[TenTec] TWINCOM feedline ?

[Gary Hoffman]

Perry,

Well, naturally, I agree with you. :)

I have to say that I am very pleased to see that this thread
is continuing to be conducted in a very nice fashion... no flaming, just
a good technical discussion.  As always, there exist multiple points of
view worthy of discussion.

My latest comments are these... conventional transmission line
theory is not, in fact, wrong.  It is just that people often try to apply
it under conditions where its prerequisites are not met.

For example... spacing has been discussed.

Now, in the limit... as spacing goes to zero... then the two opposite
points in the line become co-located.  In such a case, all of their
radiation
cancells at all points in space.  It cannot be otherwise.  It most certainly
does not depend on the location of a hypothetical observer.

Now I agree, as I always have, that as the lines become separated by
a non-trivial amount, that then their radiation does not completely cancel.

How perfect is good enough ?  This is left up to the user, but obviously
the lines MUST be a very small fraction of a wavelength apart, or the
theory goes out the window.

Now, RF in the shack is being discussed as if it were connected to the
type of feedline in use.  It is implied that regular transmitting twin lead
type
lead ins ---  PROPERLY applied  --- can and will cause RF in the shack.
This is simply not true.

On the other hand, many persons using Coax will tell you that they get
RF in the shack as well.  This of course can be caused by many
maladies, not just misapplication of the feedline.  I won't go into it here
because a complete treatment is impossible in a short note.

Finally...  ANY RF can cause TVI and other interference.  The SOURCE of
the RF doesn't matter !  It may come from a radiating feedline, but it
may just as well come from the antenna itself, as intended !

The sad fact is that huge numbers of consumer devices are adversely
affected by RF, regardless of the fact that they are supposed to be
designed to accept such interference.

Oh well..  the fast buck rules when it comes to commercial designs I fear.

Regards to all.

73 de Gary, AA2IZ


----- Original Message -----
From: <w8au@sssnet.com>
To: "Gary Hoffman" <ghoffman@spacetech.com>
Sent: Wednesday, October 16, 2002 9:57 PM
Subject: Re: [TenTec] TWINCOM feedline ?


> Gary:
> I hesitate to get involved in the discussion because
> I don't have time enough to address it properly.
> You have been doing a good job!
>
> But I wanted to buttress your counters to "Dr. Jerry's"
> way out concepts by stating that his latest posting confirms
> he "isn't able to see the forest, for the trees..."
>
> Ending his latest epilogue with the statement about open
> lines causing TVI, telephone interference and hot mikes
> really costs him his credibility.   (or part of it)  :-)
>
> Obviously, these maladies are caused by the inadequacies
> of the affected device.   Oh, my.......
>
> Keep up the good work, Gary.
>
> 73,
>
> Perry     w8au
>
>
>