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New antenna from Sirio Gain-Master
- Thread starter dxswe
- Start date
No-Ox-Id is a great product that I have used on occasion for resolving surface contact issues in connectors. For antennas, Burndy Penetrox A, or NSI OX-8 is a much better choice for aluminum to aluminum or aluminum to copper connections. As far as paint is concerned, try to choose a paint with a low percentage of titanium dioxide content. I have recently used Rustoleum white appliance epoxy, to paint an Antron 99 copy that I was giving to a friend. I could not detect any SWR differences in my before and after tests. Would be nice if it was available in other colors such as camo.
They (Sirio) are likely attributing the 1 - 2dB gain to apparent gain from lower TOA.
Also, keep in mind the current nodes on the Gainmaster are fully in-phase, whereas bottom-fed 5/8 produce an out-of-phase lowest 1/8 wave which I can't imagine wouldn't cause cancellation with respect to the next 1/8 wave up.
I wonder if Rustoleum OD Green is a metallic paint, utilizing Titanium?
I also wonder if adding anything to, on or near the coil (even paint or electrical tape) might not have a negative effect on the exact tuning of the radiator, by possibly changing the velocity factor of the coil's shield, thus perhaps retuning the Gainmaster into an out-of-balance condition?
? ZYP Coatings - Titanium Nitride Coatings
http://www.repeater-builder.com/antenna/antenna-painting-notes.html
You wouldn't be the same needle bender in Cali that I hear on skip?
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Is it worth it for me?
Lots of great info here guys, but the thread is huge to try and read it all. I see a few mentions of the GM needing height to really work. I am interested in getting one, but unfortunately due to the situation of where I live, a 20 foot mast is going to be all I can do. There is a few trees, but not right up to where the install would be. I would have the bottom of the antenna roughly 12 feet above my poolhouse roof (shingles, with a small tin chimney for the heater), where the install would be. So I ask for you guys to take a guess and what do you figure about performance in this sort of install. Is it going to be enough height, or am I going to be wasting my money. I don't really want any sort of antenna with a bigger "visual footprint" so to say in respect to my neighbors and wife, so I want to stick with a stick type antenna. Imax2000 or the GM? One more thing, I am strictly a dx'er, so I am after dx performance. Dont' care at all about local chitty chat
Steve 9BC999
Lots of great info here guys, but the thread is huge to try and read it all. I see a few mentions of the GM needing height to really work. I am interested in getting one, but unfortunately due to the situation of where I live, a 20 foot mast is going to be all I can do. There is a few trees, but not right up to where the install would be. I would have the bottom of the antenna roughly 12 feet above my poolhouse roof (shingles, with a small tin chimney for the heater), where the install would be. So I ask for you guys to take a guess and what do you figure about performance in this sort of install. Is it going to be enough height, or am I going to be wasting my money. I don't really want any sort of antenna with a bigger "visual footprint" so to say in respect to my neighbors and wife, so I want to stick with a stick type antenna. Imax2000 or the GM? One more thing, I am strictly a dx'er, so I am after dx performance. Dont' care at all about local chitty chat
Steve 9BC999
All antennas work better when you get them higher up, especially locally.
I wonder how many of these "got an extra 1/8th of a S point" claims were actually down to the fact the antenna was higher than the previous one as well as using better/newer connectors and coax?
I certainly understand the fact of height always being better. I just wanted to ask about my particular scenario.
Steve
Steve
I did some modeling of a standard 5/8 wavelength ground plane antenna and a Gainmaster at low heights. At 1/4 and 1/2 wavelengths high the ground plane antennas peak gain is in a higher angle lobe. These antennas have a low angle lobe as well and, gain wise, these lobes are very close to the Gainmaster's low angle primary lobe.
At 3/4 wavelength high the Gainmaster is beginning to pull away from the ground plane antenna performance wise, but at this point it is not significant enough of a gain to be noticed.
At 1 wavelength high the Gainmaster has an additional 0.51 dB gain, 2 wavelengths high an additional 0.87 dB gain, and three wavelengths high an additional 1.14 dB gain, all over ground plane antennas at the same heights.
I guess on could interpret the data to say that the ground plane antennas outperform the Gainmasters at low heights, but looking at the plots over average ground the differences with the 0 to 25 degree portion of the patterns are insignificant at best.
I'm happy to post these patterns if anyone wants to see them...
The DB
At 3/4 wavelength high the Gainmaster is beginning to pull away from the ground plane antenna performance wise, but at this point it is not significant enough of a gain to be noticed.
At 1 wavelength high the Gainmaster has an additional 0.51 dB gain, 2 wavelengths high an additional 0.87 dB gain, and three wavelengths high an additional 1.14 dB gain, all over ground plane antennas at the same heights.
I guess on could interpret the data to say that the ground plane antennas outperform the Gainmasters at low heights, but looking at the plots over average ground the differences with the 0 to 25 degree portion of the patterns are insignificant at best.
I'm happy to post these patterns if anyone wants to see them...
The DB
Sirio GM height vs gain and TOA
The DB,
I would be very interested to see the patterns.
I am considering putting up a GM at 84' ~2.2 WL with a 3 element horizontal 10, 15, 20, 40 meter beam 8' below it. Is there anyway to know if there would be an interaction with the horizontal beam below it?
What would the TOA be?
Dennis in Lone Jack, MO
The DB,
I would be very interested to see the patterns.
I am considering putting up a GM at 84' ~2.2 WL with a 3 element horizontal 10, 15, 20, 40 meter beam 8' below it. Is there anyway to know if there would be an interaction with the horizontal beam below it?
What would the TOA be?
Dennis in Lone Jack, MO
Lets see. They are both 5/8 wave antennas, both use some type of impedance matching device, both were designed for 11 meters. As long as you retune the things either/both should do about the same on 10 meters. Could one 'out perform' the other? Probably, but that 'performance' is going to be so close that I can't imagine any significant differences at all. Do you have a 'brand' preference? What's the difference in cost and is that 'brand' worth that difference? Or would you rather take all the outrageous claims made for either of them as 'gospel'?
- 'Doc
- 'Doc