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Author Topic: Calculation of broadband TTFD (T2FD) for HF from 1 to 50 MHz  (Read 1749 times)

Offline US5LOC

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Offline LU6DO

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Re: Calculation of broadband TTFD (T2FD) for HF from 1 to 50 MHz
« Reply #1 on: December 09, 2013, 04:47:56 UTC »
Hello my friend. Is possible translate to english the details of antenna
http://goryham.qrz.ru/ant/7/ttfd.htm
73 & Dx de LU6DO
La radio es maravillosa, pero, siempre recuerda que lo más importante en la vida son los afectos y las vivencias.

Offline SM5JAB

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Re: Calculation of broadband TTFD (T2FD) for HF from 1 to 50 MHz
« Reply #2 on: December 09, 2013, 08:57:17 UTC »
Hello my friend. Is possible translate to english the details of antenna
http://goryham.qrz.ru/ant/7/ttfd.htm
73 & Dx de LU6DO


Strictly speaking I don't think you want a TTFD for QRP-operations anyway. Its only virtue is the low SWR over a large range of frequencies. The bandwidth comes at a cost of VERY low efficiency. You lose much power into the antenna's loading resistor. At the lower frequencies it radiates only a few percent of applied power.

In a sense the antenna transforms a 100W transceiver into a QRP-rig...

DF5WW

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Re: Calculation of broadband TTFD (T2FD) for HF from 1 to 50 MHz
« Reply #3 on: December 10, 2013, 09:43:09 UTC »
Hi SM5JAB,

you got right. Broadbandantennas are antennas for high Power. A lot of the power will be heat up the world, hi hi. Not really good antennas for QRP. I prefer doublets or loops with ladderline (open feeder) and a symmetric antenna coupler. Those antennas are "Multibands" and don´t lost 2much of the radiation power.

73´s, Juergen, DF5WW

Offline ve3lyx

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Re: Calculation of broadband TTFD (T2FD) for HF from 1 to 50 MHz
« Reply #4 on: December 11, 2013, 11:37:20 UTC »
MMMMMM I don't know if its so. For years I used only monobands. Even had a cushcraft A 3 on a tower 1/4 wave up. From this QTH it was always difficult. Since stringing a long wire which is a multiband as well and feeding it with a tuner I have never looked back. Best antenna at this particular QTH I have used. In fact I am taking down my inverted vee for 40M next good WX day. I am really a bit upset that all these years I avoided using a multiband antenna with a tuner and when I finally did (more or less to prove it was a waste of time) it turns out to be my top performer. I also use a beverage to receive. No noise and good sig strength. A very well kept secret.  I have come thru experience to believe that different antenna suits different QTHs
Don

DF5WW

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Re: Calculation of broadband TTFD (T2FD) for HF from 1 to 50 MHz
« Reply #5 on: December 11, 2013, 14:03:30 UTC »
Hi Don,

you´re right. A multiband longwire with a good tuner is a fantastic antenna. But the threadowner needs a T2FD and that´s not a good antenna for QRP. A good antenna coupler costs you 1 dB less but a F2FD "eats" mor than 50% of the radiated power and change it into "heat".

Sorry abt. my english but i think you know what i mean ;-) :-)


Offline ve3lyx

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Re: Calculation of broadband TTFD (T2FD) for HF from 1 to 50 MHz
« Reply #6 on: December 11, 2013, 15:24:22 UTC »
Ja kein problem
Dulmage war Dolmetsch
Don