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Old April 22nd 05, 11:17 AM
Gary
 
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Default Coax Length for G5RV and Center Support for Ladder Line ?

I've done a bit of reading on G5RV's and I plan to just use the
standard configuration of a 102' dipole center fed with 32' of 450 Ohm
ladder line. Then I'm going to attach RG8X to the ladder line and
right near the connection construct a current choke of 8 turns of coax
about 6" in diameter. And then run the coax to my antenna tuner. some
of the sites I've run across mention that the G5RV needs at least 70'
of coax to function properly. This seems pretty lossy to me and I
don't see the need for the 70' of coax, perhaps someone can enlighten
me ? I'd like to keep the run of coax as short as possible.

Also I was digging through my insulators and I can't find one that
would offer strain relief for the ladder line and perhaps a connection
on top to use a wire or rope to add support to the center of the
antenna. I wonder if anyone has a source for one.

Once again, thanks in advance.

73 Gary K8IQ

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Old April 22nd 05, 12:44 PM
KC1DI
 
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HI Gary,

If you have read the excellent Article by Cebik you should take a look
at it you can find it at http://www.cebik.com/wire/g5rv.html

The best thing if your using 450 ohm window line would be the ladder
grabber think you can get it from the Wireman www.thewireman.com

the 70' of coax helps on 3.5 mhz but i'm with you keep it as short as
possible.

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Old April 22nd 05, 04:46 PM
Cecil Moore
 
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Gary wrote:
Also I was digging through my insulators and I can't find one that
would offer strain relief for the ladder line and perhaps a connection
on top to use a wire or rope to add support to the center of the
antenna. I wonder if anyone has a source for one.


I use the black UV-resistant tie wraps for strain relief.
Run the tie wrap through one of the ladder-line windows
and then through the hole in the insulator. With stranded
ladder-line, I have had absolutely no problem with this
method.
--
73, Cecil, W5DXP

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Old April 22nd 05, 05:13 PM
Cecil Moore
 
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Gary wrote:
I've done a bit of reading on G5RV's and I plan to just use the
standard configuration of a 102' dipole center fed with 32' of 450 Ohm
ladder line.


According to EZNEC, here are the 50 ohm SWRs that you will
encounter if your 450 ohm ladder-line has a velocity factor
of 0.9. 3.8HMz, 17:1 7.2MHz, 4.8:1 10.125MHz, 55:1
14.2MHz, 2:1 18.14MHz, 35:1 21.3MHz, 23:1 25.95MHz, 2.5:1
28.4MHz, 60:1. You will definitely need a tuner. One wonders
if you couldn't do better with ladder-line all the way to the
tuner.
--
73, Cecil, W5DXP


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Old April 22nd 05, 07:40 PM
Bob Miller
 
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On Fri, 22 Apr 2005 06:17:21 -0400, Gary wrote:

I've done a bit of reading on G5RV's and I plan to just use the
standard configuration of a 102' dipole center fed with 32' of 450 Ohm
ladder line. Then I'm going to attach RG8X to the ladder line and
right near the connection construct a current choke of 8 turns of coax
about 6" in diameter. And then run the coax to my antenna tuner. some
of the sites I've run across mention that the G5RV needs at least 70'
of coax to function properly. This seems pretty lossy to me and I
don't see the need for the 70' of coax, perhaps someone can enlighten
me ? I'd like to keep the run of coax as short as possible.


See g5rv's article at http://www.qsl.net/aa3px/g5rv.htm

He said you can use up to 70 feet of coax and not suffer too much
loss; the shorter the better, tho'

He also had other recommendations for feedlines.

bob
k5qwg



Also I was digging through my insulators and I can't find one that
would offer strain relief for the ladder line and perhaps a connection
on top to use a wire or rope to add support to the center of the
antenna. I wonder if anyone has a source for one.

Once again, thanks in advance.

73 Gary K8IQ




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Old April 23rd 05, 03:54 AM
Gary
 
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Default

On 22 Apr 2005 04:44:03 -0700, "KC1DI" wrote:

HI Gary,

If you have read the excellent Article by Cebik you should take a look
at it you can find it at http://www.cebik.com/wire/g5rv.html

The best thing if your using 450 ohm window line would be the ladder
grabber think you can get it from the Wireman www.thewireman.com

the 70' of coax helps on 3.5 mhz but i'm with you keep it as short as
possible.


Thanks for the info !!

73 Gary K8IQ
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Old April 23rd 05, 03:56 AM
Gary
 
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Default

On Fri, 22 Apr 2005 10:46:08 -0500, Cecil Moore
wrote:

Gary wrote:
Also I was digging through my insulators and I can't find one that
would offer strain relief for the ladder line and perhaps a connection
on top to use a wire or rope to add support to the center of the
antenna. I wonder if anyone has a source for one.


I use the black UV-resistant tie wraps for strain relief.
Run the tie wrap through one of the ladder-line windows
and then through the hole in the insulator. With stranded
ladder-line, I have had absolutely no problem with this
method.


Thanks Cecil, I had that idea in the back of my head but didn't know
how practical it was. I've got large number of black tie wraps
already. I don't know if they're UV resistant or not but I'll give it
a try.

73 Gary
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Old April 23rd 05, 04:10 AM
Gary
 
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On Fri, 22 Apr 2005 11:13:44 -0500, Cecil Moore
wrote:

Gary wrote:
I've done a bit of reading on G5RV's and I plan to just use the
standard configuration of a 102' dipole center fed with 32' of 450 Ohm
ladder line.


According to EZNEC, here are the 50 ohm SWRs that you will
encounter if your 450 ohm ladder-line has a velocity factor
of 0.9. 3.8HMz, 17:1 7.2MHz, 4.8:1 10.125MHz, 55:1
14.2MHz, 2:1 18.14MHz, 35:1 21.3MHz, 23:1 25.95MHz, 2.5:1
28.4MHz, 60:1. You will definitely need a tuner. One wonders
if you couldn't do better with ladder-line all the way to the
tuner.


Well I've got two MFJ tuners ( one for use while the other's in for
repairs ;-) ) . The 949E is in for repairs, I've had it for about a
year or so and ( I think ) the diodes popped on the SWR/Wattmeter
circuit. The other tuner is the MFJ -993 Auto Tuner. The auto tuner
probably won't tune anything over 30:1 and I doubt the 949E would
either. But I'm primarily interested in 80/40/20 meters where the
tuners will handle the SWR. I could use the ladder line to the tuner's
wire input but that would require it to go through the 4:1 balun and
that would make it too low for the frequencies I'm interested in so
I'll probably just stick with a real short run of coax and use the
regular 52 ohm coax input.

Thanks for the information.

73 Gary K8IQ
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Old April 23rd 05, 04:11 AM
Gary
 
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Default

On Fri, 22 Apr 2005 18:40:19 GMT, Bob Miller
wrote:

On Fri, 22 Apr 2005 06:17:21 -0400, Gary wrote:

I've done a bit of reading on G5RV's and I plan to just use the
standard configuration of a 102' dipole center fed with 32' of 450 Ohm
ladder line. Then I'm going to attach RG8X to the ladder line and
right near the connection construct a current choke of 8 turns of coax
about 6" in diameter. And then run the coax to my antenna tuner. some
of the sites I've run across mention that the G5RV needs at least 70'
of coax to function properly. This seems pretty lossy to me and I
don't see the need for the 70' of coax, perhaps someone can enlighten
me ? I'd like to keep the run of coax as short as possible.


See g5rv's article at http://www.qsl.net/aa3px/g5rv.htm

He said you can use up to 70 feet of coax and not suffer too much
loss; the shorter the better, tho'

He also had other recommendations for feedlines.

bob
k5qwg


Thanks for the info and the link Bob.

73 Gary K8IQ



Also I was digging through my insulators and I can't find one that
would offer strain relief for the ladder line and perhaps a connection
on top to use a wire or rope to add support to the center of the
antenna. I wonder if anyone has a source for one.

Once again, thanks in advance.

73 Gary K8IQ


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Old April 24th 05, 10:18 PM
 
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Give a look here too

http://www.dxzone.com/catalog/Antennas/G5RV/index.shtml



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