Modified Vector 4000

[bob85]

"Is the gain and angle here about what you might expect the difference to be?"

the sigma's advantage in gain over the 5/8wave in your model is slightly higher than avanti claimed for the stock sigma eddie, i imagine 1 db or so is in the ballpark,
the difference in how they perform here is more than the gain advantage indicates,

it would be interesting to see how the sirio compares to the cte top-one mounted at the same tip height, the astroplane is a strange antenna, the sirio is also a little different from the norm, does the sirio achieve the same results,

do you think the astroplane does what is claimed eddie, providing more signal at low angles than a 5/8wave when used under the fcc height restrictions/ tip height limit above house/property for which the astroplane was designed?

i can't help with the wolf antennas, having the gamma tube open to collect rain is asking for trouble at best, its where i would look first if i had high vswr on that antenna

 

[Marconi]

I'm not surprised that Avanti found the gain difference a bit less than my two models predicted. I also agree, that in order for you to sense the differences you noted in testing, the actual gain differences must have been greater also. One db of difference may be difficult to realize without some special type of equipment.

I believe that back in the days of Avanti the science and math were available to make the calculations that are similar to today's speedier results using modeling software. IMO, the folks at Avanti probably understood the math. They just couldn't calculate rapidly...and a "what if" type of scenario just required a lot more work and time. I get the feeling that the modeling software limitation type errors we see made in applications today, tend to error on the side of seeing results inflated a bit, rather than just bad results like most seem to suggest. Goes back to the old saying: "...if something seems to good to be true, it probably is." That'll make Homer happy.

Bob, you know that I've not been able to duplicate the testing you did where the the results were greater than the gain indicated, but I think I have experienced something similar before just like you describe. I figured that situation maybe due to either a particular height where I had the antenna installed, or maybe it was just conditions that provided some combinations of angles that were in phase at the other station involved, but I never thought about steering the angle like you suggest. That idea is valid however, and whether I'm right or wrong, I still felt that experience was remarkable and different.

Re: the Wolf .64, I'm more concerned where Eddie measured the overall length of the radiator from than the problem with water in the gamma. I agree the idea of leaving the gamma open and on top exposed is a bad idea and a bad design. I still think the center bolt might be the point to measure from. One day I'll take the time and figure that all out. On testing the Wolf .64, I might still be impressed with the results, but I have changed my mind a little regarding the kits construction for the Wolf antennas. But for the price, it could be better. I will comment however, that the base element looks to be very durable and I doubt anyone would ever have a problem in that area with it being long and double wall or maybe it's just think wall tubing, but I'm not so sure about the top elements surviving a big wind.

Thanks for your comments.

 

[HomerBB]

Goes back to the old saying: "...if something seems to good to be true, it probably is." That'll make Homer happy.

Hey, Marconi, how about a Merlin? It appears to be a variation on the Top One.
May be time to make one of those . . .

 

[Marconi]

Hey, Marconi, how about a Merlin? It appears to be a variation on the Top One.
May be time to make one of those . . .

That might be a good idea Homer. For me the Merlin is more like a shortened Starduster. The coil and the top hat both may have the tendency to allow the physical radiator to be shortened some and remain resonant with resistance at or near 50 ohms at the same frequency.

The combination of the coil and top hat together will need to be figured out, but I am confident you, if anybody, can figure that out in short order. Personally, I think it is possible that combination in the radiator may actually provide for an even better resistive match at resonance, than even a full 1/4 wave element can provide by itself and stay resonant. I think the Starduster has a slight offset with the otherwise balanced dipole design it is supposed to emulate and maybe that too does some good. It is hard to say which compromise idea works the best. I love my Starduster and I make my Marconi 6x out of 7 x 1/4 wave ss whips that emulates the SD'r pretty much, and it is very effective as well.

I'm pretty sure of this with the Starduster and it may also be true of the Merlin, but you'll be surprise at how quiet they can be. Your experience with the AstroPlane should also show you how important that characteristic can be when conditions are generally quiet already and the AP is a pretty good match in that same category. Believe it or not, I'm finding the same with my new Gain Master too, and I can say that regarding my other vertical CB antennas.

I may have the measurements, but I'm not sure Cajun ever did send them to me. I'll look. I do have some close up pictures of the Merlin however.

Good luck and keep us posted.

 

[MrSuburban]

Hey, Marconi, how about a Merlin? It appears to be a variation on the Top One.
May be time to make one of those . . .

A Merlin is a copy of a Star duster.. except the idiot put a capacitance hat on it right above a coil which is a no no

 

[MrSuburban]

"So an inefficient antenna will have more gain than a efficient one?

When efficiency goes up what does gain do?"

First, an inefficient antenna can have more gain than a more efficient antenna. That's a fairly common occurrence.

Ok so if we have 2 of the same antenna one is less effcient than the other and you are saying the one that is less efficient can have more gain?

If thats the case then I guess that blows your theory out of the water so if a less efficient antenna can work better than another the measure of antenna performance must be gain. Thanks for playing

Secondly, when efficiency goes up, nothing happens to gain.

So again is efficiency the measure of antenna performance?

The thing is to define 'gain'. The commonly accepted definition of gain has nothing to do with efficiency of the antenna.

All 1/4 wave length antennas will have less gain than a 1/2 wave length antenna designed for the same frequency. That certainly does not mean that the 1/4 wave length antenna is less efficient than the 1/2 wave length antenna!


Equating efficiency and gain is like comparing apples and oranges. Big differences between them. - 'Doc

You were the one to equate them when you told me performance of a antenna isnt measured in gain. So in the end efficiency doesnt determine antenna performance. You can brag you have the most efficient antenna, I will brag mine puts out more signal.

 

[Marconi]

A Merlin is a copy of a Star duster.. except the idiot put a capacitance hat on it right above a coil which is a no no

Hey MrS, I've heard that stuff about placing a coil up near a top hat also, but in my personal experience with a similar antenna, I found the idea worked excellent, for both local and DX. Signal Engineering use to make two models they called their Golden Rod 40 and 50. My dad has both, and they work pretty good considering they are short.

Just considering the stories we hear about how a full 1/4 wave working hands down better than a shortened radiator with a top hat like the AstroPlane, I have one of the New Top Ones (NTO) and it may be working better than my old Top One knockoff of the Avanti original.

I have it mounted on my P/U pole with 4' feet of the bottom below the top of the 33'8" mast it's mounted on. My Gain Master is mounted on top of another similar 33'8" mast. This setup places the NTO 4' lower at the bottom than the GM, and the tip of the GM is about 14' feet higher than the top of the NTO, so there is a well defined disadvantage for the NTO, yet it still at times shows me a better signal to certain stations around Houston. That don't even seem possible, but I have it on video. So, I wouldn't object to much to that idea and design nor be quite so categorical...unless I've actually tested or compared it to my others, even one that is said to defy the laws of physics or theory.

Do you have a link or personal experience in the Real World or modeling that supports your claim? I know this question will get Homer's attention as Sergeant at Arms over the forum community.

I have a Starduster modeled with a 50% top hat, not one of those puny little top hats like the I-10k GP uses to make the tip look bigger in case of lightning. I'll look the SD'r model up and send you a copy of the file if you like. I think I recall it performs on paper pretty well compared to the full size model. Of course you could say that one doesn't have a coil I suppose.

I would like to try the Merlin, but I won't pay the price...just to test that one for sure.

 

[W5LZ]

MrSuburban,
Keep 'guessing', and brag all you want. Efficiency does not equal gain. Gain does not equal efficiency. Misconstrue that anyway you want, it still won't change.
- 'Doc

 

[CDX-007]

Nice to have the forum back!

If he wants to learn why dont you teach him 007?

Why shift the attention to me? He asked YOU MrSuburban, and you gave him a load of dirty baby diapers instead of some of that invaluable "by-the-hour" wisdom & genius you're so eager to blather on about.

Well, at least you did the easy part, you talked about it.

A gamma is a capacitor with a series inductor if you cant figure out how to adapt one to a tuning ring to replace the one on the Vector nothing i can say will help. Like I said get your learn on, it is up to you to do your homework and try it for yourself. I charge by the hour let me know when you want the clock to start... :laugh:

No thanks, I have better ways to spend $.25 :w00t:

 

[BOOTY MONSTER]

ok , i re-read this thread from the beginning yesterday and today . there we're several points in the development of this thread where i had ignored cause it got pretty technical , to me anyhow . and no i didn't miraculously understand it all this time , but i did pick up a few things i had missed along the way . BTW , thanks to all the folks that contributed to it , even Mr.S .

shockwave , i saw where you changed your measurements for your version . thank you for the update
so it seems a good starting point is a 30 ft vertical element with 106 inch basket/cone/ground elements . the consumer versions have stuck with a 30 inch diameter ring for the cone top , but bob85 pointed out avanti thought more gain could be had with a larger ring . that was using their original shorter basket elements though so the longer 106 inch elements may? or may-not? already be getting that extra gain ??? ....... or there may still be a little more gain to be had in addition to the longer elements by a larger ring element ???

has anyone had a chance to play with a larger diameter ring using the longer 106 inch elements yet ? if so what are your impressions ?

 

[CDX-007]

Apologies, mixed up threads

 

[RatsoW8]

Darn..I almost missed a post about another magical (read-more expensive,complicated and bigger than a dipole) CB antenna (errr, I meant 10/11 meter antenna). How long before someone improves it yet again it by adding a giant coil to the center of ther vertical element and claims 10 million watt handling capabilities.

Can't wait

 

[CDX-007]

Apologies, mixed up threads.

 

[BOOTY MONSTER]

there were some comments a bit back about tapering of the main vertical and wire vs. tubing . i didn't figure out if thats just important for the modeling programs y'all were discussing or if it's something also important on the actual physical antenna . does the rate of taper have to be consistent ?

 

[Marconi]

there were some comments a bit back about tapering of the main vertical and wire vs. tubing . i didn't figure out if thats just important for the modeling programs y'all were discussing or if it's something also important on the actual physical antenna . does the rate of taper have to be consistent ?

Booty, I could be wrong, but tapper and element size (wire diameter) is important in both applications, for real antennas and with modeling.

I think the point here was, the first model of the Vector presented was using very small size wires. I also think it was suggested this was the only way for an Eznec5 model to show any gain when modeling the very complicated Sigma4 design, with sharp angles between parallel elements, and when using tapper.

Common sense and theory both tell us that element size is important consideration for resonant type antennas, and the use of tapper is important to the physical construction, which then must also be taken into account regarding resonance.

I just put up my New Top One. I checked it alone for a couple of days, and then I installed my Old Top One using a full 1/4 wave radiator without the Cap Hat.

On the OTO, I have used several different size mast inside the antenna to mount. Originally I used a 10' section of 1.25" mast and the antenna was resonant very near the middle of the CB band.

Next I used a 1" square tubing and the resonance when up to the bottom of 28 megs, but at the time I was also figuring out the length of the 1/4 wave full length radiator and I was short in this first attempt, using the suggested length noted in the manual for the AstroBeam.

This time I used an two 1.25" side by side masts for added strength and 5' feet of increased height, and the frequency went down a bit to the low side of CB, however, I think I made the radiator 1" too long also, so I won't know what affect the two mast makes until I check and fix the radiator length.





So, wire size and tapper both have an affect on antenna responses, but I don't know what affect the rate of tapper has, albeit tapper has its affect too. I believe even the hardware used for mast to boom, element to boom, and element connectors also has some affect as well.