Homebrewing a Sirio Gainmaster using RG58 and 2.5mm wire.

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Irishman1127
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Re: Homebrewing a Sirio Gainmaster using RG58 and 2.5mm wire

Post by Irishman1127 » 15 Jun 2014, 12:10

Just a question Si... Have you or any of the other posters threw a load of watts into one of these? Say two or three hundred whiskeys and what was the result
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Re: Homebrewing a Sirio Gainmaster using RG58 and 2.5mm wire

Post by Kaos » 15 Jun 2014, 14:27

400w no bother.

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Re: Homebrewing a Sirio Gainmaster using RG58 and 2.5mm wire

Post by Irishman1127 » 15 Jun 2014, 14:57

rms or Italian watts??? Lol
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Re: Homebrewing a Sirio Gainmaster using RG58 and 2.5mm wire

Post by Kaos » 15 Jun 2014, 15:03

Texas Star American muscle watts.

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Re: Homebrewing a Sirio Gainmaster using RG58 and 2.5mm wire

Post by Irishman1127 » 15 Jun 2014, 15:27

Ah. Cool. Was just curious about it.
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Re: Homebrewing a Sirio Gainmaster using RG58 and 2.5mm wire

Post by vkrules » 16 Jun 2014, 01:03

400 watts no problem, but that was with the rg213 stub.An rg58 stub might be a different ball game.

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Re: Homebrewing a Sirio Gainmaster using RG58 and 2.5mm wire

Post by Kaos » 16 Jun 2014, 05:36

RG213 used here, though I agree with RG58.......mmmm

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Re: Homebrewing a Sirio Gainmaster using RG58 and 2.5mm wire

Post by kamikazeandi » 16 Jun 2014, 23:32

Hi Psi,
sorry, I have sent the wrong picture. Now here is the right image for the antenna with vf = 0.66:
GainMaster 15.png
And with your answer, I have created a new version with a slightly larger capacity C = 8.6pF (as the original version):
GainMaster 18.png
Ultimately, I want to build the new optimized for 10-12m antenna with the low-loss coaxial cable HF5000:
http://www.k-po.com/data/shop/download/7463/HF-5000.pdf
This coaxial cable seems to be a cheap-china-version of H2000Flex or Ecoflex10. Just at this moment, I see that the HF5000 has vf = 0.84, so I have to remodel again. This version should be completely build with this HF5000, and to the TRX not contain connectors, so I hope to reduce the loss.

Is it correct that I need to change the value to 0.84 in the "Trans-line Nr1" in point "Len" in the "Source / Load" menu, for the usage of this coax?

Until today I use the original version witch a longer vertical radiator (3.607m) and a stub length of 0.583m, completely build with RG213 (see image):
Vertikal-Strahler & Stub-Länge_kl.jpg
The position of the stubs should be at 1.265m, but I do not have this captured on film.
In this configuration, the antenna operates on both 10m and 11m band very well, and in the 12m band with an SWR of 2.5. Digital connections from West-Germany to Australia, Argentina and Japan, on the 10m and 12m HAM bands are very nice results. I was even heard in New Zealand, but unfortunately could not even receive the ZL-OMs (reports from the PSK Reporter).

My next antenna project should be an 10m or 11m-SKYPPER antenna. For 11m I have finished the modeling for vertical- and horizontal-configuration, in the program MMANAGAL_BASIC.
But, what do you think? Can we extend this GainMaster to a broadband vertical SKYPPER for the 10m to 12m band? Too crazy? At least it is a dipol-antenna!

Regards Andi
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Re: Homebrewing a Sirio Gainmaster using RG58 and 2.5mm wire

Post by PsiDOC » 17 Jun 2014, 07:51

Andi,
The numbers you have are what I'd expect to see. Curve looks good and you have the 12m band in reasonably at the bottom end. 1 thing though, I do not recommend using Rg58 for the stub. It's way too lossy and a significant amount of you TX power is lost as heat in the stub. Although that HF-5000 coax will do very nicely. The specs look good - almost as good as W-103 / Ecoflex so that will work very well.
I see from your pictures that you have used RG213 throughout. How did you get on with such thick coax for the choke coil for the bottom? Did you re engineer it to a larger diameter?
You are correct on how to change the VF for the lower radiator / feed line. I left it non editable as I assumed most would be using RG58 for the lower radiator, but you know what you are doing so please adjust accordingly. :)
I am happy to see it's working very well for you and you have adjusted the lengths to suit your needs.
RE: The skypper no that's not crazy. It'll be interesting to see if we can model it out to a 5/8 wave broadband antenna, although putting the Gainmaster on it's side does give you about 8 dbi in 2 directions on it's own. ;)

Si
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Re: Homebrewing a Sirio Gainmaster using RG58 and 2.5mm wire

Post by kamikazeandi » 17 Jun 2014, 15:06

Hi Psi,
the choke I've created also in original size (with 66mm inside diameter) with the RG213. It was not easy with this rigid coaxial cable. In the first step, I have this fixed with 4 cable ties. In the review I have this fixed with fiberglass mat and epoxy (see picture):
Choke-Balun_kl.jpg
This looks stable and it is, but was not such a good decision because the cured epoxy has cut the insulation of the coaxial cable in the bends by moving the cable. I suspect that the choke properly now contains water in the shield. This will not just improve performance. ;)
A much more secure solution is a suitable sewer pipe and an attachment with cable ties to it. A suitable tube I had at the time but not at hand. In the optimized version, I'll use a sewer pipe.

Now I have modeled a variant for the HF5000 coaxial cable and then all that remains is the implementation of the data obtained. In this version I have also adjusted the radii of the cable, because that has a non-negligible influence on the result (see picture):
GainMaster HF5000-1.png
Thank you for publishing your work in the form of the file. That was what I was missing. I can now use this file and customize. But an understanding of the stub length and the form in the program has not yet set on me.
However, I have not played with this length. This certainly has something to do with impedance matching. Do you have a tip to understand for me?

Best regards,
Andi
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Re: Homebrewing a Sirio Gainmaster using RG58 and 2.5mm wire

Post by Kaos » 17 Jun 2014, 15:21

Its a hard job with the RG213 on the choke with 66mm.

Took me a few attempts until it was tight and I was happy with it.

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Re: Homebrewing a Sirio Gainmaster using RG58 and 2.5mm wire

Post by JGR » 17 Jun 2014, 19:19

Try warming the stuff up in the sun before winding the RG213 might help.
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Re: Homebrewing a Sirio Gainmaster using RG58 and 2.5mm wire

Post by PsiDOC » 19 Jun 2014, 07:08

Hi again Guys.
You do realise you are below the minimum bend radius winding RG213 at 66mm diameter don't you? The minimum radius is 50mm so minimum diameter is 100mm and you're winding it a 66mm. Just remember that with a bit of power there is the possibility of the centre core migrating outwards through the dielectric and shorting out on the screen. Something to watch out for. ;)
Andi,
The HF5000 version stretched to 6 mhz is looking good. get building :)
I will be honest the stub I have only partially worked out mathematically. I roughly calculate it by taking 1/4 wavelength the centre frequency of the antenna then use 71% of the 1/4 wavelength x by the VF for the attach point and 29% of the 1/4 wavelength x by the VF for the stub.
It's nowhere near exact but it puts you close enough to play with on the model. Also the attach point is dependent on the capacitor size as well.
Sorry I cannnot be any more specific than that.
IrishHam, With the RG58 version I recommend no more than 125 watts. The weak point with regards to power is the coax capacitor and it can flashover if you push it too far. If you were to substitute coax used for the capacitor for something more exotic and are careful with the construction techniques, as people have with the original they will cope with some serious power.
Si
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Re: Homebrewing a Sirio Gainmaster using RG58 and 2.5mm wire

Post by kamikazeandi » 21 Jun 2014, 01:22

Hello again!
Yes, PsiDOc, of course you're right! We use the RG213 outside the specs. But what the hell, my antenna still works very well. :-D
The cable used by me, more than 30 years old, would be hiked in the trash.
In the new version I will wind the coil with the new cable to a 100mm sewer pipe. How many turns I'll probably need? With a coil calculator I have calculated 9-10 turns in the same inductance. Confirmation?
Next Friday I will go to "Ham-Radio" to Friedrichshafen. Then I hope to catch new, low-cost coax cable. And then the new version is constructed.
Andi

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Re: Homebrewing a Sirio Gainmaster using RG58 and 2.5mm wire

Post by PsiDOC » 26 Jun 2014, 21:45

Andi, Apologies for the late reply. It's been a hell of a week here between my day job and rebuilding the grandson's racing quad bike ready for an event on the weekend time has been at a premium.
Ok to business.. I'd go with 11 turns at 100mm, if the swr starts acting strange - Shooting up quicker than you'd expect - at either end then unwrap half a turn and try again... Then unwrap andother half turn etc. You know the drill. But with 11 I think you'll be very close if not there.

Si
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