I'll restate: The length of coax should be as short as feasible because the
losses from mismatch (SWR) are highest when compared to window or ladder line.
The shortest distance from my rig to the choke is about ten feet unless I bring
the window line inside (too problematic) or put the rig in t
I said earlier:
"Rick claims that when using a series connection of two different transmission
lines, one coaxial, one window line, changing the length of one (coax) affects
something or the other, while changing the length of the other portion (window line)
has no effect whatsoever.
This is
On 5/17/2014 2:29 PM, Wes (N7WS) wrote:
My apologies for confusing two different posters to this thread. Partly
a consequence of threading and me using two different computers and two
different email clients.
I thought that's what having an email client thread emails was supposed
to prevent.
For clarity: every line has loss. Every single line.
What should have been better implied is that coax exhibits a significantly
higher loss per foot than window line; while both have losses. This is well
proven over decades of use.
High SWR affects the losses in a negative way (the losses
My apologies for confusing two different posters to this thread. Partly a
consequence of threading and me using two different computers and two different
email clients.
I want to specifically address this:
Rick claims that when using a series connection of two different transmission
lines, o
Sure it does, you're changing the line losses, tweaking C and L and therefore
the SWR (always measured at the tuner, but moving peaks and valleys
closer/further away from that point) any time you alter the system.
There are specific resonant points in an antenna system (typically each half
wave
Iain,
It may be worth going back to basics and reading up on doublet antennas
as well as open wire feeders. The critical length is half of the top
plus the feeder length and this should be adjusted so that it isn't
resonant on any band you wish to use. This because it is easier to
match a m
I use a 260 foot doublet fed with 600 ohm tuned feeder (4" spacing #14
wire). It is run as an NVIS antenna - up 26 feet and flat. The K3
auto-tuner and the KAT500 both tune it very well for 160/80/40/30
meters. I do not use it on the upper bands. The feedline is about 25
feet long and is termin
On 5/15/2014 12:22 PM, Iain G4SGX wrote:
Hello,
Does anyone use a 270 foot doublet with the K3 ATU?
Yes
Is there a combination of feeder type/length and Balun type & coax
length that tunes OK on 160-10?
My primary 40/60/80/160 antenna is a center-fed dipole in an inverted-V
configuration.
Why the caveat about line resonance? Should make no difference. Besides when
the system is tuned, it's resonant.
Wes N7WS
On 5/15/2014 12:46 PM, Matt Zilmer wrote:
As long as the balanced line isn't resonant, you should be OK. I use
61 feet here (18.6m) and it works fine from 2.8 MHz up.
This makes no logical sense, unless you have a big common-mode problem.
Wes N7WS
On 5/15/2014 12:54 PM, Rick Bates, WA6NHC wrote:
Changing the length of the coax portion has a HUGE impact on where (or if) the
system tunes; the window line, none.
___
I use a 104 meter (340') dipole (double extended Zepp for 75/80 meters); fed in
the middle with 100' of 450 ohm window line on all bands. In it's original
configuration, I fed that with a 1:1 common mode choke (a DX Engineering balun,
converting the feed to coax) into the K3. The K3 tuner was
On 5/15/2014 15:22, Iain G4SGX wrote:
> Hello,
>
> Does anyone use a 270 foot doublet with the K3 ATU?
I am using circa 270 feet, as OCF. The 450-ladder-line is roughly 130
feet. The height above variable terrain is 80 feet. The ladder line
drops into a 4:1 balun then 4 feet of coax.
K3 KAT500 t
As long as the balanced line isn't resonant, you should be OK. I use
61 feet here (18.6m) and it works fine from 2.8 MHz up. The doublet
is 150 feet, total length. So far I haven't found a freq that the
K3's ATU cannot tune, and that includes many MARS channels outside and
between the U.S. Amate
Hello,
Does anyone use a 270 foot doublet with the K3 ATU?
Is there a combination of feeder type/length and Balun type & coax
length that tunes OK on 160-10?
I am currently thinking a 1:1 balun and 33 foot of 300 ohm feeder.
Obviously the coax length should be short but too short may cause r
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