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Old August 6th 03, 01:43 PM
Dave Shrader
 
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0 dBd !!!!!!!!!!

Deacon Dave, W1MCE

Reg Edwards wrote:

"'Doc" wrote Cecil,

Now all you have to do is get everyone to move so
that they are in one of those four directions from you.



============================

What is the gain in dB of a rotatable dipole relative to one which is fixed
?
---
Reg, G4FGQ




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Old August 6th 03, 02:59 PM
W5DXP
 
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'Doc wrote:
Now all you have to do is get everyone to move so
that they are in one of those four directions from you.


With a fixed resonant dipole, you only get two directions. :-)
--
73, Cecil http://www.qsl.net/w5dxp



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Old August 6th 03, 03:16 PM
W5DXP
 
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Dave Shrader wrote:
0 dBd !!!!!!!!!!


Not off the ends of the fixed dipole. :-)

Reg Edwards wrote:
What is the gain in dB of a rotatable dipole relative to one which is
fixed?

--
73, Cecil http://www.qsl.net/w5dxp



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Old August 6th 03, 06:10 PM
JDer8745
 
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I use such an antenna but feed it differently. Mine is 130 ft long and fed
with 300-Ohm xmitting twin lead.

The transmission line connects to the balanced output of a MFJ tuner.

Used it on all bands 80 through 6 till I got a 6-m Yagi and a tribander.

It is still a much used antenna, especially on 80, 40, 18, and 24.

On 40 it is a fullwave doublet and has about 1.5 dB gain over a dipole.

I have used it in 160 by shorting the two wires of the twinlead together and
feeding it as a Marconi antenna.

I agree with other posters who wud like to see the center a little higher, but
a man's gotta do what a man's gotta do!

Have fun, Jack K9CUN
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Old August 6th 03, 07:16 PM
Roy Lewallen
 
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That's simply untrue. But I guess that's what the smiley face means?

Roy Lewallen, W7EL

W5DXP wrote:

With a fixed resonant dipole, you only get two directions. :-)




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Old August 6th 03, 07:35 PM
Dave Shrader
 
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The gain of a dipole is the gain of a dipole.

Now, Directivity is another matter :-)

W1MCE

W5DXP wrote:

Dave Shrader wrote:

0 dBd !!!!!!!!!!



Not off the ends of the fixed dipole. :-)

Reg Edwards wrote:

What is the gain in dB of a rotatable dipole relative to one which is
fixed?


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Old August 6th 03, 08:15 PM
Jim
 
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"WB3FUP (Mike Hall)" wrote in message
...
You will be a much happier camper if you feed it with 450 ohm ladder line.
You will have no trouble using the antenna anywhere from 80 to 10, and if
snipped


I need to run the feeder from my dipole (80m) up thro the eaves, thro' the
loft-space to the shack at the other side (1st floor) of the house, approx
50'. No other routes feasible. Because of the route, I thought I'd have
less problems using coax, BUT from the remarks in the above recent post,
will someone kindly comment on viability of 450 ohm twin feeder over such a
route?

Many thanks
Jim M0Jim

Replies to NG pse!!




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Old August 6th 03, 10:05 PM
W5DXP
 
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Roy Lewallen wrote:
That's simply untrue. But I guess that's what the smiley face means?


Yep, *two* major lobes with a fixed resonant dipole. With a 130 ft.
dipole on 20m, I get two times or three times as many lobes. :-)

W5DXP wrote:
With a fixed resonant dipole, you only get two directions. :-)

--
73, Cecil http://www.qsl.net/w5dxp



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Old August 6th 03, 10:12 PM
W5DXP
 
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Dave Shrader wrote:
The gain of a dipole is the gain of a dipole.


Yes, and a fixed dipole doesn't have much gain off the ends compared
to a broadsided rotatable dipole. EZNEC says the maximum gain of my
dipole off the ends is "MAX GAIN = 0.88 dBi". I am extremely pleased
with my rotatable dipole. So much so that another element is just
not worth that extra half an S-unit.
--
73, Cecil http://www.qsl.net/w5dxp



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Old August 6th 03, 11:20 PM
Reg Edwards
 
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I need to run the feeder from my dipole (80m) up thro the eaves, thro'
the
loft-space to the shack at the other side (1st floor) of the house, approx
50'. No other routes feasible. Because of the route, I thought I'd have
less problems using coax, BUT from the remarks in the above recent post,
will someone kindly comment on viability of 450 ohm twin feeder over such

a
route?


=====================================

If necessary just squeeze heavy-duty 450-ohm ladder line wires close
together wherever they pass through a small hole. Line holes with a thick
plastic film or a pipe to obtain a higher breakdown voltage. Slowly twist
the cable every 2 feet between holes and keep it at least 1 or 2 inches away
from foreign materials, long metal conductors or otherwise.

If it was possible to do A-B comparisons at HF you would find little
difference - equivalent to a few pF change in a tuner capacitor setting and
1/2-turn change in the roller inductor. To be safe stick to 100 or 200 watts
unless you wish to test to destruction under worst case, but controlled
conditions (eg., very high SWR) just to see what happens. Probably nothing!

At HF a change in impedance Zo over a length of a few inches when passing
through one or two holes in timber or brickwork will have a negligible
effect on performance. The advantage of a balanced line all the way to the
transmitter may be that a tuner can be located in the shack. If an automatic
tuner is used then use easier-to-install coax and locate the tuner at the
antenna end.

Over a length of 50 or more feet, at 28 MHz, the lower loss in 450-ohm line
relative to 50-ohm RG-58 is worth thinking about. At 1.9 MHz forget it.

But it's only a matter of economics, time and labour, and the well-earned
satisfaction of having done a good job which works according to plan.
---
Reg, G4FGQ




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