Homemade Sigma 4 11 meter base antenna

[W5LZ]

I don't think there are any 'antenna clamps' as such. There could sure be such things for special/particular places of use, meaning the antenna and clamp were designed specifically for each other. But, I don't think the application in question is that 'special' or uncommon. It's a good idea to use a stainless clamp, but they are used in quite a few applications, not just on antennas. It's the weather resistance thingy that's important.
- 'Doc

 

[BOOTY MONSTER]

i didn't like quality or low stripping point when tightening down hose clamps from DXengineering or lowes so i made my own .

 

[Lil'Yeshua]

I gotta think about what kinda slots to make then. However,slots will degrade the integrity of the joint. A whole new study of tube sleeve joint connections are called for.

 

[Shockwave]

BM, One thing I saw that I wanted to point out to you is that imitation wood you are using for the spreader insulators on the cone may be robbing you of performance. I'm not familiar with that material but I know the Sigma has a very large RF potential between the cone and main radiator as you move upwards from the base.

If the insulator material conducts any RF this will cause loss of gain with the antenna because the insulator will load down the RF feeding the radiator. At high power this would cause the insulator to arc. At low power it may not become apparent it has lowered the performance of the antenna. The easiest way to tell is to throw a sample of the plastic in the microwave. If it melts or burns in under 60 seconds, I'd reject it even at HF.

 

[Lil'Yeshua]

I'm reporting this from another thread
End-fed Vertical and J-pole

 

[Lil'Yeshua]

BM, One thing I saw that I wanted to point out to you is that imitation wood you are using for the spreader insulators on the cone may be robbing you of performance. I'm not familiar with that material but I know the Sigma has a very large RF potential between the cone and main radiator as you move upwards from the base.

If the insulator material conducts any RF this will cause loss of gain with the antenna because the insulator will load down the RF feeding the radiator. At high power this would cause the insulator to arc. At low power it may not become apparent it has lowered the performance of the antenna. The easiest way to tell is to throw a sample of the plastic in the microwave. If it melts or burns in under 60 seconds, I'd reject it even at HF.

Yea,that caught my attention lately. I was concerned about the same thing

 

[Lil'Yeshua]

Plastic support for Vector 4000

 

[Lil'Yeshua]

Clamp that came with the antenna kit. These are nice. Now if I can find some more. These provide fairly even clamping pressure

 

[BOOTY MONSTER]

BM, One thing I saw that I wanted to point out to you is that imitation wood you are using for the spreader insulators on the cone may be robbing you of performance. I'm not familiar with that material but I know the Sigma has a very large RF potential between the cone and main radiator as you move upwards from the base.

If the insulator material conducts any RF this will cause loss of gain with the antenna because the insulator will load down the RF feeding the radiator. At high power this would cause the insulator to arc. At low power it may not become apparent it has lowered the performance of the antenna. The easiest way to tell is to throw a sample of the plastic in the microwave. If it melts or burns in under 60 seconds, I'd reject it even at HF.

it did pass the microwave test

 

[Lil'Yeshua]

Interesting.
Fishing Pole Yagis - G4DHF 144MHz

 

[bob85]

that style clamp is good for the lower sections, the mikalor supra clamps that came with my vectors had a stainless band with plated steel bolt that rusts after years in the elements,

it is way overkill for the sections higher up,
anything but the cheapest dollar shop chineese made hose clamps are stronger than the thin sirio tube,
all you do using big strong clamps is add weight and wind load,
imagine you are building a f1 car not a monster truck,

the punched band all stainless breeze marine grade clamps that jay uses for the 1-10k are plenty strong enough for the sirio upper sections without adding too much weight & wind load,

only slot the tube enough to get a clamp on, if you slot the swaged sections all the way its ruined.

 

[Lil'Yeshua]

Thanks. I'm looking at NAPA auto part clamps to see what they have. I have a tub of no-Ox-Id. I guess I put that on the telescoping mast clamp sections to keep from oxidizing
I might use nylon line to guy the vertical halfway up.

 

[Lil'Yeshua]

Marine grade

 

[Lil'Yeshua]

Maybe a bit much

 

[HomerBB]

Stores such as the Home Depot sell these Stainless Steel Hose Clamps individually, and in packs of 10.
I buy mine there. The prices are comparable to auto parts establishments.

Li' Yeshua, you are asking questions,and then appear to be second guessing the answers you receive from folks who've done what you are wanting to do. Trust the answers from those who know and you can save yourself frustration and time. Everyone is interested in the success of your experience.

Homer