Discone ant on 144/440?
 

Greetings all!...will a uhf/vhf discone antenna work with my Kenwood
TW-4000A? any hints/suggestions/recommendations greatly appreciated!
thank you for your time......73's....tony...wa9yoz

I plug in a 2m/70 colinear in my loft when upstairs or a discone in the
garden on a 15ft plastic pipe when downstairs.
There is hardly any difference, just one or half a point on the 0-9 scale.
Also a home made 2m dipole works just as well.
The reception is more affected by the propergation conditions and your
location relative to the surrounding terrain. I have compiled polar diagrams
for each and it is surprising how reception is stronger in some directions
than others despite the antenna theoretically being omnidirectional. I think
only significant improvement would come from using a directional array.

I would be cautious about believing a particular antenna would be a 'vast
improvement'.
The advantage with my discone is that I can listen to lots of other things
as well as using it for 2m/70cm. In that respect my colinear or dipole
doesn't work as well.

The best approach is by experimentation.

Lionel Carter
M3LRC


"Amigaman" wrote in message
om...
Greetings all!...will a uhf/vhf discone antenna work with my Kenwood
TW-4000A? any hints/suggestions/recommendations greatly appreciated!
thank you for your time......73's....tony...wa9yoz

The Radio Shack discone, while certainly not an efficient antenna at 50 MHz,
works reasonably well at 144/440 MHz, and exhibits a low SWR ( 1.5:1)
across these two bands. You should be able to use it with your radio no
problem. You can pump up to 200W RF into it.

Bill / W5WVO

"Amigaman" wrote in message
om...
Greetings all!...will a uhf/vhf discone antenna work with my Kenwood
TW-4000A? any hints/suggestions/recommendations greatly appreciated!
thank you for your time......73's....tony...wa9yoz

Just a "hint" -- If the Radio Shack discone is the one you have, be VERY
CAREFUL when assembling the element rods to the central piece. The screw-in
element fasteners are brittle (read: cheap) and can easily be snapped off.
Tighten the locking nuts securely using a small wrench or needle-nose
pliers, but DO NOT OVERTIGHTEN. I also recommend assembling the antenna when
and where you are going to actually put it up. Spoken from experience. This
antenna survives wind very well, even birds (they seem to love it), but it
does not survive being bumped, dropped, etc.

Bill / W5WVO


"Bill VanAlstyne" wrote in message
...
The Radio Shack discone, while certainly not an efficient antenna at 50
MHz,
works reasonably well at 144/440 MHz, and exhibits a low SWR ( 1.5:1)
across these two bands. You should be able to use it with your radio no
problem. You can pump up to 200W RF into it.

Bill / W5WVO

"Amigaman" wrote in message
om...
Greetings all!...will a uhf/vhf discone antenna work with my Kenwood
TW-4000A? any hints/suggestions/recommendations greatly appreciated!
thank you for your time......73's....tony...wa9yoz

Greetings all!...will a uhf/vhf discone antenna work with my Kenwood
TW-4000A? any hints/suggestions/recommendations greatly appreciated!
thank you for your time......73's....tony...wa9yoz

I tried one, then took it down and bought a nice dualband vertical. If you have
limited space and only need to work local stuff, I suppose the discone would
work.
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
73! de Andy KC2SSB - WPYI880 (GMRS)
Beachwood, NJ USA! Grid FM29vw
http://vhfradiobuff.tripod.com

Well, my experience was that my 2m/70cm vertical works much better than the
discone ever did.
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
73! de Andy KC2SSB - WPYI880 (GMRS)
Beachwood, NJ USA! Grid FM29vw
http://vhfradiobuff.tripod.com

I have a (Diamond) Discone 35 feet above ground, fed with reasonable quality
coax. My radio can run 5 /25 /50 watts.

Simplex to 35 miles base to base is easy if the other guy has elevation.

I routinely work amatuer repeaters on 145 and listen to commercial
repeaters on 450 that are 40 miles by air from here and they are full scale.
I have worked mobiles 25 miles away. The verticle pattern has nulls in it
(so does a ground plane) so when the ISS passes overhead I may lose a few
words as they go through a null.

Stainless steel is a terrible thing to use for an antenna due to eddy
current losses and lower condutivity than copper. The only way to avoid
that is with an aluminum, or copper and fiberglass antenna.

Mine is stainless steel and has been up several years. I have no intention
of changing it!

KA9CAR



"VHFRadioBuff" wrote in message
...
Greetings all!...will a uhf/vhf discone antenna work with my Kenwood
TW-4000A? any hints/suggestions/recommendations greatly appreciated!
thank you for your time......73's....tony...wa9yoz

I tried one, then took it down and bought a nice dualband vertical. If you
have
limited space and only need to work local stuff, I suppose the discone
would
work.
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
73! de Andy KC2SSB - WPYI880 (GMRS)
Beachwood, NJ USA! Grid FM29vw
http://vhfradiobuff.tripod.com

People seem to have a need to sort everything into binary categories --
like good or bad. And you've pointed out the limitations of doing that.

Stainless steel is fairly resistive stuff to begin with, although
resistivity varies widely depending on the alloy. But the RF resistivity
rises dramatically if the material is magnetic. Some stainless alloys
are magnetic and some aren't. The RF resistivity is proportional to the
square root of the permeability (because of its effect on skin depth),
so a magnetic stainless can easily have ten times the resistivity of a
non-magnetic alloy.

But even a magnetic stainless alloy isn't necessarily "bad". There are
plenty of cases where even that much resistivity is still insignificant,
and won't cause noticeable loss. In particular, if the conductor
diameter is relatively large, or its length is short (in absolute terms,
not in terms of wavelength), the loss will usually be small. This
describes just about all VHF and UHF applications. I wouldn't use small
stainless wire for an 80 meter dipole (unless I wanted to trade a bit of
efficiency for increased bandwidth, which might actually be a good
trade), and certainly not for an electrically small transmitting loop,
where the current is extremely high. But it's definitely a suitable
material for a lot of antenna applications. And it's certainly durable,
as you've noted.

If you were to trade your stainless antenna for one that isn't, there'd
be no perceptible difference in performance, and the replacement
wouldn't last as long. I wouldn't change it either.

Roy Lewallen, W7EL

KA9CAR wrote:
. . .
Stainless steel is a terrible thing to use for an antenna due to eddy
current losses and lower condutivity than copper. The only way to avoid
that is with an aluminum, or copper and fiberglass antenna.

Mine is stainless steel and has been up several years. I have no intention
of changing it!

KA9CAR

- - - - on the other hand a magnetic stainless steel tube or radio mast,
used as an antenna element, may/will have an RF resistance loss smaller than
a 14-gauge copper wire which otherwise would have been adequate.

Why? Simply by virtue of its far greater diameter and surface area.

You have the advantages of self-supporting structural ability, durability,
AND lower RF loss, AND wider bandwidth.

A deprived quantitaive familiarity, engineering dependence on popular,
plagiarised "Bibles" are dangerous things.

What was it the later, oft-quoted, Lord Kelvin said ?