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In article .com,
"RHF" wrote: On Feb 15, 6:30 pm, Telamon wrote: In article .com, "tom k in L.A." wrote: On Feb 14, 7:57 pm, Telamon wrote: In article .com, "tom k in L.A." wrote: anyone use a t2fd here? i'm considering replacing my longwire with a t2fd-- but i can't mount it on a slope-- will i be wasting my time and money? It would be a good move. Sloping it is not important. really? some people feel strongly about the sloping. elaborate telamon-- if i can get 1/2 the reception you do i will be a happy pappy! This antenna originated as a ship broadband antenna where there are stays that could be used as an antenna if insulated. The stays on a ship slope. Generally for reception higher is better so I would nix the sloping idea. You can build a simple folded dipole antenna out of TV 300 ohm twin lead and use a common 300 to 75 ohm BALUN. The TV/FM BALUN transformers are not all created equal. Some are poor below 15MHz. The BALUN units with more heft indicate a bigger core that will work well down into the AMBCB band. The twin lead will not support itself so you could tie-wrap it to nylon cord or rope. It would be good if the antenna was at least 40 foot long and longer would be better. If this works well for you then go to the trouble of building a larger capture area antenna. Telamon, Yes 300 Ohm TV type Twin-Lead will work for a Quik-and-Dirty T2FD. To simply construction - Instead of a single 450 Ohm Resistor in the Center of the upper T2FD Antenna Element with the 4:1 Balun in the Center of the Lower T2FD Antenna Element. Put a 220 Ohm Resistor at each end of the Twin-Lead. I would not use resistors at all. They are not desirable for a folded dipole. And Yes Again - You are right that the better quality 300 Ohm to 75 Ohm TV type Matching Transformers {Baluns} can work down to at least 5 MHz and as you point out these are usually the larger diameter ones which have a bigger Ferrite Cord, which is the key performance difference, besides increasing the number of windings. IIRC - John Doty wrote about using the Binocular Ferrite Cores from TY type Matching Transformers and -re-winding them with more windings to get better performance across the Shortwave (HF) Bands and down into the AM/MW Band. - - - Searching . . . You can more inductance with short lengths of wire with a binocular core. They make excellent transmission line transformers. -- Telamon Ventura, California |
#12
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On Feb 17, 2:14 am, Telamon
wrote: In article .com, "RHF" wrote: On Feb 15, 6:30 pm, Telamon wrote: In article .com, "tom k in L.A." wrote: On Feb 14, 7:57 pm, Telamon wrote: In article .com, "tom k in L.A." wrote: anyone use a t2fd here? i'm considering replacing my longwire with a t2fd-- but i can't mount it on a slope-- will i be wasting my time and money? It would be a good move. Sloping it is not important. really? some people feel strongly about the sloping. elaborate telamon-- if i can get 1/2 the reception you do i will be a happy pappy! This antenna originated as a ship broadband antenna where there are stays that could be used as an antenna if insulated. The stays on a ship slope. Generally for reception higher is better so I would nix the sloping idea. You can build a simple folded dipole antenna out of TV 300 ohm twin lead and use a common 300 to 75 ohm BALUN. The TV/FM BALUN transformers are not all created equal. Some are poor below 15MHz. The BALUN units with more heft indicate a bigger core that will work well down into the AMBCB band. The twin lead will not support itself so you could tie-wrap it to nylon cord or rope. It would be good if the antenna was at least 40 foot long and longer would be better. If this works well for you then go to the trouble of building a larger capture area antenna. Telamon, Yes 300 Ohm TV type Twin-Lead will work for a Quik-and-Dirty T2FD. To simply construction - Instead of a single 450 Ohm Resistor in the Center of the upper T2FD Antenna Element with the 4:1 Balun in the Center of the Lower T2FD Antenna Element. Put a 220 Ohm Resistor at each end of the Twin-Lead. I would not use resistors at all. They are not desirable for a folded dipole. And Yes Again - You are right that the better quality 300 Ohm to 75 Ohm TV type Matching Transformers {Baluns} can work down to at least 5 MHz and as you point out these are usually the larger diameter ones which have a bigger Ferrite Cord, which is the key performance difference, besides increasing the number of windings. IIRC - John Doty wrote about using the Binocular Ferrite Cores from TY type Matching Transformers and -re-winding them with more windings to get better performance across the Shortwave (HF) Bands and down into the AM/MW Band. - - - Searching . . . You can more inductance with short lengths of wire with a binocular core. They make excellent transmission line transformers. -- Telamon Ventura, California- Hide quoted text - - Show quoted text - I have TTFD Twisted Terminated Folded Dipole in my attic in my other QTH and it is a fine antenna. I couldn't tilt it so RHF suggested twisting it and it works very nice. If you aren't going to transmit on it then you probably will want to delete the terminating resistor. A fine antenna. I have to rig my qth for silent running so you are better to put out in the back yard. I'm off this morning to look for a new QTH here in Rochester, NY. 3.5 acres for some nice antennas I hope. regards, NEO |
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