Interesting Propagation on 6m Today. Update.

Today's FT8 monitoring of 6m had some interesting results. Propagation into North America.

While this takes place in the sporadic E season I still do not think this is classical multi-hop Es, but a different mode. Because it appears in the Es season it is correlated, for sure, but what causes this propagation is not really understood.

Between 1617 and 1847 UTC signals were detected from KP4. K8, N3, N5 and XE. First time I have detected a signal from Mexico, albeit in the Northern part near Texas, there the N5 was located.

This is where a digital weak signal mode makes things interesting. We discover propagation that we could not see before because the signals were too weak to be detected reliably in SSB or CW.

The strongest signal detected was the XE with -10dB S/N, and that could probably have been detected in the CW mode. The others were much weaker, and would have been non-detectable with my setup.

Now, my setup is **very simple**: I am using the IC-7600 transceiver with a vertical triband antenna for 70cm, 2m and 6m, the Diamond V-2000. With a beam antenna, even a small one, I am sure that I could have heard more.

Of course, all this happened while I was away from the radio, but OK, I detected the propagation.

Update, Monday July 13th:

Many stations seen this afternoon, from Texas, Minnesota, Georgia, South Carolina, a host of North-Eastern states, and one Canadian station: VA3DX.

Also, I noticed that, as opposed to May and June, in July there are more openings to Northern Scandinavia. I seem to recall that this has been the case in previous years. If anyone has more data on this I would appreciate some information.

Revival of Old Sealed Lead-Acid Batteries.

I now have some more solar panels, but not enough batteries to match them.

Enter an amateur radio friend of mine. He has a large solar array at his house, and he has a bunch of old dis-used 12V/48Ah batteries. Only trouble is that they have all but died.

He told me that it is possible to bring them back to life, probably not with full capacity, but also warned that it could take quite some time, sometimes a month or so, to bring them into a useful state.

The trick is to provide a voltage of 14.2 to 14.4V to the batteries, and if there is any current, even a few mA, it should be possible to revive the batteries. 

I got 4 batteries to try out.

Talking about this on the radio I may have found a second source of (used) batteries, we shall see how that goes.

For that purpose I got myself some modules from China:

- a 24V/14A switch mode power supply

- a few adjustable DC/DC buck converters with voltage as well as current limitation, both adjustable.

Now the DC/DC converters can be set to 5 - 23V, the current limit to 0 - 5A. That is the specification, but I intend to limit the current to considerably less for the revival process.

Having the modules connected, the process has now started.

After a week or so, the first (best initial voltage) battery does draw more than 1A current with 14.2V, but because a cell might be bad I have set the current limitation to 300mA. The voltage is now slowly - very slowly - increasing, and has reached 9.7V. Yes, there is still a long way to go, so we shall see how it goes, and how long it takes.

The second battery was connected a few days ago, and is now drawing about 100mA at 14.2V. It is slowly increasing, in the beginning the current draw was just about 5mA.

It may be a good idea to mount the two regulator modules in a box, at the moment they are just loosely attached to a shelf - or maybe make it wall mounted, with the 24V supply at the back of the shelf.

The two other batteries had an extremely low initial voltage, so I doubt that they can be revived. They may truly be dead, and if so they will go to scrap metal.

Apart from the radio activities there are some interesting times ahead.

The battery revival does not claim too much time, just some monitoring a few times a day, so other activities can slowly re-start. The electronics workbench/test-bench is still quite messy after starting the reference oscillator activities as well as the battery revival equipment. 

I see a lot of tidying and organizing  in my future ;)

Receiving FT8 With a Pixie.

After a long wait I received some crystals for the FT8, JS8Call and WSPR/QRSS frequencies on 40m and 20m, ordered some time in March.

The Ebay seller was not at fault, I suspect that the COVID-19 situation had left the package stranded somewhere on the way, for a long while. Other packages from the USA have not arrived yet, either, but who knows, they may appear one sunny day.

One set of crystals has 3 crystals per band:

7074kHz (FT8)

7078kHz (JS8Call)

7038.6kHz (WSPR/QRSS)

14074kHz (FT8)

14078kHz (JS8Call)

14095.6kHz (WSPR/QRSS)

In previous posts I have written about some experiments with the Pixie kits, and now is the opportunity to continue with that

The original 7023kHz crystal was unsoldered and a 7074kHz crystal soldered in. I am leaving the long leads at the crystal, as I think I will use it for a different receiver (or, maybe a transceiver). The frequency was adjusted to 7074.00kHz, so the test could begin. During the day not too many signals were heard, but in the evening the signals are coming in very nicely.

The antenna is a low hanging 10-15-20-40-80m dipole, so not the best, but this is excellent for the test.

Connecting the Pixie to the antenna and a set of computer speakers, FT8 signals were heard, immediately.

A quick test with a laptop, using its microphone, yielded immediate FT8 spots. A USB sound interface was found and connected in place of the speaker/microphone, and the spots poured down the screen. In the span of less than 2 hours spots were seen from North and South America, Europe, Africa and Asia. 

The system is actually working.

I left the system running over night, and in the morning I could add Oceania to the list (Indonesia). No Australia or New Zealand, but that was to be expected at this time of the year.

The experiment is a success, so now I consider the next step:

- setting the same receiver up with a raspberry Pi running headless, but using VNC, or

- inserting the 7038.6kHz crystal and setting up with a Raspberry Pi for QRSS, and maybe also WSPR.

If I just set the Pixie up for QRSS with an older Raspberry Pi, this could make for a low power, solar powered QRSS grabber system, so that is a tempting option.

Further steps could be a low power DSB or phasing SSB transceiver for FT8 or JS8Call, at first for 40m, later for 20m.

Now, if I could find a corresponding set of crystals for 60m or 80m, that could be interesting, too. On 80m, however, I could possibly use a ceramic resonator and tune it to the FT8 frequency (3573kHz). For the JS8Call a standard NTSC colour crystal (3579kHz) could be used, re-tuned to 3578kHz. It *may* be possible to use a Super-VXO (2 or more crystals in parallel) type oscillator for generating the 3573kHz signal.  

As always, too many ideas, but it is never boring.