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Post New to 6m
After hearing all the activity on Thursday (during the contest) I quite fancy doing a bit of 6m ssb and possibly doing a little 2m/70cm.
My main station radio does 6m and ATM I use an ft100d mobile which I'm finding I only ever use for 2m fm so I'm considering replacing the mobile with a duel band fm unit and putting the ft100 in the shack.
This leaves me with antennas, I know I need horizontal for ssb but I am very antenna limited by a covenant so what would people recommend? 2m is the third harmonic of 6m and 70cm the third harmonic of 2m so is there an antenna that will work on all 3 bands and be omni directional or do I need separate antennas?
I have done a lot with differant hf antennas but this is my first venture into vhf apart from fm.

Thanks for any advice
Matt M0YBT


Sun Jul 16, 2017 8:14 am
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Post Re: New to 6m
A horizontally polarised omni-directional antenna for 6m is going to be quite large and visible.

70 cm is too far from 6m to work well in one antenna.

I would first look at a 6m Moxon, and a small dual band single feed 2m/70cm beam above it.

The Moxon can be wire on thin fibreglass spreaders, and the dual band beam can be made out of 1/8" aluminium welding rod on a 1/2" or 3/4" boom, which would be much less than 3' long.

The whole lot could be supported by the lower half of a 30' fishing pole and rotated by hand, or even a TV type rotator mounted near the ground (would need three fishing line stays)

The whole lot wouldn't be too obtrusive, and could be raised or lowered in less than a minute.

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Sun Jul 16, 2017 9:03 am
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Post Re: New to 6m
Thanks for your suggestions, and I think in a normal house they would work well, however I have a masonete (house above a flat) with communal gardens.
I do have a location agreed on one of the gable ends for antennas which are 'not too obtrusive', it's well over 15m and due to the way our building is its hidden from all but a small angle.

My thought was 6m loop then possibly a 2m big wheel or halo then 70cm big wheel. The location I can use is a wrk ward to access, involving me getting the help from an experienced person with roof ladders ect so I was trying to avoid a rotator as if and when there is a fault it could be weeks or months before it's safe to access again.

Thank you again for your suggestions though. That could be what gets implemented at my ham friends house as this is an area we are both exploring at the same time.


Sun Jul 16, 2017 9:14 am
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Post Re: New to 6m
You can do well on 6m with a vertical, V-2000 has served me well during sporadic e

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Sun Jul 16, 2017 9:46 am
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Post Re: New to 6m
2E0RXT wrote:
Thanks for your suggestions, and I think in a normal house they would work well, however I have a masonete (house above a flat) with communal gardens.
I do have a location agreed on one of the gable ends for antennas which are 'not too obtrusive', it's well over 15m and due to the way our building is its hidden from all but a small angle.

My thought was 6m loop then possibly a 2m big wheel or halo then 70cm big wheel. The location I can use is a wrk ward to access, involving me getting the help from an experienced person with roof ladders ect so I was trying to avoid a rotator as if and when there is a fault it could be weeks or months before it's safe to access again.

Thank you again for your suggestions though. That could be what gets implemented at my ham friends house as this is an area we are both exploring at the same time.


Knowing more of the situation, my suggestion would obviously not be suitable.

Then maybe three big wheels, topped off by a 2m/70cm mobile vertical. If you can get away with them visually.
Add a pulley block and rope under them in case you might want to add a wire antenna later :)

I would agree, 15m high is best installed by a professional, and will take quite a bit of planning re strength of pole etc

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Sun Jul 16, 2017 10:17 am
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Post Re: New to 6m
Yeh it's difficult to explain our layout here but it's good to know you are thinking on the same lines as myself, I was planning as you gents sugest topping the whole lot off with a v2000, I have a white stick up at the moment and a pully with a wire for hf so tbh it's more a change of white stick that no one will notice and the addition of the horizontals, now to start planning and building/buying what's needed. I might even sneak a 4m vertical up somewhere while I'm at it lol.


Sun Jul 16, 2017 11:07 am
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Post Re: New to 6m
This brings me to the next question, how close do you knolageable gents think I could stack these antennas without too much interaction? Ideally I would like to put a full wavelength between them but as this isn't going to be an option would 1/2m between them be ok or am I better forgetting 70cm and spacing the 6/2 antennas further apart?

At the moment I have my 2/70 stick on an ally pole but I'm considering swiping this for a glassfiber one to avoid interactions and it spoiling the fun.

I will be testing this set up at my friends on his push up mast to prove everything is ok and it can just be mounted by my local friendley tv antenna man, he's happy to fit amateur kit but he admits hiself that it isn't where his knolage is so he wants things ready and set up first.


Sun Jul 16, 2017 11:21 am
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Post Re: New to 6m
2E0RXT wrote:
This brings me to the next question, how close do you knolageable gents think I could stack these antennas without too much interaction? Ideally I would like to put a full wavelength between them but as this isn't going to be an option would 1/2m between them be ok or am I better forgetting 70cm and spacing the 6/2 antennas further apart?

At the moment I have my 2/70 stick on an ally pole but I'm considering swiping this for a glassfiber one to avoid interactions and it spoiling the fun.

I will be testing this set up at my friends on his push up mast to prove everything is ok and it can just be mounted by my local friendley tv antenna man, he's happy to fit amateur kit but he admits hiself that it isn't where his knolage is so he wants things ready and set up first.



The big wheels are cheap and relatively easy to construct, also commercially available if you would rather pay, as for spacing, it will have to be a compromise. Does the roof have a foil layered membrane under the tiles?
If not, I would aim for 2m above and below the 6m one, and 1m between the 2m and 70cm one. Not ideal, but may be a fair compromise.

Thing is, that if you had 1m between the 6m and 2m and 50cm between the 2m and 70cm one, it will work better than something on the ground.

Would be nice to model them and see what the effects would be.

I don't see the mounting pole for the vertical affecting it too much, unless the vertical is next to it.

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Sun Jul 16, 2017 12:04 pm
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Post Re: New to 6m
I was going to mount the horizontal antennas on the same pole as the vertical tbh. I should be able to get close to those spacings and no there is no foil under the roof so that should be fine.
As for modelling that is something I have never got the hang of, I have tried a couple of times but get stuck just creating the antenna sighing the software. This may be the time to learn.

Thank you sangoma, your help and advice on this has been a big help.


Sun Jul 16, 2017 12:44 pm
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Post Re: New to 6m
I installed a 2mtr big wheel stacked above a six meter one for general monitoring a month or so back.

Both have worked extremely well with four continents worked on Six and contacts to IT9 and 9H1 on two - so can't complain about performance.

My only comments are that the main interaction between the aerials is such that the larger aerial is electrically seen by the smaller ones, hence you need to place (if possible) the stack such that the distance between two aerials is slightly more than the specified stacking distance if you were using two of the same band.
i.e between the six and two meter ones more than 650mm, and between the two meter and 70cm ones more than 215mm. The more you can get the distance between the less the chance of interaction, I have about 1300mm between 2 and 6 as I had room on the tube and it just happens to be the same as the recommended 2m stacking distance.

I would also say that you'd benefit from putting as food a quality coax as you can manage on your installation as there's no real gain from the aerials so you don't want to throw your RF away in undue attenuation :thumbsup:

I've mine mounted on the end of my metal roof barn, but at sufficient height that the 6mtr one is not affected by the roof.

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Sun Jul 16, 2017 6:38 pm
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Post Re: New to 6m
I considered the 6m Big Wheel until I saw a photo on the tinternet, it is huge! Do you have access to loft space, a Delta Loop for 6m is reasonably small and works well, can be made for next to nothing and even I managed one and I have 2 left hands!


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Sun Jul 16, 2017 7:22 pm
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Post Re: New to 6m
I'd reinforce what Kelvin said.
If you are going for compromise antennas it's really important to go for the best coax you can afford.
A cloverleaf/big wheel has only around 2.5dB gain so cable losses should be minimised.

Cheers

Tony

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Mon Jul 17, 2017 9:05 am
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Post Re: New to 6m
The more I think about it, the more I go away from thinking that big wheels are the best answer.

You could have a 3+3 6m&4M dual band single feed beam, and 1m above it a 2m&70cm dual band single feed beam, using less aluminium, less sky area, less feeders, and having less wind resistance than three big wheels, and you get 4m as a bonus. (of course it could be 6m only and not dual band)

A 3el 6m beam will be less than 1.5 m long, and still give reasonable gain, good FB and deep dips on the sides.

A TV type or small rotator would be fine, the whole lot would not need to be so high, guying would be simpler.

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Mon Jul 17, 2017 10:13 am
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Post Re: New to 6m
I have had some great help, both here and via pm.

For coax I have a new drum of west flex 103 looking for a job so I think for the short runs 10-15m tops) that should work well, I do agree that beams would be an easy answer but they are directional which causes another headache as mentioned above.


Mon Jul 17, 2017 1:12 pm
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Post Re: New to 6m
2E0RXT wrote:
I have had some great help, both here and via pm.

For coax I have a new drum of west flex 103 looking for a job so I think for the short runs 10-15m tops) that should work well, I do agree that beams would be an easy answer but they are directional which causes another headache as mentioned above.


I understand what you mean about not being able to access it for a long time if something goes wrong.

I used a Yamato TV type rotator for several years with a TH3 on it, it still works well, must be about 20 years old.
Here I used a Ebay TV type rotator for nearly three years on a 4el dual band 6/4m beam with a 7/5 el 70cm/2m beam above it, and it is fine. (I replaced it as I wanted non-preset controller)

I think that a pole with three big wheel at a suitable spacing would be heavier and require more guying than one with a small rotator and two beams.
From what I have read, the 6m big wheel is rather prone to wind damage, both in bending, and in joints becoming loose (haven't had one to say if that is accurate)

Another thing that made me think, was that here for about 40Ā° either side of north, I have a high noise level, that id not there when the beam is side or back on to it. If the aerial wasn't directional, I would be stuck with it on all signals.

The 6m beam should give OK results even if only 2m above the apex, then the 2m/70cm beam above that, so the whole thing (excluding the mobile vertical) would only be 3m above the apex.

Not trying to persuade you, just trying to show there may be choices :)

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Mon Jul 17, 2017 2:12 pm
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