New antenna from Sirio Gain-Master

[Needle Bender]

Ther are a number of flawed tests carried out with regard to the GM, the number one flaw being that the test isn't blind, the well intended helpers should be unaware as to which antenna is being tested, additionaly their results shouldn't be broadcasted for all the other testers to hear, the results should be collated later by the tester, these steps will eliminate a number of potential errors.

The other issue being a 1 S point increase, assuming a reasonably accurate scale, would equate to a 6dB gain over the Imax, but not so on receive, there is definitely some magic going on there, 6dB gain on transmit, yet nothing on receive, impossible :closedeyes: and could be indicative of flaws in the testing as outlined above.

All the above said, I'd expect the GM to be better than an Imax, it is after all a complete antenna, whereas the Imax is only half an antenna, relying on mast and coax to make up the other half, and there in lies the potential variable performance of the Imax.

I recall many people stating the GM being so much better than their previous antenna, however this isn't a surprise, the potential for their previous antenna being in need of a bit of TLC was high, how often do people take their antennas down for a service, it's something that should be done regularly to ensure all joints are good, any corrosion is removed / treated, identify any components that require replacement and to ensure its performance is maintained. For many this isn't the case, and the first time their antenna is taken down is when it either breaks or they are replacing it, of course they'll see an improvement.

I like the GM, it's a fresh look at the 5/8WL antenna, it's very clean, in that it doesn't require radials, it already has its own RF choke, and as a result has a lower visual impact, very neighbour friendly, however I don't buy into it being a miracle worker

Easily 6-8db gain over my Imax here, and considerably quieter (on the same mast & coax as the Imax) and the first antenna I've put against my P500 (in decades of testing others) that outperformed the P500 by 1-2db, but in all fairness, the Gainmaster didn't perform as well as an Imax on a friend's 40' tower, so he went back to his Imax and began to be heard again by distant stations that lost his signal while he was on the Gainmaster, (LMR-400).
Bad Gainmaster maybe? It had a low SWR from 25.5 to 30mhz so who can say?
He lives on a bit of a hill so, if anything, the lower TOA of the Gainmaster should help

 

[Marconi]

Easily 6-8db gain over my Imax here, and considerably quieter (on the same mast & coax as the Imax) and the first antenna I've put against my P500 (in decades of testing others) that outperformed the P500 by 1-2db, but in all fairness, the Gainmaster didn't perform as well as an Imax on a friend's 40' tower, so he went back to his Imax and began to be heard again by distant stations that lost his signal while he was on the Gainmaster, (LMR-400).
Bad Gainmaster maybe? It had a low SWR from 25.5 to 30mhz so who can say?
He lives on a bit of a hill so, if anything, the lower TOA of the Gainmaster should help

NB, when I model a 5/8 wave radiator with no radials and feed it at the end, vs. a 5/8 wave radiator with no radials and feed it at the center, the patterns produced are different in shape, but show the same 8* degree max TOA angle at 40' feet. These models were both over Eznec version of average real Earth.

There is a .46 dbi difference in gain in favor of the GM however.

My bandwidth curve for my GM also indicates a SWR match of less than 1.5 over 25.5 to 30 mhz range just has your friend claims, so it doesn't appear to be anything wrong with those results, and I think if the antenna was bad, then it would likely show up in the bandwidth results.

Did you happen to experience these results he claimed?

 

[northern35s]

Easily 6-8db gain over my Imax here, and considerably quieter (on the same mast & coax as the Imax) and the first antenna I've put against my P500 (in decades of testing others) that outperformed the P500 by 1-2db, but in all fairness, the Gainmaster didn't perform as well as an Imax on a friend's 40' tower

Do you think the GM is 8dB better than any Imax, or jut your Imax?

As much as the GM has changed the established method of feeding a 5/8WL antenna, it is still a 5/8WL antenna, and changing one 5/8WL antenna for another 5/8WL antenna does not 8dB make, the matching stub doesn't add to the radiation efficiency, and neither does the capacitor, so what we are left with is a 5/8WL long piece of metal if you will, the main difference being one is fed in the middle and the other fed at it's base.
With all that said, we must acknowledge how the end fed 5/8WL must be arranged for maximum efficiency, and in most cases we can see that the Imax isn't installed correctly, this may well be the reason why so many people claim the GM is much better, and why some claim it isn't an improvement

 

[Marconi]

Do you think the GM is 8dB better than any Imax, or jut your Imax?

As much as the GM has changed the established method of feeding a 5/8WL antenna, it is still a 5/8WL antenna, and changing one 5/8WL antenna for another 5/8WL antenna does not 8dB make, the matching stub doesn't add to the radiation efficiency, and neither does the capacitor, so what we are left with is a 5/8WL long piece of metal if you will, the main difference being one is fed in the middle and the other fed at it's base.
With all that said, we must acknowledge how the end fed 5/8WL must be arranged for maximum efficiency, and in most cases we can see that the Imax isn't installed correctly, this may well be the reason why so many people claim the GM is much better, and why some claim it isn't an improvement

35, I never have seen anywhere near this much gain using my GM, and I wouldn't know about mistakes in the install.

My Eznec model shows a modest improvement in gain on the GM vs. Imax, and this is probably due to a better current distribution across the entire 5/8 wave radiator, and the absence of the small out of phase cancellation in the bottom of the end fed Imax and others. I can't vouch 100% for the models either, but common sense might suggest there could be some difference between these two designs.

As typically mounted, like in this case, the GM's actual feed point is also higher. I would suggest that might make some difference, but I don't know how much. It also has to be considered that these antennas are pretty close to the same height, so the current maximums should be pretty close to the same as well. I guess we just have to decide which is more important to the comparisons, the feed point height or the current maximum heights.

This free space idea that Sirio presents...looks to show better gain at zero degrees to the horizon in a no-loss free space model. My models prove to me that Sirio's FS contention is accurate, but this minor difference in the models is probably mitigated out...when the antennas are mounted over real Earth.

These two are too close to call. I could have just blinked at a different moment, and seen a different result. Not the best idea for testing maybe, but here is a signal report on these two antennas mounted 36' feet apart:

View attachment Imax vs. Gain Master.pdf

 

[M0GVZ]

Easily 6-8db gain over my Imax here

Err, no there isn't unless it has found a way to defy the laws of physics or your Imax installation was defective.

 

[Needle Bender]

Just offering the real world results I've seen here, and I hope I'm perceptive enough to know a good antenna from a bad one, and I don't believe my Imax is extraordinarily good nor bad, just a 4-5 year-old Imax which works just like my older one did, which I gave away to a friend who needed one.

Marconi, I actually helped with Jack's Gainmaster installation and testing, fully expecting him to see similar results to mine and I am sorely bummed and frustrated with his results - like some have said, even if their performance isn't all that different, they are both 5/8 and I would expect the Gainmaster to at least keep up with his Imax, so maybe there's something else going on, such as perhaps the length of feed line with relation to the point along the current node and hence the point in the sine wave where each antenna is fed which plays with it's TOA or some other aspect of performance in order for there to be so many varying results. - I dunno, but it's too darn bad that everyone doesn't get the same results which others do so they could know what to expect.

I just hope my taping over the choke didn't cause the off-performance by changing the velocity factor of the red coax and thereby de-tuning it by changing the point where it cuts off radiation.

As much as I like my Gainmasters, I've been recommending the P500 lately due to the evidently 'fickle nature' of the Gainmaster in differing installations.

I still believe it's an ingenious design and deserves a long hard look, especially if being installed in the clear, above a tree top, and/or atop a tower w/o non-insulated metallic guy lines.

I look forward to any new, higher power handling version Sirio would produce, though my wallet shivers at the thought...

 

[Needle Bender]

Easily 6-8db gain over my Imax here

Err, no there isn't unless it has found a way to defy the laws of physics or your Imax installation was defective.

But it's precisely the laws of physics which dictate variance in performance, the trick is in finding which ones and why!

How does an installation go wrong if it's simply on top of a mast, grounded with wire to a grounding rod as well as the base of the mast, and tuned for lowest SWR and reactance? It's just two U-bolts and a mounting plate.

The Imax was on a 20' mast above the 20' roof, 60' of LMR400.
I marked the mast as I lowered it, swapped it out for the Gainmaster and raised it back to the marks where the insulated guy lines became taut. Same coax, radio, etc. Had always received a consistent S8.2 from a friend on his analog 756III meter, @10 miles, after the swap I received a consistent S9+3db - The largest single improvement he said he had seen from a simple antenna swap.

*Edit*

On the other side of the house was the P500, installed at the same mast height, (also 60' LMR400) giving him S8.9.

When I swapped out the P500 for that same Gainmaster my signal increased to S9+1db, a full 2db worse location to him in comparison to that of the Imax, leading me to believe the P500 would have provided around S9+1db to him had I installed it where the Imax had been, though I never tried that, it should have provided the full S unit improvement I have usually/always seen from replacing an Imax with a P500.

 

[hotrod]

But it's precisely the laws of physics which dictate variance in performance, the trick is in finding which ones and why!

How does an installation go wrong if it's simply on top of a mast, grounded with wire to a grounding rod as well as the base of the mast, and tuned for lowest SWR and reactance? It's just two U-bolts and a mounting plate.

The Imax was on a 20' mast above the 20' roof, 60' of LMR400.
I marked the mast as I lowered it, swapped it out for the Gainmaster and raised it back to the marks where the insulated guy lines became taut. Same coax, radio, etc. Had always received a consistent S8.2 from a friend on his analog 756III meter, @10 miles, after the swap I received a consistent S9+3db - The largest single improvement he said he had seen from a simple antenna swap.

*Edit*

On the other side of the house was the P500, installed at the same mast height, (also 60' LMR400) giving him S8.9.

When I swapped out the P500 for that same Gainmaster my signal increased to S9+1db, a full 2db worse location to him in comparison to that of the Imax, leading me to believe the P500 would have provided around S9+1db to him had I installed it where the Imax had been, though I never tried that, it should have provided the full S unit improvement I have usually/always seen from replacing an Imax with a P500.

soto my understanding you,d rank the anennas as follows
1 sirio GM best
2p500 close
3 imax

 

[BOOTY MONSTER]

Err, no there isn't unless it has found a way to defy the laws of physics or your Imax installation was defective.

don't give radio s-meter too much credit for being accurate . FWIU they do vary and can be somewhat to very inaccurate . IMO they are only good for determining more or less signal . how much more ? who knows .... but more signal is more signal .

 

[Marconi]

don't give radio s-meter too much credit for being accurate . FWIU they do vary and can be somewhat to very inaccurate . IMO they are only good for determining more or less signal . how much more ? who knows .... but more signal is more signal .

BM, are you saying this to MOGVZ or to Needle Bender?

Looks like it was NB that was talking about results on his radio's meter. His report reminds me of one from your most favorite Merlin buddies on the Internet.

 

[Needle Bender]

soto my understanding you,d rank the anennas as follows
1 sirio GM best
2p500 close
3 imax

In this case, yes, but only because I didn't have any other full size 5/8 in contention, and with the warning; The Gainmaster is fickle, your mileage may vary! Lately I've been recommending the P500 more than the Gainmaster.
I wouldn't give the Imax an automatic 3rd place over everything else out there.

don't give radio s-meter too much credit for being accurate . FWIU they do vary and can be somewhat to very inaccurate . IMO they are only good for determining more or less signal . how much more ? who knows .... but more signal is more signal .

That's why I like using him for signal reports, for years now it's never changed with the P500, and the Imax stayed the same for the 4 months I had it up.

Looks like it was NB that was talking about results on his radio's meter. His report reminds me of one from your most favorite Merlin buddies on the Internet.

Marconi, I'm only reporting what I've experienced, I got no dog in this fight - I own all of the above and simply hope for the best performance each can provide.
-Your mileage may vary!

By the way, my Merlin darstuster outperforms my 4 element Moonraker-6 by 50dB of audio distortion.

 

[bob85]

Nb,
i don't see anything odd in your test numbers vs what is sometimes seen by others in comparison tests apart from your units of measurement,
somebody somewhere once said 1-sunit = 6db and folk use that when they post even though its VERY unlikely they ever owned or ever will own a radio that has a meter calibrated @ 6db/s-unit, that is far from what any radio i ever used shows, the tightest radio i own is my jrc @ 3db/s-unit or thereabouts, if i saw a full s-unit on the jrc that would indicate one of my antennas is broke,
a precision attenuator inserted in the feedline of your rx antenna will highlight the none conformity of typical signal meters,


i find it much more unusual to claim that all antennas perform about the same since for us here they virtually never perform the same,
in my experience at multiple locations same mast/coax the gainmaster does what it says on the tin vs other no radial endfeds or short radial endfeds like sirio827,
there is no way i could convince any of my locals that their a99 or dipole performs just as good as their sirio827 on the same mast when they can swap antennas and experience the difference,

what you need to do to legitimize your results is make some keystone cops style youtube video's, they must be two mast tests on ssb rx with skip conditions,
to ensure impartiality you must use only stations that have no interest or knowledge of your tests,
make sure you mount the antennas near houses and trees and in such a way as to make rapid switches of mast/antenna position impossible to you,

it may also help if you can find a beacon for comparative signal testing,
to ensure impartiality it must be a random noise who's source is unknown to you or anybody else,

here is an example of such a test been conducted to give you some idea of how to go about doing such meaningful tests,


hope this helps
Antron99 v Imax2000 v gainmaster - YouTube

 

[Shockwave]

Bob, the only obvious flaw I spotted in that video test was the operator was hot switching the antennas with the mic keyed.

 

[Needle Bender]

Nb,
i don't see anything odd in your...

...doing such meaningful tests,


hope this helps
Antron99 v Imax2000 v gainmaster - YouTube

Sorry Bob, I can't do that, I don't have any tatoos. :blink:

- But seriously, I really only do these tests, the results of which I may share here from time to time (when I see them as perhaps somewhat relevant) for my own information, and I can usually tell, right off the bat, if I'm liking the performance of a new aerial install or not.

What really chaps my ass is Jack's bad Gainmaster experience. I've racked my brain trying to figure out what went wrong at his location, only thing I can imagine is that when I taped over his choke I may have changed the VF of the red coax significantly enough to cause a slight detuning of the choke, possibly causing an imbalance of the Gainmaster and perhaps a bad TOA (either too high or too low) because of it.

Makes me wanna go set up a test like you recommend, somewhere in a field.


...then shoot myself

 

[IMD262]

Nb,

Antron99 v Imax2000 v gainmaster - YouTube

Best video I've watched since Mark's (Cobraman) "radio ham or 11 meter man" video.