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Old August 26th 04, 12:44 AM
folio
 
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Default ANTENNA TWINLEAD FEEDER

hello to all
from Gilles ve2lx

1 st past ever on this group

I just install temporary an invert dipole feeded with tv twinlead 300 ohm

actually I have no RF interferences from 160 to 12 m (but only low on 10 m
but no more usable anyway ) compare to my end fed I had 2 month ago...!

antenna length is 66 ft or 33 ft each side and feeder length about 48
ft...the dipole is parralele to the back of the 20 appartement's house and
the full SFC remote coupler or tuner ( builted only for wire tuning ) is on
my back galery 8 ft from radio on 3 rd floor a little above hand rail...!

(((......I found 75 ohm twin lead...... )))

and ( I would like to use it instead ) for10 to 80 and 160 m ( actually I
do it with 300 ohm twin lead accepting low efficiency on 160 m and perhaps
on 80 m but it is ok.

my target
1...is to have as much efficiency as I can for all bands use primaly on 40
and 20 m ( reason for 66 ft )
2...at 75 ohm on 80 meter there will be much less SWR ( like 1/30: OR MORE
WITH 300 OHM on 80 m ) due to unmatch compare to 300 ohm
3...there will be better energy transfer because dipole is + or - 75 ohms
and feeder also and the tuner will search less value to match then therefore
les chance of RF problem radiations form feeder ( les larger ) and so on
4...feeder length will have less effect at 75 ohm on a all bands
consideration...?

is this thinking correct

wishing to ear from amateurs with good experience with balance or twin lead
feeder


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Old August 27th 04, 01:09 AM
Hal Rosser
 
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I dunno about the exact measurements - but I used 300-ohm belden twinlead
(the kind with copper-clad-steel conductor) as a feeder - but tried to keep
to the G5RV measurements - and had good luck with it.

"folio" wrote in message
. ..
hello to all
from Gilles ve2lx

1 st past ever on this group

I just install temporary an invert dipole feeded with tv twinlead 300 ohm

actually I have no RF interferences from 160 to 12 m (but only low on 10 m
but no more usable anyway ) compare to my end fed I had 2 month ago...!

antenna length is 66 ft or 33 ft each side and feeder length about 48
ft...the dipole is parralele to the back of the 20 appartement's house and
the full SFC remote coupler or tuner ( builted only for wire tuning ) is

on
my back galery 8 ft from radio on 3 rd floor a little above hand rail...!

(((......I found 75 ohm twin lead...... )))

and ( I would like to use it instead ) for10 to 80 and 160 m ( actually I
do it with 300 ohm twin lead accepting low efficiency on 160 m and perhaps
on 80 m but it is ok.

my target
1...is to have as much efficiency as I can for all bands use primaly on 40
and 20 m ( reason for 66 ft )
2...at 75 ohm on 80 meter there will be much less SWR ( like 1/30: OR MORE
WITH 300 OHM on 80 m ) due to unmatch compare to 300 ohm
3...there will be better energy transfer because dipole is + or - 75 ohms
and feeder also and the tuner will search less value to match then

therefore
les chance of RF problem radiations form feeder ( les larger ) and so on
4...feeder length will have less effect at 75 ohm on a all bands
consideration...?

is this thinking correct

wishing to ear from amateurs with good experience with balance or twin

lead
feeder


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Old September 2nd 04, 01:39 AM
folio
 
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from Gilles ve2lx

1st time on REC group

I just install temporary an invert dipole feeded with ((( tv twinlead

300 ohm )))

actually I have no RF interferences from 160 to 12 m (but only low on 10 m
but no more usable anyway ) compare to my end fed I used before...!

antenna length is 66 ft or 33 ft each side and feeder length about 48
ft...the dipole is parralele to the back of the 20 appartement's house and
the full SFC remote coupler or tuner ( builted only for wire tuning ) is

on
my back galery 8 ft from radio on 3 rd floor a little above hand rail...!


((( I seen many article on internet and on tech reference mentionning that
when it is humid, damp periode, snow and so on there might be a great
variation of swr during these conditions......?

Is there some one on the groupe that used 300 ohm feeder with a dipole for a
long periode especially during fall and winter to learn about there
experience with that type of installation......?

wishing to ear soon with




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Old September 2nd 04, 01:56 AM
Dr. Daffodil Swain
 
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i have. Don't worry about it. Use it and have fun.

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"folio" wrote in message
...
from Gilles ve2lx

1st time on REC group

I just install temporary an invert dipole feeded with ((( tv twinlead

300 ohm )))

actually I have no RF interferences from 160 to 12 m (but only low on 10

m
but no more usable anyway ) compare to my end fed I used before...!

antenna length is 66 ft or 33 ft each side and feeder length about 48
ft...the dipole is parralele to the back of the 20 appartement's house

and
the full SFC remote coupler or tuner ( builted only for wire tuning ) is

on
my back galery 8 ft from radio on 3 rd floor a little above hand

rail...!

((( I seen many article on internet and on tech reference mentionning

that
when it is humid, damp periode, snow and so on there might be a great
variation of swr during these conditions......?

Is there some one on the groupe that used 300 ohm feeder with a dipole for

a
long periode especially during fall and winter to learn about there
experience with that type of installation......?

wishing to ear soon with




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Old September 2nd 04, 02:49 AM
Cecil Moore
 
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folio wrote:
Is there some one on the groupe that used 300 ohm feeder with a dipole for a
long periode especially during fall and winter to learn about there
experience with that type of installation......?


Here is a data point for you. Instead of a tuner, I vary the length of
my "450 ohm" ladder-line to achieve a match at the current maximum
point. In very wet weather, I have seen a two-foot shift in the length
of ladder-line required on 40m from the dry length. 2 feet on 40m is
less than 2% of a wavelength. So I would say the difference between
wet and dry with ladder-line is less than the difference between
insulated and bare wire unless, of course, you lay your ladder-line
on a wet deck and deliberately coat it with soapy water.
--
73, Cecil http://www.qsl.net/w5dxp



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Old September 2nd 04, 03:24 AM
Irv Finkleman
 
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folio wrote:

from Gilles ve2lx

1st time on REC group

I just install temporary an invert dipole feeded with ((( tv twinlead

300 ohm )))

actually I have no RF interferences from 160 to 12 m (but only low on 10 m
but no more usable anyway ) compare to my end fed I used before...!

antenna length is 66 ft or 33 ft each side and feeder length about 48
ft...the dipole is parralele to the back of the 20 appartement's house and
the full SFC remote coupler or tuner ( builted only for wire tuning ) is

on
my back galery 8 ft from radio on 3 rd floor a little above hand rail...!


((( I seen many article on internet and on tech reference mentionning that
when it is humid, damp periode, snow and so on there might be a great
variation of swr during these conditions......?

Is there some one on the groupe that used 300 ohm feeder with a dipole for a
long periode especially during fall and winter to learn about there
experience with that type of installation......?

wishing to ear soon with


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.742 / Virus Database: 495 - Release Date: 2004-08-19


Used 50 ft of the cheapest TV twinlead (300ohm) I could find because it was a
temporary test. The antenna worked so well that I left it up from 83 to 96
through all kinds of weather including harsh Alberta winters. I never
noticed any noticeable SWR changes with weather, and when I took it down
I saved the twinlead for future use -- it was as good as new!

Irv VE6BP
--
--------------------------------------
Diagnosed Type II Diabetes March 5 2001
Beating it with diet and exercise!
297/215/210 (to be revised lower)
58"/43"(!)/44" (already lower too!)
--------------------------------------
Visit my HomePage at http://members.shaw.ca/finkirv/
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--------------------
Irv Finkleman,
Grampa/Ex-Navy/Old Fart/Ham Radio VE6BP
Calgary, Alberta, Canada
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