[R-390] Antenna...folded dipole...

Tue, 16 Dec 2003 14:57:49 -0500 (GMT-05:00)

AND - 

The ME-165 SWR meter originaly used with the T-368 transmitter contains TWELVE very nice 600 ohm, 50 watt non-inductive resistors - so you can 'roll your own' terminating resistor for that TTFD.  They also make nice terminating resistors for wire Vees and rhobmics. 

Fair radio has them : http://www.fairradio.com/associ.htm (pic: http://www.fairradio.com/me-165.html)

I found one all beat up with a broken meter for $5 at a hamfest - the resistors were undamaged....a bargain for high-power noninductive R !!!!!

Al, WA0HQQ
..

-----Original Message-----
From: [email protected]
Sent: Dec 16, 2003 1:46 PM
To: [email protected]
Subject: Re: [R-390] Antenna...folded dipole...

I use TTFD dipoles - and have for over 20 years.   I currently have two of them

They are NOT as efficient as a 'tuned' dipole, but on HF, I find the tradeoff of 1-2 'S' units of gain for fast QSY and broadband operation acceptable.  

My R-390A's can't even tell the difference between a TTFD and an ordinary dipole - until you get down to really really small differences in signal and noise.

W4RNL (L B Cebik - http://www.cebik.com/ ) has a couple of really fine articles about them - they are very enlightening.  My operational findings agree closely with his assessments.

No- I don't want to get into any arguments about something else that is better - TTFD's are 'good enough' for me.

Al, WA0HQQ
..

-----Original Message-----
From: Roy Morgan <[email protected]>
Sent: Dec 16, 2003 11:41 AM
To: "Kenneth G. Gordon" <[email protected]>, Dave Faria <[email protected]>
Cc: [email protected]
Subject: Re: [R-390] Antenna...folded dipole...

At 03:08 PM 12/15/03 -0800, Kenneth G. Gordon wrote:
>On 15 Dec 2003 at 10:56, Dave Faria wrote:
>
> > GM list.  I want to build a Folded Dipole antenna for my station.

...No folded dipole I have ever seen in antenna books or other
>literature, or that I have built, ever needed a terminating
>resistor.

Ken and others,

I think he meant the Tilted Terminated Folded Dipole, "TTFD" which does 
have a terminating resistor opposite the feed point and is described quite 
fairly at:
<http://www.radiohc.org/Distributions/Dxers/ttfd2.html>

There have been many "animated discussions" (aka arguments) about the 
principles, use, and performance of these antennas.  Some such discussions 
I have read included reports from fellows who use them in VietNam with 
success.  Apparently a commercial supplier made them for the armed 
forces.   (Was it B&W, perhaps?)

As described at the link above, the thing has wide spacing between the 
parallel wires, a non-inductive terminating resistor that dissipates up to 
one third of the applied power, and performs best with a 6:1 balun at the 
feed point and coax transmission line.

I have neither built one nor talked with anyone who's used one.

Roy

- Roy Morgan, K1LKY since 1959 - Keep 'em Glowing!
7130 Panorama Drive, Derwood MD 20855
Home: 301-330-8828 Work: Voice: 301-975-3254,  Fax: 301-948-6213
[email protected] --

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