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HY-GAIN SPT-500 or Tornado 27?
- Thread starter T23
- Start date
If you have one not needed, I would welcome it, and hope it leads to even better antenna performance.
May I PM you the info? Could I cover the cost of shipping?
And how do you think a bottom fed 1/2 wave compares to a center fed 1/2 wave dipole, if they are both installed with their tops at the same height?
My experience has me thinking that a lot of things are going on with the signal over distance, and not just relative to simple gain figures and varying atmospheric conditions, but even within static conditions, it seems one design beats others especially at distance as if there's more than meets the eye, such as possibly how the signal blends or cancels it's other angles depending on the E & F layers, and at certain distances.
The P500 always seemed to hang in there when other guys in my area were losing the signal on their APs, Stardusters, Sigma4s, Macos and Imaxs but I could still communicate on the P500. It kind of gave me a reputation for being one of the bigger stations in the area. Only the guys with the Sigma5/8 rivaled it.
Could you also send some measurements where I should begin tuning, or do you think the new Vector 3/4 specs are the way to go? And if you have a copy of their assembly manual I'd like to buy one of those, too.
Sorry I been away for a few days. I have several of the new hubs Sirio sent me to replace older ones noted for failing. As long as you're in the USA, shipping is no issue. My PM's don't seem to work here. They end up getting blocked so you might have to use the email here.
I think the there will be little difference between the half wave center fed or end fed, only the drive impedance will change. The current distribution will be the same on the 1/2 wave, unlike the 5/8 wave when center fed. You can download the Vector manual from the Sirio website.
Range isn't antenna dependent, it's propagation dependent. Sorry, 11 meters is not line-of-sight, it's HF where line-of-sight does not figure into things much. At VHF/UHF, yes, lot's of line-of-sight, but not HF. Antenna height certainly does make a difference. To some absolutely ridiculous amount, more is better. But lower antennas can do the same thing at times, back to that propagation thingy.
With that mast you plan, you'd better also plan on guying it correctly.
- 'Doc
With that mast you plan, you'd better also plan on guying it correctly.
- 'Doc
If you don't think the band has line of sight propagation, what do you call it when you're talking to your friend across town? It's not ground wave because the wavefront does not bend down at 27 MHz. like ground wave does. Ground wave is the extension beyond line of sight on low frequencies like medium wave where the signal bends down over the horizon. This band does have more penetration then UHF or microwave line of sight, but local contacts are still considered line of sight.
I'm sure you also know the antenna has something to do with range. Any chance a rubber duck on a 50 foot tower is going to have the same range as an 8 element Yagi? Of course not. Although many antennas have differences in gain that are much harder to notice then this example.
More height is also not always an advantage. Generally speaking more height is better for line of sight propagation although you will reach a point where the signal under the antenna will begin to drop out in close proximity due to the TOA without downward beam tilt.
Skywave propagation is a little different in terms of height. Since we are reflecting a signal off the ionosphere and ground reflections will have a major affect on these angles, adding 20 feet can easily mess up performance with a horizontal antenna. Every half wave of height will cause a complete reversal in location between secondary lobes and nulls as more are added into the pattern.
That means if you had a nice lobe at 15 degrees when the antenna was at one wavelength in height, if you add another half wave of height you can expect another lobe to form at a higher angle while a deep null drops right down into the 15 degree area. Could be bad for DX depending on the range you work most.
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FYI - I have had great luck installing several types of 5/8 at 40' above ground at the radials, putting the high current node right about 54' which is 1.5 wave lengths above ground. Seems to bring them alive like it's a 'hot-spot'.
Back to no-internet for few more days :sad:
Shockwave,
It deals with names, terms, common and accepted usage. That HF 'line of sight' thingy is also called ground wave (as opposed to 'sky wave'). Right, wrong, or indifferent, if you don't follow normal conventions it always results in confusion. Change, only for the sake of change, is very stupid.
Antenna height. There is no 'perfect' antenna height, it always depends on specifics of purpose availability and practicality. As a generality, more is better.
- 'Doc
It deals with names, terms, common and accepted usage. That HF 'line of sight' thingy is also called ground wave (as opposed to 'sky wave'). Right, wrong, or indifferent, if you don't follow normal conventions it always results in confusion. Change, only for the sake of change, is very stupid.
Antenna height. There is no 'perfect' antenna height, it always depends on specifics of purpose availability and practicality. As a generality, more is better.
- 'Doc
yet another physics defying statement.line of sight/direct wave is the exact form of propagation that is used for the vast majority of local cb contacts, which many people wrongly call groundwave,
sure the actual "true" groundwave/surface wave at 27mhz dissipates extremely quickly, but line of sight can cover tens of miles dependent on geography and antenna mounting height/radiation angle, and it is distinctly different from skywave which in itself consists of many propagation forms (sporadic e,f layer, backscatter,auroral etc etc).
in certain conditions unusual forms of other propagation types more common on higher frequency bands show up on 11m, just like they do on 6m/50 mhz although obviously not as often.
some form of ducting happens on 11m too, i have witnessed it a few times over the years, living in a valley you get to know your limitations quite quickly, every so often you get days those normal limitations don't apply but the distances achieved aren't generally great enough to warrant it being normal skywave conditions from e or f layer, but more likely a duct at much lower altitude, i have witnessed the same thing a few times at the seafront too which i term sea ducting ( it is often on days of no skywave and all contacts you hear are relatively close to a coast)
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what has common or accepted usage got to do with you being wrong AGAIN?
lets analyse this, you called it line of sight, others mistakenly call it groundwave, that's common or accepted usage albeit wrong too.
i requote:
this statement isn't common or accepted usage (except maybe by you) as it is completely wrong, you didn't state line of sight or direct wave as being groundwave which many commonly do,
you stated it doesn't figure much on 11m or hf, which 11m is part of, which is total bullshit.
11m may well be a far cry from 50mhz but it shares many traits and the laws of physics still determine how both propagate signals.
if only 11m propagated signals as well as you propagate, myth, misinformation and nonsense, i'd have a fantastic qsl collection from all those impossible fantasy line of sight contacts i've made on 11m over 3 decades.
Line of sight (LOS) != ground wave propagation
For those who don't know, != means does not equal.
Every RF frequency works line of sight. It literally means the average human eye can see the receiving antenna from the transmitting antenna (or vice versa). Technically it is a propagation, although not usually considered as such by most people. It also does not always extend to the horizon, depending on the height of the antenna(s) in question.
If it does not meet the above requirements it is not line of sight, and thus to communicate with it you must use a non line of site (NLOS) propagation method. This could be caused by one or more trees, a building, a hot air balloon that happens to be drifting in between the antennas, a hill/mountain, the horizon (some cases), rain, and pretty much anything else that would obscure vision.
All forms of propagation other than line of sight are forms of non line of sight propagation. Groundwave is one of them, skywave is as well. Being reflected off of or refracted around an item is also non line of sight. This also includes using repeating stations, such as wimax.
It doesn't matter what frequency it is, if the average human eye can see an antenna from another antenna it is line of sight. It doesn't matter that we happen to be using HF frequencies, as the frequencies involved are irrelevant.
To try and put it a different way, it is a matter of definition. Line of sight is a defined quantity. It is a very limited definition, but it includes every RF frequency, light, and sound. Actually it includes any transmitted wave form.
The DB
For those who don't know, != means does not equal.
Every RF frequency works line of sight. It literally means the average human eye can see the receiving antenna from the transmitting antenna (or vice versa). Technically it is a propagation, although not usually considered as such by most people. It also does not always extend to the horizon, depending on the height of the antenna(s) in question.
If it does not meet the above requirements it is not line of sight, and thus to communicate with it you must use a non line of site (NLOS) propagation method. This could be caused by one or more trees, a building, a hot air balloon that happens to be drifting in between the antennas, a hill/mountain, the horizon (some cases), rain, and pretty much anything else that would obscure vision.
All forms of propagation other than line of sight are forms of non line of sight propagation. Groundwave is one of them, skywave is as well. Being reflected off of or refracted around an item is also non line of sight. This also includes using repeating stations, such as wimax.
It doesn't matter what frequency it is, if the average human eye can see an antenna from another antenna it is line of sight. It doesn't matter that we happen to be using HF frequencies, as the frequencies involved are irrelevant.
To try and put it a different way, it is a matter of definition. Line of sight is a defined quantity. It is a very limited definition, but it includes every RF frequency, light, and sound. Actually it includes any transmitted wave form.
The DB
the average person knows nothing about radio, therefore they would normally associate line of sight with frequencies in the visible light range, approx 430 to 750 trillion hertz (Terrahertz), or at best the 88-108 mhz fm broadcast band or uhf/vhf tv bands, they certainly wouldn't associate it with amateur or cb radio.
if your trying to make out by your question the average person only associates line of sight with 2m repeaters, its gonna take a lot of convincing of people on this forum,
i think JJD has more chance of convincing us of the predators audio gain.
here's some very wise words from a very wise man who once led your country to greatness:
Tis better to be silent and be thought a fool, than to speak and remove all doubt. Abraham Lincoln (1809-1865)
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