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Old 5th Aug 2022, 8:19 am   #1
Malcolm T
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Default 144 Mhz Cubical quad SSB end

I'm back on it again a year later! Hoping to get this aerial working for some SSB operation on a lift, there have been some reports of some very good VHF propagations during this hot weather.
However following a design page where the frequency is typed in and you magically get the correct dimensions and spacing it flopped dramatically. I adjusted the driven element so it is now 70mm longer in total length and re-spaced the gamma match, it now appears to work well but i'm not sure about adding a tuning stub to the reflector or how this thing should be adjusted as a procedure ie steps 1 2 3 etc .
So are there any VHF gurus out there who have cubical quad experience?
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Old 9th Aug 2022, 12:11 pm   #2
Graham G3ZVT
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Default Re: 144 Mhz Cubical quad SSB end

I love it when the empiric triumphs over sums
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Old 11th Aug 2022, 8:14 am   #3
FrankB
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Default Re: 144 Mhz Cubical quad SSB end

IIRC, 73 Magazine and QST both had articles on cubical Quads back in the early 70's.
HTH.
(Mine are all packed away, so I am unable to look through them.)
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Old 13th Aug 2022, 8:55 am   #4
Malcolm T
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Default Re: 144 Mhz Cubical quad SSB end

Thank you for the replies i will give QST a look .
Cant imagine my antenna building skills are this good because i,m getting almost 1.1:1 in the SSB part of the band .
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Old 13th Aug 2022, 10:13 am   #5
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Default Re: 144 Mhz Cubical quad SSB end

Quote:
Originally Posted by rambo1152 View Post
I love it when the empiric triumphs over sums
There is no exact design for a yagi, be it rods or quads that comes out of unambiguous maths. They all have an empirical basis.

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Old 13th Aug 2022, 11:01 am   #6
Malcolm T
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Default Re: 144 Mhz Cubical quad SSB end

Definitely experimental here LOL.
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Old 13th Aug 2022, 5:17 pm   #7
David G4EBT
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Default Re: 144 Mhz Cubical quad SSB end

I'm a 'RHINO' these days (Radio Ham I Name Only), but when I was active on air (up to 2003) I made all my own antennas for VHF and HF.

Back in the late 70s (I was licenced in 1977), I made a 'Quagi' Quad Yagi for 2 Meters which performed very well. At the time, I lived in North Lincolnshire, and often had QSOs with Dutch amateurs as there was a fairly clear take-off across the North Sea. Back then, most 2 Metre activity was on SSB, and the 'Liner 2' was much in vogue. (A step up from using modified ex PMR Pye Cambridge AM rigs, 'tuning high to low', which won't mean much these days).

Full constructional details including dimensions for various frequencies are here:

https://www.amateur-radio-wiki.net/quagi/

A bit more about the theory and design here on Youtube:

https://www.youtube.com/watch?v=XhuRCV3ZxW4

And here:

www.overbeck.com/quagi.htm

Hope that's of interest.
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Last edited by David G4EBT; 13th Aug 2022 at 5:22 pm.
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Old 14th Aug 2022, 9:39 pm   #8
Malcolm T
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Default Re: 144 Mhz Cubical quad SSB end

Thanks Dave, i will look at the links you sent . Every aspect of this hobby is so interesting.
I have yet to hear SSB DX on 144mhz , heard plenty on 50mhz on the home made quad .
I chose a quad as i thought it had some attributes the yagi seems not to have , as far as the text books say !.
Mechanically it has a character of its own , a bit of a beast to assemble and take down.
I wonder what has changed between the 1960s and today regarding solar activity and its effects on earths atmosphere and the layers. I dont know whether its my imagination but there seemed to be so much more on the air in the 70s ,
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