My 16Ø dipole (1Ø5 each leg and 75ft twin lead) wont tune 3Ø with auto
tuner on rig. Its fine on the other low bands I want to work (40/80/160)

Anyone know a way to help it tune ???? It tries and even finds a low SWR
of about 1.1 - 1 but then goes off into the sunset detunes and times
out.

In article ,
"R. Scott" wrote:

My 16Ø dipole (1Ø5 each leg and 75ft twin lead) wont tune 3Ø with auto
tuner on rig. Its fine on the other low bands I want to work (40/80/160)

Anyone know a way to help it tune ???? It tries and even finds a low SWR
of about 1.1 - 1 but then goes off into the sunset detunes and times
out.

R.-

Isn't 105 feet close to 30 Meters? That would make the feed point a
high impedance.

The twin lead acts like an impedance transformer. As a test, try adding
about 20 feet of twin lead, and see what changes.

Fred
K4DII

"R. Scott" wrote in message ...

My 16Ø dipole (1Ø5 each leg and 75ft twin lead) wont tune 3Ø with auto
tuner on rig. Its fine on the other low bands I want to work (40/80/160)

Anyone know a way to help it tune ???? It tries and even finds a low SWR of
about 1.1 - 1 but then goes off into the sunset detunes and times
out.

You might try changing the feedline length. That won't do anything for the
antenna system SWR, but it will move the impedance seen by the tuner to a
different position on the Smith chart.

Your tuner might be happy with that new impedance.

Wayne

W5GIE

Feedline is sealed (commercial antenna), but I think I can break it open Ill let you know how it goes.

In message ,
writes
Feedline is sealed (commercial antenna), but I think I can break it
open Ill let you know how it goes.

Why do you need to 'break it open'? At the TX end, isn't there some sort
of connector which connects it to the TX? If so, that's where I would
attach the additional length of feeder. [Also, what (if anything) is
connecting the balanced feeder to the (presumably) unbalanced output on
the TX?]

Assuming it's a plastic twin feeder, its velocity factor will be (say)
0.9 - so the physical 75' will be equivalent to around 88' electrical.
The 105' each leg of the antenna, plus 88' of feeder, adds up to 188' -
or 57.3m.

On 30m, a halfwave is 15m, so 57.3m is 3.82 halfwaves, or 7.6
quarterwaves. So on the face of it, the impedance looking into the twin
feeder is unlikely to be extremely high (which I understand some
auto-tuners don't like) or extremely low (which I understand they are
reasonably happy with).

However, as others suggest, adding a few additional feet of feeder will
probably bring the feed impedance to something that the tuner accepts.
--
Ian

In article ,
wrote:

Feedline is sealed (commercial antenna), but I think I can break it open Ill
let you know how it goes.

If the twin lead transitions to Co-Ax, I think you would get results by
adding a length of Co-Ax. I had assumed your twin lead went all the way
to the tuner.

Fred
K4DII

On 10/12/2015 1:09 PM, R. Scott wrote:
My 16Ø dipole (1Ø5 each leg and 75ft twin lead) wont tune 3Ø with auto
tuner on rig. Its fine on the other low bands I want to work (40/80/160)

Anyone know a way to help it tune ???? It tries and even finds a low SWR
of about 1.1 - 1 but then goes off into the sunset detunes and times
out.


Does it have a halt or stop button so you can make it stop where the low
SWR occurs? If so, have you tried that?