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Vhf yagi saga

Then, put bluntly, banana plugs are not the right connector.

The dip is 20MHz or so low. This means typically the driven element is too big.

I have just noticed reading that article posted the tap point for the coax is not on the ends where i have connected to in fact look at figure 2 in the article and see the feed points are the inner points which moves the tap point around 1.5" .

Matt

Then you can fix the coax closer and the effective elements would be shorter…

I think all the messures you made in other frequencies are irrelevant. What i miss is something that matches the antenna from symetric of the dipol to coax. I cann’t see this on the fotos.

Maybe it works if the coax is in a special length… but that would be coincidence.

If i were you - i would make a simple dipol with a simple ugly balun… and messure this. If it’s ok. I would fix the balun at the yagi - to see where the fault at the yagi is.

good luck - 73 - Armin

How many turns or rg58 round a 22mm former would i need ? 9 ?

matt

Well tried as short as i can tails and still high swr done a choke no difference.

Think time for another design this one testing my pacience especially when made it 4 times now .

Matt

This?
http://www.hamuniverse.com/wb2vuo2elyagi.html

Call it a shameless plug for one of my videos but it would be good if the yagi seen in the video from 4:06 could be reintroduced. Light, works well and does 2M and 70cm :stuck_out_tongue:

73 Chris M0RSF

Shame still dont make them anymore chris .

Matt, 2E0FGX

Even better was that antenna along with the unit to fit on top of an inverted Leki walking pole. No need for a long pole since on a summit, extra height doen’t make a lot of difference. Can’t find a photo but I did use on several FM activations.

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I guess if Richard @G3CWI found enough interest he might be persuaded to make a one-off batch.

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Was it called the SB3? Still got one, and use it regularly :slight_smile: Quite amazingly effective on 2m and good on 70cm horizontal but found it not so good 70cm vertical for some reason.

Was called the WASP ISTR. Still got one of those too, but less frequently used…

73 de paul G4MD

Hi Matt,

You’ve tried that method a few times and it’s still not indicating resonance on the desired frequency.

Whenever that happens it can be best to check everything you are using, including even the analyser. If you have a known good dummy load rated for 144 MHz just check that the analyser indicates it is ok. I have one of those analysers and it is excellent, but it’s worth checking it, even just to go through the process of assessing all the equipment.

One of the suggestions above was to make a simple dipole and adjust that for resonance at the desired frequency. That’s worth doing. It’s another step of the process of validating assumptions and confirming that core components like your connectors, coax cable and measurements are correct.

A source of very good articles that are current and have been validated by a number of people building them can be found at vk1nam.wordpress.com, where my friend Andrew has published practical designs of antennas he has built, tested and used, recently. And he also uses an AA600 analyser.

I would recommend building the “flower pot vertical” described on the referenced website. It requires no soldering and only the connector that plugs into the radio, so there are very few things to go wrong. I have built two of those myself and can confirm that not only does it produce a good SWR sweep, but it works considerably better than any other simple vertical antenna I have attached to the HT. You might even find that antenna does everything you need, and one of its advantages is that it is omnidirectional, so there is no need to turn it to work different directions.

Wishing you well in your experimentation.

73 Andrew VK1DA/VK2UH

Thank you Andrew , sadly i dont have a dummy load i can use .

I have made a simple dipole and yes it works fine low swr as it should be so im just guessing the overlap of the dipole is causing problems , even used the same coax with 1.5" tails on the dipole too .

I have a flowerpot style antenna which yes works extremely well but i was after something i could use on ssb while operating sota . While i got the analyser on loan i may try a moxon .

Normal ssb on 2m i will be using a standard yagi type antenna when operating from the car .

Matt 2E0FGX

Hello Paul,

I’m sure I had a similar yagi that was the SB3. That’s a while ago and I believe that’s older than the one in my video. The elements of the driven elements were slightly offset like the design Matt has built.

Mine is the SB270. It has 3 elements for 2M and 6 elements for 70cm. Maybe it became difficult to source the parts but it’s a shame it isn’t in production anymore.

73 Chris M0RSF

I used a Flower Pot antenna to qualify a summit using Aircraft Enhancement on SSB. So they are useful on SSB.

Guess i need to build another on some conduit with a t halfway down for horizontal mounting .

Matt 2E0FGX