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Old October 15th 04, 11:23 PM
Amigaman
 
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Default Discone antenna & antenna tuner?

Greetings all!..I've got one of them discone antennas, you know, like
28-500mhz, blah..blah...on the roof...do I have to use an antenna
tuner if I would, let's say, try to operate on 2/6 or 440?... I don't
want to damage my UHF xcvr if there is a high SWR...any info from
you experts or who done did that is greatly appreciated...You all,
have a nice weekend & 73's....tony...wa9yoz...Amiga computer user
going over 12 years now.. Ciao!
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Old October 15th 04, 11:29 PM
Fractenna
 
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Greetings all!..I've got one of them discone antennas, you know, like
28-500mhz, blah..blah...on the roof...do I have to use an antenna
tuner if I would, let's say, try to operate on 2/6 or 440?... I don't
want to damage my UHF xcvr if there is a high SWR...any info from
you experts or who done did that is greatly appreciated...You all,
have a nice weekend & 73's....tony...wa9yoz...Amiga computer user
going over 12 years now.. Ciao!


Hi Tony,

The true discone part only works above about 100 MHz. Occassionally these
hybrid antennas have spikes of SWR from 100 MHz to 440, but I would say you
should probably be fine--without tuner.

73,
Chip N1IR
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Old October 16th 04, 04:55 AM
Mispan
 
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Default


"Fractenna" wrote in message
...
Greetings all!..I've got one of them discone antennas, you know, like
28-500mhz, blah..blah...on the roof...do I have to use an antenna
tuner if I would, let's say, try to operate on 2/6 or 440?... I don't
want to damage my UHF xcvr if there is a high SWR...any info from
you experts or who done did that is greatly appreciated...You all,
have a nice weekend & 73's....tony...wa9yoz...Amiga computer user
going over 12 years now.. Ciao!


Hi Tony,

The true discone part only works above about 100 MHz. Occassionally these
hybrid antennas have spikes of SWR from 100 MHz to 440, but I would say

you
should probably be fine--without tuner.

73,
Chip N1IR


Discone lower frequency cutoff is near the length of the skirt (1/4
wavelength) so measure it 100 Mhz is about 2.5 feet, 28 would be 9 foot.
Impeadance is great over the range, should not need tuner, unless the
discone is built cheap. I have a Mil one, good from near 200 to about 1.2
Ghz high power. It has 12 rods that make up the skirt. Google it to check.
UHF should be great.


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Old October 16th 04, 02:13 PM
Tam/WB2TT
 
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"Mispan" wrote in message
...

"Fractenna" wrote in message
...
Greetings all!..I've got one of them discone antennas, you know, like
28-500mhz, blah..blah...on the roof...do I have to use an antenna
tuner if I would, let's say, try to operate on 2/6 or 440?... I don't
want to damage my UHF xcvr if there is a high SWR...any info from
you experts or who done did that is greatly appreciated...You all,
have a nice weekend & 73's....tony...wa9yoz...Amiga computer user
going over 12 years now.. Ciao!


Hi Tony,

The true discone part only works above about 100 MHz. Occassionally these
hybrid antennas have spikes of SWR from 100 MHz to 440, but I would say

you
should probably be fine--without tuner.

73,
Chip N1IR


Discone lower frequency cutoff is near the length of the skirt (1/4
wavelength) so measure it 100 Mhz is about 2.5 feet, 28 would be 9 foot.
Impeadance is great over the range, should not need tuner, unless the
discone is built cheap. I have a Mil one, good from near 200 to about 1.2
Ghz high power. It has 12 rods that make up the skirt. Google it to
check.
UHF should be great.

My understanding is that there is also a problem at the other frequency end.
For example, if it actually works on 6 meters, then, at 432 MHz you will
have very high angle radiation; i.e. going up, instead of along the horizon.

Tam/WB2TT




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Old October 16th 04, 02:16 PM
Tam/WB2TT
 
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Default

Richard,
Sorry I stepped on you. Hadn't read your posting.


Tam/WB2TT


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Old October 16th 04, 03:20 PM
Fractenna
 
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Default

My understanding is that there is also a problem at the other frequency end.
For example, if it actually works on 6 meters, then, at 432 MHz you will
have very high angle radiation; i.e. going up, instead of along the horizon.

Tam/WB2TT


Hi Tam,

If its the design I've worked with, it should be OK on the horizon on 432.

When the disc section no longer functions as a counterpoise, then multiple
resonances happen across the cone and you get a lobe on the horizon. That is
probably what you are describing.

73,
Chip N1IR
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Old October 22nd 04, 05:39 PM
Jimmie
 
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Default

You say it covers from 28Mhz to 500Mhz. The one I am familiar with that
does this is a modified discone that acts as a 1/4 wl antenna with ground
plane at 28(probably 27Mhz) If this is the antena I am thinking about it has
a long whip coming out of the cneter of the disk and 3 or 4 extra long
radials in the skirt. These antennas worked on 144, 220, 432 bands with
reasonable SWR.

"Amigaman" wrote in message
m...
Greetings all!..I've got one of them discone antennas, you know, like
28-500mhz, blah..blah...on the roof...do I have to use an antenna
tuner if I would, let's say, try to operate on 2/6 or 440?... I don't
want to damage my UHF xcvr if there is a high SWR...any info from
you experts or who done did that is greatly appreciated...You all,
have a nice weekend & 73's....tony...wa9yoz...Amiga computer user
going over 12 years now.. Ciao!



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