I recently built a decent 3-element 2 M Quad that fits inside my insulated
attic (just barely) and is all connected to my shack. Worked great... The
problem now is that the SWR is very high (3:1) on all freqs above the 145
MHz channels.

I think that the Quad, when tested inside the house had a great match across
the band from what I recall.

This thing is fed with RG-8 and I purposely put a whole bunch of turns into
a 5" coil near the feed point, and I'm wondering if I should have done that
at all now. I'm sure that the match would be different regardless since
it's now located in a different space, and I understand how that can change
things.

It's dark and itchy up there - before I go up there and unwind the whole
BALUN, can you guys tell me whether or not I even need that thing, or have I
got another problem.

FWIW it works great - decent gain and nicely directional - but the SWR is
too high, and it resets all the programmable thermostats clocks in the house
when I key up (interesting RFI huh?) which my attic ground-plane DOES NOT
do.

help?

Kevin VE9-XYZ

On Mon, 12 Jun 2006 19:17:44 GMT, "K. Hastings"
I think that the Quad, when tested inside the house had a great match across
the band from what I recall.

Hi Kevin,

You have just defined its environment.

This thing is fed with RG-8 and I purposely put a whole bunch of turns into
a 5" coil near the feed point, and ... it resets all the programmable thermostats clocks in the house
when I key up (interesting RFI huh?)

Do you find the hidden clue when all the excess verbiage is cleared
away?

A whole bunch of turns is not very specific except to indicate you
probably overdid it and negated any benefit you might have expected.
Would it help to say fewer turns on a smaller form?

That, however, is probably not what is responsible for the SWR. You
are going to have to tune the antenna in place AFTER you successfully
isolate the drive line.

73's
Richard Clark, KB7QHC

"Richard Clark" wrote in message
...
On Mon, 12 Jun 2006 19:17:44 GMT, "K. Hastings"
I think that the Quad, when tested inside the house had a great match
across
the band from what I recall.

Hi Kevin,

You have just defined its environment.

This thing is fed with RG-8 and I purposely put a whole bunch of turns
into
a 5" coil near the feed point, and ... it resets all the programmable
thermostats clocks in the house
when I key up (interesting RFI huh?)

Do you find the hidden clue when all the excess verbiage is cleared
away?

A whole bunch of turns is not very specific except to indicate you
probably overdid it and negated any benefit you might have expected.
Would it help to say fewer turns on a smaller form?

That, however, is probably not what is responsible for the SWR. You
are going to have to tune the antenna in place AFTER you successfully
isolate the drive line.

73's
Richard Clark, KB7QHC

Hi Richard

As you know, I have been getting good results with the high permeability
ferrite tubes for decoupling the coax feed line on my balanced antenna. I
bought a bunch of inexpensive ferrites that were intended for absorbing RFI,
from All Electronics. Would it be practical for Kevin, the orginal poster,
to get decent results with a few ferrites covering the coax where it
seperates from the boom??

Jerry

On Mon, 12 Jun 2006 21:46:31 GMT, "Jerry Martes"
wrote:
Hi Richard

As you know, I have been getting good results with the high permeability
ferrite tubes for decoupling the coax feed line on my balanced antenna. I
bought a bunch of inexpensive ferrites that were intended for absorbing RFI,
from All Electronics. Would it be practical for Kevin, the orginal poster,
to get decent results with a few ferrites covering the coax where it
seperates from the boom??

Hi Jerry,

Sure, but you have the advantage of being able to measure the Z of
those ferrites. However, buying them rummage style and hoping they
will work does not always bring a satisfactory solution.

73's
Richard Clark, KB7QHC

"Richard Clark" wrote in message
...
On Mon, 12 Jun 2006 21:46:31 GMT, "Jerry Martes"
wrote:
Hi Richard

As you know, I have been getting good results with the high permeability
ferrite tubes for decoupling the coax feed line on my balanced antenna.
I
bought a bunch of inexpensive ferrites that were intended for absorbing
RFI,
from All Electronics. Would it be practical for Kevin, the orginal
poster,
to get decent results with a few ferrites covering the coax where it
seperates from the boom??

Hi Jerry,

Sure, but you have the advantage of being able to measure the Z of
those ferrites. However, buying them rummage style and hoping they
will work does not always bring a satisfactory solution.

73's
Richard Clark, KB7QHC

Hi Richard

I realize that I place way more emphasis on "Amateur" in the HAM concept.
I'm not inclined to depend on using only the best component. But, it seems
that any of those ferrite tubes that were intended to be used to minimize
RFI will work well at 144 MHz. So, since they are cheap and available, I
thought it might be worth trying some inexpensive, high permeability tubes
instead of coiling the coax into a coil.
I did measure the impedance across a loop of RG 223 with 4 tubes around
the outside. The problem I come up with is my ignorance of *whats needed*
for adequate decoupling of the balanced antenna from the outside of the
coax.
I depend on you to shed light on alot of the things I try.

Jerry

On Mon, 12 Jun 2006 23:40:19 GMT, "Jerry Martes"
wrote:

I did measure the impedance across a loop of RG 223 with 4 tubes around
the outside. The problem I come up with is my ignorance of *whats needed*
for adequate decoupling of the balanced antenna from the outside of the
coax.

Hi Jerry,

Just think of the antenna as the "source" and consider its
characteristic Z. Now consider the common mode circuit of the
transmission line and its Z. So often this is an unknown, and if we
were always lucky, it would be a half wave multiple to present a very
high Z indeed. Thus 'twould be the end of the story.

How high is high enough? I offer three values for choking:
3 times antenna Z at a minimum;
5 times is practical;
10 times is lab grade.

So, tell us what those 4 tubes measured?

73's
Richard Clark, KB7QHC

If the Swr is better below 145 than above the radiator must be over
length. You need to trim it or match it. If you are measuring through
lot of coax the match at the antenna is a lot worse than 3:1.

Any kind of choke arrangement amounts to working on the wrong problem
to me.

On Mon, 12 Jun 2006 19:17:44 GMT, "K. Hastings"
wrote:


John Ferrell W8CCW

Thanks John - I may have thought the balun assembly was somehow involved.
I'm new to the group and a fairly new amateur, and your respone was the only
one that dealt with my question.

What I thought was a relevant description was mis-read as "excess verbiage"
I guess. I'll try trimming the loop, and hope also to cure the electronic
thermostat problem which is fairly significant.

73

Kevin

e"John Ferrell" wrote in message
...
If the Swr is better below 145 than above the radiator must be over
length. You need to trim it or match it. If you are measuring through
lot of coax the match at the antenna is a lot worse than 3:1.

Any kind of choke arrangement amounts to working on the wrong problem
to me.

On Mon, 12 Jun 2006 19:17:44 GMT, "K. Hastings"
wrote:


John Ferrell W8CCW