"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