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discone or scantenna?



 
 
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  #1  
Old January 4th 05, 06:53 PM
redrum
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Default discone or scantenna?

Which is better?

is scantenna really omnidirectional? is it built for a better reception on
the most used frequencies or is really multiband?

who sells the better implementation of discone?

my needs on scanning are 25Mhz to 1.3 Ghz.

I own a uniden bc-796d and a bc-246t

Thanks for any help.

Greetings from Chile!



  #2  
Old January 5th 05, 05:35 PM
Richard Clark
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On Tue, 4 Jan 2005 14:53:35 -0400, "redrum" ninguna wrote:

Which is better?

is scantenna really omnidirectional? is it built for a better reception on
the most used frequencies or is really multiband?

who sells the better implementation of discone?

my needs on scanning are 25Mhz to 1.3 Ghz.

I own a uniden bc-796d and a bc-246t

Thanks for any help.

Greetings from Chile!


Hello OM,

There are many omnidirectional designs. There are many multi band
designs. There are very few that accomplish both successfully for a
wide variety of signals over a wide variety of frequencies.

Wide band antennas like a Discone are really only useful over roughly
2 or 3 octaves (doublings of the base frequency). They are often
specified by impedance match; and as correct as this specification is,
it is not complete. You also need to consider the angles that it is
most sensitive to. For the first 2 or 3 octaves, this would be toward
the horizon. For the 4th and higher octaves, the most sensitive
regions for listening begin to climb higher into the sky. Who do you
want to listen to? Where are they? This is the meaningful relation
you should seek to optimize.

73's
Richard Clark, KB7QHC
  #3  
Old January 6th 05, 06:24 AM
Ed
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Can't say which is better.... but I've always been happy with the Diamond
D130J discone antenna. It might be your best choice if you really want to
put your scanner frequency range to full use.

sample info can be found at: http://www.grove-ent.com/ANT9.html


Ed K7AAT

  #4  
Old January 6th 05, 06:51 AM
Richard Clark
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On Thu, 06 Jan 2005 06:24:05 GMT, Ed
wrote:
sample info can be found at: http://www.grove-ent.com/ANT9.html


This is a case in point of specs-manship:
Designed for use with wide-frequency coverage VHF/UHF scanners
and receivers, the Diamond D130J Discone consists of 16 rugged,
stainless steel elements and is capable of transmitting up to 200
watts in the amateur 50, 144, 220, 432, 900, and 1200 MHz bands.

As a receiving antenna, the D130J is omni-directional for continuous
25-1000 MHz (and above) coverage. A base-loaded, vertical top
element is used as a low band (30-50 MHz) frequency extender.


In the 1200 MHz band (to which it will faithfully match), this antenna
is going on 4 or 5 wavelengths tall. This gives it strong gain -
STRAIGHT UP. If you want to work satellites overhead, great; if you
want to work a signal across town, deaf.

73's
Richard Clark, KB7QHC
  #5  
Old January 6th 05, 01:58 PM
GLC1173
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Redrum wrote:
my needs on scanning are 25Mhz to 1.3 Ghz.


Nothing is as wide-band as a discone. That's why military airfields use
them so much.


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  #6  
Old January 6th 05, 02:11 PM
Cecil Moore
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GLC1173 wrote:
Nothing is as wide-band as a discone.


Nothing? I'll bet my Bird Termaline is wider-banded. :-)
--
73, Cecil, W5DXP

  #7  
Old January 6th 05, 02:54 PM
Jack Painter
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"redrum" ninguna wrote
Which is better?

is scantenna really omnidirectional? is it built for a better reception on
the most used frequencies or is really multiband?

who sells the better implementation of discone?

my needs on scanning are 25Mhz to 1.3 Ghz.

I own a uniden bc-796d and a bc-246t

Thanks for any help.

Greetings from Chile!


You will find that your scanning needs are probably quite narrower than the
capabilities of either receiver or antenna. The stolen trademark "Scantenna"
which is widely produced (although no longer by Radio Shack, who was forced
to discontinue marketing this design) has been highly favored by scanner
enthusiasts for it's confirmed superior performance over Diamond or any
other standard discone antenna. It is not better than a standard discone in
a few narrow bands, but in bands most popular for scanner receivers (118
Mhz - 860 Mhz) it is vastly superior. Other limitations of the Scantenna
design are it's lack of transmit capability, and weak open-rolled aluminum
tubing design, which fold over in winds 50kts. At least one hobbyist I
know personally claims it is slightly directional, and he has it mounted on
a channel-master rotator for this reason. I have owned several and confirm
the significant extended reception in most vhf and uhf bands over various
standard discone antennas.

73,
Jack Painter
Virginia Beach Virginia


  #8  
Old January 12th 05, 08:31 PM
Dave VanHorn
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GLC1173 wrote:
Nothing is as wide-band as a discone.


Nothing? I'll bet my Bird Termaline is wider-banded. :-)


Possibly higher gain too!



  #9  
Old January 12th 05, 11:42 PM
Cecil Moore
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Dave VanHorn wrote:

GLC1173 wrote:
Nothing is as wide-band as a discone.


Nothing? I'll bet my Bird Termaline is wider-banded. :-)


Possibly higher gain too!


Is that a cruel world joke? :-)
--
73, Cecil http://www.qsl.net/w5dxp


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