gainmaster vs i10k a quick test with locals

[Henry HPSD]

I don't have a clue what the dbs/sunit is on my radios and without testing, I don't think anybody else has a clue either. It should be evident to us all that the same goes for others that have reported even more difference than my results indicate, and some have even showed us in videos.

.

How about trying this:
example:
Double your power = 3dB
That migth show for example a increas signal strength at neighbour s7-s8

In that case you can take advantage of the knowledge that the Smeter at your neighbour indicates 3dB difference between a signal reading of S7 and S8.

Bare in mind that S-meters are not calibreted (nor is your power meter probarbly but that power meter is probarbly more accurate than a s-meter)so only use S7 and S8 (or in between).

With the above you certainly wont have it "accurate"...
But it is the best one can do with "limited" measuring equipment.
and it will give a impression.

Regards,

Henry 19SD348
All about antennas

 

[BOOTY MONSTER]

how much i move someones s-meter isn't the goal for me . it's being herd .
but , i guess putting everyone's needle in the read for 50 miles would be some nice bragging rights

 

[W5LZ]

And because of the inaccuracy of 'S' meters, on the air 'testing' will very, very seldom give you any meaningful numbers to quote. That inaccuracy also applies to the 'ear' of the one doing the reporting. That's always going to be a 'subjective' kind of thing, I know my 'ears' change from time to time, sometimes better, sometimes worse. So, on the air testing will always be a 'gross' type thingy. Either good/average/bad sort of thing. If that will satisfy your 'test', good. If not, then you have a lot of variables to get rid of, and count on it being work.
- 'Doc

Nothing wrong with this sort of testing but don't think that it's very definitive.

 

[NRG]

its not meaningless to me that he hears me stronger like im half as far away. i also read back a few months about a guy testing diferent meters and they werent even close to 6dbs s units and those were hamm radios like his yazoo. now i come in like im 5 miles away from him but im 13 and he still wont believe i dont use a lineur. im glad i bought my gainmaster

 

[bob85]

update,
the local using the gainmaster has replaced it with an imax2000 with radial kit on the same short mast, feedline, icom radio, what did he get for his efforts/expense?, he got a notable loss in signal,
the gainmaster is going back up.

 

[BOOTY MONSTER]

DING DING DING ...... ROUND TWO !!!

 

[Marconi]

update,
the local using the gainmaster has replaced it with an imax2000 with radial kit on the same short mast, feedline, icom radio, what did he get for his efforts/expense?, he got a notable loss in signal,
the gainmaster is going back up.

Bob, here is what my simulated models without support mast or feed lines show for the GM, Imax with GPK, and a Imax without a GPK, all set at 19' feet.

View attachment Bob's buddy with Imax vs. GM.pdf

Do you think the GPK hanging low might have a bearing on your buddies poor results at a low install height for the Imax with GPK?

I also notice in this comparison that the Imax with GPK shows a 1* degree increase in angle vs. the other two. I increased the height by 2' foot increments for the Imax with GPK and it never showed to make a better pattern than the plane Imax. The difference was somewhat remarkable too. That surprised me a little.

Do the guys over there tend to give higher marks for the Imax with a GPK in other installs that are up higher?

 

[bob85]

not sure what use 6ft radials are on a not isolated imax eddie, there is more difference in signal than is indicated in the lower lobe of the models both at his house and my own on short masts with or without radials,

the reason he tried the imax is pretty funny imho, he said he thought the gm was directional because when he had the a99 up he could hear us to the east notably better than the guys in sheffield to the west,
when we put the gm up he said the sheffield crew were mixing it up with us making listening more difficult, he had the same complaint with doncaster to the south making him unsure if he liked the gainmaster,

maybe we are using the upper lobes and getting some of that tropo boost HiDef talks about.

 

[Marconi]

not sure what use 6ft radials are on a not isolated imax eddie, there is more difference in signal than is indicated in the lower lobe of the models both at his house and my own on short masts with or without radials,

the reason he tried the imax is pretty funny imho, he said he thought the gm was directional because when he had the a99 up he could hear us to the east notably better than the guys in sheffield to the west,
when we put the gm up he said the sheffield crew were mixing it up with us making listening more difficult, he had the same complaint with doncaster to the south making him unsure if he liked the gainmaster,

maybe we are using the upper lobes and getting some of that tropo boost HiDef talks about.

That is sure something to consider, because you'll note that my model for the Imax w/GPK shows a marked advantage in max gain 4.36 @ 31* over the GM's 2.15 @ 34* and the Imax w/o GPK 3.48 @ 31*.

Here are the same antennas at 40' with no mast, and we see the GM a bit ahead at low angles, but the Imax w/GPK really ahead at the higher angles. This is what makes all this stuff of comparing antennas so difficult. I never know if the antennas are responding to higher reflected signals or to line of sight type signals at low angles.

What does this suggest about the Imax with GPK? It doesn't look good to me, whether mounted high or low, unless high angle reflections dominate. But, I don't know anybody with an Imax w/GPK, so I'm not sure what the word on the street says.

View attachment Imax GM at 40'.pdf

BTW, I guess you mentioned 6' foot radials for the Imax because your Buddie used a regular GPK. My model does show 6' feet in the Wires View, but the radials are really 8.5'. This is due to the wires hanging out in space and being slanted down. Any element out of the X,Y,Z coordinates makes the perspective skewed, but the software adjust this skewed length back to the proper length. That really cornfused me in the beginning.

 

[bob85]

your imax has the upper lobe dominating which is what i have seen in other peoples models of 5/8 groundplanes at a similar height above ground,

he could isolate and choke the imax with radials to see if cm currents which the gainmaster supposedly has in check are to blame,
the mast is a little higher than the surrounding single story houses, the antennas are about the same length yet the gm clearly has the edge over the imax at my location or his, maybe adding a mast to the imax model would reveal why that may be.

 

[Marconi]

your imax has the upper lobe dominating which is what i have seen in other peoples models of 5/8 groundplanes at a similar height above ground,

he could isolate and choke the imax with radials to see if cm currents which the gainmaster supposedly has in check are to blame,
the mast is a little higher than the surrounding single story houses, the antennas are about the same length yet the gm clearly has the edge over the imax at my location or his, maybe adding a mast to the imax model would reveal why that may be.

Bob, I'm not sure this is exactly what you might be looking for, but I took my Imax and configured it 6 ways, three with GPK and three without. I made one of the three with no mast, one with mast, and the other with an isolated mast. I include a pattern overlay for each of these 6 antennas, along with the antenna view for antennas with and without the mast, and with and without the GPK...just to show what Eznec indicates for the current flows. I see nothing that disagrees with your observations.

I also find that height plays a significant part in how these currents flow and don't flow, so that has to be considered here as well. These examples are just for 40' feet.

This height might be suggestive of the worst case scenario that W8JI modeled in his report on the issue.

Surprisingly this work was more confusing to keep up with the descriptors and titles along with the proper pattern traces than it was to do the models.

Hope this helps.

View attachment Bob's Imax overlays.pdf

View attachment Bob's Imax ideas.pdf

 

[bob85]

the plots don't show what is happening with my locals 1/2wave mast resting on the ground eddie but they do show the cloudwarmer action of a no radial endfed on a longer pole, maybe the same effect could be giving the gainmaster the advantage in our tests,

thanks.

 

[Marconi]

the plots don't show what is happening with my locals 1/2wave mast resting on the ground eddie but they do show the cloudwarmer action of a no radial endfed on a longer pole, maybe the same effect could be giving the gainmaster the advantage in our tests,

thanks.

Yep, IMO the height does have its affects, and at some points even a foot or two seems to make a notable difference in cmc magnitude. That said however, and if my Eznec files are even close, I don't find this magnitude, due to height, being exactly linear in form like I use to think.

Within about 100' feet that I've checked, I see maybe 2 or 3 points in this height range where these current affects tend to get better and then worse. Maybe the affects of height/cmc are more sinuous in form than linear.

So, I guess we can't always say that higher is better. On occasion I've experienced such antenna responses, but I didn't understand it. I probably figured that it was conditions, and that in time it would change. I'm not sure, and I don't know as I can prove this idea, but maybe it is something to consider. I was surprised to see the current magnitude vacillate on the mast as I increased height 1' foot at a time.

I also have not yet determined that all vertical antennas act the same in this regard.

 

[davev8]

That surprised me......... if i had to put money on which is the best out of imax no gpk no mast (dark blue) and no gpk with mast (green) id gone with green which as bob puts it, a cloud warmer,
I just noted 1 trace is black ... should that be yellow? and yellow and red both read imax w gpk no mast??

 

[Marconi]

That surprised me......... if i had to put money on which is the best out of imax no gpk no mast (dark blue) and no gpk with mast (green) id gone with green which as bob puts it, a cloud warmer,
I just noted 1 trace is black ... should that be yellow? and yellow and red both read imax w gpk no mast??

Dave, the yellow does not show up well so whatever model ends up as yellow, I run it again...and it shows up as red. I do this just so the line is easier to see. So you're right, the red and yellow are the same model in this case. I wish I could change the colors and/or the width of the lines to help make this function look better, but we can't.

The black line is noted in the descriptor list as *Primary. The Primary pattern is the model that is open and being displayed at the time. The other patterns are overlaid on top. The title for the Primary is noted below the pattern, so in this case it is, "Imax 40' no GPK mast isolated."

It looks like to me the Imax with no GPK, and with an isolated mast is the best pattern among these models, and it is marked in black. The dark blue is next, but there is no mast. So Bob is right about the isolated mast, but I'm not sure about the need for the GPK. It looks like the GPK tends to kick the max lobe skyward in all cases.