JT what - Ah, JT9!

Well,

A while ago I had a play with JT9 - its a cousin of the popular JT65. JT65 was designed for V/UHF comms and JT9 was designed for L/MF. Now JT65 has proved popular on the HF bands generally, and , for example on 20M, you would find JT65 with a dial frequency on USB of 14.076. Now, JT9 is typically found 2KHz above this, so on 20M this would need a dial frequency of 14.078.

The latest and greatest piece of software from the gang that develop the WSJT software, more specifically WSJT-X, have now included a bi-lingual feature! The software can receive both JT65 and JT9 at the same time!

To do this you need a radio capable of a wide RX - 4KHz required here for the full spectrum of both types of transmission. I have completely failed to find  way to do this with my FT-DX-3000, but have managed to get the FT-DX-5000 configured to do this.

I hoped to do this in PKT mode, but the width is fixed at a maximum of 2.4KHz in this mode, but in USB you can set the bandwidth to 4KHz (I struggled to see this full bandwidth in the waterfall until I remembered that I had a 3KHz roofing filter in line - doh!).

So, here is a screen shot from the latest WSJT-X:

including my first JT9 QSO with CT1FBK - thanks Miguel! The JT9 signals are to the right of the blue line at 2500Hz in the smaller window with the JT65 signals to the left.

Now, most (if not all) commercial SSB transceivers include an audio filter in the TX path, this means that the radio cannot generate the tones over the necessary spectrum for both JT65 and JT9 with a single dial frequency. To get round this the software includes CAT interfacing and you run the radio in split mode, using VFO A for RX and VFO B for TX. When you TX in JT9 the dial frequency on the TX VFO is altered and the appropriate tones generated.

Simply genius!

It's cheating - I know!

Well,

This weekend is the IARU HF World Championship:

http://www.arrl.org/iaru-hf-championship

and propagation hasn't been that bad; there have even been some openings on 10M.

Now, my CW is simply rubbish. I passed the Morse exam when I was 19, then I spent a few years going things like getting a degree and a job - I didn't use the Morse for many years - not that the test even began to prepare you for on-air CW...

Anyway, here's a screen shot of me working LY0HQ in CW:

I am using Logger 32 (http://www.logger32.net/) - this is my preferred day-to-day logging program. It includes a CW machine for sending CW using a simple interface between a COM port on the PC and the KEY jack on the radio, my interface is made like this:

Then also on the screen you can see I also run CW Skimmer at the same time:

http://www.dxatlas.com/cwskimmer/

This monitors the audio from the radio that's being fed into the PC soundcard. It's a really neat CW decoding application - you can use it with narrow radio filters to focus on a single signal or it can decode multiple signals over a wide bandwidth - very neat.

I also have a monitor of "antenna cam" on the screen too - primarily just because I can!

Anyhow, that's how I go about cheating and working CW. Cat's not impressed:

Good though egh?

I've finally sacked him for being useless!

Well,

You may remember the trauma I sustained trying to stop the back of the house and the sitting area below getting constantly covered in bird ****.

At the bottom of this post was where I recruited the services of Oliver the Owl:

http://g0mgx.blogspot.co.uk/2012/08/top-band-what-happens-there-then.html

Oliver has proved to be quite useless apart from serving as a great vantage point for the birds to perch... so today I have finally got round to getting rid of him.

Instead I asked on one of the eHam forums here:

http://www.eham.net/ehamforum/smf/index.php/topic,90940.0.html

and as a result have got some mirror finished plastic stuff and some garden twine and have ended up with this:

If you look closely you will see that there are five shiny mirrored things suspended between the two antennas.

Time will tell, but I think I might have cracked it!

Sneaky, egh?

This week I'm 9H3JM - that means I am in Malta!

Well,

Finally I have some time off work and have taken a trip to the island of Malta for a holiday with my Wife.

I brought my FT-817, a PSU, buddipole and a laptop with me (and yes, I got stopped at customs AGAIN):

Getting a license for Malta was really easy. I already hold a HAREC - that's a Harmonised Amateur Radio Examination Certificate which means that I qualify for a license in CEPT countries without sitting the local qualification. I simply filled out a form, sent it off with copies of appropriate bits of paper and the license fell through the front door a couple of weeks later.

It's rather nice here, and have had an hour or so today playing radio:

I don't expect to work the world with my 5 watts of RF out of the FT-817, but it sure is fun. I am on EU-023 (I think) after all! Only running JT-65 ad PSK-31 but getting out well considering the limited nature of the station.

Fun, egh?

Can we do it with Less - Part II

Well,

Following my musings last time about how far not much RF can travel, I took another look at the site of W3PM here:

http://www.knology.net/~gmarcus/

This is where I found the inspiration for my WSPR beacon back here:

http://g0mgx.blogspot.co.uk/2012/05/back-to-real-homebrewing.html

So I took a look at the latest software for the project - noting that my callsign appears in the credits! - then just reprogrammed my project with the latest code after changing the appropriate bits like callsign and locator et cetera.

I then calibrated the output for an accurate 100mW - I also calculated the loss in the coax between the output and the antenna - I make that about 1dB.

So, I have 100mW or 20bBm out of the box, 1dB loss in the coax = 19dBm or about 80mW into the antenna.

Remembering that propagation conditions are quite poor at the moment, here are the results of an overnight run:

Simply stunning, egh?

Can we do it with less?

Well,

My 30M QRSS Arduino based beacon is still on the air; and I am receiving reports via e-mail from time to time. The most recent was from Andre, DL8WX; he is in JO30WE 716.75 km (445.390 miles), bearing 112.3 degrees from me and said "I found ur beacon last night with a strong signal on 10140.02 kHz for the first time!". The beacon project build is here:

http://g0mgx.blogspot.co.uk/2013/06/qrssing-again.html

Last night, I left my FT-DX-3000 WSPRing on 40M using the dipole I made here:

http://g0mgx.blogspot.co.uk/2013/04/well-further-to-my-musings-last-time.html

and here's the result:

Before I left it alone I measured the power out exactly using my Arduino based power meter from here:

http://g0mgx.blogspot.co.uk/2012/11/the-power-is-with-me.html

and the list of stations heard/hearing looks like this:

So, you have to wonder, if this is achievable with 40dbM (10dBW or 10 watts), what could we achieve with far less power?

Given that the most recent 50mW QRSS beacon project is Arduino based, I could write some software to generate WSPR using that, I would need a GPS to give me an accurate time source, there's also exactly that in a (not quite finished) project from here:

http://g0mgx.blogspot.co.uk/2012/05/more-wspring-and-qrssing.html

or even this Hans Summers project from here will do it exactly as I describe above (GPS and WSPR):

http://g0mgx.blogspot.co.uk/2012/07/qrssing-again.html

So, time to fiddle!

As a slight aside, I'm going to Malta for a week soon and I have 9H3JM for use there; as my FT-450 is in Doha I have bought myself an FT-817 to take with me. This radio is capable of outputting much lower power levels than the other radios I have here, so perhaps the easiest option for some really low power WSPR is to use that?

Lets see.

So, Why would you want one?

Well,

It's a great question - we're talking Spectrum Analysers here, by the way - my first offering would be, why not? Second would come, because I can.... but really, let me try and show you.

None of this has any real importance, but you can say that about anything, can't you?

I've just been aligning (read fiddling with) an SSB transmitter that I made a while ago. Now, part of the circuit mixes the BFO frequency (in my case it's about 12.9MHz) with the audio that's being injected. Under normal operation this would be from a mic, but for this exercise I'm using an audio signal generator and injecting a 1KHz tone.

The signals are mixed together in a simple diode based doubly balanced mixer, and the output contains a whole pile of stuff. There's the BFO frequency, the audio frequency, the sum, the difference and all sorts of other harmonics in this signal. On a scope, when the balanced modulator is un-balanced it looks like this:

As you can see the signal is a complete mess, and very hard to see what's going on. This was a single shot take on the signal as there is so much that the 'scope cant really decide what to trigger on.

Here's the same signal on the Spectrum Analyser:

Now, this makes a whole pile of sense. The left hand peak is the LSB, it's exactly 1KHz (the audio frequency) below the next peak which is the carrier or BFO (remember I said the one of the things in the output was the difference between the carrier and Audio frequency). The right hand peak is the USB - this is the sum of the carrier and the Audio frequency. What we actually have here is an AM transmission - a carrier and two sidebands.

So it's very clear here - this part of the circuit contains some components to suppress the carrier (remove it) but the circuit needs to be balanced before this will happen correctly. Using the adjustment available and looking at the Spectrum Analyser I can adjust to this:

So, I can clearly see that the carrier is now well down into the noise. The next part of the transmitter chain is the crystal filter, that will suppress the unwanted LSB to create SSB as what we have here is DSB (double side band). Once again, using a Spectrum Analyser, I can watch the RF output and alter the BFO to place the USB inside the filter passband and the LSB well down the skirt of the filter. Only then will we have what we are trying to create; Single Sideband (SSB).

Simple, egh?