Feed Line Length - Ladder Line
 

I've had a store bought (so sue me) dipole fed with 600 ohm ladder line up
35 feet for about a year and a half now and I love this antenna. It's 66
feet in length and I can pretty much tune everything from 40 through 10
meters with a Dentron Super Tuner. This thing came with 50 feet of ladder
line and I have it draped all over the place trying to take up the slack
before it finally feeds into the shack.

My question is can I safely cut some of this excess ladder line off? I
assume that it will impact the tuning but I'm also assuming the tuner will
take care of it. I guess I can always cut it off and if it doesn't work I
can wire nut it back together again. It just looks sloppy with all this
extra feed line drooping off the roof and suspended by the fence (and over
to grandma's house we go) before it finally comes into the shack.

Your thoughts are appreciated.

Pat Whelton wrote:
My question is can I safely cut some of this excess ladder line off? I
assume that it will impact the tuning but I'm also assuming the tuner will
take care of it.

May be a rash assumption. Trimming the feedline will change the
impedance the tuner sees and the tuner may (or may not) like the
new impedances. How about downloading the free demo version of
EZNEC from www.eznec.com and seeing for yourself what the
tuner will see?
--
73, Cecil http://www.qsl.net/w5dxp


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On Sun, 03 Jul 2005 17:50:55 GMT, "Pat Whelton"
wrote:

I've had a store bought (so sue me) dipole fed with 600 ohm ladder line up
35 feet for about a year and a half now and I love this antenna. It's 66
feet in length and I can pretty much tune everything from 40 through 10
meters with a Dentron Super Tuner. This thing came with 50 feet of ladder
line and I have it draped all over the place trying to take up the slack
before it finally feeds into the shack.

My question is can I safely cut some of this excess ladder line off? I
assume that it will impact the tuning but I'm also assuming the tuner will
take care of it. I guess I can always cut it off and if it doesn't work I
can wire nut it back together again. It just looks sloppy with all this
extra feed line drooping off the roof and suspended by the fence (and over
to grandma's house we go) before it finally comes into the shack.

Your thoughts are appreciated.

Cut it, there is nothing magic about 50' other than it's half of 100'.

BTW, is it really 600 ohm line or window line?

50 foot is a neat length in that if you plot all the impedances at the
various bands you fill find a current max fairly close to 50 feet.

Cutting the length may move you closer to a match on some frequencies and
further away, and beyond the range of your tuner on others. I am not
familiar with the specs of your tuner so can not be more definitive.

All this being said, cut it, if your tuner matches it your golden. If not
reattach the cut section.

Take a look at Cecil's site, he has an antenna that he tunes via feedline
length. He has a number of graphs and a smith chart that will answer your
questions.
http://www.qsl.net/w5dxp/notuner.htm

"Pat Whelton" wrote in message
k.net...
I've had a store bought (so sue me) dipole fed with 600 ohm ladder line up
35 feet for about a year and a half now and I love this antenna. It's 66
feet in length and I can pretty much tune everything from 40 through 10
meters with a Dentron Super Tuner. This thing came with 50 feet of ladder
line and I have it draped all over the place trying to take up the slack
before it finally feeds into the shack.

My question is can I safely cut some of this excess ladder line off? I
assume that it will impact the tuning but I'm also assuming the tuner will
take care of it. I guess I can always cut it off and if it doesn't work I
can wire nut it back together again. It just looks sloppy with all this
extra feed line drooping off the roof and suspended by the fence (and over
to grandma's house we go) before it finally comes into the shack.

Your thoughts are appreciated.

Pat, the correct length for a feedline is that which reaches from the feed point
of the antenna to the terminals of the tuner.

Having used the Dentron Supertuner I doubt if you'll have any trouble matching
any impedance you'll find at the input of the feed line.

If it doesn't match on any particular band there are four ways to achieve the
match, depending on the specific impedance at the input of the line. Try a
series cap in the line, or try a parallel cap across the line, or do the same
thing with an inductor to see which works. It's cut and try, but it's better
than having the line coiled up in the bathtub.

Walt, W2DU

Pat Whelton wrote:
I've had a store bought (so sue me) dipole fed with 600 ohm ladder line up
35 feet for about a year and a half now and I love this antenna. It's 66
feet in length and I can pretty much tune everything from 40 through 10
meters with a Dentron Super Tuner. This thing came with 50 feet of ladder
line and I have it draped all over the place trying to take up the slack
before it finally feeds into the shack.

My question is can I safely cut some of this excess ladder line off? I
assume that it will impact the tuning but I'm also assuming the tuner will
take care of it. I guess I can always cut it off and if it doesn't work I
can wire nut it back together again. It just looks sloppy with all this
extra feed line drooping off the roof and suspended by the fence (and over
to grandma's house we go) before it finally comes into the shack.

Your thoughts are appreciated.


I'M SHOPPING FOR SUCH AN ANTENNA

Who sells it? specs, price etc.

remove nospam
Yodar in O'do

CUT IT OFF

Pat Whelton wrote:

I've had a store bought (so sue me) dipole fed with 600 ohm ladder line up
35 feet for about a year and a half now and I love this antenna. It's 66
feet in length and I can pretty much tune everything from 40 through 10
meters with a Dentron Super Tuner. This thing came with 50 feet of ladder
line and I have it draped all over the place trying to take up the slack
before it finally feeds into the shack.

My question is can I safely cut some of this excess ladder line off? I
assume that it will impact the tuning but I'm also assuming the tuner will
take care of it. I guess I can always cut it off and if it doesn't work I
can wire nut it back together again. It just looks sloppy with all this
extra feed line drooping off the roof and suspended by the fence (and over
to grandma's house we go) before it finally comes into the shack.

Your thoughts are appreciated.

Yodar wrote:
Pat Whelton wrote:
I've had a store bought (so sue me) dipole fed with 600 ohm ladder line up
35 feet for about a year and a half now and I love this antenna. It's 66
feet in length and I can pretty much tune everything from 40 through 10
meters with a Dentron Super Tuner. This thing came with 50 feet of ladder
line and I have it draped all over the place trying to take up the slack
before it finally feeds into the shack.

My question is can I safely cut some of this excess ladder line off? I
assume that it will impact the tuning but I'm also assuming the tuner will
take care of it. I guess I can always cut it off and if it doesn't work I
can wire nut it back together again. It just looks sloppy with all this
extra feed line drooping off the roof and suspended by the fence (and over
to grandma's house we go) before it finally comes into the shack.

Your thoughts are appreciated.


I'M SHOPPING FOR SUCH AN ANTENNA

Who sells it? specs, price etc.

remove nospam
Yodar in O'do


Yodar, where are you shopping? Go to Lowes or Home Depot and get #14
stranded wire, plexiglas for insulators, and screws, nuts and bolts to
put it together. Get some 450 ohm ladder line (Wireman, w7fg I think),
or make your own from wire and PVC from Lowes. To put the whole thing
together should be 30 minutes or less, I do it every year at field day.
Make the dipole as long and high (within reason) as you have room for,
and the 450 ohm line long enough to get from the antenna feedpoint to
your tuner. There you have what you have been shopping for.
Radioworks among other folks have pre-put together antennas, but
where is the fun in that?
Gary N4AST

You would be hard pressed to beat the VanGorden antenna. 130 foot stranded
wire dipole with 100 feet of 450 Ohm ladder line. All insulators, ready to
go for $29.95 delivered to your door.

"Yodar" wrote in message
om...
I'M SHOPPING FOR SUCH AN ANTENNA

Who sells it? specs, price etc.

remove nospam
Yodar in O'do

On Tue, 05 Jul 2005 22:14:20 GMT, Yodar wrote:

Pat Whelton wrote:
I've had a store bought (so sue me) dipole fed with 600 ohm ladder line up
35 feet for about a year and a half now and I love this antenna. It's 66
feet in length and I can pretty much tune everything from 40 through 10
meters with a Dentron Super Tuner. This thing came with 50 feet of ladder
line and I have it draped all over the place trying to take up the slack
before it finally feeds into the shack.

My question is can I safely cut some of this excess ladder line off? I
assume that it will impact the tuning but I'm also assuming the tuner will
take care of it. I guess I can always cut it off and if it doesn't work I
can wire nut it back together again. It just looks sloppy with all this
extra feed line drooping off the roof and suspended by the fence (and over
to grandma's house we go) before it finally comes into the shack.

Your thoughts are appreciated.


I'M SHOPPING FOR SUCH AN ANTENNA

Who sells it? specs, price etc.

remove nospam
Yodar in O'do


he probably has one of the 600-ohm fed dipoles from www.w7fg.com

try their web site.

there are also lots of dipole kits at www.thewireman.com

or get the arrl's antenna book & do-it-yrself. fun.

bob
k5qwg