31 Dec 2011

Happy New Year

A very happy New Year to all readers of this blog.

2012 should bring us even better HF conditions as we approach the peak of Cycle 24. With luck and hard work we may get a new MF band around 480kHz. As ever, there are challenges from VLF to light beams to be enjoyed and I hope you have as much fun with our hobby as I shall.

My priority once the Christmas holiday is over is to complete my 481THz lightbeam transceivers and test these locally. Further projects will be to improve my VLF earth mode DX and to set up a lower noise VLF grabber in anticipation of more activity in the months ahead. In addition I shall continue with QRP WSPR and QRP operation mainly on 10m and 6m.

Netherlands on 500kHz and 70MHz

Some good news: amateurs in The Netherlands now have access to the 500kHz band (again) and 70-70.5MHz (4m).  Countries permitting 4m operation are growing every few months. Let's hope one of the major equipment manufacturers includes the band in multimode HF-6m rigs. Adding 4m cannot be too hard.

28 Dec 2011

Elecraft KX3 can now be ordered

On Dec 27th 2011 Elecraft announced that their new QRP radio can now be ordered with deliveries starting in about 8-9 weeks time. As a QRP radio the KX3 is likely to be "best in class" with some excellent features, but it is not low cost when loaded with options and imported into the UK after VAT and any duty is paid. See the KX3 page for more details.
The basic KX3 includes:

   * 10 watts output typical (13.8V) on 160-6 meters. (Up to 5W using internal batteries)
   * All modes (SSB, CW, Data, FM, AM)
   * Many features from the Elecraft K3, including the same full-size LCD
   * Advanced DSP features, including PSK31 and RTTY text display, noise reduction, auto-notch
   * Built-in 8-AA-cell battery holder
   * USB serial cable for firmware upgrades and for use with logging/contesting software

Available options include:

   * KXPD3 precision attached keyer paddle
   * KXFL3 dual-bandwidth roofing filter module for SSB/CW/Data modes
   * KXAT3 internal wide-range automatic antenna tuner
   * KXBC3 internal NiMH battery charger
   * MH3 hand mic with UP/DN VFO controls
   * RS232 control cable (optional replacement for supplied USB cable)
Although I certainly covet this little radio, I have not decided if I can justify the purchase, or indeed afford it!

24 Dec 2011

Happy Christmas

To everyone that reads this blog from time to time, may I wish you and your friends and families a very happy and peaceful Christmas. It is a time to both give and receive love and kindness - enjoy it.

Shortwave broadcast QSLs

Talking about QSL cards makes me think of my very first QSL cards received back in the 1960s. In those days I used the ISWL QSL bureau which handled broadcast band QSLs (I think it still does) and well remember the thrill when I got my very first cards. The first ever QSL was from Radio Nederland and it was an exciting moment. Somewhere I still have that red card with a windmill on!

In the subsequent years I did a fair bit of QSLing when using just my shortwave crystal set and got a few cards back from these reports. I heard stations all over the globe using that simple crystal set with best DX being Radio Havana Cuba, All India Radio and even Radio Australia, all direct and not via any relays. Not bad for just a tuned circuit, a diode a resistor and a crystal earpiece. I must have another go at a shortwave crystal set just for fun, especially as HF conditions are so good now, but these days shortwave broadcasting is not what it was. Using a decent toroid and a bridge detector it should be possible to arrive at a sensitive design with quite good selectivity.

WSPR QSL cards?

Just been having an interesting debate on Facebook about someone requesting an eQSL for an exchange of WSPR reports. Some would argue that, simply exchanging reports via the WSPR database does not constitute a "real" QSO, so a QSL is not appropriate. Indeed, some would say the WSPR database report is itself a confirmation of the report (which it is) so what is the point of a QSL card? On HF contests it is VERY common for only one callsign to be heard in reports such as, "G3XBM 599233 TU" yet such exchanges are used for DXCC credits if a QSL card is sent following such a "contact".

Personally I would eQSL a full 2-way exchange of WSPR data if done within, say 10 minutes, on any given band and consider this valid. I will only do this in response to one received. Others may violently disagree!

23 Dec 2011

Quartz crystal suppliers in the UK

Recently I wanted to buy a couple of non-standard crystals for a VLF project with the crystal divided down using a 4060 divider. After asking other people for advice it looks like Quartslab can provide the service.  Individual crystals range from around £12-14 depending on frequency and type.

This is not cheap, but at least they can offer the low quantity service. There is a minimum order charge of £22.29,  so I will probably order a couple of crystals for 4.59264MHz to give me a stable signal on 8.970kHz when divided by 512.  The company contact is Dave Hayes G4AKY 020 7100 6357.

Ultra-simple WSPR

G3XIZ has been having a lot of success on 40m WSPR recently using a 100mW DSB transmitter to generate a WSPR signal. All that is needed is an audio source (for the baseband WSPR signal), a balanced mixer and a PA. Of course, with this arrangement 3dB of power is lost in the "other" sideband which will appear outside of the WSPR sub-band. At some point - when I've got my lightbeam kit finished in January - I hope to try this arrangement on 28MHz WSPR. A very inexpensive 14.060MHz QRP frequency crystal will double to 28.120-28.130MHz so will be ideal to generate a 28MHz DSB WSPR signal at 28.1246MHz. Of course one could convert the TX into a phasing exciter and null out the other unwanted sideband. This should not be too difficult either as the phasing has only got to be good over just a 200Hz wide audio band, unlike speech which needs good phase balance over the full 300-2.4kHz band.

18 Dec 2011

15kW HF PA - definitely not for a QRP man!

A friend sent me this link http://www.dc9dz.de/en/index.html which shows the design and construction of a 15kW HF PA circuit for the amateur bands based around the Eimac 4CX10000D valve. Although I have no real interest in very high power and I do not expect to hear this on the air (please no!), it is a rather elegant piece of radio engineering.

17 Dec 2011

EU bureacracy threat to ham radio kit building?

The excellent Southgate Amateur Radio News site has some information which should concern amateurs who build kits. They recommend writing to your local MEP to make you views known.
"Thilo DL9KCE, reports a threat to amateur radio kits and modified equipment arising from changes to the EMC directive.  Currently amateur radio kits and modified equipment are specifically excluded from the directive but under the proposed changes they would be fully subjected to the EMC directive. The resulting high compliance costs could make it uneconomic to develop and sell kits so killing off the kit market. If radio amateurs wished to modify equipment it appears they would also incur additional costs and bureaucratic hassle."
The aim of the EU as a common market for trade is sensible but, like many here in the UK, I abhor it when the bureaucrats in Brussels start to interfere and try to fix things that are not broken. I don't want to get into a debate here about the merits of the Euro, but do feel that 2012 will be a year in which the citizens of Europe, and that includes the UK, will face some very tough decisions.

15 Dec 2011

Waters and Stanton - wake up guys!

Today, having still received no feedback from Waters and Stanton about my emailed question on the FT-450D TX hum (has Yaesu fixed it yet?), I decided to ring them up, check prices and ask the question directly. To my amazement the sales person said, "I have never heard of the TX hum problem". Well, he can't be too well in touch with the market and customers then.

I also asked what was the best price for the rig ("same as in the magazines, no deals") and then asked if they still had the 3 year warranty running. "What 3 year warranty? I've never heard of that." I pointed him in the direction of several recent RadCom and Practical Wireless adverts.

In summary, I was NOT impressed with the responses, or rather lack of them, from this well known UK supplier. At a time when business near Christmas is tight surely it is important that sales staff  know about the product and can answer questions as simple as "what is the length of the warranty?".

Unless this supplier wakes up a bit I think I will defer my decision about purchasing the FT-450D.

Incidentally, they did say that Yaesu would be at Hockley this weekend for the W&S open day. I expect people going will ask about the TX hum question directly. And I wonder if there will be any news about the FT817's replacement?

14 Dec 2011

Simple speech processing

Recently Peter Thornton G6NGR sent me a number of example circuits for speech processors, some dating back to the 1960s. Anyone who operates QRP SSB on HF or VHF will appreciate how important "punchy audio" is when running low power. One circuit I remember working extremely well was one based on an idea by John Hay G3TDZ. Back in the 1970s I was using 100mW AM on 2m and wanted to be heard across Cambridgeshire. My audio stage consisted of a couple of pre-emphasis stages followed by a hard audio clipper and a low pass active filter. The result was an amazingly punchy signal with barely any change in audio level when talking. The 12dB/octave pre-emphasis helped to ensure that clipping of LF signals did not result in many artifacts within the audio passband. The LPF was essential because the heavy clipping  results in many audio harmonics which would otherwise result in a broadened signal. With just 100mW and a dipole the QRP AM signal was excellent copy across the county. I keep meaning to try the same circuit (if I can remember it) with the FT817. It would produce a mighty punchy QRP signal!

KX3 release date

The Elecraft KX3 10W QRP transceiver is edging slowly towards formal release for orders. There is an enormous pent up demand for this 0.1- 10W QRP full featured HF/6m radio. Elecraft are still expecting to be able to announce that orders can be placed by the end of December with first products reaching customers in Feb 2012. I am still unsure if this is a possible candidate for my replacement to the IC703.

FT-450D hum?

Although usually/mostly a QRP operator, I've been considering an update to my main station transceiver since selling my 10W IC703 to a local friend. One possible candidate rig is the 5-100W Yaesu FT-450D. It is getting very good reviews with excellent comments on its  receiver features. For a "full feature" HF/6m radio it is good value for money.

But, I am bothered about one thing: many reviews and comments on the FT-450D Yahoo group confirm a design issue with TX hum, believed to eminate from the poor grounding of the display unit. Nothing I've seen or heard has convinced me this widely reported issue has yet been properly fixed by Yaesu. This is not a problem with the display set to its brightest setting, but should one pay around £800 for a radio with a fundamental design issue not solved in a recent upgrade? No.  A question to Waters and Stanton asking if Yaesu has fixed it has not received a reply yet after 2 days: I suspect they don't want to say "no". I have said that if it hums it would be returned.  So, until I hear the problem has been resolved my "buy" decision is on hold. I am in no great hurry.

More optical comms tests

A few days ago I received some 10000mcd 5mm "high brightness" Toshiba TLSH180P LEDs from Maplins.  Today I did some tests without optics using these. Still using just my NE555 1kHz oscillator output directly driving the LED the signal is considerably brighter. It should be some 10dB better than the high brightness LED used before. Using the Toshiba LED both as TX and (unbiased) RX detector the signal could be detected over a range of around 20m in daylight. The beamwidth of the LEDs is narrower (8 degrees) so aiming is quite critical. Further may well be possible with very careful beam alignment.

So, with 100mm lenses at each end (24dB minimum gain each) 5km should be possible and maybe up to 20km.  Progress on the full FM/SSB systems has slowed as Christmas approaches with other activities taking priorities in the family, but the 481THz work is my main priority ham radio-wise.

7 Dec 2011

You Kits SSB transceivers

For some reason I have missed the news that YouKits are producing (or about to) 2 band and 4 band HF SSB/CW transceiver kits at very reasonable prices. See http://www.youkits.com/ . One is a backpack and one a handheld. Quite interesting. See TJ2A and TJ4A code numbers on their website.

Micropower generation/power harvesting

Linear Technology lists the LTC3108, an Ultralow Voltage Step-Up Converter and Power Manager than runs with an input of just 20mV producing a 5V output to power things such as low power wireless devices and processors. Surely there must be an application for such a device in ultra-QRP portable equipment? Imagine, where can you find 20-500mV of noise from? 50Hz crud in the ground, a thermo electric sensor, solar cells etc. I wonder who will be the first person to make a QRPp uW beacon powered using the 50/60Hz buzz available between a couple of earth electrodes in the ground?

Elecraft KX3 internal photos

Elecraft KX3 rear view inside
Lots of QRP operators are eagerly awaiting the release of the KX3 from Elecraft early in 2012. This is a very compact all mode 10W rig suitable for home or field use. It was first lauched back in May 2011 and Elecraft have been busy completing the design and doing field tests. I came across some internal photos on VA3KV's site that I'd not seen before which give some idea of the design. It can be fitted with internal batteries and an internal wide range auto-ATU making it a very versatile transceiver packed with features. Spec is expected to be excellent and not far off that of the K3.

5 Dec 2011

481THz progress update

TX beacon optics
This morning I bought a length of 110mm waste pipe from the local Plumb Centre shop. It came in a 3m length and only just fitted in the car to get it home! After lunch I created my first attempt at some optics inserting my Poundland 100mm lens into the end of a cut section of the pipe. At the focal length I mounted my 10 pence high brightness, prefocussed, LED beacon with Bluetac. With this (crude) set-up on an old tripod and with a taped on gun-sight to help with aim, I set the TX baseband beacon running and pointed it from the stairway through a double glazed window aiming down the road. With my handheld baseband head using just the high brightness 10p LED as the detector I walked down the road to see how far I could get. In the beam in daylight I could detect the signal at the receiver at 120m. With a magnifying glass in front of the RX LED signals at 200m were strong (could not test at greater range), but it was difficult to keep the RX aligned. The red LED was quite strong visibly at the 200m test point even though running just 15mA or so through it. The double glazed window no doubt added a small amount of attenuation. What I'm not sure about is how good (or bad) this result is. Clearly with a really high brightness Golden Dragon LED the range even with this system would be considerably further.

4 Dec 2011

LF tests with the earth electrode "antenna"

Following the great success on 160m with the 20m spaced earth electrodes yesterday, I fired up the WSPR transverter into the same "antenna" today on 137.5kHz. Although I managed to decode G8IMR at 188km several times, no reports of my signal were received. This ties up with tests last year which suggested the earth electrode system was around 8dB down on my 80sq m vertical wire loop. With results on 137.5kHz hard to get with 500uW ERP it was perhaps not surprising that no-one managed to decode me on the earth electrodes.

I now have a choice on 137kHz: either re-erect the wire loop, but double the wire thickness when I do so, or change to a Marconi vertical with a large loading coil. The thicker loop will increase ERP by up to 6dB but I suspect more is to be had with the vertical. It would be daft of me not to give the Marconi a try both on 137.5kHz and on 500kHz. Even with my limited space I can still manage around 8m of vertical with around 20m of top section.

3 Dec 2011

Amazing evening on 160m ...without an antenna

160m WSPR reports - using 5W to 20m spaced earth electrodes

What an amazing evening: tonight I let my 5W WSPR beacon run with my VLF earth electrodes (20m separation with a low wire feed) as the "antenna" i.e. no conventional antenna in the air at all. Just look at these results! 6 countries and best DX 896km to the Shetland Is. If the earth electrodes are acting as a "loop in the ground" then the Shetlands are in the wrong direction i.e. in the null of the loop.

Sunday I intend to try 137kHz with the earth electrodes as I now have some 6dB more power than the last time this was attempted.

Earth electrode "antenna" on HF

Today I had to prune the tree to which my 80m sq wire loop is attached, so the loop had to come down for a while. Instead I connected up my 20m spaced earth electrode pair "antenna" with the connecting wire about 1.5m off the ground coming back along the garden fence. This is the antenna I use on VLF earth mode tests with the best DX reception of my signal being 6km away when using 5W at 8.76kHz.

I have been amazed how well this works on 160-40m this afternoon. This is the log this evening on 160m with 5W WSPR - best DX report so far from OZ7IT at 853km. On 40m I reached over 2000km with a report from the north of Norway.

10m - still WIDE open

A small wire halo antenna, 5W from an FT817 and WSPR software and these are the loggings of my 28MHz QRP signal in just a few minutes this morning. Best DX report 16964km from VK2ALC.

30 Nov 2011

481THz (light communication) progress

This afternoon I did a bit more on the optical front. I repeated my outdoor range tests using a low-cost high brightness LED as both a baseband optical transmitter and receive detector. With around 10mA TX current into the LED I was able to copy a 1kHz tone at 20m with another high brightness LED as the detector, without any additional optics other than the LED's built-in lenses at each end.

A 100mm lens properly focussed has a gain of >24dB (nearer 30dB if correctly adjusted). Assume 24dB "antenna" gain at each end of the link and we will have 48dB system gain over the simple LEDs on their own. Based on these calculations my optical transceiver should have a range of at least 5km.  If the gain of the lens is 30dB then the range could be as great as 20km. This is without using high power LEDs as the TX or using larger Fresnel lenses which would have even higher gain.

I now have the 100mm lenses I intend to use as well as 2 gun sights bought off eBay. The next step is to buy some drain pipe to house the optics. I have still to decide whether to build fully self-contained FM transceivers (simpler) or to build the optical transceive heads with separate transverters to use with the FT817.

RF skill levels

In my professional life I interviewed many graduates aspiring to become RF engineers. Very few, in recent years, had what I would call "the knowledge". By this I mean a "gut instinct" for RF that does not come from an academic course, important though this aspect is.  Rather, this "jizz" comes by living and breathing RF through building RF things yourself, however simple. A great many 2:1 graduates in communications electronics knew almost nothing about RF, had never touched a soldering iron ever and were rejected. In all honesty I believe I could sense who would make a good RF engineer within 2 minutes of the interviews starting.

Today I received a request from a Spanish amateur who professed (more or less), "I`ve a problem. I know nothing about electronics and would be unable to build the SAQ converter on your website." He then offered to pay me to build and ship the converter to him. Surely, a radio amateur in ANY country should have learnt basic RF skills as part of his training in preparation for his licence? At the most basic level the understanding may not be deep, but how can a radio amateur really not know how to put together a basic circuit?

In the UK we have a growing, and very serious, issue with poorly educated science and engineering graduates who are simply not coming out of universities with the skills needed to start work in industry. One answer was the sandwich course in which young A-level students were accepted on a company training scheme that married "on the job" skills training with educational training, usually to HND or degree level. People spotted young, with real RF "jizz" (easily judged in interviews) usually went on to become the best engineers we had.

29 Nov 2011

Sunspot peak to be over 100?

The latest NOAA sunspot predictions show cycle 24 now peaking in May 2013 at a smoothed sunspot high of exactly 100. This is UP on earlier forecasts and the actual trend since this forecast was made is still upwards, I believe at a rate faster than NOAA was predicting.

So, despite the gloomy predictions of even 6 months ago, we seem to be enjoying a decent solar cycle after all with every prospect it will be better than even current forecasts suggest. Whatever, conditions on HF will continue to be good for 5 years to come, so go and enjoy them.

Today my QRP WSPR was copied in Australia a couple of times on 10m yet again. It appears that every time I fire up it gets >16000km. I just wish a few more East Coast USA stations would  come onto 6m WSPR as this is where the excitement will be for the next  few weeks if F2 MUF reaches 50.293MHz.

27 Nov 2011

Busy amateur VLF weekend

G3ZJO's reception of DK7FC on 8.97kHz
Yesterday's test by DK7FC from his fixed location was a resounding success with reception all over Europe by many stations including G3ZJO, G3WCD and G3KEV, and what is believed to be the first transatlantic reception of an amateur VLF signal by a station in the Eastern USA. Results are being checked as I write.

Stefan's ERP was later re-calculated as around 800uW. It is incredible that such a tiny VLF signal can be detected so far away. If confirmed, this certainly heralds the dawn of a new and exciting phase of VLF amateur work. With another 3-6dB ERP, worldwide amateur VLF DX is now a real possibility. Of course such VLF DX reception requires incredible frequency stability, very narrow RX filters and long signal integration times; signals are far too weak to hear.

Also, Marcus DF6NM ran a 8.97kHz test today using a kite antenna. G3ZJO received a good signal in IO92ng 20dB above the noise in 424uHz bandwidth. Marcus was also well received by many other stations across Europe.

In summary, this weekend has been a BUSY one on the Dreamer's Band.

25 Nov 2011

More POWER - why??

Today I see that amateurs in New Zealand are to be allowed 1kW power in future; their limit was 500W earlier I believe. I've read something about amateurs in Eire asking to be allowed 1kW in contests and I think something similar is being requested of OFCOM here.  My simple question is why?

As an example, last evening I had a totally solid QSO on CW with KT5E in Denver, Colorado on 28.060MHz 2-way QRP with 5W each end.  My antenna was a small wire halo. Like many people, I have worked well over 100 countries with QRP on CW, PSK31 and SSB and always with simple wire antennas like dipoles, never a beam.

When more power is used it just creates more splatter, and more unnecessary QRM. OK there are times when 100W rather than 5W would make QSOs much easier with fewer repeats. But do people really need to run 1kW? OK you may blast a signal through the pile-up, but do you go to bed at night with any more satisfaction than someone working DX with a few watts or even milliwatts? I very much doubt it. Power is about egos, pure and simple.

22 Nov 2011

28MHz WSPR with 50mW

50mW WSPR Reports 28MHz
It really is too easy now on 28MHz! In just a few minutes, these were the reports when using just 50mW to my small halo antenna. Some reports suggest 1mW would have been enough. I need to build a bigger attenuator.

CB interference to the 28MHz band

Interference from CBers on the 28-29.7MHz band is getting worse. I guess they've been there a long time now but with good conditions their presence is more evident. Doesn't seem to cause problems with CW and WSPR operation though. The availability of rigs covering 26-30MHz capable of being easily switched from CB coverage to 10m coverage must be one of the problems and to CB operators the wide open spaces must be attractive. Use it or lose it.

21 Nov 2011

More 481THz lightbeam progress

670nm receive head and converter to 80m

Today I did some further light beam experiments, this time using a 25kHz modulation signal on the light beam and receiving the signal on my FT817 with this head/converter unit above. It consists of a BPW34 photo-detector feeding a cascode FET/transistor stage into an emitter follower and SBL1 mixer to convert the signal to around 3.584MHz. With a current into the TX LED of just 10uA (a very dim glow from the red LED) the signal was 20dB S/N in 0.67Hz bandwidth on Spectran at a distance of 25cms without optics. If my calculations are correct, this means a range of around 100m could be obtained even with this miniscule power if 100mm lenses were added at each end to give some 27dB gain at each end. Using the same TX LED at 10mA (1000 times the current) then the range is already in the many km region, and this is without using power LEDs. This is encouraging progress. Tomorrow I want to repeat the test with the same LED as the TX as the detector.

20 Nov 2011

80m FETer outing

This evening I came on 80m to listen for G6ALB who was taking part in the valve QRP day. Using my  18mW output FETer transceiver (18 parts total) I was able to hear almost all of the stations active around 3.56MHz using QRP.  G6ALB was worked (599 each way, but we are only 3km apart). I had forgotten how effective this little transceiver was and it was a pleasure to use it once again.

481THz (light) - first test results

Today I carried out my first optical communications tests since 1966. I built a small "baseband" (i.e. not on a sub-carrier based) optical transmitter producing a tone at around 800Hz feeding a standard low cost high brightness red LED at around 10mA current. The LED has a small built-in lens which produces a beam of around 20 degrees.

For the receiver I built the first stage of the optical head described in the RadCom articles (March-May 2011) using an identical  red LED (reverse biased) as the detector. I also tried a BPW34 detector, but it was not that different. This was followed by a couple common emitter transistor stages using my ubiquitous 2N3904s feeding a crystal earpiece. With the TX "beacon" running from a 9V battery and aiming out of my garage I walked across the road with the receiver and a 4 inch magnifying glass. Across the road, at about 25m range, this produced a quite respectable signal as long as the magnifying glass was focussed onto the RX LED. This was all a bit "Heath-Robinson" as I had to hold everything in my hand and move things around to get it spot on. There was quite a bit of interference from the street lights nearby.

I have no idea how much "antenna" gain there is in the built-in lens on the TX LED (a few dB?) or with the magnifying glass on the RX but with this set-up correctly aligned I would think 100m range is certainly possible.  This is just the beginning of a series of tests, but I am already happy that the optical head is sensitive and that good, well aligned optics will be essential to get decent distances. More TX power is easily available by using a power LED.

Next stages are:
  • A better beacon TX capable of operating at higher power on both baseband and subcarrier frequencies.
  • Putting the optical head into a screened enclosure, even if a temporary one.
  • Starting to think about optics. Using the same LED on both RX and TX will save on optics as just one set is needed at each end of the link.