135 ft flat top antennas, again, ad infinitum

[George-122]

My 2 cents worth is:  Theory is one thing and actuality is another thing.   I use a 130 ft inverted vee, fed with about 55 ft of 450 ohm ladder line.  The apex of the vee is about 65 ft up.  The ladder line stops at the eave of my house, just outside the shack, where I use a 4:1 balun.  From the balun to the homebrew tuner, I use a 7 or 8 ft piece of RG 213.  It works FB on all bands from 80-10 m, including 30 m, and is absolutely the best all band wire antenna I have used in my 51 yrs of hamming.  It works especially well on 75 and 80 m.  It would possibly work even better if I broke up (with insulators) the guy wire which is almost parallel to one leg of the vee.  Also, the antenna is surrounded by several trees which are 15-25 ft higher than the antenna.  I guess the moral to this is, don't let theory stop you from trying stuff.

73, N4ym
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[Sandy W5TVW]

I would strongly warn everyone who uses this method of feeding the centerfed
"tuned feeder" dipole about a problem with this.  Let me start by saying I have
done it and still do it with lowered powered rigs (under 100 watts).
There IS a danger, that of overheating the 4:1 balun and losses in the balun
( or even destruction!) under some conditions.
Most "baluns" want to see a relatively reactance free impedance transformation.
Also one which is close to the transformation ratio (commonly 1:1 or 4:1)
I use a 135' dipole at 50' with about 100 feet of 450 ohm line.  The impedances
presented to the "generator" are usually not (in my case) a 4:1 ratio or have
a lot of inductive or capacitive reactance on some bands.  Broadband baluns
don't like this condition and when higher powers are used,the baluns will
cause losses and/or overheat under these conditions.  After playing with
baluns for quite a number of years, I decided to try the old fashioned
"balanced line" antenna tuner configuration instead of the "T" network
high pass transmatch (most commonly available "tuner") and a 4:1 or a 1:1
broadband balun.  Yes, the balun WILL work under a lot of conditions
but not really well.  Only if the transformation ratio is "in the ballpark"
or a high reactance condition does not exist and the feed point presented
to the output end of the balun.
A "balun" is no cure all or "simple solution" for a proper matching network,
or the "proper network" for matching an unbalanced 50 ohm transmitter
to a "tuned feeder" type dipole.  I repeat: It WILL work or appear to work
under a lot of circumstances, but often times is an inefficient way of
doing things.  One quickly finds out about this when using higher powers
and when the conditions are not within the normal parameters of the
"balun".
I repeat again, I have done this many times, but I usually cringe at doing it
because of the reasons stated.  If you are running QRP, you want every
microwatt you can muster into the "ether" to be radiated, not thrown
away as heat.  Ditto for high powers, except at kilowatt levels, sometime
improper devices will burn and smoke or at least get very hot.  Why throw
the power away?

My two penny's worth.

73,
Sandy W5TVW

----- Original Message -----
From: "George" <[hidden email]>
To: <[hidden email]>
Sent: Tuesday, October 03, 2006 3:23 PM
Subject: [Elecraft] 135 ft flat top antennas, again, ad infinitum


| My 2 cents worth is:  Theory is one thing and actuality is another thing.   I use a 130 ft
inverted vee, fed with about 55 ft of 450 ohm ladder line.  The apex of the vee is about 65 ft up.
The ladder line stops at the eave of my house, just outside the shack, where I use a 4:1 balun.
>From the balun to the homebrew tuner, I use a 7 or 8 ft piece of RG 213.  It works FB on all bands
from 80-10 m, including 30 m, and is absolutely the best all band wire antenna I have used in my 51
yrs of hamming.  It works especially well on 75 and 80 m.  It would possibly work even better if I
broke up (with insulators) the guy wire which is almost parallel to one leg of the vee.  Also, the
antenna is surrounded by several trees which are 15-25 ft higher than the antenna.  I guess the
moral to this is, don't let theory stop you from trying stuff.
|
| 73, N4ym
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[k6dgw]

George N4YM wrote:
> I use a 130 ft inverted vee, fed with about 55 ft of 450 ohm ladder line.
 > The apex of the vee is about 65 ft up.  The ladder line stops at the
 > eave of my house, just outside the shack, where I use a 4:1 balun.
 > From the balun to the homebrew tuner, I use a 7 or 8 ft
 > piece of RG 213.

I knew I should have patented this antenna! ;-)  Mine is 135 ft (42.148
meters) on each leg with a central angle of about 120 deg opening east.
  The ends are a little over head height.  The apex is at 70 ft (21.366
meters) right below the tri-bander.  I used EZNEC4+ to model the feed
impedance, and then TLW (ARRL Antenna Book, 20th Ed, and also available
on the ARRL Web site) to calculate a compromise length of 450 ohm ladder
line (turned out to be 61 ft) where I put a DX Engineering 10 KW 4:1
balun.  Coax to the shack is about 120 ft (36.576 meters) of RG-214.  I
use a tuner in the shack to put 50 ohms on the Tx, but actually the SWR
isn't all that bad.  The KAT2 and KAT100 match it easily

It is a fairly efficient cloud warmer on 160, although I've worked JA,
HL, and one VK on it.  It's gangbusters to the east about as far as
Omaha, and then starts to peter out, although I have worked the East
Coast a few times with 100W. It seems to excel on 80 and has a much
lower radiation angle.  It's pretty directive on 40, and works great
E-W, but not too cool into WA, OR, and VE6/7.  Oddly, when the path is
open, VY1 is very strong on it as are KL7's.  It works great on 30 and
sort of OK on 20.  Above 20, the pattern gets really goofy with lobes
squirting RF all over the place ... not always where I would like it.

YMMV, but you never know until you try

Fred K6DGW
Auburn CA CM98lw
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[Tom Skinner-3]

George wrote...

"I guess the moral to this is, don't let theory stop you from trying stuff."

I would like to add what I firmly believe is the ONLY absolutely true law of
physics when it comes to antennas.  I learned it in the mid-50's and it is
just as true today...

"If it stays up, it ain't big enough."

72 es 73,

Tom, KJ3D (K2: 4991)




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[Paul Gates, KD3JF]

Hey George you said it right!! I have been reading all the
email about what will work and won't. The best antenna I
ever haad was the 130 ft Vee feeding it with 450 ohm ladder
line. Now don't laugh, the length of the feedline was
whatever it took from the center of the VEE to my shack!
Then I hooked up the ladder line to tuner and 4to1 balun.
It worked on every band fine!

I would have that kind of antenna here but would have to
move a couple of buildings. I live in an apt above the
church and I just cannot swing it. I have thought about it
a lot. I have the G5RV up at present.

I do have made up a 40 meter Delta loop I would like to get
up off of the deck but that will have to come after
surgery. Next Tuesday I go in for a full replacement on my
right knee. I had the left leg done a year ago and it is
fine.

Paul, KD3JF

--- George <[hidden email]> wrote:

> My 2 cents worth is:  Theory is one thing and actuality
> is another thing.   I use a 130 ft inverted vee, fed with
> about 55 ft of 450 ohm ladder line.  The apex of the vee
> is about 65 ft up.  The ladder line stops at the eave of
> my house, just outside the shack, where I use a 4:1
> balun.  From the balun to the homebrew tuner, I use a 7
> or 8 ft piece of RG 213.  It works FB on all bands from
> 80-10 m, including 30 m, and is absolutely the best all
> band wire antenna I have used in my 51 yrs of hamming.
> It works especially well on 75 and 80 m.  It would
> possibly work even better if I broke up (with insulators)
> the guy wire which is almost parallel to one leg of the
> vee.  Also, the antenna is surrounded by several trees
> which are 15-25 ft higher than the antenna.  I guess the
> moral to this is, don't let theory stop you from trying
> stuff.
>
> 73, N4ym
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
>  http://mailman.qth.net/mailman/listinfo/elecraft
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>

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[crmabbott]

Amen!

>"If it stays up, it ain't big enough."
>
73 Chuck AA8VS

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[roncasa]

I can see Spock saying, in his confused expression, "That is not
logical".
"Why would one want a antenna that keeps falling" ??

(smile)

Ron, wb1hga

Chuck wrote:
> Amen!
>
>
>>"If it stays up, it ain't big enough."
>>
>
> 73 Chuck AA8VS
>

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[Joseph Reed-2]

Perhaps as Dr. McCoy would say "Damnit Jim, I'm a doctor not an engineer."

----- Original Message ----
From: ron <[hidden email]>
To: "[hidden email]" <[hidden email]>
Sent: Wednesday, October 4, 2006 4:07:31 PM
Subject: Re: [Elecraft] 135 ft flat top antennas, again, ad infinitum


I can see Spock saying, in his confused expression, "That is not
logical".
"Why would one want a antenna that keeps falling" ??

(smile)

Ron, wb1hga
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[crmabbott]

----- Original Message -----
From: "George" <[hidden email]>
To: <[hidden email]>
Sent: Tuesday, October 03, 2006 4:23 PM
Subject: [Elecraft] 135 ft flat top antennas, again, ad infinitum


"My 2 cents worth is:  Theory is one thing and actuality is another thing.
I use a 130 ft....."

There is experience, judgement and theory.  When it comes to antennas
judgement comes
from experience and experience comes from both good and bad judgements.  But
don't
hesitate to try stuff!

<snip>
73
---
Chuck
"In theory there is no difference between
 theory and practice.  But in practice there is.."


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