-
You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
A99 vs dipole
- Thread starter kaos513
- Start date
W9cll, after I posted my assumption about the meaning of your words, I had second thoughts about making such a wild guess again. Second guessing what is on the minds of others will getting us hung out to dry if we're wrong.
Thanks, and very glad to hear I was right for once.
Now thats the truth if ive ever heard it.....! Wow there are more of us in the world...... good to know bro
a99 and dipole will have close if not the same performance not much there to compare
unless ya mount the dipole horizonally then i give the dipole a advantage ,especially
if ya wanna talk to other flatside operators
unless ya mount the dipole horizonally then i give the dipole a advantage ,especially
if ya wanna talk to other flatside operators
All things being equal, they'll work out about the same. However, it one were strung horizontally, it would be better suited for DX, while the vertically strung would be better for local.
All things aren't equal, the A99 has a lossy coil, was this modelled? The feedpoint is at the voltage maxima, dipole has feedpoint at current maxima.
As for horizontal v vertical, there's absolutely no reason why a vertical can't outdo a flatside antenna even when working a flatside antenna, as the ionosphere skews polarity more often than not, its not outwith possibility for a flatside signal to arrive vertical and a vertical antenna to arrive flatside, now depending on the polarity of the receive antennas one or other could actually not be heard at all when the other is and vice versa,
also when you lie an antenna horizontally the height is very critical, as depending when the reflected wave arrives from the ground it can add to or cancel the following waves, there's far more to this than flatside is better for dx and vertical is better locally, if two local stations are working flatside beams and locked onto each other, two verticals ain't gonna touch them, no matter what verticals you use,
I've run a beam under a mighty magnum 3 and sometimes magnum could hear stuff beam couldn't and vice versa, that was the case for both local and dx, there was very little if any interaction between antennas that I ever noticed.
T77 Chevy who said he compared a centrefed dipole taped to an I max, now there's a real flawed test, you have an I max with nothing conductive near it, unless you left the dipole taped to it, you didn't make that clear when you said you tested the I max, and then you have a centrefed dipole, with a resonant conductor within cm of it, possibly same was true for I max or possibly I max had nothing near it, can you clarify that please.
Then you have the fact I max is 5/8 wave or .64 whatever, and dipole is only a half wave, so again a discrepancy, I max has lossy coil too like A99 and dipole has no coil whatsoever, top of that coil is at least a thousand ohms and its tapped at 50 ohm point, its not a dipole either like the A99, dipole is fed at nominal 72 ohm point with no matching device and swr depending on height and surroundings. With a dipole its always best to run coax away from it at 90 degree angle, unless its a centre fed dipole like shakespeare big stick or gainmaster or T2LT.Where coax either runs up centre of lower section like big stick or coax is lower part of radiator like Gainmaster and T2LT, both of which need an rf choke to make the length of the lower section, otherwise like the A99 and I Max it will use coax shield and probably mast too as counterpoise.
I know you said it was by no means a lab condition test, but if the I max had nothing on it, then you tested dipole taped too it, the I max is always going to win
Just out of curiosity as I ain't into modelling antennas, mainly due to the fact I think most modelling software is highly flawed, do any of these programmes model the coil ? Or are you guys assuming the I max and A99 are centrefed, because they are far from it. Also are you modelling transmission line as well, because its part of the antenna if not choked and decoupled. Then comes the other question, are you modelling the mast too, because its also part of the radiating system, you can't just model the bits you like and ignore the rest of the system, can they model an rf choke? If a choke is used is it optimised for 27 mhz or is it copied from the hamuniverse page that claims coaxial wound air rf chokes cover 80-10m which is pure and utter bollocks. In reality they are very narrow banded at optimal choking impedance. Take a look at Steve G3TXQ's page on air wound chokes and you'll see just how untrue that ham universe page is.
A T2LT done right is almost a balanced antenna with almost no coax radiation just like the gainmaster, the I max and A99 the coax shield outer skin is almost definately radiating due to common mode current and the skin effect.
Coax is not a 2 conductor cable unless it is balanced, as soon as you feed an unbalanced antenna with it with no radials or choke to decouple RF it is a 3 conductor cable, it has the centre conductor,the inner shield/braid and the outer shield/braid, due to the skin effect RF does not penetrate more than a few microns into the surface of the shield on either side, if you add an rf choke with a high enough choke impedance you can reduce common mode current to almost zero and make the coax a nigh on balanced cable with so little radiation its virtually unnoticed and cancellation occurs between inner conductor and inner braid/shield. Which in turn reduces radiation to almost zero, you can never reduce common mode current to zero as that would require infinite choke impedance, but with high enough choke impedance you can get it pretty damn close.
There seems to be a hell of a lot of misinformation on these particular antennas. And none of them has anywhere near quoted gains,
That's before you even consider ground losses and ground reflected waves and what phase they are which will vary with mounting height.
The one thing I do agree with is they should be measured with current maxima at the same height, but many will argue feedpoint should be same height or tip should be same height, there is so many variables I think these modelling programmes and most tests are flawed on,
the biggest flaw of all is mounting them on different poles and switching between them, because that changes propagation path and obstacles between, I've seen a vehicle moved a couple of feet have a signal rise from S2 to S6 with no other changes, That was on line of sight contacts from high ground in Glasgow Scotland to various parts of Northern Ireland, something we can do every night from hills around here so no skywave involved. If skywave was involved we would most likely see qsb which we don't, signals are steady for hours, night after night., the only factor that changed was the exact location we parked on different nights, but no matter where we parked, or what signal we got, it was off a constant level and could be increased and decreased just by moving car a few feet in some instances, so two masts 30 feet or so apart are going to have staggeringly different propagation paths.
The other thing many discount, the night they do the test there could be ducting, skywave backscatter or any number of propagation modes happening, the test would need to be repeated at different times of day, for a few days to make sure that isn't the case, in my life I've seen two types of ducting on 27 mhz, ducting over land with different temperature layers where I could reach stations well outside my normal line of sight range, (common in the morning for some reason,) but well short of the minimum expected sporadic e range could also be doen to auroral backscatter, but that tends to be given away by bubbly audio that can be very difficult to decode even to the sharpest ears.
Then there's what I call sea ducting same thing but at the coast, when again you can hear coastal stations well out of normal range, I remember cursing the day I had no skip but heard a station from Blackpool Seafront in N.England from Ardrossan on clyde coast, about 100 miles or more, I couldn't get back to him even though I was getting him s2 as I'd left the linear at home and he was besieged with 29 division stations across the Irish sea from him, I had him at same signal strength for 3 hours on an otherwise dead band, despite calling several times I couldn't get past the bigger signals straight across from him, but I did get answered by a boat crossing the north channel of the Irish sea from 108 to 68 division and he confirmed he was also getting the English station in Blackpool, I've only ever seen it a couple of times at the coast but it was definately the longest distance I've heard with a hy power 4000,
even from the Hills here I've got into Cumbria in North 26 division nightly but never as far as blackpool a good 30 miles further south and at sea level, the guy Julian in Cumbria was higher up than I was, and belting into me about S3 every night, Locals in the valley below me thought I was talking to myself and didn't believe it till we took some of them up our hill and they heard him
After that long post, A little short one, Not often me and Beetle agree, but he couldn't be more right, what works in one location might not fare so well in another, no matter what hype,software modelling,reviewers,advertising and who's worked where is said, at the end of the day, it's night and in reality the only way you'll ever truly know what's best for your particular situation is by putting them up wherever you can mount them, be it a 50 foot tower,10 ft pole, an attic or lying in your bedroom, is the only way you will find out what works best for you, it truly is that simple, and all the comparison tests in the world won't mean shit if that antenna doesn't have room to breathe however well or badly the tests or software is done, software like tests is human made, and usually flawed,
I ain't found a pc programme yet I'd call 100% stable and certainly ain't seen any tests yet that were done on same mast with same coax,within a very short time duration with high quality calibrated equipment and most important of all tests must be blind and the only way I see of achieving that and taking out human preference is to have your own two stations, with a camera feeding you back real time results on the internet so you can see both ends at same time, even better if it has the facility for you to use the remote transceiver so you can test both tx and rx. Anything less just isn't cricket as the English would say
Otherwise suck it and see as Beetle suggests.
It is the only way and even then your depending on others honesty, and there's no shortage of jails you can visit worldwide where people will tell you that not a good idea. If you tell them what antenna is which, they are going to tell you what they want to see, not what they really see. Let's face it if they own an A99, they ain't gonna tell you the bit of wire your using is better than the 60 or more dollar waste of space they have and you've just wasted 60 dollars on too.
I was speaking in generalities. Was the pharmacy (chemist) closed today?
Lmao, My chemist/pharmacy (its called that here too, but thanks for the translation, I think you forget you speak/spell our language, usually badly, oops, did I really say that, lol) is always open, llf,
It wasn't an attack on you or anyone else, I was merely pointing out more often than not all things aren't equal, tests are far from scientific and comparing different types of antenna is very very difficult due to so many factors that I ain't typing again ever, as nearly wore my keyboard out on that post. But generality speaking I like your post, was very funny
:tongue: 
This is the best answer. A antenna is only as good as how you install it.
Keep it simple and have fun.
I run a Antron 99 and it works fine. I don't care whats inside of it or what wave it is. It works and thats all I care about.
if ya can afford it buy both put up both . a99 verticle for local chatting . then dipole
flatside directly below the a99 for dx . you,ll have the best of both worlds
sirio d27 seems like a nice one. maco also has one too
flatside directly below the a99 for dx . you,ll have the best of both worlds
sirio d27 seems like a nice one. maco also has one too
