power FET such as the RD16HHF1.

Does anyone know if a 10m BITX has been done or if a kit is available for this band?

37 and 73kHz tests through the ground?

2013-05-15T21:56:00.005+01:00

Further to my comment on VLF WSPR, I am still thinking about doing some earth-mode (through the ground) transmission tests at a couple of frequencies between the 8kHz dreamer's band and 136kHz. I'd like to test in the old 73kHz band (legal with earth mode and minimal radiation) and possibly around 37kHz too. A radiated test in the old 73kHz band would not be legal despite low uWs ERP unless I applied for the modern equivalent of a testing and development licence and paid £50 a year, stupid for a couple of tests taking a few hours. Getting MoD approval for that would likely take months and months too.

As my FT817 does not cover this frequency range, and the frequencies will be too high for direct sound card reception, I shall have to build an up-converter for the FT817 with a couple of front-end filters to pre-select the desired LF frequencies or a down converter to feed a sound card directly. A loop, E-field probe or earth electrodes would be used on RX ahead of the converter with the eventual output feeding a PC running appropriate weak signal software (Spectrum Lab, Spectran, WSPR etc).

I made a request to OFCOM very many months ago to permit me to do some low ERP radiated tests in the band between 9 and 136kHz on the basis that the potential for interference with very low ERP (uWs) and transmissions lasting no more that a few hours at a time would be extremely low. Such a request required lateral thinking and empowered decisions. Many, but not all, people at OFCOM seem incapable of making common sense decisions any more. They are also hindered by stupid bureaucracy. Ho hum.

VLF WSPR test

2013-05-15T11:12:00.002+01:00

Now I have a second small PC (a small Asus X101CH netbook) the possibility exists for me to try some VLF earth mode tests with WSPR. Although I did receive G6ALB 3km away on 8.97kHz through the ground when Andrew was running around 40W, I have never tried looking for my own signal using WSPR at VLF. Theoretically it should be about as good as QRSS10, so quite weak signals may be detectable.

One idea I have is to TX the actual WSPR tone frequencies at baseband through the ground using my small 5W VLF transmitter. Using either my loop antenna or E-field probe on the car retuned to around 1.4-1.6kHz VLF, I can take some trips into the field to see how things work out.

With stability not being an issue I could even try WSPR15 (15min TX) which has performance close to that of QRSS30. Mind you, waiting at a test site for at least 15 minutes for a result could be tedious. This is where some local help from other decently equipped VLF listeners within a 10-20km radius would be very useful.

Back on 10m WSPR with WSPY TX

2013-05-15T11:06:00.000+01:00

Unique 10m WSPR spots using WIPSY TX today

Having given up on 20m CW this morning, I fired up the 10m WISPY beacon TX running around 250mW to see what spots I got. During the day I caught a couple of Es openings. 4X1RF seems to spot me whatever I do/run and on most days!

I have still to put the TX and RX parts of this project together (both parts have been separately tested) as a full WSPR/PSK31 transceiver for 10m.

Struggling on 20m CW

2013-05-15T10:42:00.004+01:00

For the last 30 minutes I've been putting out calls and listening on and around 14.060MHz CW, the QRP frequency, using my QRP OXO transmitter. Although a couple of QRP stations have been copied (DJ2GL and IZ5OVM) I have only managed to be spotted on the Reverse Beacon network myself once by DJ9IE.
Although calling CQ and hunting can be fun with QRP, it can be very frustrating with less than 1W and an indifferent antenna when conditions are poor and activity low.

G4ILO is 60 years old

2013-05-15T10:36:00.000+01:00

Julian G4ILO - 60 yrs old on May 14th - with XYL Olga

Julian G4ILO reached his 60th birthday this week on May 14th. As those who follow his excellent blogs will know, he has been successfully battling a brain tumour, although battling the DVLA to get his driving licence back seems to be harder, HI. I am sure everyone here wishes both Julian and his XYL Olga a VERY happy 60th birthday and many years of happiness in the future.

See http://onefootingrave.blogspot.co.uk/

472kHz in the USA - when?

2013-05-14T21:52:00.001+01:00

Anyone know what the problem is in the USA (with the FCC I assume) that is holding up the release of the 472-479kHz band to amateurs in that country? It rather makes the USA look like a backward 3rd world failed state, incapable of passing what should be a simple piece of legislation! I am sure that many in the USA are waiting with bated breath for the release of this fascinating new band that most of us have been able to enjoy for some months now.

Come on FCC - are you a mice or men?

HT-200 QRP HF transceiver from Tokyo Hy Power?

2013-05-14T21:43:00.004+01:00

The HT-200 HF QRP transceiver

Some years ago (in 2006) I posted news of the HT-200 HF QRP rig from Tokyo Hy Power. There was a page about it on my old website. The image showed a prototype of what looked like a very useful little transceiver but, regrettably, nothing more was seen of it.

Unless I have completely missed news of it, I assume they decided not to continue the development and production of this unit. I expect this was to do with profit margins, development costs or the general state of the economy in Japan.

If anyone knows what really happened and why this never made it to market (I think) then please let us all know.

Solar flare and cycle 24

2013-05-14T16:56:00.003+01:00

The BBC website has news of the solar flare on Monday. See http://www.bbc.co.uk/news/science-environment-22525233 . As we are around the peak of solar cycle 24 - the jury is still out on whether or not we will have a second peak in the cycle larger than the one of Nov 2011 - such flares can be expected. They can occur at any time though.

Of course the media, including the BBC, likes to "hype up" the dangers of extreme flares: talk of wiping out satellites and power grids etc. All these things can occur, but we have better ways of protecting from these risks and with some advanced warning the dangers of black-outs can be reduced.

In many ways, I prefer the quieter years in the sunspot cycle: working DX with QRP is more challenging on the higher HF bands and, as I mentioned a week ago, WSPR will really be useful in winkling out the openings that fleetingly may occur.

Japanese amateur gear prices - down please!

2013-05-10T08:36:00.002+01:00

Sorry to labour this point, but in the last few months the Yen has lost over 25% of its value against the UK pound. Why are we NOT seeing prices of Icom, Kenwood and Yaesu gear falling significantly? By now the FT817ND should be retailing for less than £500. I know there are other factors, but it would be nice if our dealers passed on SOME of the exchange rate improvements.

SSB generator using a modulated PLL (by PE1NNZ)

2013-05-09T20:41:00.001+01:00

Guido PE1NNZ has been doing some very impressive work on direct SSB generation using a PLL and implemented it on a Raspberry Pi mini computer. I don't claim to understand a word of it (!) but this really is clever stuff. He tells me he has made several contacts on the 40m and 20m bands with his Raspberry Pi!

For your interest, here is more information about the SSB experiment: http://pe1nnz.nl.eu.org/2013/05/direct-ssb-generation-on-pll.html

73, Guido
PE1NNZ

To Argentina on 10m WSPR today

2013-05-09T20:06:00.001+01:00

The 2W WSPR beacon was copied several times today in Argentina (LU8EX, 11208km) and by CX2ABP (11127km) a few days ago. 4X1RF seems to copy me most days. 10m seems to open mainly on the N-S paths although I did spot a DU station (Philippines) a few days ago.

This evening I have fired up the 472kHz WSPR kit into the earth electrodes. PA3ABK is coming through despite my high local noise level and 6 stations so far are copying my 1mW ERP signal. PA3ABK is the best DX report of my signal so far at 306km but the beacon has only been on for an hour so far.

WSPR - how long to get a decode?

2013-05-08T12:09:00.003+01:00

A question for my esteemed readers please.

Using WSPR (WSPR2 that is) the transmission burst is nearly 2 minutes long, but I believe strong signals can be decoded when only a part of the burst is received. My question is, how short a burst can be decoded? Presumably it depends on how strong the signal is.

LB9YE was coming through quite well this morning but there was no decode of a very strong (I assume MS) burst at 1048 which lasted about 30 seconds. Of course with MS there may also be some Doppler shift which can mess things up a bit.

If you know about WSPR and can help with the answer, I'd appreciate it. I am particularly curious to know how WSPR might do with short MS bursts which can be strong but only last a few seconds. It also begs another question: there is now a longer version of WSPR (WSPR15) with better decode S/N levels. I wonder if a shorter version of WSPR has been considered? Then again I think there may be better modes for MS.

Night watch on 10m

2013-05-08T07:58:00.001+01:00

Overnight, I ran WSPR on 10m just for fun. Although my 2W wasn't spotted until 0600, a couple of Germans were spotted here around 0400 presumably by Es or MS. Without modes like WSPR such brief night time openings would go unnoticed.

One Laptop Per Child project

2013-05-07T22:09:00.000+01:00

When I left paid work in 2008, the One Laptop Per Child project was in its infancy. At that time the idea of a low cost PC or netbook was not really on the horizon, although the Linux 7 inch Asus EEE PC was a sign of the future. As far as I can tell, the availability of low cost netbooks and tablet PCs has rather overtaken this project: low cost computing is now available from many sources.

The idea of making low cost computing and internet access available to under-privileged children and others worldwide is a noble one and one I fully support: knowledge is power and knowledge and education are rights for all citizens of the world.

However, there seems to be some doubt about the success of the OLPC project 5 years on. It was a "good idea" but maybe market forces overtook it?

One of the reasons I like QRP projects is because they have the potential to make useful radio technology accessible to all at low cost. Like the OLPC project, my dream is a simple, low cost, easily reproducible, HF transceiver design that really can produce useful results. There is something beautiful is "elegant simplicity" don't you think?

The £20 decent HF transceiver thoughts

2013-05-07T21:48:00.002+01:00

I never fail to be impressed by what other people know and that I don't. Several people have responded to my post about the "£20 decent HF transceiver challenge" with ideas that use PICs and similar micro-controllers in novel ways to generate SSB signals. In all honesty I wouldn't have a clue about how to start doing this, so I am VERY impressed.

My own approach to the £20 transceiver would be very low tech indeed: not an IC in sight probably and certainly no processors. Having said that, I would be very interested to see how such novel approaches could help to realise a low cost decent HF transceiver. As an example of this look at the HF WSPR transmitters produced entirely using a Rasperry Pi PC.

One thing that life has taught me is that it is impossible to know about everything: some of us know lots about RF (I am only a surface scratcher) whereas others know lots about software or something else. Some very talented people have a wide span of knowledge.

We should be grateful for the unique knowledge WE have and gracefully accept that others know lots more than us about something else. It never does any good to be stressed about what we don't know. In my work days I always told my staff never to be afraid to ask the dumb questions as there are lots of others waiting for someone to ask them!

Incidentally I have done nothing yet towards this design. Weather has been too nice to be inside engineering, HI.

Solar activity - a second peak?

2013-05-07T21:36:00.003+01:00

Looking at the sunspot and solar flux levels in the last month, it looks like we are seeing evidence of a second peak to cycle 24. Whether it exceeds the peak of November 2011 remains to be seen. As the slide down from the peak(s) is slower than the rise towards the peak(s), we can expect reasonable HF conditions for several more years yet before we return to the quiet years when activity on 12 and 10m is very low indeed.

10m WSPR

2013-05-07T21:26:00.001+01:00

My 10m WSPR system has been running most of the day with powers between 500mW and 2W. The only reports were from 4X1RF at 3519km. Best DX station copied here was DU1MGA at 10710km.

One of the reasons I like WSPR is that you can do other things at the same time whilst checking on how propagation is changing. I am really looking forward to running WSPR in the quiet sunspot years on 10m and expect far more openings that might be found by calling CQ on CW or SSB with 5W.

New QTH work

2013-05-06T20:43:00.001+01:00

New QTH rear garden - with the "roof tile feature"!

The work on our new (to us) QTH in Burwell is progressing steadily and if things go to plan we should be in later this summer. Today I was at the new location sorting out the garden - as much as I could - in the beautiful sunshine. There is still a great deal of builders rubbish and mess around and it will be some months before the garden can be properly worked on: for example, we have a row of roof tiles neatly stacked down the middle of the rear lawn and the front of the house has a pile or 2 of sand and bricks! The drive has a skip in it which is rapidly filling with neighbours rubbish too.

I am still thinking about ideas for antennas. At least in the new QTH I will have a dedicated shack where I can both build and operate: in 37 years at the current QTH this has not been possible. Currently I have called off the plans for VHF/UHF SSB/CW/data operation as I don't think there will be enough activity. So, an effective, neighbour friendly stealth antenna for the higher HF bands and 6m will be the immediate priority.

ISWL

2013-05-06T20:31:00.001+01:00

Back in the 1960s, when in its heyday, I was a keen member of the International Shortwave League (ISWL). In those days its membership was measured in thousands from all over the world.

A few years ago I rejoined and enjoyed the monthly magazine called Monitor. I contributed a few articles too. Sadly, membership has been declining steadily and now, I believe, the membership numbers fewer than 300 people. The club keeps going as a result of the dedicated hard work by its voluntary staff who put together the magazine each month.

This last year I have started to take the magazine as a .pdf copy. It really isn't the same as a paper magazine you can take to bed and flick through. I find the pdf version much less satisfying.

After some thought, I've decided not to renew my subs this time as it is surely now only a matter of time before the ISWL folds. It served its purpose in its day, but those days have passed. This last month a final coffin nail was the closure of the ISWL QSL bureau, one of the last to process broadcast QSLs as well as amateur ones.

The £20 DECENT HF transceiver challenge

2013-05-04T21:17:00.000+01:00

Ideas for the £20 (or less) new HF transceiver so far, based on past experiences:

VXO controlled, single band- GQRP crystals are inexpensive, but will allow around 10-15kHz easy pulling on 14MHz, more on 21 or 28MHz.
Single balanced diode RX mixer - homebrew with low cost diode and toroid matching
2N3904s everywhere - these low cost (5p or less), ubiquitous transistors work well as oscillators, PAs (if several paralleled up) and are OK in audio stages. Maybe an IRF510 PA if a lower HF band chosen,
Deadbug build - on a small piece of copper laminate and low cost using a few MeSquares to help ease construction
Low cost metal box - e.g. Maplin Aluminium box or a diecast enclosure. A mint box would be less expensive but too small.
Few controls - a 1k pot for RF gain is all that's needed on RX
Capable of running from a PP3 9V supply or external 12v - rechargeable 9V packs are low cost from 7dayshop. 69p each non rechargeable and £2.60 for a rechargeable one.
Low-Z stereo headphones will be less expensive than a crystal earpiece these days - may need an extra audio stage but at around 10p for this, this is a price worth paying.
Probably CW, although DSB not out of the question.
No ICs at all - these are too expensive (maybe an NE602 might be cost effective and I'm not sure about a low cost IC for the RX audio).
TX-RX offset essential - so that listening on the actual TX frequency is possible
Does not have to be pretty - the aim is a transceiver that can be thrown in a rucksack and survive reasonable abuse levels.
Wire antenna - a simple dipole or end fed half wave.
At least 2W RF out, ideally 5W - so that the rig has a reasonably good chance of being heard on a busy band

Is anyone else up for this challenge? The target is a really credible HF transceiver with decent, not compromised, performance that can be made with all new parts for less than £20.

GQRP club sales offer some very good prices for components if you are a GQRP Club member. If you are not a member then you are missing out on the very best magazine (SPRAT) available. I cannot recommend SPRAT and the GQRP club highly enough.

Back home again

2013-05-04T20:48:00.000+01:00

Well, the week long holiday in South Devon is over and we are back home in Burwell again. The portable HF operation was very successful and enjoyable, operating from a mix of locations, mainly clifftop sites with excellent take-offs across the sea to the USA, Africa and S.America. Average QSO distance with 2.5W SSB was over 3000km, with several QSOs with the USA and Canada on the higher HF bands using just 2W and a short base loaded whip.

In all, not that many hours of actual operation in between just relaxing and enjoying the very best part of England. I say this as this is my "promised land", where I was born and brought up. Out of season, when there are few tourists around and in weather like we had last week - perfect wall-to-wall sunshine - there is honestly no better place on this planet, but then I am biased.

My video, taken yesterday, shows the town of Salcombe in South Devon where I lived until I was 10 years old. In those far off days I took all this for granted: I knew nowhere else really. The view from my junior school window was up the beautiful estuary and the sunlight playing on the water would reflect on the classroom wall. Sunny days indeed, long before ham radio and the worries of adulthood.

Now I'm back home my challenge is that £20 (all new) portable backpack transceiver with decent performance that I've been challenged to design. In between cutting grass, weeding and paying the bills!

Farmyard DXing

2013-05-02T18:18:00.003+01:00

A carpet of bluebells on a Devon woodland walk today

No radios out on our walks today, but a quick session outside my brother's house netted a couple of 2W SSB QSOs with Europeans on 15 and 12m. Will have another clifftop mini-DXpedition tomorrow before we return home to East Anglia on Saturday - no real hills, miles from the sea, higher noise floor, bills, phone messages.....can I stay on holiday in this glorious sunshine?

More seaside DXing today

2013-05-01T19:23:00.001+01:00

Location today at Rock House beach at Thurlestone, Devon

Today I was busy visiting National Trust places with the wife, but managed a little DXing on the Devon coast again. Lots of DX on 15,12 and 10m SSB with some choice ones in there. All I managed was a 51 report from Madeira Is on 12m SSB with the 2.5W from the FT817.

One thing is amazing when operating from electrically quiet spots: signals just appear out of a silent band, quite unlike the situation at home where the noise floor is always many dB higher. I had no idea how good the noise floor on my FT817 could be!

Another observation is that most DX stations would be workable 2-way (with 2W) but it is the competition in pile-ups that causes the problems most times. On WSPR, all stations have an equal chance of being copied or copying DX stations, so this gives a much better idea of real propagation with low power.

QRP DXing from clifftop and coastal sites is great fun, but it is more of a masochistic rat race in the last analysis. A few days is fun, especially in the lovely sunshine. More than that I'm not so sure. When I told my wife that I wasn't getting too many contacts as other people were using much more power and got heard first she said, "why don't you use more power then?". Hmmm.