Homebrewing a Sirio Gainmaster using RG58 and 2.5mm wire.

[Stronty]

Just got to add, loving this thread.

Excellent work from PsiDoc and the pointers on wwdx and on here i'm thinking I might build one.

Credit to you all and happy New Year.

[wa10]

thanks for the offer psi but its ok, the curve was lobsided and higher than we wanted in frequency, we knew the stock red coax was not rg58 so a guesstimate for stub position was used, we have not tried any trimming as we got sidetracked into building a different antenna, im sure i had a sweep plot from the minivna i could have posted but i can't find it on my laptop.

[Ashtec]

Some Excellent work from PsiDoc i must say!!!!!!!!!!!

[PsiDOC]

Cheers all.
Well, Last night I swapped the RG58 stub for one made of westflex 103 and I am please to say my calculations of 72cm for the W103 matching stub was right on the money and the antenna is exhibiting the same swr characteristics as it did with 55cm of Rg58. So the calculations I have posted I can safely say are valid and correct. You simply need to know the velocity factors of your coaxes to make the changes to the match feed point and the match stub length.

During testing the coax choke decided to spring apart. This was late last night and I was by this point tired so the antenna is now in my bag here in work awaiting me to find 5 mins to rewind it on some kind of former. Weather permitting it'll be back up on the test pole this evening.

Psi

[MrWeetabix]

what would you call it? you always have a name for your creations.

few thoughts....

Home master

Home Gain?

Gain Homer

Homer Master BB

GM BB Couger Thunderbird Fire Hawk Ultra 2000

[HomerBB]

what would you call it? you always have a name for your creations.

few thoughts....

Home master

Home Gain?

Gain Homer

Homer Master BB

GM BB Couger Thunderbird Fire Hawk Ultra 2000

Too funny LOL

[wa10]

lmao

[PsiDOC]

Another follow up for you all. After doing some research, using RG58 for the matching stub was a big no no.
According to some calculations I have done approx 40 - 45% of the power being fed into the antenna was being lost in the stub. Not good at all! By using westflex 103 as the stub these losses have been significantly reduced.
So please... DON'T USE RG58 FOR THE STUB! Westflex 103 can be bought for about £1.70 / Metre and it'll be the best £1.70 you'll spend if you make this antenna.
The antenna is back on the test pole and working well. Height above ground is 2.5 meters to the coax choke (9.5 to the tip) and approx 75m above sea level so quite low in both respects. Yesteday on 28mhz 7 solid contacts into the East US (Staten Island NY, Upstate Ny and Pennsylvania) were made with the lowest signal being a 5/7. Switching to the wire made very little difference to signal rx or reported tx back.

I think this one's a keeper!

Psi

[Black_Pirate]

is there a you-tube vid, of this? or if you make another can you do one...???

[PsiDOC]

Does it really need a build video? There's only a bit more to it than making a simple coaxial dipole.
The measurements are all there in the picture.

[HomerBB]

I will be doing this,
Thanks for posting it.

[PsiDOC]

I will be doing this,
Thanks for posting it.

Homer, to a man of your skills this is a lunch break antenna build. It's a simple antenna to make that performs well.
If you get any problems at all post here or PM me.

Have fun.

Psi

[HomerBB]

Thank you, Sir. Will do.

[PsiDOC]

Not a problem bud.

PS: The only people that address me as Sir are the cops. That makes me nervous. Si will do nicely

Psi

[Eddy]

Hello, newbie here.

I'm pretty new to this hobby and don't really have the theories behind all this in my head, but I've tried to read and learn as much as I can in these last few months.

So I began looking around this project and came up with some questions, if you don't mind.


Did I understand correctly, that you cut the coax at 218,5cm up from the choke, and connected the stub and the upper part of the coax to the lower part with a screw in terminal? (Forgive my lack of knowledge on the technical terms, English is not my native language and my skills are rusty.)

Due to the season all I have and can get at the moment is 6m telescopic fiberglass fishing pole to use as a mast. How would it affect the performance, if I wound the wire above the capacitor, or the whole thing for that matter, loosely around the pole to match its length better?

How much difference it would make if I used different than 2,5mm2 wire for the upper part?

Can I get this antenna to work as expected with just a cross needle swr/power meter?

As I've understood, some antennas need to be tuned where they are/will be installed to work properly, and others can be tuned (pretty much) anywhere and don't need any further adjustments if they are installed elsewhere. How does this antenna work? Set and forget? Or do I have to tune it up every time I change the location`?


I hope I didn't ask too many (dumb) questions. Thanks for the informational post, this just the kind of stuff I've been looking for, and thanks in advance.