I wonder if u could help me, i have a tri-band beam erected and am
considering using 450 ohm feeder due to the less amount of loss on the
line (as opposed to RG58)

The radio i am using is an IC-756PROII, with inbuilt ATU, will i be
able to connect the feeder direct to the beam and run it straight into
the back of my 756 (using 259 connector) ??

Or will i requrie a balun at either the beam or radio end???

hope you can shed some light on this, have got a bit confused with it

thanks in advance

Stephen Catterall

VK3SC

wrote in message
oups.com...
I wonder if u could help me, i have a tri-band beam erected and am
considering using 450 ohm feeder due to the less amount of loss on the
line (as opposed to RG58)

The radio i am using is an IC-756PROII, with inbuilt ATU, will i be
able to connect the feeder direct to the beam and run it straight into
the back of my 756 (using 259 connector) ??

Or will i requrie a balun at either the beam or radio end???

hope you can shed some light on this, have got a bit confused with it

thanks in advance

Stephen Catterall

VK3SC


Unless you are running over 200 meters of coax, just go with the rg-8 size
coax of a good brand. There is not that much loss in the rg-8 coax below
30 mhz to make any differance , especially by putting in the baluns.

No you can not just connect the open line to the so239 connectors. The rig
is looking for something around 50 ohms and you already have a 450 ohm line
with the open line. Most beams are designed to be fed with 50 ohm line
also.

wrote:
I wonder if u could help me, i have a tri-band beam erected and am
considering using 450 ohm feeder due to the less amount of loss on the
line (as opposed to RG58)

Matched line loss for 450 ohm ladder-line is indeed less than the
matched line loss for coax. But using ladder-line to feed a tri-beam
will result in an SWR on the ladder-line of around 10:1 so you will
be losing power because of higher SWR. If your coax run is less than
100 ft., I would just upgrade to a better grade of coax than RG-58.

The radio i am using is an IC-756PROII, with inbuilt ATU, will i be
able to connect the feeder direct to the beam and run it straight into
the back of my 756 (using 259 connector) ??

Or will i requrie a balun at either the beam or radio end???

To do what you want to do will require a choke-balun at the IC-756.
In addition, what you want to do will require you to feed the beam
with a multiple of half-wavelengths of ladder-line. That means you
will be required to change the length of the ladder-line when you
change bands in order to get an impedance that your IC-756 tuner can
match. To use such a system, you have to know exactly what you are
doing. I do use such a system myself.

If you don't want to change the length of your ladder-line when you
change bands, your best solution is probably to go with a good grade
of coax like RG-8, RG-213, or LMR-400.
--
73, Cecil http://www.qsl.net/w5dxp

On 31 Dec 2005 16:51:02 -0800, "
wrote:

I wonder if u could help me, i have a tri-band beam erected and am
considering using 450 ohm feeder due to the less amount of loss on the
line (as opposed to RG58)

The radio i am using is an IC-756PROII, with inbuilt ATU, will i be
able to connect the feeder direct to the beam and run it straight into
the back of my 756 (using 259 connector) ??

Or will i requrie a balun at either the beam or radio end???

hope you can shed some light on this, have got a bit confused with it

It would have helped if you disclosed the feedline length, it has
bearing on selection of solutions.

On the one hand, one respondent has told you 200m of RG8 is ok (that
is about 6dB of loss at 28MHz), and another has told you that the VSWR
on 450 ohm line will make it unattractive... you can only make these
calls if the length of the feedline is known (and the 450 ohm line
need not operate at high VSWR).

Do you rotate this beam? Will you need a coax tail at the rotator, or
have you some scheme in mind for using open wire line at this point?

There is probably already a balun at the beam feedpoint... but you
will probably continue need to use coax right close to the beam (the
rotator issue).

Owen
--

I would never use RG 58... use a good RG 8 or RG 213 instead of the
ladder line for proper impedance to the antenna and rig.

Steve


On 31 Dec 2005 16:51:02 -0800, "
wrote:

I wonder if u could help me, i have a tri-band beam erected and am
considering using 450 ohm feeder due to the less amount of loss on the
line (as opposed to RG58)

The radio i am using is an IC-756PROII, with inbuilt ATU, will i be
able to connect the feeder direct to the beam and run it straight into
the back of my 756 (using 259 connector) ??

Or will i requrie a balun at either the beam or radio end???

hope you can shed some light on this, have got a bit confused with it

thanks in advance

Stephen Catterall

VK3SC

"Owen Duffy" wrote in message
...
On 31 Dec 2005 16:51:02 -0800, "
wrote:

I wonder if u could help me, i have a tri-band beam erected and am
considering using 450 ohm feeder due to the less amount of loss on the
line (as opposed to RG58)

The radio i am using is an IC-756PROII, with inbuilt ATU, will i be
able to connect the feeder direct to the beam and run it straight into
the back of my 756 (using 259 connector) ??

Or will i requrie a balun at either the beam or radio end???

hope you can shed some light on this, have got a bit confused with it

It would have helped if you disclosed the feedline length, it has
bearing on selection of solutions.

On the one hand, one respondent has told you 200m of RG8 is ok (that
is about 6dB of loss at 28MHz), and another has told you that the VSWR
on 450 ohm line will make it unattractive... you can only make these
calls if the length of the feedline is known (and the 450 ohm line
need not operate at high VSWR).


Got to admitt I ment 200 feet instead of 200 meters. That is less than 2 db
for rg8. Even the rg8x is only about 3.5 db for 200 feet at 30 mhz. By the
time you factor in the loss due to the swr and probably a couple of baluns
and the trouble to run open wire up a tower and in the shack you do not gain
much over a good grade of rg8 with open line up to 200 feet or more.

Owen Duffy wrote:
... another has told you that the VSWR
on 450 ohm line will make it unattractive...

Not unattractive, just less attractive than if
it was a matched line case. I feed my 20m rotatable
dipole with 300 ohm ladder-line and put up with the
SWR loss in order to gain 20m/17m/15m/12m/10m
operation.
--
73, Cecil http://www.qsl.net/w5dxp