I am a bit puzzled ..the Sirio Megawatt 4000 is a 11m mobile antenna ..its 6feet 6inch long and base loaded ..however, Sirio gives it out as a 7/8 wave ,, well i know a 1/4 wave don't need a matching device and a 7/8 wave will need one ..but the Sirio don't need one which would lead me to believe its at least pretending to be a 1/4 wave ...so how do Sirio call it a 7/8 wave and what is it really ??..if i had to guess i would say its a 1/4 wave that's been shortened and had a coil/inductor added to compensate the missing length but is it not still a 1/4 wave as it don't need a matching device
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7/8th wave ..or not
- Thread starter davev8
- Start date
Typically when companies make such claims they are using the physical length of the wire, not the electrical length of the antenna, in said claim. The thing is, the physical length of the wire is irrelevant to the performance of the antenna itself.
The DB
The DB
It is a well performing antenna (all the 2 meter long Sirio's are fine, I have a 4000 Hi Power here) However I would be surprised if the coil + whip = 9.6m of wire. I have seen a cross section of the coils in these length Sirio antennas and I would be surprised if the coil was more than 3/4 a meter straightened. It's a reduced 1/4 wave. I would be inclined to go for the 4000 Hi Power or P2000 Trucker if you can stretch the budget just a little. (Coil copper is thicker @2.5mm instead of 1.8mm and as such will likely be slightly less lossy)
edit to add : this is for the Sirio Megawatt 4000, the 4000 Hi Power is a little thicker coil below....
edit to add : this is for the Sirio Megawatt 4000, the 4000 Hi Power is a little thicker coil below....
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SIRIO sell 1/4wave antennas as 5/8 & 7/8, 7/8 just has less wire more whip,
i used to mod sirio to take longer stiffer whips from valor & avanti by removing a turn from the top of the coil, you will find less than 1/2wave of conductor in any of them,
they are not alone in the mickeymouse wavelength claims, most european brands do it.
i used to mod sirio to take longer stiffer whips from valor & avanti by removing a turn from the top of the coil, you will find less than 1/2wave of conductor in any of them,
they are not alone in the mickeymouse wavelength claims, most european brands do it.
I sure appreciate the abundance of treasures stored in wwdx, lot's of good info that the search engines or sites just can't provide!It is a well performing antenna (all the 2 meter long Sirio's are fine, I have a 4000 Hi Power here) However I would be surprised if the coil + whip = 9.6m of wire. I have seen a cross section of the coils in these length Sirio antennas and I would be surprised if the coil was more than 3/4 a meter straightened. It's a reduced 1/4 wave. I would be inclined to go for the 4000 Hi Power or P2000 Trucker if you can stretch the budget just a little. (Coil copper is thicker @2.5mm instead of 1.8mm and as such will likely be slightly less lossy)
edit to add : this is for the Sirio Megawatt 4000, the 4000 Hi Power is a little thicker coil below....
It's an old thread but it's good finding more positive reports on this antenna as I should have one today or tomorrow. It'll replace a laird cb27 nmo and expect a jump in performance compared to the current set up, I hope.
After looking at the other sirios like the 5000 or others like it, I decided this one because it doesn't have the what looks to me like an odd handle for tilting. The build on this one is a little different but will still tilt by using the provided tool.
Once received I will give it a trial run and report back.
The laird nmo-27 has been working so well that I've not been in a huge rush to try the Megawatt 4000. Time constraints have played into not trying it out as well but I'll get to it.
After looking it over well, I realized that there are a few versions of this antenna. There's the regular 4000 black or silver that have the tilt feature then there's the 4000 black/silver rigid that doesn't tilt. I didn't know that until the rigid arrived which is what I ordered unknowingly. It's ok to me, I'll just find a way to hold the whip over to pull the car in the garage.
More to come
After looking it over well, I realized that there are a few versions of this antenna. There's the regular 4000 black or silver that have the tilt feature then there's the 4000 black/silver rigid that doesn't tilt. I didn't know that until the rigid arrived which is what I ordered unknowingly. It's ok to me, I'll just find a way to hold the whip over to pull the car in the garage.
More to come