Propagation Comments For Activators

In most case, for DX contacts better to work closer to MUF. We have new solar cycle started, and MUF moves a little up - maybe around 20 MHz. This is my explanation why 17 m band may be the best for long distance contacts with low power SOTA activators. I made contacts with John, ZL1BYZ on 17 m band during my SOTA activation from West Coast of US. It was night time at his location.

Hi Andrew,

I have to disagree. The path makes huge difference. At the moment I can work EU only when pointing North, basically to JA. I call that short path. When pointing South (over South Pole) I hear absolutely nothing. That direction is open only when sun spot numbers are good and at around 17:00 NZ local which is 4 - 5 am UTC (depending on daylight saving). The polar paths are most difficult.

Regards & 73!
Andrei, de ZL1TM


HF really do be like that sometimes…

Hi Patrick,

my rather simple explanation: Ionisation in the F-Layer doesn’t vanish once the sun has set. It takes time for the free charge carriers to recombine. Hence, MUF is decreasing over time. During SS-maximum the MUF will remain fairly high all night, reaching the minimum about one hour before sunrise.
Additionally, parts of your signal might hit the ionosphere 1000…1500 km away. If your signal travels towards the west, there might still be some sunlight up there…
During the last weeks I was running a WSPR beacon at 33 dBm on 20 metres. My tiny signal has been heard frequently on the east coast well after our sunset.

If you look at the following page, you’ll find helpful MUF charts. Just check “DB049 Dourbes” and click on “Refresh”

73, Roman

I do not agree, 1000 km is a long distance, for example yesterday I heard you work at W4KAC and here in EA7 I didn’t hear it (X7 at 12 + 1m).
About @ZL1TM surprising. My last 4 summits:

ZL1TM 23/12/2020 12:49:09 SOTA EA7/GR-062 DME-18099 CW 20m
ZL1TM 14/01/2021 13:22:10 SOTA EA7/GR-059 DME-18024 CW 20m
ZL1TM 20/02/2021 11:15:19 SOTA EA7/GR-064 VGGR-268 DME-18168 CW 20m
ZL1TM 18/02/2021 12:22:37 SOTA EA7/GR-069 DME-18024 CW 20m
on EA7 / GR-069 with an AX1, filmed by my wife, minute 2:42.

Hi José,
1000 Km is a long walking distance, even a driving one, but it’s not that much when you speak about general propagation conditions on 20m band, which is what I was speaking about.
The fact that you couldn’t copy an american activator yesterday during the very instant I was chasing him, doesn’t surprise me at all, but that doesn’t mean that general propagation conditions are so different between you and me. Probably you could have copied him a bit earlier or a bit later.
I also heard DJ5AV chasing a NorthAmerican activator yesterday on 20m CW when I wasn’t yet copying that activator, but just a very few minutes later, I started copying him and I managed to chase him. That’s what I call instant propagation and that varies a lot even within very short distances.
Let me give you an example of how instant propagation can change in very short distances: EA2LU and I have our QTH about 20Km appart and we have several times experienced how a NorthAmerican activator is copied by one of us and not by the other, but a few seconds or few minutes later, everything can be the other way around and some few seconds or minutes later both of us can be copying him perfectly. That’s instant propagation and it shouldn’t be confused with general propagation conditions.

My point was that general propagation conditions for DX on 20m are pretty much the same in ON and EA2. The demonstration is that Andrei ZL1TM has been consistently chasing European activators on 20m from different locations as different accross Europe as EA7, EA2, I, ON, F, HB and HA).

When chasing Northamerican activators, I have several times heard chasers like ON4VT, G4OBK, EI6FR, DJ5AV and others doing very well. They are about 1000 Km up North from me. In many cases, they didn’t hear the activators at the very same and exact instant as me, but that’s instant propagation and it can change very rapidly in a matter of seconds or few minutes. But the general propagation conditions remain pretty much the same or at least very similar.



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Hi Harry,

I remember when back in 2014-2015 I often chased KX0R better on 15m than on 20m, while he was activating from W0C (Colorado).

However, I can tell you that this is not the case right now. I’m often chasing NorthAmerican activators on 20m, but I never copy any of them when they show up on 15m. I haven’t chased NorthAmericans on 17m recently either, but the antenna I have for that band is not comparable to the yagi I have for 10, 15 and 20m.

I have some few times chased NorthAmerican activators on 17m, but that was quite some time ago and it’s not something I’ve done recently. I wish I could have a beam for 17m but that’s not a top priority for me right now.

There are several hams having beam antennas for 17m, but they are less than those having beams for 10-15-20m and that’s why there are better chances to be chased by DX on 20m than on 17m.



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OK we are talking propagation here. Is there anyone out there who tried an activation of a summit for the duration of 24 hours? In doing so one could profit from being able to make maximum use of day and nighttime propagation to get chasers and S2S in his log?

Hi Patrick.
In my JA / HG-282 activation on February 20 and with the intention of being able to work different continents and especially the east coast of the USA and also South America, I operated from UTC 0700-0900 (local time 1600-1800) and UTC 2100-2300 (local 0600-0800) In the first stage I was taken by the RBN of Uruguay and several of the USA both in 20 and 40.

Thank you for sharing your experience. It is, or was my thought that SOTA activations are always short in time.
What I think is possible, is activating 24 hours from a suitable summit with regard to weather conditions and access difficulty.
Special activations such as 2m tropo in autumn, Es on 6m in Es season. Or 24 hour HF, may be 2 or 3 man operation to get all the gear up + working in shifts to get a 24/24? power for trx via battery + small wind generator as on sailing yachts? If no one comes back after some time calling CQ, chasing DX S2S?

And low noise levels compared to Europe.

Also, those ZLs located on the coastline seem to do especially well in putting good signals into Europe.

73 Ed.

Let me give you an update about this.
Yesterday, I chased Mike WB2FUV on 20m CW in a W2 summit

and I was able to hear all or most of his Northamerican chasers.
A few minutes earlier, I was stalking for Pete WA7JTM in a W7A summit

and I copied him, but just for a very brief instant so I couldn’t chase him, but I did hear many of his chasers.

Today, I chased Dan NA6MG in a W6 summit on 20m CW

and could hear many of his chasers. He later went to 15m and not only he wasn’t copied at all, but neither of his chasers, if any, was ever heard on my side.

My conclusion is: 15m is not yet ready for SOTA DX and trying is quite a waste of time.



This is probably why Guru:

The Maximum usable frequency didn’t get up to 17m let alone 15m yesterday - in fact you were lucky on your timing on 20m from what I can see.

This is a great website by the way - switch to the Dourbes (Belgium) site if you are located “on the continent” otherwise whose whichever of the other two sites are providing data if you are in the UK or Ireland.

73 Ed.


Thanks, Ed, for the interesting web site.

Indeed, it was very rare copying California. I wonder what setup was Dan @NA6MG using (output power and antenna), because I had been stalking for other activators from California in previous days but couldn’t copy a dit.
Yesterday was special and confirmed the maxima of don’t ever assume or give anything for granted and give it a try just in case.
The magic of radio keeps giving us very nice surprises from time to time and that’s what many, if not all of us, like so much of this great hobby.



Today I experienced kind of unusual propagation from North Chalone Peak (W6/SC-149). I did night activation last Sunday, and was able to make 2 contacts only on 40 m band. Today I started a little early (20:40 UTC) and my first contact on 20 m band was F4WBN. His signal came with specific Aurora sound and most likely came over the North Pole. Another surprise was a contact with NR0R on 20 m. He informed me that he uses QRPP radio, and his power is only 100 mW (!). The distance is about 1467 miles. NR0R recorded that QSO KD7WPJcontactMar12-2021.mp3 - Google Drive I can not complain about propagation today!

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Hi Andrei,
Seems odd to be sending you text here rather than on the radio!
Re the polar path, it seems to me very likely you are experiencing the impact of the polar anomaly at the south pole, whereby the ionosphere is bent downward towards the pole by the magnetic field, so produces reflections in rather different directions than what you might expect if it was a continous layer at 120-150 km agl. In that case you may find better results by not beaming 180 degrees from the short path, instead searching at 150 to 210 degrees in the hope that some bending of the right type occurs at those angles. However I am just guessing here, trying to think like a vhf dxer (which is my other job) and looking for alternatives. I have never had an HF beam to play with.

Good luck with the dxing

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It was great to work you yesterday on 20 meters. It has been a long time since our last QSO. I was running 5 watts with a KX3 and a 100’ doublet fed with CAT5 twisted pair. On Flint Peak, 3 miles from home, I can easily install that long a wire with a good drop off to the northeast.
Dan, NA6MG, usually runs a KX2, 10 or 12 watts I think, and a different length (~60’) end fed wires tuned with the radio. (I know he worked a few EA stations as well as SA4BLM and others Tuesday.)
Flint Peak (1890’) is about 9 miles southwest of Mt Wilson (5900’). Mt Wilson is part of the San Gabriel mountain range that rises to over 10000’ at Mt San Antonio at the eastern end.
SoCal summits, like W6/SC-229, with paths to the northeast that are clear of the mountains have a better chance to reach Europe, I think. As the solar flux rises this becomes less of an issue.
Tuesday I was thrilled to work S52AU, DJ5AV and GM0GAV on 20 meters. F4WBN, a regular, called in with a good signal but I was in the middle of an s2s QSO with K2JB. His signal is sometimes auroral, but Friday he was heard with a loud and very pure non-auroral signal, as were other EU stations.
What is interesting is that ZL1BYZ has been absent from my log for a good while. He often calls in on 20, 17 or 15 and gives me a 319. I almost always hear him first call.

I eagerly anticipate more DX during SOTA activations, especially s2s. Please let me know by sending QRS or QRQ how I can help you hear me better.
David N6AN (almost always running 5 watts on a summit)


Thanks, David, for your message.
Yes, it’s been more than a year since our previous QSO.
These are all the QSOs we’ve had so far:
The 1st one in November 2010 looks like a CQ WW CW contest QSO.
All the others have been SOTA chases.
Your 5W and that 100’ doublet in that summit with good take-off to the North-East, really worked very well.
I hope to keep chasing you.
Regarding ZL1BYZ, I’ve also been missing him for quite a long time in my activation logs, but he seems to be actively chasing because he’s been recorded in some of the videos ZL4RA has posted here lately. Perhaps he is not currently available at the times/dates we are activating.


Yes, Guru, that first QSO was during CQWW. I was operating from the Caltech ARC station.

I spoke with Dan, NA6MG, today while we activated two summits. I was incorrect about his output power.
He is usually running 5 watts. Occasionally he will increase power if someone cannot hear him well enough to complete a QSO.
David N6AN

Ok on Dan’s 5W. Thanks for the info.
I saw on SOTAwatch that you were activating the same summit yesterday. I was QRV but propagation was not favourable neither for the US West coast, nor the East coast, as I couldn’t copy an activator in W3.
Well, we’ll be QRV for the next conditions improvement.