300 vs 450 ohm ladder line
WB7ASR
either? What about wire gage? Catalogs sell different sizes.
WB3U
>What are the major differences and advantages/disadvantages of using
>either? What about wire gage? Catalogs sell different sizes.
The impedance won't be a factor if you're feeding a non-resonant
antenna. If you're using a resonant folded dipole though, you would
want the 300 ohm variety.
Generally speaking, the lowest loss will be incurred in lines with the
largest conductors and the least amount of dielectric between them.
If you live in a climate subject to lots of snow and ice, you might
want to consider building your own open wire line. If the run is
fairly long, say 50' or more, SWR will be much more stable with open
wire line.
At the moment, I'm using about 100' of 450 ohm ladder line. Whenever
it's covered with snow or ice, the SWR creeps constantly during a QSO.
Sometimes it's so bad I have to retune every 10 or 15 seconds. :(
73,
Jack WB3U
WB3U
>If you live in a climate subject to lots of snow and ice, you might
>want to consider building your own open wire line. If the run is
>fairly long, say 50' or more, SWR will be much more stable with open
>wire line.
Ooops, guess you don't have that problem in CHANDLER, AZ. ;)
Rick Rikoski
ja...@pinetree.microserve.com (WB3U) wrote:
> tom_...@ccm.ch.intel.com (WB7ASR) wrote:
>
> >What are the major differences and advantages/disadvantages of using
> >either? What about wire gage? Catalogs sell different sizes.
The 450 ohm ladder line will have significantly lower loss at vhf and uhf.
This will show up as improved signal to noise ratio at your receiver.
On transmit, the larger wire gage will give better efficiency, ie more
signal transmitted per watt coming from your final, everything else being
equal.
--
Rick Rikoski
Chicago/Indiana Dunes
rik...@niia.net
Cecil A. Moore~
WB7ASR <tom_...@ccm.ch.intel.com> wrote:
>What are the major differences and advantages/disadvantages of using
>either? What about wire gage? Catalogs sell different sizes.
>
lower loss than 300 ohm ladder line. #18 gauge wire will handle
more power than #20 gauge wire. 300 ohm ladder line matches low
impedances better than 450 ohm ladder line. 450 ohm ladder-
line matches high impedances better than 300 ohm ladder line.
The range of SWRs on 300 ohm ladder line that will result in
a 50 ohm SWR of less than 2:1 at a current node is 3:1 to 12:1.
The range of SWRs on 450 ohm ladder line that will result in a
50 ohm SWR of less than 2:1 at a current node is 4.5:1 to 18:1.
You can route 300 ohm ladder line closer to metal than you can
450 ohm ladder line. 450 ohm line has a higher velocity factor.
If you achieve a Z0-match you can get away with using a 4:1
balun on the 300 ohm ladder line. From a performance standpoint,
I doubt you can tell the difference.
73, Cecil, KG7BK, OOTC (not speaking for my employer)