Showing posts with label HF. Show all posts
Showing posts with label HF. Show all posts

25 Feb 2016

Useful propagation charts

This series of charts (change months and bands as required) is a useful guide to HF propagation. Like all such forecasts, caveat emptor as they said in Rome. I think this comes from G0KYA.  See http://www.infotechcomms.net/propcharts/february/ .

Another source for solar data was http://www.solan.info/solar , but when I last checked this page had gone. I am not sure what happened. All I get now is a link for hotels!

Another source (which works) is http://www.solarham.net/ .

As you know, I try to add current data on my blog most days. This comes from http://www.hamqsl.com/solar.html .

Somewhere in this lot you should find the data you need.

29 Sept 2015

2m big-wheel and feeder on HF

As an experiment I loaded up my feeder and 2m big-wheel on HF tuned against a mains ground. It matched on 40m, 30m, 20m, 17m and 15m but it did not like 10m. I have still to try other bands. On 15m it was getting USA spots on the first transmission at 2W and on 40m it got 9 spots (all Europeans) in the first TX with no effort. It was receiving well on all the bands I tried and giving plenty of stations spots via WSPRnet. The feeder and 2m big-wheel, tuned with my LDG ATU, would allow me to WSPR on most HF bands. One night I shall try the 2m big-wheel and feeder on 472kHz, using a ferrite rod to resonate it and a 3C39 toroid to match it. It will be interesting to see how this compares with the earth-electrode "antenna".

UPDATE 1427z:  I see my 10m WSPR has been spotted by FR1GZ (9724km) using the 500mW beacon and Par triband end-fed wire. Conditions on 10m are good.

UPDATE 1556z:   LA9JO (2096km) spotted me on 7MHz, for my best WSPR DX, so far, on that band.

30 Mar 2015

The future of HF broadcasters

Deutsche Welle (DW) is closing its last relay station, which is in Kigali, Rwanda. In recent years DW like many shortwave broadcasters, has been facing financial cutbacks. Also there are far fewer broadcasters using shortwaves these days.

As a youngster in the 1960s, I recall shortwaves crowded with AM broadcast stations, many from all over the world transmitting in English, with their distinctive interval signals. There was a magic about shortwave broadcasting back then. Quite a few could be copied with very simple receivers too. There is something quite nostalgic about listening again to those long-gone interval signals from behind the Iron Curtain. I remember getting some excellent freebees from China back in the early 1980s. Of course, it was all to spread the propaganda.  All I really wanted was their QSL card!

These days, users are often reached using the internet. Of course, it begs the question, "who is now filling the empty, vacated channels?"  In the long run amateur radio might gain some allocations, although the noise floor on HF is increasing too. SMPUs, cable TV and numerous other sources are mainly to blame.

See http://www.dw.de/deutsche-welle-closes-kigali-outpost/a-18340960.

Pixie Files

My assembled 40m Pixie
The Pixie is a very simple HF transceiver. Usual power out is in the 200-1000mW region, depending on band and DC power source.  It was first developed some years ago but the basic concept is using a PA transistor as a mixer in a simple direct-conversion receiver. On TX this is used as the TX PA.

Being simple, it has a number of limitations but it certainly works. A major issue can be AM broadcast breakthrough, although my 40m version is perfectly usable. I was very impressed with my little kit that came with all parts including a silk-screened PCB, all sockets and a crystal. It needed low-Z Walkman type headphones, a morse key and battery - that was all. On 40m the sensitivity is pretty good with 0.5uV clearly audible and my RF power out is around 400mW. A lack of both RF and AF RX selectivity is also noticeable.

Kits are available from several sources at prices that are hard to beat. I recently bought a kit for $10 with free airmail from China. It is available for less than half this price I subsequently found out. Unbelievable for a fully functional HF transceiver. Of course, being so simple you may prefer just to build it dead-bug fashion. I bought a kit as I wanted to see how my building skills were.

As a mature design, it has been through several iterations, some improve the basic design, but most do so at the expense of increased complexity. You'd be hard pressed to find a circuit for a complete HF CW transceiver much simpler.

See www.gqrp.com/The_Sprat_Pixie_File.pdf .

13 Dec 2014

HF contests

I am not a great fan of HF contests.  As a QRPer, I find CW contests all but impossible as people tend to send and receive at incredible speeds usually with PCs. SSB is usually better and often the "other end" has worked you before realising you are running QRP.  Later stages of contests are usually easier as the big guns are sweeping for remaining points and looking to work weaker stations.

I have been unable to work in the ARRL 10m contest (visitors this weekend) ) and I forgot the CQWW SSB contest this year! Last year, I was in hospital. It is 2 years since I last took part in CQWW SSB, which I find a very fruitful contest. I usually stick with 10m only.

Each Tuesday evening the RSGB organises a rotating series of VHF/UHF contests (UKAC) and I try to come on for the 50, 144 and 432MHz contests where I am at home and available.  I use 5w pep and a V2000 vertical on 50MHz, a 3 el on 144MHz and 5 el on 432MHz.  On 144 and 432MHz the antenna is hand-rotated. On 50MHz it is vertical and fixed.  I can usually work 150-250km in these contests despite my 5W.

9 Apr 2014

10m today - still good

http://www.hanssummers.com/images/stories/ultimate3/1/5.jpg
All afternoon I have been receiving WSPR spots for my 2W WSPR transmissions.  Up to now ALL spots have been from transatlantic stations in the USA. The band is still in good shape.   The sunspot count is drifting gradually downwards (94 today) but, for now at least, HF conditions on the higher bands like 10m remain generally good.

This weekend I may make a start on my Ultimate 3 WSPR beacon kit (see image above on Hans Summers' site).  This is a complete (no PC needed) beacon kit for modes like WSPR and QRSS3 and very reasonably priced even if buying the GPS timing kit too. Mine cost £37 including postage from Japan with GPS.

I feel a bit better than I did and less clumsy. We'll see.

25 Jan 2014

Second peak for cycle 24?

It looks more and more likely that cycle 24 is going to have a second peak with a greater magnitude than that of the first peak of Feb 2012. Today the sunspot count is 150. It will take several months before the smoothed sunspot number is known, but the indicators are good.

Recent excellent conditions on 10m are further evidence of good times. Since home from hospital (Jan 3rd) 10m has been open to N.America every afternoon that I have listened.

As the slope down to the minimum is more gradual than the ascent to the peak(s), we can expect decent HF conditions for a few years to come.

The new peak is not great and we may we be heading to a Maunder Minimum with very little sunspot activity for perhaps 40-50 years. Enjoy these HF conditions while you can  because we may not see them again in our lifetimes.

See http://www.solen.info/solar/ .

UPDATE 1300z:  My first report from the USA (running 2W WSPR) was as early as 1244z, indicating a VERY early 10m stateside opening today at my very low power level.. Conditions remain excellent on 10m.  7088km, not bad.

6 Jun 2012

The future of HF amateur radio

There is no doubt that HF amateur radio is changing. Fewer people ragchew these days (do you agree?) and there is considerably less activity outside of contests, mirroring a change already seen on the VHF bands. More people are using digital modes instead of phone and there is much more use of software tools to detect DX, decode and encode CW, PSK31, etc. The hobby is changing: some of the new ways of operating are very good, but along the way we are in danger of losing something of the appeal of the hobby perhaps?

Now, there is also another factor: it is very likely we will have seen the end of active sunspot cycles once the present low peak of cycle 24 declines. Many of us who experienced the peaks of 1957 through to 1980 are very unlikely to experience similar ones in our remaining lifetimes. Propagation on HF may never be as good as the second half of the 20th century for another 100 years. There are also theories that HF propagation is not as good as it was, even assuming similar solar activity, as if the ionosphere is actually changing its behaviour.

Then there is the challenge of spectrum pollution. This is already a menace for many of the lower HF bands but even bands like 10m and 6m are affected.

So, the challenge now is to look to the future, positively, and see how the future of HF will be redefined. I have no idea what the next 10 years will bring, but I suspect the use of our HF bands will be quite different by the 2020s.

29 Mar 2012

ZL9 Campbell Island (near New Zealand)

There is to be a DXpedition to Campbell Island (OC-037) in November this year. See http://dx-world.net/2012/zl9hr-campbell-island-dxpedition/ .  This reminds me of the excellent conditions on 20m AM back in the 1960s when I remember hearing a station on Campbell Island working the UK with S9 signals early one morning. In those days I'm sure the prefix was ZL4 though.

Is it just me, or is it much more difficult to hear and work DX stations these days compared with back then? Some believe that the ionosphere has actually deteriorated in the last 40 odd years so that, despite rising sunspot numbers, conditions are not as good as they were years ago.

5 Feb 2011

JT65A on HF

Having seen the article on how to do this in the latest edition of Practical Wireless, I have installed the software and taken a listen/look. Main issue seems to be that the AGC in the FT817 is fierce and with close-by PSK31 signals it kills the gain of weak JT65A signals nearby. Anyway, it looks a useful mode. For HF use, download the HF tailored version at http://jt65-hf.sourceforge.net/. Not yet had a 2-way QSO but will soon when I've got the hang of this.

2 Jun 2010

HF transceiver ideas site

Vanyi Istvan Vanyi YO5OFJ has an excellent website with links to a whole list of HF transceiver designs from around the world. Most are QRP designs with links to the originating sites.

13 Dec 2009

YO5OFJ's pages with everything

Vanyi's Homemade/homebrew HF transceivers page is a collection of lots and lots of circuit ideas showing transceivers from 160m - 10m created by various people over the years. It is a good place to look for ideas when thinking about new projects.

16 Jan 2009

Long-term HF deterioration?

Some time back I recall discussion about a theory that the ionosphere was not behaving nowadays as it was, say, 50 years ago. I'm not talking here about sunspot cycle issues but whether or not there are factors at work that mean HF comms today is more difficult than many years ago due to ionospheric structural changes. I'm also ignoring things like increased noise floors due to SMPSUs, lights etc.

Can anyone point me in the direction of any definitive references to this theory?