DM/BW-089: SOTA outing of our local radio club

Hi everyone,

members of our local radio club (Tuebingen, P12) have scheduled a SOTA activation for tomorrow, July 31st on nearby Farrenberg, DM/BW-089.
We might be on air on different bands/ modes at the same time. Spots will be submitted to sotawatch accordingly.
I’d like to ask for your patience when operating is slow. Most operators are new to SOTA. Please work them even if you already had a QSO with someone else on BW-089 on that day. There is a good chance that some call signs will show up more frequently in the future :slight_smile:

Hope to cu tomorrow!
73, Roman


Hello Roman @DL3TU

Have fun with the activity in the group. A nice idea and many nice QSOs to you all :+1::goat:

73 Marcel DM3FAM


Thanks, Roman & Co., it was fun to meet you and work new callsigns on S2S SOTA.

Vy 73 de Markus, HB9DIZ


Hi Roman,

Tnx S2S :wink:

73, Jarek


Thanks Markus, Jarek and all other chasers/ activators for the numerous QSOs! It was great fun :slight_smile:

Six members of the local radio club Tuebingen (DOK P12) participated in this joint activation of DM/BW-089 which is our local summit.
If you haven’t seen it before, here is a fantastic aerial view of Farrenberg.

The weather forecast for Saturday was perfect: Sunny with few clouds and low winds.
When we reached the summit at about 8:30 utc, it was completely deserted. Within the next half hour we set up five stations so everyone had a fair chance to get on the air for an extended period of time.

The first QSO was on 20m CW followed by 15m SSB which - to our great pleasure - was open to Western EU.
It didn’t take long until the first S2S-QSOs with our friends DO1TBE and DG1PSI on nearby DM/BW-110 went into the log (on 15m SSB ground wave with strong signals)

More QSOs on 15m and 20m followed and while the last technical issues were solved (an ATU which wouldn’t tune properly), I activated on 40m CW. Then it was already time for lunch break.

Various aspects of SOTA were discussed during the meal before we proceeded with the activation, now on 20m SSB, 17m CW and 60m SSB & CW. Again we were surprised by the number of callers, especially the ones who waited their turn patiently or called in more than once to give every activator the chance of a successful activation.

Finally, while the first teams were already taking down their stations, DC1SAF remembered to activate on 30m CW. This way we performed a full activation on all bands from 60 to 15 metres :slight_smile:

Once everything was dismantled and packed up, we made our way back home, where we ended the day discussing what we had experienced over coffee and some delicious cake in the garden of one of our members.


With so many different stations set up, everyone had a chance to see the features/ performance of the various transceivers and antennas (QCX, home brew, mcHF, Xiegu G90, FT-817, KX3, MTR-3B // short vertical MP-1, random wire, centre-fed and end-fed dipoles with Un-Uns and L-Tuner)
For some team members it was their first SOTA activation and they liked it. Some members already had some experience and were able to add new impressions.
There were definitely lots of opportunities to learn new stuff and hence this event may be repeated in the future :slight_smile:

Thanks again to all chasers for the QSOs and hope to cu from the next one!


Hallo Roman

You had a great event there. Worthy of imitation!

Will you write something about your experiences with the different devices and antennas?

It’s amazing that it worked on 20m. At first I thought that we had found a gap in the Black Forest and that the signal was over groundwave. But that was probably not the case.

73 Armin


Hello Roman.

You had a good time at the summit. Nice pictures. Glad everyone enjoyed it and nice to hear and work more new calls from the mountains soon :+1::slightly_smiling_face:

73 Marcel DM3FAM

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Hi Armin,

Interesting, in the past I experienced similar effects and could also cross the Black Forrest on the 20-meter band in SSB with 5W, but with very marginal signals.

I found two interesting documents that I briefly skipped through:

On 14MHz one doesn’t necessarily need line of sight, but of course it helps for increased field strength. In simplified terms, it seems, the lower the frequency, the higher the field strength for non line of sights distances, due to deeper ground penetration.

It also depends on the ground conductivity and many other factors, like on the sea the wave height! The same antenna polarization probably also helps. It changes even over the season, i.e. usually better during winter time, see figure 21 in the ITU document (I assume due to higher ground water levels).

So maybe our long-term bad weather has also a positive influence on the ground conductivity :thinking:.

Have fun and 73, Stephan


I have often experienced that the ground wave goes at rather low frequencies. Our qso in your test of the TX500 was also probably over ground wave.

I suppose that is something like Tropo for HF … a few weeks ago I was in Cuxhaven and had a qso with Paderborn on 20m with 10 watts … I also found that remarkable. By the way, we were both active with vertical antennas.

This means in any case (as a chaser for SOTA): you should also try the ground wave at higher frequencies.

73 Armin

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… thanks, Armin!

Sorry that I didn’t reply to your request through Signal messenger yesterday when you asked me to try it on the lower bands. I was fairly busy at that time.
Later I heard of your QSO with DC1SAF/p on 20m CW. His antenna was located directly at the cliff, so definitely a good take of from his end.
There was sporadic E at the time of your QSO but I’m not sure if such a short skip can be explained by that. Probably not.
Ground wave, as @HB9EAJ mentioned, could also be an option. But it would be an extraordinary QSO when running QRP on both ends while still exchanging good signal reports!
Did you notice some kind of “multi path” sound during the QSO?

… interesting, anyway :thinking:
73, Roman

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Hi Armin,

If you mean the 60-meter QSO we had on 25th of July at 08:47z, I think this was skywave or a mix of both, but I don’t recall.

Update: I looked-up your address, and even not exactly line of sight (probably the Tüllinger-Hügel is in the way), groundwave is also possible. Further, we were only about 65km apart and the signals were pretty good: I received you with 59, you received me with 55.

I hear sometimes the phase cancellation due to small time differences of both signal paths with stations that are very close-by, e.g. within maybe 50km distance. This of course usually only happens on low bands. But a 20-meter band QSO over >100km distance with a good signal as Roman @DL3TU noted, is extraordinary.

Indeed, it would be interesting to know if the signal was stable or if you had some fading or changing sound during the course of the QSO.

73 Stephan


…during our qso I was in Opfingen in the shadow of the Tuniberg


No I have not had these effects. It was a weak clear constant signal. I was above Opfingen on the Tuniberg… with a clear view over Freiburg in your direction.

I have there antenna wires for my EndFed cut to length and tried as it is to have 2 antenna wires at the same time on the telescopic mast. It works.
I now have one balun and 2 wires on one mast. One wire fits 80 / 60 and 30… and one is for 80 / 60 / 40 / 20 / 15 and 10… they both hang on top of each other as an inverted - V and I just change the wires at the balun. I clamp them separately and then have a little distance between them.
Normally I work with the tuner of the KX2. But I bought a small MX-P50 amplifier - and this wants tuned antennas… And I needed a balun that could handle 50 watts… :wink:

73 Armin

Not a big difference though:


73 Stephan

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Hi, everyone,
Roman, @DL3TU drew my attention to the exciting discussion on the reflector.

Armin, @DL6GCA many thanks for our QSO yesterday from Farrenberg :slight_smile:

I noticed that the reports for contacts with German stations were noticeably reduced compared to the more distant stations.

Especially for the QSO with @DL6GCA I looked at the Fresnel zones. Even if the direct line of sight through the Black Forest (see post above) is blocked, the picture for the 1st Fresnel zone on 14 MHz is not quite as dramatic. However, the first Fresnel zone in the Black Forest will also be interrupted piece by piece. The 3rd Fresnel zone shows at least continuous areas.

Could that explain the radio contact and also the reports?
Currently I imagine that diffraction and scattering effects in particular made the radio contact possible.

Fresnel zone tool for Google Earth


I think so too - and the large distances to the obstacles will have helped.

73 Armin