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Old June 30th 08, 02:42 PM posted to rec.radio.amateur.antenna
Andy[_5_] Andy[_5_] is offline
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First recorded activity by RadioBanter: Apr 2008
Posts: 71
Default 40m centre feed dipole, I want to add 80m

Hi all,

I have now tried all sorts of combinations and the best that I have found to
work best in such a small place is a 40m centre fed dipole, fed direct with
40 feet of 50 Ohm RG58 c/u then into a Ugly Balun made of RG58 c/u then into
RG213 back to the ATU. This is just how it all worked out, come the end.
I then made a couple of 40 meter traps for 80m.
The 40 meter section of the dipole barely fits the garden with no room to
spare. The traps and the added lengths of wire are dropped down and tied
back slightly to keep it away from the mounting pole, It is still kept at a
right angle to the main part of the antenna.
I have a 1.1:1 - 1.3:1 on the main frequency that I want to use on 40m and
80m without using the ATU.
It seems to work very well for what it is.
Thanks all for your help.

73 Andy


"wa2rqy" wrote in message
...
On Jun 17, 4:04 pm, "Andy" wrote:
Thanks for all your suggestions. When this wet weather clears I will try
them all out and see where I end up..

73 Andy

"Highland Ham" wrote in message

...

Andy wrote:
Hi,


I have a 40 meter centre feed dipole cut for 40 and feed direct with
50
Ohm coax. The house end is connected to the centre of the coax and the
pole end is connected to the braid. Seems to work best this way round.
The antenna is fixed tight to the house and the other end is tight to
the
metal pole in a straight-line, diagonal across the garden, both ends
are
insulated. The garden is about 64 feet give or take a couple of feet.


I cannot drop the ends down because of the house and metal pole at the
end of the garden being so close. I can only feed the antenna with
coax.
The neighbours are OK with coax but not the ribbon feeder hanging down
and I don't want to upset them if I can help it.


My question. What are my options to enable me to operate 80 and 40m on
this same antenna wire?
===========================================
300 Ohms ribbon twin feeder is hardly more visible than coax feeder .
You don't have to use the 'wide' 450 Ohms ribbon type.
300 Ohms ribbon has an approx velocity factor of 0.8 ,so if you make
half
the dipole + the feeder (roughly) an electrical 1/4 -3/4 -etc
wavelength
at 80 meters ,you will be home and dry with an appropriate matching
unit
or a choke balun in combination with a 'coax-in ,coax-out' matching
box.


Frank GM0CSZ / KN6WH


I just put up a 66' center fed zep, fed with 450 ohm ribbon line.
This line goes to just outside my radio room where it terminates into
a 4:1 Home-made (off the www) balun, coax feeds into the house to a
Nye tuner. Easily tunes 80 to 10 mtrs & works good.
Many good ways, this is just one!
GL.....
Rich WA2RQY/4