Rather obvious EMC problem…

I noticed just now that the Raspberry Pi that runs my ADBS receiver and also has ‘1-Wire’ temperature sensors for the central heating registered a pipe temperature of a theoretically impossible -1700C.

Oh, did I mention that my 20m / 6m dipole is in the loft… and the Pi is in the loft… about 2 feet from one leg of the dipole… Hmmm. I can see a connection here given the timestamp was the same as a JT65 transmission.

JT9 blues

I’ve had a couple of JT9 attempts these past two days on 20m where I’ve answered a CQ and received a signal report  back, and sent mine but then received the same -nn signal report again. And again. Presumably the remote station has not been able to decode my reply. So I never get to the 73. I’m guessing the band just fades away from underneath me…

If I remember right it was the same remote station each time. I’ve had successful JT9 QSOs so I am putting these down to bad luck and I hope the other guy isn’t getting frustrated!

JT9

Well another first for me tonight, a JT9 QSO, and on my second attempts at answering a CQ. This was with a USA station apparently over a 5,600km path. But again the replies come in the Band Activity window on a different frequency. Not sure what I am doing wrong there, but this was a complete QSO ‘by the book’.

Edit: I never did follow up on this post. This is, of course perfectly normal operation, for example where someone sits on a quiet part of the segment but listens across the whole.

JT65 – mostly

I spent a couple of hours yesterday with WSJT-X trying to make some contacts by answering CQs and getting nowhere. After a lot of fiddling with settings (I spotted the ALC on the FT450D was going haywire – who’d have though it had a display!) I now have much better settings of sound system output and Tx control on the SignaLink. The Tx is now set to just below to 9 o’clock position, so almost to the third tick mark, and the sound system output is set to 29% via the Pulseaudio volume control. The power setting in WSJT-X is set to -0.9db at which level the signal still triggers the PTT relay in the SignaLink but at 100% (-0db) the ALC triggers. But no luck with answering CQs.

Actually the Pulseaudio setting threw me at first because WSJT-X uses ALSA, but the ALSAmixer shows the same 29% as set by Pulseaudio so I’m not fussing. Also, it still gives the expected power output on the PS modes and a test call on BPSK31 worked fine, so it’s all be written down.

And today I got a reply to my reply to a CQ. But it was confusing. WSJT-X has two windows, one for Band Activity and one for Rx Frequency. It’s all made very easy, you double-click on a CQ in the band Activity window and it moves your Tx and Rx frequencies to that station and pre-fills standard messages. The system can also be set to enable Tx when you click but I’ve not done this. There is time (seconds) between clicking the callsign, checking everything is ok and clicking Enable Tx.

So back to my first JT65 QSO. I clicked on a CQ as above and clicked Enable Tx and off went my reply. Remember these take a full minute each, with replies coming in a few seconds ahead of the minute mark, and everyone’s clock must be very accurate or it does not work. Well, the next message from the CQ’ing station, the reply to me showing my remotely received signal strength came on a different frequency. So it displayed in the Band Activity window and not the Rx window as I had expected. But it was a valid reply and so my next one went out – my reply including R-xx, R for received and the -xx being the strength of the station as received by me. The next message from the remote station was the same as the previous, i.e. my signal strength as received. So I halted the transmission there assuming I had got something wrong.

So not a complete QSO  but I received an eQSL card for it and so I am counting it as my first ever on JT65, and it proves my system works.

Anyway I persevered amongst other things and managed a complete JT65 QSO later in the day, but the replies still came back in the Band Activity window on a different frequency than my transmissions, and the original CQ that I answered still showing in the Rx Frequency window. Why the difference? The QSO ran fine, all messages exchanges right to the 73’s. When I can see both sides of other QSOs, or even the relevant bits they all appear at the same frequency. (note ‘frequency’ here is that displayed by WSJT-X in Hz, not the dial frequency)

PC screen real estate…

One thing I’ve noticed is the screen required for these digital modes. I have a 22″ 16:9 screen and I had a secondary 19″ 4:3 one attached when I was writing my Ph.D. but it generated a load of RF hash. So now I just have the 22″ and it’s not big enough!

Many shack photos show dual screens or even dual PCs and multiple screens and I can see why. Ok I have the MacBook for logging and other things, but the shack PC desperately needs more screen size and/or more screens. Something else to work on. Unfortunately the PC is a scrapper that has no HDMI output so I am limited to a DVI and a VGA screen. Hmmm… so I need a better PC too…

I am just beginning to experiment with JT65 having set up WSJT-X recently and the screen is full.

…and a close one.

So far I have totted up 19 countries – finally including the UK. I managed a BPSK63 QSO with a station just a few miles away, on 20m again as this is still my only HF antenna. I’m guessing this was ground wave. Funny, I’ve been interested in, and fiddling with radio for 40+ years and yet I am only now learning about propagation, helped in a large part to the two pieces in TX Factor. See http://www.txfilms.co.uk/txfactor/ – these are really good programmes.

BPSK125

I’ve seen several BPSK125 calls about 20m but missed them all – they are so fast that by the time I settle on one QSB has knobbled it. But tonight I managed a short QSO with the Falkland Islands no less!

Data modes continued

Nice sunny Saturday here and I failed to get a reply in to several BPSK31 calls but then managed to reply to a CQ on MFSK16 – another new mode for me. MFKS16 is quite a ‘fat’ signal compared to the PSKs and I had to scrabble about for my printout of modes to see what it was. I tried Domino first to no avail, then found the red bars in fldigi just fitted MFKS16 and it decoded nicely, and an eQSL to boot.

SignaLink USB

I solved the drive issue… got a SignaLink USB box which has its own sound card built in. The box needs four wire jumpers installing inside and these are supplied, along with a diagram of where they need to go. The Allen key needed to open the box is also provided. This device plugs into the FT450D’s Data socket and a USB on the PC – no audio leads needed.

It was quite easy to set up except Linux is not supported officially and the sound setting instructions are for Windows. But, hey, you run Linux you are sort-of expected to know stuff, right? So I figured out what the sound card was called and found it in in Pulseaudio – it found it as PCM2904. My settings in the Pulseaudio volume control – so far so good – are:

Playback – playback on PCM2904 – I set the level to 100%. I tried this at 50% but got no ‘music’ when listening via the ICR2; at 100% it ‘sounds’ fine, and obviously worked because I managed a QSO.

Recording – capture from PCM2904 – again set to 100%

Output devices – PCM2904 and 100%

Input devices – PCM2904 and 100%

My levels seem ok on the SignaLink at Tx straight up, and Rx about 11 O’clock. I had a good quick BPSK-63 call to prove it, and the FT450D shows peaks of 10W on the meter (10W is the Foundation licence limit).

I noticed the overall audio bandwidth is less than I had with the audio lead cable I was using. For example, when tuned to 14.070 the BPSK-63 QSO was right at the right-hand side of the waterfall and the Tx generated very little power – I had to re-tune to 14.071 and then got the full whack. This is no biggie.

The other thing to note is the box itself sorts out the PTT. I had fldigi using flrig for PTT before so I deselected that option so the SignaLink box can get on with it.

Nice box. I’ll see how things go earlier in the day – it was quite late when I got home and the band is flattening out.

More digital

I had my first BPSK-63 QSO today. I like these modes, just set the rig to 14.070 and follow the matrix-like display… with no audio to annoy the wife.

Mind you, as yet I have had no success having a CQ answered. I’ve sent plenty but currently the rather poor drive from the PC results in very little RF power. I hope to rectify that next week.

There is a lot of RTTY about with the BARTG contest. Plenty of decodes but I’ve not joined in because I am not up to entering. Once the contest ends I’ll have a good sniff for RTTY. Pity I don’t have a nice old clattery Creed 7E to do it properly… but that is probably a step too far as I am still only a lodger in the spare room (aka study, aka shack) and may well be turfed out into the shed!