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70cm multimode activations

70cm multimode activation, Thursday afternoon, 19th May

In my five years of SOTAing I feel I’ve neglected 70cm, occasionally working a few FM stations after qualifying a summit on 2m. My default VHF/UHF antenna for SOTA, a Diamond RH770 ½-wave telescopic whip, gets good reports but I thought it was time to get a 70cm Yagi suitable for portable use [via a birthday pressie].

That means being light enough (~1kg) to be handheld (as well as mounting on my 3m pole) and the boom length short enough (~50cm) to go in my 30L rucksack albeit sticking out the top a bit. Yes, a 15-el Yagi would be great for super Dx but I know I’m never gonna lug such a monster up a mountain.

I settled on a 7-element Z.L. Special which has a folded driver/dipole and a folded reflector. Assembly was straightforward enough despite woefully inadequate instructions. But it was devil to tune and I messed around over three days using coax capacitive stubs and beehive trimmers trying to persuade it to resonate at 432-433 MHz rather than 5-10 MHz higher. In the end I used a coax stub twice the length of the supplied one to get excellent SWR in the 70cm band.

Pointing the Yagi towards GB3NGI 70cm beacon 240km away in Ballymena N.I. from an upstairs bedroom and hearing its digital burble in the noise confirmed it seemed to be working. A field trial followed this morning with Rick 2E0FRS near Bleasdale Fell and me on Arnside Knott (G/LD-058) for antenna tests, both running 100mW FM and giving/getting 5/3 reports.

That convinced me to do a short-notice [sorry!] 70cm-only activation tomorrow afternoon (Thursday 19th. May) - before the rain starts again - from Gummers How G/LD-050 with my FT817 for 5W FM [vertical polarisation] and SSB [horizontal] and CW, if I can get it.

I’ll use a modest 3m pole as I don’t fancy trying to hold the Yagi, logbook & pencil and paddles in two hands. It’s only a 7-element Yagi so I’m not expecting to break any Dx records, but it should be fun. Hope to work some of you on one of those modes.
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Regards Andy G8CPZ / M0ALC

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Will listen out for you Andy as I had never heard anyone on 70cms before until I got Ian G0AZB earlier on blasting through on a 59+
Best 73

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Thanks for trying Allen.

Slim pickings on 70cm – not unexpected outside of a 70cm event, 3 on FM, 1 on SSB, none on CW. No matter, it confirmed the Yagi is tuned correctly, and the views [from Gummers How G/LD-050] in the bright sunshine over Lake Windermere and the Irish Sea were lovely.

I noticed a problem immediately with the Yagi on my shortest pole, insufficient friction meant that the Yagi was moving about in the stiff breeze [strong enough to blow my sunhat off]. The 3m-length coax feeder wasn’t long enough to mount the Yagi on my longer pole (which works well with my 2m Yagi).

With the long-pole arrangement the Yagi would be fixed to the pole and could be rotated conveniently by turning the bottom of the pole whilst sitting at its base. It has an O-ring that sits between two sections of the pole and is loose enough so that the pole can be rotated without snagging the guy strings.

I’m replacing the short coax with 7m of Hyperflex-7/PL259. Hope to field-test that solution soon.

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Sorry Andy maybe next time if the bands improve.
Best 73

Hi Andy,

I used to piggy back 70cm onto my 2m activations… in G/SP and G/LD I also called on 23cm FM with quite a bit of success. I don’t think activity is as good as it was a decade ago. Many VHF/UHF enthusiasts have moved on to other things and unfortunately some are silent keys. Such is life.

It was a pity that there wasn’t more time between you having the idea and the activation. I could possibly have gone out to our local-ish high spot which has an excellent take off northwards. Maybe another time.

73, Gerald

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Hi Gerald, yes after a few days trying to tune the Yagi at home, I was impatient to try it ‘in the field’, er I mean on a hilltop. Once I’ve confirmed the Yagi and longer feeder is rotatable on the same pole I use for the 2m Yagi, I’ll be sure to give a good few days notice via an alert and this thread.

I usually activate late mornings to early afternoons on weekdays (being a retiree) but if you have a preferred time of day or weekday/weekend, let me know.

Hope to work you then on 70cm.

Regards, Andy

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Ah-ha… failure designed in :wink:

Thanks for the 70 cms chase Allen, you were super audio on my summit :+1:
Ian GI0AZB

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Blame Yaesu (for the choice of FT817 antenna socket).

Funny, mine came with a BNC on it.

Have you looked round the back, Andy?

Not since I slid the protective case on.

The PL259 gets a bad press, most of it utter rubbish. I mean, for instance, this business about it not being 50 ohms. So what, for a cm or two? Open up the rig and what is behind the socket? A few cm of unshielded wire to the PC board! Yes, there are some really trashy PL259s about, but there are good quality ones, too, its just a matter of being selective. In my 70cm days (would you believe that in the late 60’s 70cm was busier than 2m?) I worked well into Europe from Brum using a TV plug and socket, a PL259 would have been an improvement on that, and we’d never heard of N type!

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One has to take Andy FMF’s provocative remarks with a pinch of salt, one’s not sure whether he’s being serious or not. I like ambiguous humour (leaving the recipient unsure which way to take it) and use it a lot but it does get me into trouble sometimes [usually with my wife].

On a serious note, most of my HF antenna feeders are BNC terminated [to suit my KX2] and VHF/UHF feeders use PL259 (except 23cm). It’s a really nice feature on the FT817 having two antenna sockets especially when you want to switch quickly between HF and VHF antennas. However, it’s fiddly when accessing the knobs/buttons next to the BNC coax.

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Don’t think I have ever connected anything to the back antenna socket on either of my 817s.

I could hear you yesterday Ian but you obviously couldn’t hear me. :frowning_face:

Yes Allen it was hard on 70 yesterday, the TV transmitter was strong on the Wrekin so maybe next time :+1:

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Hopefully a little easier on G/WB-009 Worcestershire Beacon this morning. Thanks for the contacts. Despite it being line-of-sight from my QTH, today’s the first time I’ve chased it. :wink:

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Rightly deserved as only breakers and people who have a problem with expert evidence try to justify them.

From a SOTA point of view the simplest reason not to use them is (from my tests) they weigh more than a BNC. That is the most basic reason to not use them, excess weight. Some of us have enough of that around our middle already.

We had a great time on this one on 70 cms, even managed a couple of S2S to another of the WB.
Thanks all for taking the time to chase, a lot of really helpful operators. We had to cut HF short as lightening strikes were showing near Banbury :smiling_face_with_tear: