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IMAX v Homebrew GM; OMG.
Topic Started: Sunday, 2. February 2014, 17:12 (1,639 Views)
Kaos
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13 Charlie Tango 013

Just put up my homebrew Gainmaster as I was a bit peeved about other stations near me hearing more than me.

Well what a huge surprise........

No S5 noise floor and I can hear all sorts of things. Good things like voices that I wouldnt normally hear. Cept the ones in my head.

The AE of choice before was an IMAX2K and this has convinced me never to put up fibreglass again. I fell off my chair when I plugged it in. Its a dream. No S5 noise during the day (garage lights I think).

If filmed it on the 2 Grants with AM and LSB and they are both clear as crystal.

I am hugely impressed by it.



Thats a recording in the summer after I made it.
Edited by 13CT025, Sunday, 2. February 2014, 19:48.
13CT013 Tim aus Germany

So Mote it be
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13CT025
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Kaos
Sunday, 2. February 2014, 17:12
I can hear all sorts of things. Good things like voices that I wouldnt normally hear. Cept the ones in my head.

I wonder if what they say is in agreement with what mine tell me. :P


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Lowflyer
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108 Charlie Tango 036

If the ones in your head told you to make a psychedelic pot belly pig avatar George then I very much doubt it. :D

Luv your HBGM Tim, great that its working so well now ! top job. Nothing more satisfying than a homebrew when it works as well as the commercial kit. ! top job!

LF

108CT036
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Cozzmik
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26 Charlie Tango 465

Tim you say "never put up fibreglass again" but isnt your hbgm fibreglass?

While ive heard many say the fibreglass antennas (a99,imax etc) are noisey ive never actually seen this here at my qth (i use an a99 amongst others),as i have a s0-s1 max unless theres a storm over head when its been known to rise to s3 max.

Good to see it works well for you in your location :thumb:
Edited by Cozzmik, Sunday, 2. February 2014, 19:27.








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Kaos
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13 Charlie Tango 013

Ahhhhh I see where you are going Sam.

The pole (made from fibreglass) is just for support. The GM is zip tied to it.

There is a defo difference and I had to check my connections a few times.

It works and is staying put.

13CT013 Tim aus Germany

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Cozzmik
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26 Charlie Tango 465

Cheers for the info matey,well it certainly seems to work in your qth and thats all that matters.Ive tried various antennas over the years and tbh ally,fibreglass and even a copper j pole all received similar levels of noise here....
Isnt it nice to have a low noise floor and hear those back of the box stations :thumb:








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Kaos
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13 Charlie Tango 013

Wait till the vid uploads.

Eye opener for me.
13CT013 Tim aus Germany

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EKaye1971
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26 Charlie Tango 2781

:clap: well done tim for the homebrew beating the imax and getting less static.static is a post code lottery and anyone who gets s1 and less lucky :censor: lol .i get s3 to 7 so you need a s9lus to hear anyone anyways il get off my sop box now lol :cheers:
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BigTone
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26 Charlie Tango 4498
Melodies heard are sweet.
Noise unheard even sweeter!
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Mudslinger
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I did try an Antron here once and I did get quite a lot of noise on it compared to a metal 5/8 wave.

However during my first CB stint in the early 1990's I ran an Antron with no noise problems. So it could be just a modern interference thing or even just the location.
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EKaye1971
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26 Charlie Tango 2781

exactamundo i remember getting s3 noise max in the mid 80s and being :censor: off lol with a thunderpole 2 pre computer and plasma days . oh yes there were zx81s and the like but i dont think they interfered
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13CT025
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Kaos
Sunday, 2. February 2014, 19:36
Wait till the vid uploads.

Eye opener for me.


Yay, I'm first :P

Video: "President Grant 1 and President Grant 2 ASQ on homebrew Gainmaster." by Tim




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Cozzmik
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26 Charlie Tango 465

I get exactly the same noise floor as you on my a99,sigma 4,t2lt,hori dipole and 2 ele and it makes working those back of the box stations easier for sure!. So as we know location is a factor here but tbh the first test only showed a slight difference in noise between the two antennas but you say in your latest video that there is a big difference and who am i to dispute,most importantly your hbgm works well :thumb:

I will say the g2 isnt a patch on the g1 for rx quality in my opinion but i was brought up on 80s radios so my ears are more accustomed to this sound.

But you`ve saved me a few notes as i wont be buying the g2,my superstar 360 sounds far better :cheers:
Edited by Cozzmik, Monday, 3. February 2014, 08:00.








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MadMark1
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163 Charlie Tango 020
I have no noise with my A-99.... its up about 20 ft.... For a real comparison try using the same radio, As different radios different RX... etc... To make a real comparison it really needs to be the same radio... I would rather watch the difference then, As its on the same radio... But good on you for building one a giving it a go... :clap:



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Mudslinger
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You can say that again Mark. :P
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13CT025
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Cozzmik
Monday, 3. February 2014, 07:41
(...) it certainly seems to work in your qth and thats all that matters.Ive tried various antennas over the years and tbh ally,fibreglass and even a copper j pole all received similar levels of noise here....
_____

I get exactly the same noise floor as you on my a99, sigma 4, t2lt, hori dipole and 2 ele and it makes working those back of the box stations easier for sure!

So as we know location is a factor here but tbh the first test only showed a slight difference in noise between the two antennas
(...)
you say in your latest video that there is a big difference and who am i to dispute,most importantly your hbgm works well :thumb:
Mudslinger
 
However during my first CB stint in the early 1990's I ran an Antron with no noise problems. So it could be just a modern interference thing or even just the location.
MadMark1
 
For a real comparison try using the same radio, As different radios different rx... etc... to have a rea test try this... I would rather watch the differeance then as its on the same radio...

Yes.

Probably it is best to analytically have a look at the things which could (!, not must!) have an influence on the noise which is being picked up, and on the way the noise is being perceived by the operator. The following, long list is only supposed to show that there are many things:


  1. Feed line radiation/reception. The feed line is an inseparable part of the whole antenna system, just like a dipole branch is. A dipole branch might, or might not radiate. The same goes for the feed line (and the radio, the PSU, ground etc. - the whole package together is what "radiates").

    Unless you are 100 % certain (by measurements) that there is no common mode current on the feed lines, this has to be considered as a very likely source of differences in signal-to-noise, because the feed lines are often very close to noise sources (dirty power supplies, dirty LED lamps, computer noise, etc.).

    Even if both antennas are at the same place, and if for both measurements the same feed line is used, there can be differences. One example of many would be, if the coil of the Gainmaster is not at the correct resonance frequency. The GM would then have common mode current on the feed line, while the other antenna (hopefully) doesn't. In this case the GM would sound more noisy, but the situation could be vice versa as well (if the GM works without feed line common mode current, but the other antenna does).

  2. Antenna location. As you know, only slight variations can make a large difference (example: think about noisy TV sets, which all of a sudden get good reception if you walk/move only a few centimeters). This applies especially if the antenna is close to metal objects.

    For a comparison, both antennas would need to be at exactly the same location (which necessitates doing the tests/measurements after one another).

  3. Directional pattern of the antenna, also for "omnidirectionals". While the azimuthal (= horizontal) patterns of the compared antennas are probably rather similar (unless disturbed, see item 1), the elevation patterns definitely differ. Thus, both antennas will pick up signals with different relative strength.

    Example: Let's assume that there is only one noise source. If antenna A has a gain maximum in direction of this noise source and antenna B has a gain minimum in this direction, antenna A will probably seem more noisy. But if you move the noise source (or the antennas) in such a way that the "gain towards noise source" situation is reversed, of course antenna B will seem more noisy.

  4. Antenna mounting conditions. E.g., if you hang up a wire antenna alongside to a fiberglass mast (a dielectric material), it will experience slight dielectric effects from only one direction, leading to a slight directionality. This in turn can influence signal-to-noise level directionally (because of the above reasons), and again the antenna location plus the orientation in respect to the mast will play a role.

    This is probably the weakest of all influences on signal-to-noise.

  5. Radio type. This is obvious: Cheap quality radios often sound more noisy, for various reasons. When comparing two things exactly, all conditions should be the same (e.g. to compare two antennas, the same radio should be used, and when comparing two radios, the same antenna should be used).

    Otherwise, you might conclude that cars swim better (in a puddle on a nice weather day) than boats (sinking in the Gulf of Mexico, in the middle of a category 5 hurricane). :)

  6. Radio-sided conditions. Example: Plug one radio into a very noisy power supply (PSU), and the other into a well-filtered, stable PSU, and guess what happens. This is a rather likely factor for signal-to-noise differences.

  7. Radio location. Even this can influence the perceived signal-to-noise ratio (example: if one is in direction of a noisy street while the other isn't, or, the acoustic properties of your room can play a role). Again, for an exact comparison, all conditions would have to be the same (only one radio at the same place, when comparing two antennas).


I've surely missed a few things in this list.


Summary:


  1. The (perceived, or real) signal-to-noise ratio is not really a property of the antenna system itself, but of the surroundings and conditions.

  2. It is therefore not really possible to do this comparison at all, but if one insists to do so, it will be extremely difficult to do it in a fair way, especially when shortwave antennas are compared (also this is nothing new, I guess).

  3. Congratulations to Tim that he has managed to build a great working antenna, that he has shown to us that these Gainmaster antennas are effective and how they can be built at home - that's what really counts! Many thanks for the nice thread, the pictures and the videos, Tim! :thumb:


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163ct034
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Looking at the both video's to me it seems your Imax seems to pulls in more static at your location than mine myself i think it all depends on where the antenna is located at your end myself back in the 1990s used to run a antron A99 for many years with great contacts all over the globe with no noise problems lovely antenna. I see many on here would would slag off! the A99 and refer to it as a large dummy load! knowing what a dummy load is the A99 doesn't seem to work that well as one being that it would transmit a signal imho tongue in cheek! ;) but getting back to the Imax 2000 I have one up here and i'm in the middle of a large city i don't get any static with mine here I have been reading all the fab reports of the gain master so i bought one and to be honest my I-max pulls in a stronger signal by about 2 s points with both antennas at 50 feet next to each other both are good but my i-max 2000 beats my gainmaster thats my pounds worth! you pay your money you take your chance :D
Edited by 163ct034, Monday, 3. February 2014, 17:09.
163-CHARLIE TANGO #034 CITY & COUNTY OF SWANSEA ON THE SOUTH WESTERN COAST OF WALES!

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The DB
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Just to expand on George's post, there seems to be in some areas a "blanket" of noise above houses, especially in city/suburb environments. If your antenna is in this area above the houses you tend to get more noise than if it is above or below that area. I have heard others mention this and have experienced a phenomena like it myself. I have seen this not only at HF frequencies, but as high as the 440 MHz Ham Radio band.


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The DB
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WelshDragon
Monday, 3. February 2014, 16:56
Looking at the both video's to me it seems the I-max pulls in more static at your location but i think it all depends on where the antenna is located at your qth I used to run an antron a99 for many years with no noise lovely antenna many on here would would slag it off! and refer to it as a large dummy load! funny because for a dummy load it doesn't work that well being that it would transmit a a signal imho tongue in cheek! ;) but getting back to the Imax 2000 I have one up here and i'm in the middle of a large city i don't get any static here at this qth been reading all the fab reports of the gain master so i bought one and to be honest my I-max pulls in a stronger signal by about 2 s points both antennas are at 50 feet next to each other both are good but my i-max 2000 beats my gainmaster thats my pounds worth! you pay your money you take your chance :D
Have you considered swapping their locations?


The DB
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MadMark1
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163 Charlie Tango 020
Thats the other point that the DB has mentioned... Trying both antennas in the same location... Same coax etc... Ive tried antennas here... and found one to be much better against another... Swapped them over and the good antenna is now down on the other.... Huh...

You get reflections, Anything metalic will effect the antenna... etc...In the end i took mine upon the mountain and tried Them there.... Lol... This is what makes antennas and antenna building so fascinating... Keep up the good work...


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