Question about T2FDs
 

In article ,
Eric F. Richards wrote:

Telamon wrote:

Sorry, Telemon, but I disagree with you here. A stopped clock is
right twice a day, and so it is with Dave here.

I'm going to have to disagree with you there as I used to read David's
posts and he was lucky to be right twice a month.

True enough, but it's the same idea, different scale.

I have high regard for Joe Carr and if anyone has a need they should buy
one of his books.

I'm not surprised your experience is good with a T2FD, it's a good
design.

There is a purpose behind the T2FD design and it is for transmit and
receive. For people wanting to use it only for receive the additions to
a basic folded dipole design so it will load well on transmit over a
range of frequencies are not needed and will not help on receive.

I'm not so sure I'm convinced by that, simply because of the amount of
material I've read on the T2FD. Yes, it was designed as a transmit
antenna, and yes, the resistor is vital to that role, but like in a
rhombic or Beverage, it still plays an important role in reception.


For receive only you are much better off using a BALUN of the right
transformation depending on the basic shape of the folded dipole you
construct.

Unfortunately, I've no experience modelling the antenna, or I would do
so to see if that's correct. Do you have a model to back up this
assertion? I'm interested in seeing this result.

I don't model antennas because as don't see the need. A folded dipole is
well understood.

--
Telamon
Ventura, California

Question about T2FDs
 

Telamon wrote:

I don't model antennas because as don't see the need. A folded dipole is
well understood.

But it's not a simple folded dipole.

Somewhere I may have modelling data on the T2FD, but I have more
pressing things to do today.

But whatever -- I don't know why you feel the need to beat on the
thing so much. The bottom line, for /me/, is that it works and works
well. In /my/ situation, it far outperforms a well-designed end-fed
wire.

So my advice to the original poster is, go ahead and try it. For that
matter, try slinky-dipoles, end-fed wires, whatever. See what works
for you, and give it a run.

The original poster can play games like using the resistor, opening
that end of the dipole, shorting that end of the dipole, whatever.
Let him decide what works best for him.

--
Eric F. Richards

"Nature abhors a vacuum tube." -- Myron Glass,
often attributed to J. R. Pierce, Bell Labs, c. 1940

Question about T2FDs
 

On Nov 12, 9:56 am, David wrote:
On Sun, 12 Nov 2006 14:23:44 GMT, Bob Miller
wrote:



I'd wonder how it would compare to an ordinary non-folded,
non-terminated dipole, although that might not be a valid comparison,
since a dipole is typically designed for a single frequency. Oh,
well...

- A dipole, as used by most SWLs, is unbalanced
- and has no CMR.

David can you expand on this comment ?

* Dipole is Un-Balanced {As used by most SWLs}

* Has no CMR.

David what is CMR ?

i want to know - iane ~ RHF

Question about T2FDs
 

On 14 Nov 2006 23:56:14 -0800, "RHF"
wrote:



On Nov 12, 9:56 am, David wrote:
On Sun, 12 Nov 2006 14:23:44 GMT, Bob Miller
wrote:



I'd wonder how it would compare to an ordinary non-folded,
non-terminated dipole, although that might not be a valid comparison,
since a dipole is typically designed for a single frequency. Oh,
well...

- A dipole, as used by most SWLs, is unbalanced
- and has no CMR.

David can you expand on this comment ?

* Dipole is Un-Balanced {As used by most SWLs}

* Has no CMR.

David what is CMR ?

i want to know - iane ~ RHF
.
.
. .
http://www.w8ji.com/common-mode_noise.htm

Question about T2FDs
 

On Nov 15, 5:41 am, David wrote:
On 14 Nov 2006 23:56:14 -0800, "RHF"
wrote:







On Nov 12, 9:56 am, David wrote:
On Sun, 12 Nov 2006 14:23:44 GMT, Bob Miller
wrote:

I'd wonder how it would compare to an ordinary non-folded,
non-terminated dipole, although that might not be a valid comparison,
since a dipole is typically designed for a single frequency. Oh,
well...

- A dipole, as used by most SWLs, is unbalanced
- and has no CMR.

David can you expand on this comment ?

* Dipole is Un-Balanced {As used by most SWLs}

* Has no CMR.

David what is CMR ?

i want to know - iane ~ RHF
.
.
. .http://www.w8ji.com/common-mode_noise.htm- Hide quoted text -- Show quoted text -
David - Thank you ~ RHF
That explains "CMN" Common Mode Noise
? Was CMR a typo ?

Question about T2FDs
 

On 15 Nov 2006 22:05:20 -0800, "RHF"
wrote:



On Nov 15, 5:41 am, David wrote:
On 14 Nov 2006 23:56:14 -0800, "RHF"
wrote:







On Nov 12, 9:56 am, David wrote:
On Sun, 12 Nov 2006 14:23:44 GMT, Bob Miller
wrote:

I'd wonder how it would compare to an ordinary non-folded,
non-terminated dipole, although that might not be a valid comparison,
since a dipole is typically designed for a single frequency. Oh,
well...

- A dipole, as used by most SWLs, is unbalanced
- and has no CMR.

David can you expand on this comment ?

* Dipole is Un-Balanced {As used by most SWLs}

* Has no CMR.

David what is CMR ?

i want to know - iane ~ RHF
.
.
. .http://www.w8ji.com/common-mode_noise.htm- Hide quoted text -- Show quoted text -
David - Thank you ~ RHF
That explains "CMN" Common Mode Noise
? Was CMR a typo ?
.
CMR is the ability of the system to balance out local (near field?)
noise.

Question about T2FDs
 

On Nov 16, 6:27 pm, David wrote:
On 15 Nov 2006 22:05:20 -0800, "RHF"
wrote:







On Nov 15, 5:41 am, David wrote:
On 14 Nov 2006 23:56:14 -0800, "RHF"
wrote:

On Nov 12, 9:56 am, David wrote:
On Sun, 12 Nov 2006 14:23:44 GMT, Bob Miller
wrote:

I'd wonder how it would compare to an ordinary non-folded,
non-terminated dipole, although that might not be a valid comparison,
since a dipole is typically designed for a single frequency. Oh,
well...

- A dipole, as used by most SWLs, is unbalanced
- and has no CMR.

David can you expand on this comment ?

* Dipole is Un-Balanced {As used by most SWLs}

* Has no CMR.

David what is CMR ?

i want to know - iane ~ RHF
.
.
. .http://www.w8ji.com/common-mode_noise.htm-Hide quoted text -- Show quoted text -
David - Thank you ~ RHF
That explains "CMN" Common Mode Noise
? Was CMR a typo ?
.CMR is the ability of the system to balance out local (near field?)
noise.- Hide quoted text -- Show quoted text -

David -?- "CMR" = Common Mode Rejection ~ RHF
http://acronyms.thefreedictionary.co...Mode+Rejection
http://www.edn.com/index.asp?layout=...850&ref=n bra

http://www.benchmarkmedia.com/caig/html/caig04.html
http://www.maxim-ic.com/appnotes.cfm...e_number/2045/