At 06:45 PM 8/19/2007, R wrote:

Hi Tony:

I still have it there but it is slow on QSL.net, so I also have it stored at:

http://www.mediafire.com/?3bzn1vuzzjn

it is a lot faster to download.

K5AI / Ron Porter

Thanks Ron! 73, Tony AA2TX

Yes, inquiring minds want to know. I was considering the same modification to the great design to avoid the use of ferrite chokes.

John WAQ4WDL

----- Original Message ----- From: "SV1BSX" [email protected] To: "Anthony Monteiro" [email protected] Cc: [email protected] Sent: Monday, August 20, 2007 9:43 AM Subject: [amsat-bb] Re: 70cm Parasitic Lindy

Hi Tony,

Thanks for publishing of your "Para-Lindy", definitely your arrangement solved all difficulties and puzzles from the previous complicated designs. Its quite simple now and easy to make it, for anybody. My compliments for your clever design.

Just a question:

Why not the coaxial-feeder inside of down-part dipole's tube (as sleeve) but outside of this?

Thanks again for publishing.

73 de Mak, SV1BSX

--- Anthony Monteiro [email protected] wrote:

...

Ron Porter, K5AI was kind enough to convert it to a pdf and put it on his web site. Anyone who wants it can get it here:

http://www.qsl.net/nwlarn/sat/70ParaLindy.pdf

This is from the 2006 AMSAT Space Symposium.

73, Tony AA2TX

---

Building a website is a piece of cake. Yahoo! Small Business gives you all the tools to get online. http://smallbusiness.yahoo.com/webhosting _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb

----- Original Message ----- From: "Anthony Monteiro" [email protected] To: "SV1BSX" [email protected] Cc: [email protected] Sent: Tuesday, August 21, 2007 3:08 AM Subject: [amsat-bb] Re: 70cm Parasitic Lindy

At 09:43 AM 8/20/2007, SV1BSX wrote:

...

Hi Tony,

Thanks for publishing of your "Para-Lindy", definitely your arrangement solved all difficulties and puzzles from the previous complicated designs. Its quite simple now and easy to make it, for anybody. My compliments for your clever design.

Just a question:

Why not the coaxial-feeder inside of down-part dipole's tube (as sleeve) but outside of this?

Thanks again for publishing.

73 de Mak, SV1BSX

Hi Mak,

Thanks for your interest!

When I was working on this last year, I had a lot of trouble getting consistent performance using a sleeve BALUN (i.e. with the coax running down the center) so I came up with the ferrites as an alternative. Just running the coax down the center is not sufficient to decouple the feed from the antenna. Whats more, I want the antenna to be very easy to build using standard plumbing parts and not require any machined parts or require any high-precision work to get good results. This means it needs to have a wide bandwidth.

But, I have continued working on this antenna and hope to have a new version to present at the 2007 AMSAT-NA Space Symposium that will in fact use a sleeve BALUN instead of the ferrites.

The trick is to use a very thin coax cable along with the plumbing parts that dielectrically load the sleeve so that the resulting BALUN presents a high decoupling impedance across a wide bandwidth. This eliminates the need for tuning or high-precision work.

I am still finalizing the design but with a little luck I will have it for the October Symposium.

73, Tony AA2TX

Hola Tony, AA2TX

Usted habla y entiende muy bien espanol y entonces te voj a escribir en castillano.

Como usted sabe lo che pasa sin balun es che la corriente que percurre el lado de un dipolo abierto balanceado conectado al conductor interior de un cable coaxial no es igual a la corriente que percurre el lado del dipolo conectado pero con la media del cable.

Este pasa por la razones muy bien explicadas en el libro escribido por Walter M. Maxell W2DU "REFLECTIONS Transmission Lines and Antennas "

Yo creo que es posible de hacer un balun-bazuka con relacion de impedancia 1/1 para la antena Parasitic Lindy en manera muy simple de esta forma.

El balun-bazuka se compone de un trozo de media recuperada por un qualquier cable coaxial posiblemente de trama muy espesa.

El trozo de media tiene que ser enfilado sovre la funda de polivinil del cable de alimentacion de la Lindy y su largueza para 435 MHz tiene que ser de 81 mm a partir desde el punto donde el cable es conectado al dipolo

La otra estremidad del trozo de media largo 81 mm tiene que ser saldada al esterior de la media del cable de alimentacion pero dejando libre el lado avierto cerca del dipolo.

El punto de saldatura de la dos medias tiene que ser protegido con Heat-Sink tubing

De esta forma siendo la media del cable y la media del balun un cortocircuito en el punto de saldatura la impedancia del quarto de onda en este punto es zero ohmios siendo pero infinita al otro lado cerca del dipolo donde el trozo es mantenido abierto y el voltaje es elevado.

A partir del dipolo la corriente que percurre atras la parte esterior de la media del cable de alimentacion larga 81 mm es igual y contraria a la corriente que percurre con reflexion total la parte interior de la media del balun-bazuka largo tambien 81 mm

Las dos corrientes son iguales pero siendo con ida y vuelta contraria con reflexion total al punto del corto estas se borran una con la otra dentro de el balun-bazuka y no pueden ser irradiadas por la restante media del cable che sale hasta el equipo Receptor/Trasmisor

De donde viene la largueza de 81 mm para el quarto de onda de media a 435 MHz ?

Simplemente porque el dielectrico entre la media del balun y la media del cable de alimentacion no es aire si no es PVC II quere decir Vinil Polychlorure que tiene una constante dielectrica desde 4 hasta a 5 a segun del tipo.

Considerando un valor medio de 4.5 para el dielectrico segue que el factor de velocidad Fv para las corrientes que percurren el interior del balun es:

Fv = 1/(SQR 4.5) = 0.47 con respecto a la velocidad de la luz

Sigue que:

1/4 de onda electrico para 435 MHz = 300/435/4 * 0.47 = 81 mm

Este deberia ser un balun-bazuka con relacion 1/1 muy simple y sovre todo muy barato.

Vamos a ver si esta idea nos trabaja.

73" de

i8CVS Domenico (AKA Domingo)