31 Dec 2012

Goodbye 500kHz - it was good to know you.

This evening the 500kHz band is being withdrawn from UK amateurs at midnight, as it is in most other countries too, to be replaced by the 472-479kHz band. So, this evening is the end of an era.

With 2 young grandchildren staying with us for a few days (and using the shack as a bedroom), opportunities to get on the band have been very limited, but I did manage an hour of WSPR beaconing around tea time tonight as my way of saying "farewell" to the band. There were plenty of stations active as the reports below indicate.
So, I'll be QRT for a few days then starting up on 472kHz, although if I get a chance I shall be WSPRing during some of the day on New Year's Day.
Stations receiving my 10mW ERP 500kHz WSPR signals this evening

28 Dec 2012

Recording the last hours on 500kHz?

Back in the late 1940s G5UM and others recorded the last few hours of operation on the old 56MHz (5m) band on an old 78rpm disc. Sadly this disc and copies of it appear to be lost forever.

I am very much hoping that a few stations in the UK and Eire will record the last hours on the 500kHz band which is being withdrawn on Dec 31st for ever, to be replaced by 472-479kHz.  Such recordings are a valuable piece of amateur radio history which will be treasured in years to come.  It would be a pleasure to pull such recordings together for posterity, but I shall be unable to listen myself because I'll not have access to the shack at that time.

If YOU can listen between 2300-2400GMT on Dec 31st and make a few recordings of the CW activity, please send me copies and I will produce a CD or MP3 file of them all.

472kHz (quiet) RX preamp

When the grandchildren and family have all gone home next week, my first project will be to improve the RX antenna system for 472-479kHz receive. As mentioned before, I am suffering badly from SMPSU noise pick-up inside the house, so plan to install a magnetic loop and preamp somewhere towards the bottom of the garden in an attempt to minimise pick-up from my own home and from neighbours. With a loop there is also the ability to sharply tune the antenna and to null interference from the worse directions. The circuit I propose to use is a version of my 9kHz tuned preamp, which has been used to copy G, DL and OK amateur stations on 8.97kHz last year. The loop will simply be retuned to the new MF band.  Not sure whether series or parallel connection to the loop will be better as both should work depending on the FET stage configuration (common base or common source).
Proposed tuned preamp, but with values changed for 472-479kHz

26 Dec 2012

Last days on 500kHz

With just a few days left before the 500kHz permits are withdrawn for ever I've been doing a last gasp bit of WSPR beaconing. It is not easy to get on as we have grandchildren sleeping in the shack, but I managed to get on for a couple of hours early this evening.
Recent 500kHz WSPR reports (10mW ERP)
Reports were received from G, PA, DL and F stations. My local noise from the central heating controller prevented me copying much on the band. Before many days I shall have to erect a separate RX antenna for 472kHz.

25 Dec 2012

A Happy Christmas

A very Happy Christmas to everyone who reads this blog. Today has been spent with some of the family enjoying good food, drinks and games. More of the family comes here tomorrow and yet more later in the week. We are now sitting down watching the typical Christmas TV fare in front of the roaring fire.

Quietly in the background, my WSPR beacon has been running with best DX 2-way reports with Brazil and best reception the Nambian WSPR beacon. 

One of my presents was a book of maps of the South Devon Coastal Footpath and another the second edition of QRP Basics. In a later blog I'll review the new version.

But now it is back to mince pies and a cup of tea!

24 Dec 2012

5MHz NoV

A band that I have never tried before, apart from brief periods listening, is 5MHz. So, this afternoon I applied for an NoV, which was received by return email. Not sure what kit I shall use to get on the band (or when) as nothing I have covers 5MHz TX. Perhaps another transverter design is called for.

V5/DK1CE Namibia

Whilst in the shack this morning I turned on the FT817 to hear an unidentified (for nearly 10 minutes) CW station working people and giving 599 reports in the main. I called a few times and eventually got a 599 report, still not sure who the station was. Then, finally, he gave his callsign V5/DK1CE in Namibia. All the more pleased now I know that "3 blobs" on the FT817 is just 2.5W out to the halo antenna. And another DXCC entity this year.

23 Dec 2012

FT817 "power blobs" question

Having owned my FT817 (original version, not ND) for nearly 12 years I am almost too embarrassed to ask this question now.
http://upload.wikimedia.org/wikipedia/commons/5/55/Yaesu_FT-817_(1).jpg
When checking an old Bird RF power meter today I measured the power of my FT817 on and off a PSU at all power level settings. All these years I had assumed that "3 blobs" on the screen (when on a PSU) meant that I was putting out 5W. What I measured was closer to 2.5W. This did not change when the PSU was disconnected: still 2.5W. Then I pressed the button to "no blobs" and the power went up several dB, to I assume a nominal 5W. When on batteries it was "blinking 3 blobs". having re-read the FT817 (original) manual I was none the wiser: it does not mention a "no blobs" setting.

I think all these years when I had assumed my DX was being worked with 5W I was actually using just 2.5W. It looks like I should have gone to the "no blobs" setting with a PSU to get the full 5W.

So, can someone please clarify what power the FT817 should produce at all the different "blob" settings on batteries and on a 13.8V PSU?

UPDATE: I have the answer from Pete M3KXZ

Hi Roger.

On PSU:
- no blobs, output is 5W
- 3 blobs, 2.5W
- 2 blobs, 1W
- 1 blob, 0.5W

On internal batteries, the radio will default to "L///" and output 2.5W. If you
select high power, you will get 5W with "///" blinking. The other blobs are same
as for PSU.

I always run off external battery pack and the max power setting shows no blobs,
until the voltage starts to drop a bit when it automatically goes to "///"
blinking.


Well I'll be damned!  So for 12 years nearly I've been running 3dB less than I thought.

Birthday card co-incidences

Today I celebrate my 64th birthday, although it is only 5 minutes since I was 18, so be warned: time passes very quickly and speeds up as you get older!
One strange thing today was some of the birthday cards. When in Oxford a few weeks ago my XYL bought me a card for my birthday, from the OXFAM shop, with the title, "Instructions are for wimps" showing a man operating 1920s radio gear - very apt for a radio amateur. Well, blow me down, I got the same card from 3 people! If you want one to send to your friends, they have plain insides so can be used for an occasion, they come from  www.cathtatecards.com.

Now, to my mind, the operator looks a bit like Julian G4ILO. Perhaps it was his grandfather!

22 Dec 2012

Surplectronics - useful source

Steve G1KQH has just pointed me to Surplectronics who supply all manner of electronics parts at VERY reasonable prices. Several of the crystals they stock are just 25p each and 50MHz clock oscillators (packaged, complete) just 99p.

Tenbox 10m AM crystal

Although I've not finished off the Tenbox 10m AM transceiver yet- too cold in the workshop and too many Christmas preparations! -  I have been looking around for some low cost crystals that would be suitable for the transmitter. Ideally, I was looking for a low cost source of HC49 crystals on 29.05MHz but have not found any. Then I spotted that the German QRP-shop has 29.000MHz crystals at a reasonable 5.5 euros. I may order a couple so I can complete a pair of QRP 10m AM transceivers. I have used QRP-shop before and they give good service.

The Tenbox may not get finished until the New Year now as we have family here for the next 10 days more or less. When there are 4 grandchildren around, amateur radio takes a back seat, especially as my operating shack is used as a bedroom for the 3 and 5 year olds.

JT65-HF QSO

It is some while since I last tried JT65-HF mode for a QSO, so this evening I had a go on one of my difficult bands in the evenings (because of the local noise level) i.e. 80m. A short listen and reply to DK6CS resulted in a very solid QSO both ways with QRP. I must give this a go on the higher bands, although I find the 1 minute TX/RX slots rather slow, with a minute to know if your response to a CQ has been successful. Still it works with weak signals and allows me to work stations that might not otherwise be possible.
JT65-HF screen on 80m a short while ago

Countries worked this year

There is no way I would call myself a DX chaser at all, preferring to build simple kit and use it to experiment rather than "countries chase" as such. Nonetheless, I thought I'd look back through my logs to see how many countries I'd actually worked on each band during 2012 with my 5W or less QRP.  It is quite surprising to see how many countries I did NOT work and also how few QSOs I had on some of my less favourite bands. At the present time it looks like I worked 46 different DXCC countries with 1-5W SSB/CW. Most QSOs were SSB. By far the most countries were worked on 10m. This season I did not do my usual sport of seeing how many countries I could work on 6m and ended up only working 6 countries this year! Some years I'd worked almost 50. Notice also how few countries I've worked on 160m - 12m: hardly any!

Not included in this list are all the WSPR spots I have received and given around the planet. There are several stations/countries with which WSPR spots have been exchanged that have not been worked in 2-way QSOs.

There is no doubt in my mind that had I concentrated on DXCC with 5W it would have been possible to work well over 100 entities this year even with my very compromised antenna system and 5W or less. Maybe one year I'll give DX working a real blast just to see what I can work, but really I prefer to leave this to others in the main and enjoy other aspects of our wonderful hobby.

21 Dec 2012

Selling my Elecraft K1

For some years I've had the Elecraft K1 transceiver that I made. It covers 40, 30, 20 and 15m with a built-in auto ATU.  This is a nice little CW radio, but I rarely use it, preferring to use home designed kit on MF and 10m these days. It has always been used at home and is in as-new condition.

This afternoon I fired it up, using the coax feeder to my 10m halo as a vertical and tuned this against my central heating ground using the internal ATU. It is a far from optimum antenna and suffers from QRM from my central heating controller's SMPSU right next to the feeder on RX.
RBN spots with my K1 today (intermittent operation)
Conditions were not great but several reports were seen on the Reverse Beacon Network (see above) and half a dozen QSOs are in the logbook on 7MHz and 10MHz (in DL, I, EI and LX) in not a lot of actual operating time: we had neighbours around for Christmas nibbles and drinks most of the day!

I really ought to think about selling the K1 as I don't use it enough to justify keeping it.  Ahead of my move next year I should be doing more de-cluttering as well, HI.

20 Dec 2012

Good review of the Argonaut VI by K4SWL

Although I was critical of the price of the Ten-Tec Argonaut VI QRP transceiver at $995, I see it has received a rave review on the QRPer blog today from K4SWL who was one of the beta testers.  In his opinion it is better than an Elecraft K2 with a receiver that is likely to be highly rated in the Sherwood tests.

The Argonaut VI image on the QRPer.com website
As he points out, this is not really a "trail-friendly" radio. Rather, it is a small radio designed mainly for home use where its excellent performance, size (a bit smaller than the K2) and good ergonomics make it ideal. He praises the simple uncluttered controls and ease of use and the nice flywheel tuning knob. But, overall he rates it and likens it to a miniature Ten-Tec Eagle with superb DSP performance and RX dynamic range.

The lack of 60m and 12m and an auto-ATU disappoint me, as does that high price tag, but it does look like this is a very capable little radio. It is just such a pity that it is so expensive. It will be very interesting to see a side-by-side comparison against the KX3 in the coming months.

See also the eHam.net review at http://www.eham.net/reviews/review/115480.

Now if only Father Christmas would bring me either a KX3 or an Argonaut VI, HI.

472kHz WSPRing (now QRT)

It is now clear that the issue of my NoV for today's date was an error, either with OFCOM or the RSGB and that there was, sadly, no intention of releasing the band earlier than Jan 1st 2013. So, I have now gone QRT on the band again until the new year. I question why an NoV should be needed at all: why not just release the new band in the UK to all full licence holders and save the time wasting and paperwork chasing!

In the few hours of operation with my antenna very wet and lossy, so the ERP was around 10-20mW only at best, results achieved were very promising.
472kHz WSPR TX results today (10-20mW ERP)
Reports of my WSPR signal were received from 4 countries with the best DX being from Germany and the far NW of Eire.

I'm now back on 500kHz WSPR for the rest of the evening.

472-479kHz NoV received

Today I received my 472-479kHz NoV via the RSGB website. The NoV for 5W eirp (about 20dB more than I can run!) seems to indicate that the new band may be used by NoV holders immediately judging by the date of issue.

There is some confusion as the OFCOM website says:
"However, as a result of the World Radio Conference, under Agenda Item 1.23 amateur radio has been given an alternative allocation, on a secondary basis, of 472 479 kHz. We propose that Full Licensees should be able to to apply for an NoV to operate in this band from 1st January 2013. Application can be made online at http://www.rsgb.org/operating/novapp/nov-472-479-khz.php

My official OFCOM NoV says applicable from Dec 20th start date so I am allowed to operate from today unless told otherwise later by email or phone from OFCOM. This may be pedantic, but they should have checked before sending out the form.

My first WSPR reports have been received from PA3ABK/47 at around -24dB S/N with my ERP currently around 10mW only (too much wet on the antenna). Also received a report from G8HUH (250km) and PA3FNY (360km).
It now seems that the official 472kHz NoVs issued this afternoon (mine was this morning)  now state a Jan 1st 2013 start date.  So, am I legally operating I wonder? If the world ends tomorrow, at least I've got a few 472kHz reports in the log, HI.











19 Dec 2012

10m WSPR today

Today my 200mW from WISPY beacon was not enough on 10m to get any reports. So, I went up to 5W with the FT817 and managed a few reports this afternoon. Conditions were not good. Nonetheless reports came in from North and South America and from Germany.

10m WSPR reports today with 5W and halo

The ISWL

Many here will not be aware of the International Short Wave League (ISWL) but at one time this was THE club to belong to if you were interested in shortwave amateur and broadcast listening and transmitting. At one time it had a great number of members from all over the world.

Today the ISWL is still going strong, albeit not as large as it once was, but they produce a good A5 full colour magazine packed with articles and news every month called Monitor. Unlike most amateur magazines, this has good coverage of shortwave broadcast news and reports as well as lots for SWLs and radio amateurs with monthly RX and SWL reports. The ISWL offers a number of other benefits to its members and you may like to consider membership. The magazine has few adverts and is a real amateur/SWL magazine, rather than a shamateur magazine for those with deep pockets. Like the GQRP club, the ISWL is run totally by volunteers. I like its ethos.
 
Membership is £18 a year for the paper magazine version but just £12 if you take the magazine electronically.

First QSL cards at G3XBM

Earlier this evening I was thinking about QSL cards. I send out very few paper cards these days (although hope to send out more after I move next year and have the chance of putting a nice windmill on the card!) but was trying to remember the very first QSL cards I ever received back in my SWL days in the early 1960s.

If my memory serves me right, the first ever QSL card came from Radio Nederland like the one on the left which had a flamingo and a windmill on it.  It was for reception on my shortwave crystal set. Subsequently I got several more cards using the crystal set and it became quite a challenge to see how many countries I could confirm with QSLs using the crystal set.  Although I heard stations worldwide - genuinely worldwide, not via relays - such as Radio Australia, All India Radio and Radio Havana, I don't think I ever managed any cards for crystal set reception beyond Europe.  My first ever amateur card was from a station in London that I copied on 28MHz in South Devon. I cannot remember the callsign sadly, but probably still have the card somewhere.The first card for a 2-way QSO was from my mentor G4PJ who had a shack right on the water's edge in Salcombe. His earth rod when straight from the shack into the salt water, so his signal was excellent even on my crystal set at 4 miles.

I still enjoy getting cards from the bureau and the quality of some cards these days is remarkably good and a far cry from the thin paper cards from the USSR when I was first licenced, although these were just as prized.

472-479kHz NoV Applications

The RSGB now has a link on its website (although at this time it does not appear to be working, but it did earlier for some) for the form to apply for an NoV to operate in the UK on the new 472-479kHz band.

This is the link I have http://www.rsgb.org/operating/novapp/472-479-khz-nov.php

I have yet to succeed and get my NoV application through, but hope to do so before Jan 1st 2013 when the band will be available to full UK licence holders as long as they have the NoV.

18 Dec 2012

Dell PC update - a grateful customer!

You may recall that I wrote to the MD of Dell last week after getting nowhere with my 4 year warranty claim for replacement of an intermittent power socket and was pleasantly surprised when the corporate office offered to arrange for my laptop PC to be repaired free of charge.

Dell Inspiron 1545 laptop
Well, today the Dell service engineer turned up and replaced the WHOLE motherboard and the DC PSU. I am happy to report everything is now working well.  The engineer was courteous and efficient. Dell even rang from India to check the engineer had turned up and the job was done.

So, I'd like to put on record that I am, in the end, pleased that Dell performed so well. But, as a comment below points out, it took a carefully worded pleading email to the MD to get them to see sense and learn that the customer should be treated fairly and with respect.

WISPY reports

For the first time in a few weeks I set the WISPY 200mW 10m WSPR beacon running to see what reports I got whilst getting on with jobs.
It is fascinating that G8KNN who is just 12km away often gets me at similar levels to the reports I get from K1OF who is 5455km away, all due to the vagaries of HF propagation.

17 Dec 2012

Ten-Tec Argonaut VI - at $995 FAR too much

Ten-Tec has now got the new low power HF transceiver, the 10W Argonaut VI listed on its website with details about its specification and how to place an order. It looks a neat, clean, simple radio and I believe it is not much bigger than the FT817.

Not having ever used Ten-Tec rigs and knowing that many people very much like Ten-Tec products, I cannot comment on how good this new radio is likely to be. However, I do feel qualified to comment on the price.

$995 for the basic radio (I guess around £995 here in the UK?) sounds far too much. I'm not sure this includes a microphone. The KX3 is a similar price yet covers ALL the HF bands and 6m as standard, with an optional 2m module, auto-ATU, battery charger and internal battery pack.  It has a more comprehensive features set and, probably, a higher dynamic range (i.e. better) RX.

The Argonaut VI does not cover 5MHz, 24MHz or 50MHz, even as options. There is no provision for an internal auto-ATU.

In my view, these omissions are unacceptable in a new HF QRP rig. The 12 year old FT817 covers ALL HF bands, and 6m,2m and 70cms with ALL modes yet is considerably less expensive. OK I expect the Ten-Tec has a better RX than the FT817, but to be honest I am pretty happy with the FT817 which hears most things and manages to hold its own from 136kHz (with a preamp) to 432MHz pretty well on RX.

To say I am disappointed with the Argonaut is an under-statement. Why, oh why, didn't they get this onto the market at a highly competitive $695 instead?

14 Dec 2012

HF conditions

It is December 2012 and we have either have just passed, or are just approaching, the sunspot maximum for cycle 24. Conditions cannot be called fantastic can they?

Some of you with long memories may recall the BIG peaks of the late 40s and 50s and look back at them fondly.  I think we have no choice but to accept that those days have now gone for a generation and we have to make the best use of our bands as they are and will now be.

Even with much lower sunspot numbers the higher bands will still be able to support DX more often than thought. WSPR beaconing through the full solar cycle may reveal some surprises. In many ways the quiet times offer more interest although monitoring 10m for days and days on end and hearing just noise can be disheartening! This is when WSPR will be especially useful.

Anyway we are still near the peak and there is DX to be worked so let's enjoy it!

More WISPYs on 10m

The G4SFS version of WISPY
Yesterday I received a nice email from Peter G4SFS who told me that he and Dave G6WZA had made a couple of WISPY 10m WSPR beacon TX units using the schematic on my website. A few values changes were needed - not unexpected - but that they are now working well and receiving spots from distant monitors. This is a photo of one of them. WISPY is a simple QRP WSPR beacon for 28MHz using a low cost 14.060MHz crystal and inexpensive 2N3904 transistors throughout.

Conditions on 10m have not been too great of late, although I did exchange reports with PY2SDR at 9616km and 4X1RF. Interestingly, there have been a few early evening WSPR reports from DL which I assume are probably a result of wintertime Es propagation.  At this time of year there is a mini-peak in sporadic-E propagation, so it is worth keeping an eye on 50MHz and 70MHz too.

13 Dec 2012

Dell - they listened

A few days ago I mentioned my run-in with Dell support and their refusal to repair my laptop's power connector socket under their 4 year hardware warranty claiming it was "wear and tear". Well one of my readers Mark G0NMY kindly sent Michael Dell's email address michael@dell.com - he is the founder and MD - so last night I wrote a well reasoned letter to him explaining my disappointment with the level of customer service and why I believed they were wrong.

Blow me down, this morning I got a phone call from the corporate office saying they had arranged an engineer to come out next Tuesday to fix the laptop free of charge!  To say I was amazed is an understatement. It took conversations with 4 people and an email to the MD of Dell to get the correct response but, bless them, they've "come good" in the end.

So, thank you for listening Dell. You are in my good books again.

12 Dec 2012

Updated 472-479kHz countries list

Following feedback, Rik Strobbe ON7YD updated his list of countries with (or about to get) access to the new MF band as follows:

Monaco (18/05/2012)
Malta (11/06/2012)
Germany (13/06/2012)
Philippines (30/08/2012)
Slovakia (01/09/2012 ?) - special licence(s)
Czech Republic (01/09/2012 ?) - special licence(s)
Sweden (01/10/2012) - special licence(s)
Norway (30/10/2012)
Greece (01/11/2012)
New Zealand (20/12/2012)


Australia (01/01/2013)
Denmark (01/01/2013)
The Netherlands (01/01/2013)
UK (01/01/2013)  - available to full licence holders by NoV
Switzerland (01/01/2013)
Finland (early 2013)
Spain (early 2013)


11 Dec 2012

Dell - rubbish service

My wife has a Dell Inspiron 1545 laptop which came with a 4 year hardware warranty. It has a year to run before the warranty expires.

For nearly a year now the hexagonal power connector socket has been intermittent. So today I contacted Dell to get the connector replaced under warranty. The socket is on a small daughter board along with a couple of USB and other connectors.  After about 15 minutes on the phone to India I was fobbed off with "this is wear and tear" and I would be charged to get it repaired. A quick look on the net shows pages and pages of people complaining of the same issue.  It is a DESIGN WEAKNESS, as clear as day to me.

The power socket is on the side of the PC and it is all but impossible not to put a slight strain on the socket. Older laptops, ones that do not have built-in obsolescence features that is, have the power connector fixed so that any strain on the plug is not transferred to the socket. One laptop I have is now 12 years old and still going strong.

After being passed up 3 levels at Dell in India, I was passed to the Dell Legal Manager and Customer Relations Manager for UK and Europe who again, despite my reasoning, still stood by the "it's wear and tear" statement. It may be wear and tear, but only because with this poor design it impossible not to have wear and tear!

So, I will attempt the repair myself now, following the instructions on the internet from very many others with the same issue.

Dell will never again be graced with my business. Next time I shall buy from a decent manufacturer who listens carefully to customers and who actually cares, assuming there is one!

In my opinion, this demonstrates a total ignorance of how to manage customers well. In my business life I was taught  to value customers so they came back again and again. At three levels in Dell, not one of them seemed to understand that a dissatisfied customer rarely comes back and shares his bad experience with at least 10 others. By this blog I hope to reach a few thousand.

Dell (or should it be renamed Dull?) - sorry, but your stance is unbelievable in the 21st century.

I now know what DELL stands for: Do Everything to Lose Loyalty.

Digital Audio on HF (1.1kHz bandwidth)

An interesting post on the Southgate ARS blog today about FreeDV, a free to download and use digital modulation system than needs less than half the bandwidth of conventional SSB. It needs audio processing with a PC on both RX and TX. The article includes the quick start guide for set-up and a clip of a QSO using the mode on 14MHz with 25W. Speech quality sounds excellent.

More information at the FreeDV homepage http://freedv.org/tiki-index.php.  An important point to note is that the codec and modem are both open source, patent free so anyone can experiment with them and modify them.

At the moment activity is centred on 14.236 MHz.

Countries with access to 472-479kHz

An interesting post on the LF reflector today from Rik Strobbe ON7YD - OR7T about which countries have, or soon will have, access to the new MF band.

This was Rik's list:

Monaco (18/05/2012)
Malta (11/06/2012)
Germany (13/06/2012)
Philippines (30/08/2012)
Slovakia (1/09/2012)
Czechia (1/09/2012)
Sweden (1/10/2012)
Norway (30/10/2012)
Greece (1/11/2012)
 

Denmark (1/01/2013)
Netherlands (1/01/2013)
United Kingdom (1/01/2013)
Switserland (1/01/2013)

10m conditions

After my break away last week I've been doing some 10m WSPRing these last 24 hours and am disappointed with the results: only a few spots from Germany, Israel and the UK of my own signal and just 4X, ZS and DL copied. Conditions seem to be very poor for a December in the peak sunspot period. Looking at the WSPR screen all I am seeing are a few wispy signals not lasting more than a few seconds. Conditions can change rapidly though, so I'll keep the WSPR beacon running whilst getting on with other stuff.

10 Dec 2012

VHF yagis - amazingly high prices

Just browsing the Waters and Stanton website and I noticed some nice yagis for 2m. Rather larger than I could ever consider as the one I was viewing would stretch over my garden and the next two, HI.

.......and then I saw the price.

The 22-element yagi from InnovAntennas (see 22-LFA2-144 22 element 144MHz LFA2 Yagi 3kW (17.001m long) 18.55dBi gain) is a whopping £605.95 !!!   Probably delivery is not included either. 

Of course, if you want a moonbounce station you may have to buy several of these big yagis, phasing harnesses and booms, plus a large AS-EL rotator, a big tower, low loss cable ....and an expensive rig. This soon looks like a hobby for the seriously rich only.

Now I've no doubt whatsoever this is an excellent antenna that is well designed and optimised, but it is just 20 odd pieces of aluminium, plus a few insulators, nuts and bolts in the last analysis.  OK design costs have to be recovered, but the mark-up is a conservative ten times, if not more, on the raw material prices. Is this justified?

We are all different and I am not judging what others should do with their hard earned cash, but it's just not amateur radio (in my view, others will disagree) when you have to pay silly money for rigs, antennas and accessories.

UK NoV changes

OFCOM has announced some intended changes to the Notice of Variations issued to some radio amateurs in the UK. See http://licensing.ofcom.org.uk/radiocommunication-licences/amateur-radio/full-licence-jan-2013/ . The main changes are to the 5MHz band (more fixed frequencies), the removal of 501-504kHz NoVs and the release, by new NoV application, to the new 472-479kHz band. Changes are expected to come into force from Jan 1st 2013. Details of how to obtain the new NoVs has not yet (to my knowledge) been made known.

9 Dec 2012

Batteries by Royal Mail - some change to rules

Some changes are about to come into force which will affect what can be sent by Royal Mail.  It would appear that some rules are being relaxed whereas others are being made more strict and this could have an effect on sending certain items, such as lithium batteries, via Royal Mail. 

Steve G1KQH sent me this which he received from Battery Force, a battery supplier:
"From the 10th of January 2013 due to legislation outside our control, Battery Force will no longer be able to send Lithium batteries using Royal Mail Post. All Lithium batteries sent after this date, will have to go by courier. Using couriers will unfortunately increase the delivery charge for lithium batteries."
 
The Royal Mail website attempts to clarify the rules here:

At the moment I'm not clear what the implications will be. It does sound a little like "job's worth" and health and safety gone mad although, like all such moves, the intention is good: to make the mail service safer.  But before long we will not be allowed to walk across a road because of the danger
How did we manage in years gone by?

Miracle Antenna products

Although not the world's best performing antennas, the Miracle Whip and its associated variations have their uses when one is looking for a compact and easily tuned antenna for field use. On the higher HF bands the loss compared with a full 1/4 wave is less than might be expected if a decent counterpoise is used (1-2 S points down only).

Recently the Canadian owner, Robert, sadly died after a year or so of health problems. There were some doubts whether or not the company would continue, but it appears it will. Perrin VK3XPT made enquiries about the availability of one of their products, the Miracle Ducker and reported as follows to the Miracle Whip Yahoo Group:

UPDATE:

Here is the current status of Miracle Whip stock, globally. I hope this will help someone else here on the group!


- Miracle Antenna do not have any new stock of the Miracle Ducker range. They are waiting on some parts to arrive in the next couple of weeks, which enable them to complete a shipment of new Miracle Ducker TL that they will be sending to Hamcity. This looks to be the only shipment that will be made to any dealer for some time.


- WSPLC.com appear to have some stock, and I have placed an order with them. Fingers crossed that their website is up to date, and showing correct stock levels.


- I have contacted all (yes, all) other Miracle Antenna dealers, and even though some websites are showing stock, this is not actually the case!


So, if you want a Miracle Ducker TL any time soon, Hamcity and WSPLC.com look to be our only and best options. I hope this helps and I will keep the group updated on my progress.


73s
Perrin VK3XPT

8 Dec 2012

Walking in Devon

No posts for a few days as I've been away staying with my 68 year old brother in South Devon. I managed a couple of nice walks along the cliffs and lanes in the cold bright winter sunshine. I believe in the Met Office definition of winter starting Dec 1st. The lanes were VERY muddy but Salcombe, my home town in my childhood was quiet and beautiful.
My 2 Devon walks plotted using the G730 GPS tracker
My Ventus G730 GPS tracker - available for around £34 from Martin Lynch - plotted the 2 walks.  One was around 14km and the other 16.5km.
This shot is of the coastal path near Thurlestone. There are a few nice seats on the walk and I have worked some good HF and VHF pedestrian portable DX from them, although I took no radio gear this time.

3 Dec 2012

Long-term Solar Outlook - downwards!

Chris N7ZWY has put an interesting graph on his website showing his predictions for the future solar cycle progression. His graph shows the solar cycle progressions since the 17th century and Chris's predictions for the future. No-one can be certain of the accuracy of predictions, but as time goes by we are gathering more detailed understanding. I have little doubt Chris is broadly right.

Chris says:
"The average sunspot count for October was 61.4, higher than last month and no indication of the final decline which should bottom out around 2017 or 2018, which will then be followed by two more similarly low sunspot cycles and then a third with almost no activity during a phase reversal."
See http://www.home.earthlink.net/~christrask/Solar%20Activity%201600-2100.pdf

Now, looking at the plot it is highly likely that the sunspot peaks for the next 40-50 years will be weak ones, or even non-existent. The next few years are likely to see the end of the good times on the higher HF bands. Those of us who were around in the 1950s and 1960s didn't know just how lucky we were. Many newcomers to the hobby at that time worked all over the world with 5-10W of CW and AM with S9 signals.

Flying Pig 40m 5W transceiver

Thanks to Dave in Jakarta (don't know your call Dave) I've been pointed towards the Flying Pig 5W CW transceiver for 40m from Kits and Parts.

The receiver uses a clever direct conversion design using an NE602 with some AGC applied to it. Like the RockMite, it uses some front end crystal filtering to help overcome dynamic range/overload  issues, but with the limitation this is a single frequency radio, for example parked on 7.030MHz, the QRP frequency. Still, a full 5W on the QRP frequency will permit plenty of QSOs.
This is the photo on the http://www.kitsandparts.com/ website
The best news is the price - $40 only, which is good value for a kit. Available from Dec 10th 2012 according to the website.

2 Dec 2012

Drawing schematic diagrams

Several people have asked me what I use to produce schematic diagrams for circuits I put on my website and here on the blog. Well I use a package called sPlan which is available from http://www.abacom-online.de/uk/html/splan.html.  This is the package that many SPRAT authors use. Mine is an early version but the latest version is available for 39.9 euros.
Abacom has a range of useful resources such as front panel labeling software and some very simple PCB layout software.  sPlan is remarkably easy to use and a circuit like the Tenbox can be drawn up in about an hour, simpler circuits even less time.

The Abacom website gives details of distributors in many countries.

Wikipedia

en.wikipedia.org/
Don't know about you, but I refer to Wikipedia just about every single day. It isn't perfect, but it certainly is one of the most useful free resources on the Internet. The quality and quantity of data available there is nothing short of remarkable. I've added a few entries myself over the years too. As a thank you I made a small donation via Paypal and encourage you to do the same if you can spare a little.

As they say in their thank you email, the resource is used by people from all over the world including in schools in developing countries. By ensuring Wikipedia remains free and neutral we are helping to keep the Internet free for future generations.

Magnetic loop HF TX antennas

Although I have successfully used a large 80m sq vertical wire loop (made with 32 x 0.2mm PVC covered wire) on both 137 and 500kHz, I have never tried a hi-Q small loop on HF transmit. There is a very useful calculator available at http://www.66pacific.com/calculators/small_tx_loop_calc.aspx which suggests a 3m circumference loop using a 5mm diameter conductor - for example small bore copper pipe or a thick coax cable - would have a loss of only 0.9dBd and a bandwidth of 352kHz at 28MHz.  This would comfortably cover both 28MHz CW, data, WSPR and beacons without retuning.

An advantage of magnetic loop antennas is reduced detuning from nearby objects so this antenna, if mounted in the loft space, might make a neat and efficient stealth antenna for 10m. I guess one could even arrange to switch the tuning capacitor remotely so that several sub-bands could be covered. When using QRP power levels, as I do, the high voltages and currents that are encountered in small loops are less problematic. For example, choice of variable or fixed tuning capacitors is less onerous than if using 100W.

http://www.kr1st.com/magloop.htm
KR1ST has some nice information on magnetic loop antennas on his website.  I hope he doesn't mind me linking to the image of his magnetic loop on his site. There is also some useful loop information on the Wikipedia site.

In all, I think I'm missing out (so far) on a whole range of antenna experiments!

1 Dec 2012

SAQ (17.2kHz) transmission Dec 24th

The following is from the SAQ (Sweden) website:
We plan for a traditional transmission on Christmas Eve Monday 24 December. We plan to start the transmitter at 07:30 UTC and will be on air a few minutes later. A message will be sent at 08:00 UTC. The frequency is 17.2 kHz CW.

 QSL-reports are kindly received:

 QSL reports can be given via:

- E-mail to: info@alexander.n.se
- or fax to: +46-340-674195
- or via SM bureau
- or direct by mail to: Alexander - Grimeton Veteranradios Vaenner, Radiostationen, Grimeton 72, S-432 98 Grimeton, SWEDEN

Note: SAQ is a member of the Swedish Amateur Association (SSA) and "QSL via bureau" is OK.

First on-air testing of the Tenbox TX

This evening, with little sign of F2 propagation, I ventured out to test the range of the 10m Tenbox TX as it is currently. For the TX antenna I used the coax up to my 10m halo as a vertical tuned with the Elecraft T1 ATU. At the RX end, in the car, I used the FT817 with a small base loaded mag-mount.
Tenbox AM TXing with MP3 callsign message on the PC
What I should have thought about was the noise on AM from street lights! When the signal is strong in the village this is no issue at all, but traveling to the next village 3km away there were several spots where the buzz from sodium street lights just killed the little signal. Both antennas are compromised, so another 3-6dB of signal level should be possible with a proper 1/2 wave antenna at each end or with a better car antenna.

Maybe this project, although great simple fun, isn't going to quite meet my needs, whereas a DSB transceiver would?  Receiving the DSB signal as SSB and the improvement over AM will be around 9dB with better noise immunity. However a simple direct conversion RX would not be suitable to use (easily) with a DSB TX, whereas the AM Tenbox would be fully 2-way compatible with another identical AM unit.

Conclusions so far
(a) 6-10dB more may be needed to meet the design objectives with AM.
(b) It is worth repeating the very same test now using a DSB TX with the same power to compare.

The first Tenbox Schematic

The breadboarding of the Tenbox 10m AM transceiver for local cross-town night-time nattering is almost complete now, with just a receiver audio amplifier to drive a loudspeaker to be added. Power output is a conservative 250mW AM carrier (peak power around 1W).  The first schematic draft is shown here, but as always I warn that I may have forgotten to correctly label some parts and the values may change as the circuit is further developed. I hope to road test this over the weekend going out in the car with a mag-mount antenna whilst AM beaconing with the rig from home. As with WISPY, I have paralleled up 4 2N3904 transistors for the PA. This is a very inexpensive way of making a 10m PA stage! The alternative, such as a 2N3866 would be about 5-10 times more expensive.

29 Nov 2012

Small Wonder Lab Kits

Dave Benson K1SWL has produced some wonderful Small Wonder Lab kits over the years including the famous RockMite transceivers, but he has decided to slow down a bit and get back to enjoying the hobby as a hobby. I think we don't realise just how much work is involved in a small ham radio company producing and supporting a range of kits. Dave's point about technical support and repairs rings bells with me: I get around 5-10 questions a week from people interested in my website projects and I am not even selling kits!

This was the notice on his website last week:

"Folks-

I took a ‘leap of faith’ in 1996, leaving the corporate world to undertake ‘Small Wonder Labs’ as a full-time venture.  Since then, it’s been a great experience.  I have to face facts, though: I’m getting older. The shortcomings in vision can be overcome with close-up glasses. More troublesome, though, are the muscular issues from spending hours a day at the computer, or with my head down, sorting parts into bowls.

Over the years, I’ve assisted countless customers with no-questions-asked replacement parts and troubleshooting advice. The issue of repairs has been problematic, though.  While no one really objects to paying $50/hour to have a $1000 rig repaired, that’s not true of a $50-100 kit. I’ve had some good people doing repair work for me, but it’s just not economically viable. Neither can I do the work in a timely manner. Therefore, and effectively immediately, I will not be accepting returns for troubleshooting/repair.

It’s not clear to me at this point if I’ll release any additional product offerings. Although I love the creative process involved in a new design, everything that follows is now just ‘work’.   Along the way, I lost the ‘hobby’ aspect of ham radio. I have not been on the air in almost 5 years. I want my hobby back!

I’ve finished our home here in the woods of New Hampshire, and it’s time for me to move on to other interests.  I’ve still got a garage/barn to build, a garden that grows larger each year, and a wealth of outdoor activities I can’t seem to find the time for. Retirement is clearly not for the faint-of-heart!

I’ll continue to sell RockMites forever, apparently.  Demand is still brisk, with more than 8000 of them out there so far. Ongoing activity for the RockMite as well as support for ‘legacy’ kits occupies me for 2-3 hours each day.  At this stage of my life, that’s ‘enough’.

73- Dave Benson, K1SWL
19 November 2012"

ARRL 10m contest (48hrs Dec 8-9th)

A reminder that the ARRL 10m contest is on next weekend (not this) over the full 48 hours Dec 8th and 9th. As conditions on 10m are pretty good right now this will be a good chance to work a fair number of US, Canadian and Mexican states and provinces, even with QRP levels in CW or SSB. I'm away on the Saturday but hope to be on for the Sunday.

26 Nov 2012

Cutting big pieces of copper laminate

When I was working I had access to a guillotine to snap out large pieces of copper laminate to convenient sizes for project breadboards. Being retired I no longer have this method to hand. SO, I asked a question on the GQRP Yahoo group this evening to find out what other people did. Several suggestions but the favourite is "scoring and snapping", summarised by the post from Duncan G4DFV which I have reproduced below.
"My method of cutting large pieces of copper laminate:-
  • Place a steel rule along a previously drawn line on the board where you require to cut.
  • Pressing down firmly on the rule, using a stanley or other utility knife, score along the line.
  • Repeat the scoring in the same cut for perhaps 10 times, then
  • looking at the edges of the board, you will see each point where the
  • scoring starts and finishes. 
  • Carefully mark these points over on to the other side of the board and  
  • place the rule exactly along a line between these points and score as before.
  • After about 10 scorings, place the board on a flat surface such that the
  • scored line is on a straight edge.
  • Holding the board down with one hand, press down over the straight edge with the other.
  • The board should break cleanly along the scored line.
  • Any uneven/rough edge can be smoothed with sandpaper.
Duncan G4DFV"

Tenbox TX progress

Good progress today with the transmit side of my Tenbox 10m AM transceiver.

The series  modulator was breadboarded a few days ago, so today I built the 3rd overtone oscillator, the buffer and the modulated PA stage. Results were as expected with around 50-60mW of clean well modulated AM available at the output. With a single linear amplifier with around 10-13dB gain (easy at 29MHz) this will take me into the 500mW-1W carrier level, which is my design aim. As I did not have a suitable 29.05MHz crystal (anyone know where these can be obtained cheaply?) I used a 28.500MHz one on a dummy load. With this frequency, any range tests will have to be done at night to avoid QRM to SSB stations.

When the linear is added , maybe even before then, I'll do a local "drive around" test with the TX on "speech beaconing" mode (using an MP3 file on the PC) and with the RX attached to a mag-mount antenna on the car. This will establish the useable local coverage.  Assuming this power level is OK, I'll then complete the full design on a tidy breadboard and publish the initial schematics on my blog and website. After that, a PCB may be in order and a neat enclosure.

This project is great fun: a simple, straightforward and easily reproducible design and a project that will be useful at the end. Much more fun than working DX with 400W and a 5 el beam in a contest with a £5k commercial HF transceiver.  Honestly, I'm having a real ball with this.

25 Nov 2012

10/20W versions of popular transceivers

In the Japanese home market, several of the transceivers available in the USA and Europe are available in lower power versions too. For example, the IC7000 is available as a 50W version and a 20W version. Prices aren't always lower though. For example on the www.icom.jp site, the IC7000S (20W) is available at 168000 yen, the same price as the 100W radio.

The reason these lower power radios are not available outside of Japan is clear: lack of sales volumes and lack of the necessary approvals. It is a pity that the major dealers like W&S and Martin Lynch don't offer to import these on request though if they met EMC specs as I can imagine a reasonable market with QRPers with a bit of advertising: they have enough space in RadCom and PW after all!

How to avoid expensive calls to 0870 numbers

The website http://www.saynoto0870.com/ is a useful resource in the UK if you are looking for a lower cost, or even free, way to contact companies such as Virgin Media or Dell where an expensive 0870 call make be needed.  I get infuriated when big companies keep me waiting on an expensive call saying things like, "your call is important to us" then waste the next several minutes with drivel.

Most of these alternative numbers get in "via the back door" and work on the assumption that you will be transferred internally to the correct department. It may not always work, but if you want to save a few pounds it is worth a go.

CQWW CW - guess who forgot!

Julian G4ILO has posted a piece on his excellent blog about the CQWW DX CW contest this weekend. Well, yesterday was my wife's birthday and we had family here and today I did my tax return. In the process I managed to miss this contest completely! For some reason I thought it was NEXT weekend. Never mind, there will be other occasions to work the DX.

The hazards of LF operating

On the LF reflector there was a salutary message from Mike G3XDV today.  Doing some 136kHz tests overnight his loading coil caught fire melting his flat roof extension!

LF amateur radio can be very dangerous as extremely high voltages and/or high currents can be generated with even quite modest powers because of the electrically short antennas. This is one reason why I stick to QRP(ish) powers on 136 and 500kHz.

See Mike's post:
Damage to the G3XDV loading coil ....and roof! See http://g3xdv.blogspot.com
"I am currently off the air following my loading coil catching fire and damaging the house. I have had to take my mast down to allow access to the builders who are repairing the damage. Fortunately I was insured.

Hopefully I will be able to receive before Christmas and transmit again some time in January.


Details and pictures are on my blog at:
http://g3xdv.blogspot.com

Mike, G3XDV"
This picture (linked from Mike's blog) shows the damage.It begs the question of how readily will an insurance company pay up when an amateur installation fails?

More 10m (28MHz) Projects

With the Tenbox coming along just fine - I should have a completed breadboard version on-air this week - I am beginning to think that I could spend nearly all my free time designing different ideas for this, my favourite, band!

Here is just a brief list of some of my 10m ideas (all do-able with some time):
  • 10m QRP AM transceiver (Tenbox)
  • 10m QRP DSB transceiver
  • 10m pocket SSB/CW "holiday" receiver
  • 10m mixer-VFO controlled CW transceiver
  • 10m compact portable antennas for mobile and hand-portable
  • 10m VXO controlled QRP TX
  • 10m phasing SSB transceiver (10W)
  • 10m beacon RX
  • 10m test box (power meter, ATU, SWR bridge, FS/mod meter)
  • Modules for 10m rigs (VXO, mixer-VFO, LPF, TX strip, DC RX, AM modulator, audio power amp etc)
Now, as I like to do so many different things in this exciting hobby - including on-air operating some times! - it is unlikely all these will get done anytime soon.

What occurs to me, if I had the time, is that a mini-series in a magazine like PW or RadCom entitled "Ten Projects for Ten Metres" would be a nice idea. 10m is one of the best bands for homebrewing as layout is not too critical, as long as sensible RF rules are followed, antennas are small, superb DX is possible in the better years and Es DX possible for 4-5 months every year, local ranges are useful for nattering across town. All in all, this band has SO much to offer.

A 2m AM calling frequency

At the recent RSGB Spectrum Forum Meeting (Nov 3rd 2012) the ongoing matter of an AM calling/working frequency was raised. At issue is why our national society, which is there to help and support ordinary experimenters like you or I, seems to be totally against putting a 2m AM frequency properly in the UK band plan. 144.55MHz is the frequency of choice.

This is what appeared in the minutes:
"7.7 G-QRP
Report accepted

Listing of an AM centre of activity frequency in the Band Plans
It was noted that this has been raised previously with no success. It was suggested that a “custom and practice” approach would be the only way of moving forward i.e. identify a frequency, use it and make it known."
Excuse me dear Spectrum Forum members, but this is stupid!  You have centre frequencies for all manner of other modes, but not AM. So, why not just print these words in the bandplan? :-

144.55MHz   AM calling frequency and centre of AM activity

I am not one to get easily irritated, but the RSGB stance on 2m AM is beyond belief.

Taxing times

Today I'd planned to finish the breadboard TX of the Tenbox 10m AM transceiver and do some range tests locally. The plan was to put the TX on at home with a PC voice recording and drive around with the FT817 and the Tenbox super-regen to see what sort of range was reliably possible.

Instead, I started to do my annual HM Revenue and Customs tax return, a task I hate doing as so much form filling is needed and lots of bits of paper have to be found in order to fill it all in. I do mine online, so the deadline is the end of Jan 2013. Starting at about 10am it took me until 4pm to complete, not because of the complexity of my affairs particularly, but because I couldn't find all the bits of data I needed. On their website they have a nice picture of a guy smiling away whilst filling in his form online. I spent about 6 hours pulling what little hair I have left out!  A reminder that the deadline for online self-assessment tax returns in the UK is Jan 31st 2013, or you get a fine.

Anyway, job done. Yet again I owe money - why do they never owe me money? - and will pay up in the next few weeks. So, a boring, tedious, annual task done and this week I can return to the interesting amateur radio project stuff.

24 Nov 2012

Simple TRF based AM radio ICs

Many years ago when my sons were little I made them a couple of Medium Wave AM radios using just a ZN414 3-pin TRF receiver IC. It worked very well considering how simple the circuit was using just a small ferrite rod antenna and a crystal earpiece. This IC is no longer available but there are other similar parts available such as the MK484. Although I have not tried one of these as an IF stage I have no doubt they could be useful in simple rigs like the Tenbox currently under development. The advantages over a super-regen would be selectivity. These devices have input impedances of around 4Mohm so if a ceramic filter was to be used ahead of the IC a step-up transformer would be needed to minimise loss. As they only work to around 3-4MHz they would only be suitable as an IF in the Tenbox 10m AM transceiver.

A useful page I've just found on how to get the best from these simple ICs is http://theradioboard.com/best-of-the-best/mcgillis-mk484.htm.  The datasheet for the MK484 is available here.

A page showing the use of the MK484 as an IF stage in a simple 160m RX is  http://www.vk6fh.com/vk6fh/mk484radios.htm . See also http://www.youtube.com/watch?v=qdlXVKOITe4. I am told that a similar design appears in 'Radio Projects for the Amateur' Volume 4 by Drew Diamond VK3XU. 

I'm still likely to stick with a very simple super-regen RX in the Tenbox - they ARE the best in the intended application - but I may make it in a modular form so that different TX strips and RX strips can be used and compared.  I can see a whole series of simple AM designs in the pipeline, HI.

More big wheels and turnstiles

When looking around for possible homebrew designs I saw an article that appeared in QST back in 2008.  Looking at this approach I am not convinced it is easier than the conventional big wheel design though. See http://radio-amador.net/pipermail/cluster/attachments/20100107/a2f81f3e/AntenaHPOD.pdf

A design for a 70cm big wheel, designed to be used with a beacon, is available at http://www.qsl.net/dl4mea/antennas/bigw.htm .

The turnstile design on the EA4EOZ website
Another simple approach to a VHF or UHF omni-directional horizontally polarised antenna is the simple turnstile (a pair of phased cross dipoles that produce an almost 360 degree clean radiation pattern with about 0.9dBd loss only). These can be stacked to produce gain, as with the big wheel.

Overall, the conventional big wheel design is my favoured approach for 2m and 70cm. Whether I make my own or buy a Wimo version remains to be seen.

Another ham radio company bites the dust

Via an email from Steve G1KQH I've just heard that Snowdonia Radio Company has ceased trading completely and closed its business. If I understand correctly they closed down last year but had one last try again this year. You may recall that this company produced antennas such as the X80 HF vertical antenna which appears on an earlier blog entry last year I believe. I erected and used one and it worked very well.

This is sad news as it was a small UK company making good products for the amateur market. Clearly the market is not big enough to support the volume of trade they had and all their commercial overheads. One wonders how many other small companies can make a success in our market unless they get major publicity in the big magazines or have a good website that attracts a world-wide audience of potential and actual buyers. I cannot recall SRC advertising too widely: maybe this was their problem - getting a critical mass of customers who told others and came back for more themselves.

This was the message on their website today: 
Due to an ongoing decline in trade Snowdonia Radio Company has stopped trading.
All contact avenues have stopped.
This has been a hard decision as we only reopened in January 2012, but ongoing high costs and a rapid decline in trade have forced our family business to close permanently.

Thank you for the business over the years from Simon and Liz, and we hope to speak to you on air.
Please note that there are some poor quality non SRC antennas available, These antennas look like SRC products but are not. SRC do not make antennas for anyone else......

73,   _._

23 Nov 2012

Big wheel antennas?

www.wimo.com big wheel
When I move to my new (higher) QTH on top of our local East Anglian "hill" next year I'll have to give some thought to what VHF/UHF antennas to erect for horizontal SSB/CW/digital DXing. I could go for a decent set of beams and a rotator or I could go for an alternative approach and erect a stack of big wheel antennas for 2m and 70cm. A single big wheel has a horizontal gain of around 2-3dB over a dipole but a couple will give almost 5dBd, which is similar to an HB9CV beam but without the hassle of a rotator and with almost 360 degree coverage.

For my sort of (occasional) 2m and 70cm DXing the big wheel may be a suitable solution. I have around 6 months to sort this out, so no rush, but I'd value inputs from people on this. Have you used big wheels? How effective were they?

Incidentally, even from my old QTH I've worked all sorts of decent VHF DX with just a halo and a few watts QRP in contests, so a lot depends on how prepared one is to wait for lifts or big contest stations to work. Clearly if the aim is to work 600-700km under flat band conditions then 100W and a largish beam are almost essential. I'm not entirely ruling such a station out of the question, but it would be a big change from my usual QRP, so pretty unlikely.

A photo in QRP Basics (2nd edition)

My wife has bought me a copy of QRP Basics (2nd edition) by G3RJV for Christmas. It came this week so we opened the pack to check all was well, before putting it away for a month.

Imagine our surprise when we spotted a photo in it of me with grandson Lucien (when he was very young) at my operating table.  Lucien is the little lad (now 5) who was tapping out CW on one of my YouTube videos and playing with my audio kit on another. As I never did manage to get either of my two sons interested in ham radio, I'll be lucky to get any of my grandchildren interested, but I shall try.  Regarding the rest of the book, I'll let you know on Christmas day after reading it with a minced pie in hand. As it is written by Rev George Dobbs, I am sure it will be another excellent book about QRP.

20 Nov 2012

10m local range?

With the 10m AM Tenbox design coming along nicely I'm reminded of the fun we had in the early 1980s with 10m FM using converted CB rigs here in the UK. Using a converted CB radio with 4W FM into a vertical half wave antenna I was usually able to make contact with similarly equipped stations up to around 25-30 miles away pretty regularly. Certainly within a 5 mile radius signals were fully quietened, even to mobiles.

So, I am wondering how I'll get on with 0.5W of 29MHz AM? My expectation is that with a similar antenna (1/2 wave vertical - I currently use a horizontal halo) I should be able to cover 3-5 miles without too much problem. I'm wondering what sort of ranges people achieve with AM CB radios (WITHOUT add-on PAs!) where this mode is legal?  Running a few dB more power is no problem if required of the Tenbox design.

When 10m is wide open it is possible to work thousands of miles on FM but I always found that the competition was too great and therefore the mode is not well suited to DXing. The aim of the 29MHz AM Tenbox is just for very local communications and definitely not for DX working. In my mind I see the Tenbox being a modern version of the old Heath HW19 (the Tener) rig - see the image and data on the Rigpix page

WISPY 10m WSPR beacon video

A few people have requested a video of WISPY, my QRP WSPR beacon for 28.1246MHz. This video shows the TX beacon only. I have a companion RX breadboard that works well and at some point these will be combined into a small 10m WSPR transceiver.

Tenbox 10m AM RX video

It is hard to contain my enthusiasm for simple transceivers and super-regen receivers! This video shows just how well the RX breadboard for the little Tenbox 10m AM transceiver works. 1uV (-107dBm) is a very good signal and it will still detect a well modulated AM signal at -120dBm. Selectivity is not good with this type of receiver, which is the main drawback. However for its intended application - a simple transceiver for local nattering across town - it should be fine. Some people use super-regens as the IF stage of AM receivers. If a filter is added ahead of the super-regen IF this overcomes the selectivity issue but makes the RX design more complicated.

19 Nov 2012

Tenbox 10m AM rig - a bit more

Although I had little time today, I experimented with adding varicap tuning to the Tenbox AM transceiver's RX section. Only problem was I had no varicaps, so tried using a few different diodes and a transistor as a varicap. 1N4148 and a Germanium diode reverse biased hardly produced any change in capacitance going from 2-12V. I know a 1N4007 works quite well but could not find one. Then I used a 2N3904's base-collector junction and got a few pF of change. In the end I just did as I did in the Sixbox and used a fixed capacitor in series with a 365pF polyvaricon tuning capacitor. This moves the RX frequency as much as I need at around 2MHz maximum.

2 countries worked on 500kHz with JT9-1 mode

Well, the JT9-1 test QSO with G3ZJO was a total success and completed in around 10 minutes this evening. Later, I called CQ on JT9-1 and got a reply from OR7T in Belgium who is 334km away. We worked, exchanging reports and 73s but I am not quite "all with it" with the sequencing of reports, R, RRR etc in JT mode exchanges.I am learning, HI.

G3ZJO in QSO with G3XBM this evening on 500kHz
The WSJT digital mode JT9-x is certainly an interesting mode. There are a few bugs in the code still, and more bugs in the operator using it (me!) but I am sure to use this mode more in future on 472kHz and 136kHz.

500kHz JT9-1 test this evening

G3ZJO and I have reported each other's 500kHz WSPR signals and each managed to get reports from close on 1800km away but, despite being only 50km or so apart we have yet to work each other on MF. This evening we are going to attempt a WSJT mode QSO using JT9-1 mode with 1 minute TX periods. I'll report back later how we get on!

More Chromebooks

The new Acer C7 Chromebook on the
www.cnet.com site
A few weeks ago I mentioned the Samsung Series 3 Chromebook which is available in the UK for £229. Now I see there is a new entry, the Acer C7 Chromebook which retails for just £199 here and $199 in the USA. This sports a 320GB hard drive and, like the Samsung, a high resolution 11.6 inch display.

The main drawback (or is it an advantage?) of a Chromebook is that it uses the Chrome OS and depends a lot on cloud based applications, although quite a lot of applications work off-line too these days.

Certainly for a second PC at home and on the move it has to be a good bet.