472kHz transverter (rev K)

Several people have now built versions of my 472/500kHz transverter. The latest version is shown below which includes provision for an additional low pass filter when using a fairly long (less sharply tuned) antenna. Although some capacitors could be combined to reduce the component count, I've shown it using readily available high voltage capacitors. The 16uH inductors are 43turns of 0.71mm wire on 22mm white PVC pipe.

In the last few minutes I've been looking on 472kHz WSPR and see that SM6BHZ and DK7FC are coming through OK despite my S8 noise floor.

SM6BHZ and DK7FC this afternoon on 472kHz WSPR

December's Practical Wireless

The December 2012 edition of "Practical Wireless" has my article about the 2m AM Fredbox and the 6m AM Sixbox transceivers that are described in more detail on my website. These simple QRP VHF transceivers proved to me that you don't need to spend lots of money to make simple transceivers that work. Both have produce interesting QSOs: the 2m Fredbox had several 90km QSOs with one at 160km, despite being only 10mW output and using just a whip antenna!

Today there is not that much AM activity on the bands but I think this is a great pity as the mode has a lot to offer. I do hope the RSGB can be (eventually) persuaded to add 144.55MHz as the AM calling/working frequency in the band plan. It is mentioned (almost lost) in the foot notes, but it needs to be properly shown. For some reason the RSGB seems to have a problem with 2m AM.

I hope others will build simple AM gear for 144.55MHz or crystal up some ex-commercial PMR radios and again enjoy the fun of 2m AM. Second hand AM gear for 4m and 2m can often be obtained for just a few pounds as no-one wants it.

GPS Route Logger

Last week I bought a Ventus G730 GPS Route Logger from Martin Lynch for £34.95. Today I tried it out for the first time on a walk in the bright autumn sunshine at Ickworth park, near Bury St Edmunds. I am totally delighted with it.

The map below shows the route taken as plotted on Google Earth. The data that comes out of the logger shows route taken, speed (average and instantaneous) , distance traveled, and altitude up and down. If linked to a digital camera file it can be used to geotag photos on a walk. I am very impressed that something this small shoved in your pocket can produce such fun results. I now need to find a use for this in my amateur radio experiments.

Google Earth plot of a walk today using data from the Ventus GPS logger

500kHz WSPR tonight

My last post with this title got corrupted when I tried to edit it, so this is a shortened revised version. 500kHz WSPR this evening has been very good. In the last couple of hours I've been getting 8-9 reports with each transmission slot when running less than 50mW ERP. Best DX 707km to DG3LV.

500kHz WSPR reports this evening

I've downloaded the latest version of JT9 software and hope to try this for 2-way QSOs later this week on 500kHz. My current problem is the S8 noise floor which I hope to reduce by using a better sited E-field probe or loop antenna (for RX only) further away from the house.

There are still plenty of CW stations on 500kHz. One evening last week I had a very enjoyable CW QSO on the band with G3XIZ. Semi-locally there are around 3-4 stations on a regular Sunday morning 500kHz CW net.

Projects pause

This week I am having a bit of a rest from amateur radio. We have two of our little grandchildren staying with us until Sunday and they take top priority. Anyway, one sleeps in my bedroom shack!  So it is off to ride on toy tractors, eating some cakes in a cafe and help Grampy deliver poppies.

With the XYL and grandchildren

There are some geomagnetic storms around so HF conditions are unlikely to be very good for operating.

Next week should see me back in action. My first task is to make some changes to the 472/500kHz transverter - adding an additional filter as shown in the Rev H schematic on my website so that it meets FCC requirements before an article on the small transverter appears in QST magazine next year all being well. It has been accepted. I've also got to update the schematic and parts list.

Next on the list is probably to get my 10m halo down for its rebuild that didn't get done last week. Then I am in to several possibilities including getting "Lesser Chirpy" going on air (the chirp free version of Chirpy) and casing it up. Also, there is the 481THz NLOS beacon with those BIG powerful LEDs I bought a month or so ago. There is also a new 136kHz transverter (like the 472kHz design but for 136kHz instead). And then there are all sorts of other ideas floating around in my head which probably won't get done for another year. These include a simple Fredbox version for 10m AM, an ultra-stable GPS locked frequency source to use on VLF and maybe microwaves later,  my permanent E-field probe and grabber for VLF/LF/MF,  an improved 136kHz stand-alone receiver, etc, etc. Hey ho!

More DX on 10m today

This must rank as one of the most fun CQWW DX contests I've taken part in. Plenty of DX could be worked with just 5W SSB from the FT817 and my small Homebase-10 halo today and yesterday. If anything conditions were better on 28MHz today than yesterday.

HK1NA (worked today) operating CQWW

 ...and in contrast G3XBM operating CQWW today!

Stations worked include LR3M, LP1H (Argentina), C5A (The Gambia), HK1NA (Colombia), CR2X, CR3A, CT3HF (Azores), CN3A (Morocco), ER3AU (Moldova), A65BB (UAE), 3V8BB (Tunisia), ZW5B, ZZ2T, PY1NX, PS2T (Brazil), EY8MM (Tajikistan) plus loads of US, Canadian and other stations. My ears are sore with SSB signals! I have now filled my third page of contacts in the logbook.

Some of the operating skills were amazing: PJ4X was working stations at a rate of one every 5 seconds. He spoke so crisply and quickly that by the time I'd called he'd already worked another station! 

First signals seen on JT9-2 mode

On 500kHz this morning PA0A and G3ZJO were testing with the new JT9-2 weak signal mode. Not yet copied Eddie, but PA0A was coming through well. This is a screenshot with his decoded signal overlaid.

500kHz first JT9-2 signal received

Choice DX on 10m SSB today

The CQWW DX Contest continues to brighten up things on 28MHz SSB, although the competition is fierce for some of the rarer stations.

XV1X QSL card

Some DX is surprisingly easy to work though, responding after just a couple of calls with QRP.  My 5W QRP SSB got through to EY8MM and A65BB but failed (so far) to work XV1X (Vietnam) or JT1BV (Mongolia).

JT9: a new digital mode for MF and LF

Hot news from Joe Taylor K1JT on the RSGB LF Yahoo group this evening about a new 9-FSK digital communications mode (for 2-way QSOs rather than beaconing) optimised for MF and LF bands. With winter approaching and better LF conditions, this is an exciting development.

The wide graph display for JT9

"I invite you to try a new digital mode called JT9, designed especially for making amateur QSOs at MF and LF. JT9 uses the structured messages introduced in 2003 for the JT65 mode, now widely used for EME and for QRP operations at HF. JT9 can operate at signal levels as low as -27 dB (in a 2500 Hz reference bandwidth), with one-minute timed transmissions. It also offers slower transmissions of 2, 5, 10 and 30 minutes duration, and the slowest mode can decode signals as weak as -40 dB. With one-minute transmissions, submode JT9-1 has a total bandwidth of just 15.6 Hz -- less than one-tenth the bandwidth of a JT65A signal. The other submodes are narrower still: a JT9-30 signal occupies about 0.4 Hz total bandwidth.

Note that these JT9 sensitivity levels are comparable to or better than those of WSPR, which uses simpler messages and is not intended for making 2-way QSOs.  JT9 has much higher throughput and reliability than QRSS CW, including DFCW modes.

JT9 is implemented in an experimental version of WSJT called WSJT-X. Some further details can be found at http://www.physics.princeton.edu/pulsar/K1JT/WSJT-X_Quick_Start_Guide.pdf , and an early version of WSJT-X can be downloaded from
http://physics.princeton.edu/pulsar/K1JT/WSJTX_01r2695.exe.

Please note: WSJT-X is in an early development stage. A number of improvements and enhancements are already in the works, and others will surely be added. 

Your feedback will be much appreciated!

-- 73, Joe, K1JT"

CQWW SSB DX contest 2012 (28MHz) - a recording

Well, Oct 27th 2012 and the CQWW DX contest is in full swing. 28MHz is filled with SSB stations all the way from about 28.25MHz right through to 29MHz, with even a few SSB stations on top of the AM users around 29.05MHz. Conditions appear to be excellent for the contest and they are likely to hold up for tomorrow too.  I was able to work 5 continents in 50 minutes this morning with 5W SSB and a halo.
 
In 5 years or so, this day will seem like a dream with 10m probably dead and devoid of activity. So, for posterity, I made a sound recording late this morning of the 10m band as I tuned across it and later this video at around 1630z.

Here is an earlier sound recording CQWW SSB DX contest 1125z October 27th 2012. Recorded near Cambridge, UK.  Feel free to share/use this recording and video. I only made them for posterity so I can remember, in years to come, what 10m was like at a sunspot peak.