I bought some wire and kite winders from Sotabeams at the Norbreck rally a couple of years ago, and today I got around to building an 80 / 60 / 40 linked dipole using dimensions from the SotaMaps calculator.
Nice wire to work with, very reluctant to tangle - looking forward to trying it on GW/MW-026 tomorrow.
It’s too big to play with in my garden, so I may take an analyser with me tomorrow and spend some time fine tuning. (I’ll take the T1 AATU as well, so I should be able to try it on air first).
Thanks Rod @M0JLA for reminding me about the loading coils for 160m, I might work on those soon…
I’m not saying that any of the stations you worked were WABers, Nick, but with 40m all but dead, most are listening on 80m. Out of interest what frequency were you on?
Yes indeed, but if it’s alerted by early am of the day of intended activation, I’ll no doubt pick it up as I always do a summary of alerted UK summits for the WAB media. 3760 is always worth a pop, even if the net is not currently active.
Sorry Richard, nothing heard here.
I listened for you in CW, then in SSB … NIL
I did work 2 others on 80m though, G8CPZ/P came in at 529, GW4AZS/P at 419.
Don’t know what power they used;
73,
Luc - ON7DQ
Not uploaded my logs yet but thanks to you and also to Bruno (HB9CBR/P), Adrian (GW4AZS/P) and Richard (G4TGJ/P) for CW S2S’s on 80m. I’ve very pleased with first portable use of new 80m dipole - Call me lazy (I do have a linked dipole) but the KX2 ATU also loaded great on 60, 40 and 30m giving me good reports for S2Ss and others on those bands.
Richard, I listened to you on 3.760 SSB - you were a great signal with me: 5/9 S2S (with no noise!). I tried calling you back but probably messed up - think I need to read the KX2 manual on how to use the internal mic/SSB.
Luc, I was running 5W from FT817, thank you for making it work!
Andy - sorry for calling you Gerald, but thanks for the S2S!
Here is my log from today:
The analyser produced some unexpected results on the linked dipole. It seems to be a bit too long on 80m (which is a good starting point) but too short on 60m and 40m, which suggests that I gooffed up in the measuring department.
It was deployed over a wire fence which might have had some effect, but I need to re-check the design and implementation, then maybe try it over normal ground.
Anyway, the Elecraft T1 tuner coped with it, and I was pleased to make a few nice contacts on 80m (my first from a summit, I think) and one on 40m.
Thanks again to all who called me, and to Richard for starting this thread…
80m band was completely dead for me in south western France from 07:00 UTC, and i finally worked Richard… on 20m in good conditions
Let’s have another trial later in the year (or earlier in the morning )
Vy 73
I struggled on 80m and made only 5 contacts, 2 of them with Adrian. I’m not sure if my new antenna gets out too well on 80m since Adrian had far more QSOs than me using the same type of rig. But then Andy says I was a great signal on SSB!
However, my 80m EFHW worked well on 40m and 20m with 11 CW contacts on each band. Plus it was a beautiful day to be sat on a hilltop.
Unfortunately my 2m slim jim appears to be kaput. I saw Allan’s spot for Tryfan and set up the slim jim but I heard nothing at all on the band and I had high SWR on transmit so I think that’s my next SOTA aerial project!
The noise level at the summit yesterday lunchtime was virtually zero (what a pleasure!) whilst listening to you calling CQ on SSB/80m. Yet, during the previous few days, using the same dipole at home listening late morning on 80m SSB, the noise was about S8. This makes me think QRM from electrical appliances is a bigger factor than D-layer absorption. I also aligned the dipole with your northern location in mind.
I noticed a sharp noise step yesterday at around 3.755; it is still there this morning.
No chasing yesterday on anything above 3.730 - an extra 2 or 3 s points of noise above that; a threshold like this has been mentioned to me while activating and moving lower down the band brought in more chasers.
If I get there I will see what the situation is on GW/SW-012 later today.
What surprised me was the amount of noise on the bands from a summit away from any electrical equipment. Clearly a lot of the noise is not created by domestic equipment. I suspect my antenna is not as efficient as Adrian’s because he got far more contacts than me at the same time using the same power. My matching transformer is made on a FT140-43 toroid with 14:2 turns. The impedance of the winding probably isn’t high enough at lower frequencies. Also the counterpoise is very short but perhaps a longer wire would be better on 80m. I could have a go at making a dipole for 80m but this won’t work at 40m or 20m unlike the EFHW. But I do like antenna projects so perhaps I will try it (after I’ve made a new 2m antenna).
It’s also an interesting point about some chasers having louder noise at different parts of the band and changing frequency when contacts aren’t coming is a good strategy. But then that’s why having a multiband antenna is a good idea.
The other thing I haven’t considered is aerial orientation. Perhaps my wire wasn’t optimally aligned but Adrian’s was. I’ll have to get the map out and try to work it out.
At the sort of height practicable on a hill the antenna would be a cloud warmer with little or no directivity. This, though, is just what you need for daytime SOTA on 80m!
At home, the noise is a fairly steady hash around S7 or 8 across the 80m and 40m bands, but on the summit it was refreshingly low, though I didn’t record it.
Richard’s signal was lifting the FT817 bars above noise, significantly so on CW.
The wire fence beneath my dipole may have acted as a reflector to increase high angle radiation…
I think that would depend on your ATU (if you use one). I, not only got good VSWRs with my KX2 ATU on 60, 40 and 30m using my 80m dipole yesterday, but fair to good reports from Italy, Switzerland, Czech Republic and Germany with 10W CW on those higher bands. [Didn’t try 20m - was getting cold and stiff by then].
It’s about the same pack volume and weight as my EFHWs and linked quadbander dipole. The only drawback I see is the space needed on small summits. I’ld be happy to deploy it next time there’s an ‘80m SOTA fest’.
But the whole point of a dipole is not to use an ATU. My EFHW has a matching transformer in a small box and it doesn’t need any tuning so I can switch bands from 80m - 40m - 20m easily. I do have a small home made QRP Z-match I could take out but I want it to be as simple as possible on a summit.
I imagine that an ATU is no more lossy than a matching transformer - but if you can’t quantify it, it is only opinion. FWIW I use a W3EDP on 80m and it works well on 80, 60, 40 and 20m.
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