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 2m & 6m beams 
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Post 2m & 6m beams
Spent yesterday re-calculating the antennas for mounting on the same mast, doesn't affect the 6m beam much, but makes quite a difference to the 2m beam, which would answer a question asked on here a while ago.

Mainly affects the F/B ratio, and the main lobe elevation angle on the 2m beam.

Used hydraulic tube clamps for the first time, will NEVER go back to any other method, so quick and easy to assemble.




Elements are not tight yet.
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Just to make the matching now.

May even get the 6m beam done this week.


Sun May 29, 2016 11:48 am
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 2m & 6m beams 
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Post Re: 2m & 6m beams
6m beam done, the driven element and the directors have adjustable ends. Nice to be able e to get it just right, and also the aluminium is 5m long, so two elements can be had out of one length with shore extensions.

Hoping at the weekend it will be dry to get the old ones down and these up.

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Mon May 30, 2016 9:34 am
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 2m & 6m beams 
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Post Re: 2m & 6m beams
You are going to straighten those elements aren't you Steve ?

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Mon May 30, 2016 2:43 pm
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 2m & 6m beams 
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Post Re: 2m & 6m beams
M0BVL wrote:
You are going to straighten those elements aren't you Steve ?



Will it help?




Yes, I build it in the front, than I have to take it apart again and assemble it on the mast in the back, then lift the mast up.

I've made the baluns, just waiting for some inline BNC sockets, then I need a wind free dry day. With a 650 rotator, and the two beams on the end of the pole, I won't risk it if the wind is strong or the ground is slippery. (age is starting to show :) )


Mon May 30, 2016 2:51 pm
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 2m & 6m beams 
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Post Re: 2m & 6m beams
Fb on the age thing ,can't keep it away lol. As the other thread has shown 6m is wide open , thought i would have a listen on the wire to see what was going on ..been a while since ive been on 6m no yagis up here,flicked to the 5 element 10/15/20 and signal went up some 20 db ...hmm i thought check swr ,haho 1:1 .Front to back is only abt 15 db but it works lol so ive been joining in lmao

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Mon May 30, 2016 3:07 pm
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 2m & 6m beams 
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Post Re: 2m & 6m beams
Just connected the 2m beam and did a sweep.

Very pleased so far, my target is to have below 1.5:1 once it is up, looks like it should be OK



Actual sweep

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Calculated plot
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2m7elSWR.jpg
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Tue May 31, 2016 6:18 am
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 2m & 6m beams 
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Post Re: 2m & 6m beams
11am I had this


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Now it's this

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Quick tests before I tightened the mast up show it is below 1.2:1 everywhere I use it, will check in more detail after a coffee :)

Luckily there was little wind, but it too longer as I had to assemble the 6m beam in place, no space to do otherwise.


Fri Jun 03, 2016 1:32 pm
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 2m & 6m beams 
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Post 2m & 6m beams
Gm

Looking good hope you work lots of dx or whatever floats your boat. What beacons can you hear now.

Cheers

Paul

m0pnn


Sat Jun 11, 2016 6:46 am
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 2m & 6m beams 
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Post Re: 2m & 6m beams
Looks good.

What I want to know is:
Is it from any particular design? (if so whose?)
What size Boom did you use, ie square 32mm etc
What size did you use for the elements, and especially the ones that slide inside the other. Again Sizes.

I completely agree about the Stauff Clamps, brilliant devices.

Where did you source your metal from. Only really necessary if you scoured the UK for the cheapest supplier!

I am looking to build a 5 ele beam on 6m, and a 9 ele on 2 m.

Many thanks in advance

Geoff
G0DDX


Mon Jun 20, 2016 2:22 pm
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 2m & 6m beams 
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Post Re: 2m & 6m beams
G0DDX wrote:
Looks good.

What I want to know is:
Is it from any particular design? (if so whose?)
What size Boom did you use, ie square 32mm etc
What size did you use for the elements, and especially the ones that slide inside the other. Again Sizes.

I completely agree about the Stauff Clamps, brilliant devices.

Where did you source your metal from. Only really necessary if you scoured the UK for the cheapest supplier!

I am looking to build a 5 ele beam on 6m, and a 9 ele on 2 m.

Many thanks in advance

Geoff
G0DDX



It wasn't based on any "design"

The dimensions were mine for my particular needs, had to have a short boom, 18' from the ground, I don't use folded driven elements, and they must have a 50Ω feed point, and the two antennas were mounted 1m apart.
I preferred F/B ratio over a fractional increase in gain, then narrowed the bandwidth to get more gain while whilst keeping the SWR within limits on the top and bottom frequencies I wanted

Even with modern software, it takes hours and hours to get what you want, but it is worth doing.

The aluminium came from Aluminium Warehouse, and on the 6M it was 1/2" with 3/8 pieces on the end, the 2m beam was all 3/8", didn't need to make any fine adjustments.

The boom was 1 1/4" for the 6m, and 1" for the 2m.

Boom correction was triangle guesstimation, which with the Stauff clamps wasn't much.

The antennas work as predicted by the software, and the beam width is narrower than my dual band antennas, the side lobes are way down, seem to be better than the modelling.

It is not possible just to add more elements, the whole things has to be remodelled, as small changes make big differences to the feed impedance and pattern, so if you do it, and want it just right, be prepared for a very long spell on the PC.

Using more conventional dimensions and a folded driven element, or some gamma/delta match would be the way to go if you don't have any special restrictions you need to optimise it for, or don't want to model it.

I think it was worth the effort, but I have no way to prove it :)


Mon Jun 20, 2016 3:41 pm
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 2m & 6m beams 
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Post Re: 2m & 6m beams
Sangoma,
Many thanks, that's very very helpful. Its the simple things like element and boom sizes that make a lot of difference to me.
I am hoping to build a 9 ele on 2m and 5 ele on 6m. Also I have built the DG8 2m preamp that Ian GM3SEK designed which featured in Radcom several months ago. That seems to work very well and was not expensive to build. G4HUP makes them ready built and aligned. Mine cost me about £50 to build.
I'm looking forward to getting it all built and in / on the air.

Again many thanks.

Geoff
G0DDX


Mon Jun 20, 2016 10:40 pm
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 2m & 6m beams 
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Post Re: 2m & 6m beams
Using the way I make them, I found very little difference between 4 and 5 elements on 6m, the same going from 7 to 10 elements on 2m.

Unfortunately I don't keep the files (always start from a blank page) so can't give the figures.

Once you get to a certain point, seems you have to add much more metal for a small increase in performance, especially with my limited space and height, wasn't worth doing.

Good luck with yours, they are interesting projects.


Tue Jun 21, 2016 3:22 am
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 2m & 6m beams 
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Post Re: 2m & 6m beams
No problem with the files, its more a case of me not using too thinner material that it sags, or breaks etc. Also where you are sliding an elements inside another the sizes etc.

I am going to use YU7EF's designs. A mate of mine has built a couple and they have been very successful.
Again thanks..

Geoff
G0DDX


Tue Jun 21, 2016 9:01 am
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