http://www.barrettcommunications.com...nantennas.html
i have some old antenna books could not find any information on it
it's the 912 model i'm asking about
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http://www.barrettcommunications.com...nantennas.html
i have some old antenna books could not find any information on it
it's the 912 model i'm asking about
Just looks like a pretty standard dipole to me. You could build one yourself for $20-30, most of that going into the balun.
That's a T2FD:
http://www.hard-core-dx.com/nordicdx.../t2design.html
Broadband, to be sure....but you're not going to be able to run high power unless you source a high-wattage, non-inductive resistor for the thing.
The above being said, a T2FD makes a great low-noise receiving antenna - but it'll be down an S-unit or so in received signal strength as compared to a dipole of the same dimensions. A lot of DXers use them.
The Barrett 912 in the 3 wire terminated configuration is a double first cousin to the cage dipole.
These were sometimes referred to as a "clothesline antenna" years ago, also closely related to the "T2FD".
A bit awkward to build from scratch (not as bad as the cage dipole) but broad banded nun the less.
Would not be my recommendation for a part of the country where snow & ice are common unless built out of very heavy gauge materials.
Used to be seen commonly at the large commercial stations in the 30's & 40's .
The minute I see power limitations in the specs, I say "no thanks". I have no desire to waste my power heating up a resistor pack.
thanks i didn't see anything about a resister in the advertising
if so that just makes it the piece of crap that icom sells for a broadband antenna
too bad , i have access to ss cable i thought it would make an interesting project to build
You won't. It's implied by the simple fact that the claims are 2-30Mhz @ 50 ohms, fed with coax. That's simply not possible without a "matching network" at the feed-point, based on what the 912 looks like. The only thing (IMO) that could present that impedance over that wide a range of frequencies is a resistor. The second hint is the different models with different power ratings. Larger resistors for better heat dissipation at the higher power levels.Quote:
Originally Posted by VE7MGF
Icom, Yaesu, B&W, and several others.Quote:
if so that just makes it the piece of crap that icom sells for a broadband antenna
A simple 135 foot dipole, fed with ladder line directly to a tuner, is a perfectly fine "broadband" antenna and will be more efficient than the 912 overall.Quote:
too bad , i have access to ss cable i thought it would make an interesting project to build
i know the length of 135 ft dipole would put it outside my property line
i just have to go with a folded dipole with about one foot spreaders
i am still trying to find 14g ladder line around here
How much room do have?Quote:
Originally Posted by VE7MGF
Why? I run a KW into 18g ladder line.Quote:
i am still trying to find 14g ladder line around here
You can "get away with" about 90' or so with that balanced line doublet.
http://i104.photobucket.com/albums/m...xr/antenna.jpg
While we are naming antennas, there is one near where I work on a 10 story building I cannot figure out. Anyone recognIZE this one?
Oh, yeah—that's Larry.Quote:
Originally Posted by X-Rated
Larry is high.Quote:
Originally Posted by KJ6BSO
I got to wondering if it is a co-linear antenna for the VHF low bands?Quote:
Originally Posted by X-Rated
A CB antenna with a beer can stuck on it?
Mercy sake. Sake, please, bartender.Quote:
Originally Posted by kb2vxa
That 2030 transceiver looks nice - bet I can't even afford to think about one!
Must be one of them Beverage antennas.Quote:
Originally Posted by KG4NEL
That joke was pour.Quote:
Originally Posted by KJ6BSO
Makes for a great home-brew antenna, though.Quote:
Originally Posted by X-Rated
Maybe, but it would be difficult to avoid the Miller Effect.Quote:
Originally Posted by KJ6BSO
Ah, but the can is too low on the radiator for use of the Miller Effect, capacitive end loading aka a top hat. It asserts that a floating impedance element, supplied by two voltage sources connected in series, may be split into two grounded elements with corresponding impedances. That implies an antenna of a radically different design, perhaps the can is insulated from (floating) the radiator and the four grounded elements lowering corresponding impedance by half, the characteristic 50 ohms.
Back when I made beer can antennas using the Budweiser Effect feed-point impedance was calculated using standard means. Unfortunately today's aluminium cans have the same electrical characteristics as steel BUT are difficult to solder and too flimsy to be practical for anything else but containers for carbonated panther piss.