KX1 and EFHW antenna

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KX1 and EFHW antenna

Sante - IK0HBN
Hi all,
there is a plenty of schematic about End Fed Half Wave antenna, but
all them are within the range 40-10 meter. Is there one of you who
was able to run it with a KX1 in the range 80-20 meter? The idea of
getting a wire hanged somewhere, without long radials if not a 2-3
meters counterpoise is very intriguing.
BTW with the internal tuner, should KX1 be able to match it without
another external tuner, just to make things simpler with few things
to bring along?
Ciao
Sante

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Re: KX1 and EFHW antenna

Don Wilhelm-4
  Sante,

The KX1 antenna tuner has limited range due to its small size, so I
would not expect it to tune an end-fed 40 meter dipole on 80 meters.

In addition, a half size end fed dipole is no longer an end fed dipole,
it is just a piece of wire.  The "half wave" part says that is true.  A
1/4 wave wire without any other component is only half of a half-wave
dipole no matter where it is fed.

What I would suggest instead is the so-called W3EDP antenna connected to
the KX1 with no feedline.  The radiator is 89 feet (27.13 meters) and
the counterpoise for 3.5 MHz is 17 feet (5.18m).

Take a look at http://www.zerobeat.net/g3ycc/w3edp.htm.  On 80 meters,
you may need the auxiliary (external) tuning circuit, but once you have
tuned the external circuit inside any one band, you can use the KX1
internal tuner as you move around in the band.

73,
Don W3FPR

On 7/10/2011 5:21 PM, Sante - IK0HBN wrote:

> Hi all,
> there is a plenty of schematic about End Fed Half Wave antenna, but
> all them are within the range 40-10 meter. Is there one of you who
> was able to run it with a KX1 in the range 80-20 meter? The idea of
> getting a wire hanged somewhere, without long radials if not a 2-3
> meters counterpoise is very intriguing.
> BTW with the internal tuner, should KX1 be able to match it without
> another external tuner, just to make things simpler with few things
> to bring along?
> Ciao
> Sante
>
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Re: KX1 and EFHW antenna

Sante - IK0HBN
Hi Don,
thanks for support,
I'll try to guess how much inductance the coil of W3EDP is, so to use
a smaller toroid instead of a more invasive and bigger 2 inches coil...

Finally, all I need is (if possible) a single wire antenna for 80-20
meter range, so to not have to change wire every time I will change a
band. Even with somewhat like a tuner could do fine, but also with
something to check the SWR with KX1.
I know the little jewelty shows the SWR, but only after having tuned
a wire, so using an external tuner without SWR reading should be
quite difficult to prune a tuner not having an istantaneus reading of
what I am going to do.
Thanks for now
Ciao
Sante


At 00.08 11/07/2011, you wrote:

>  Sante,
>
>The KX1 antenna tuner has limited range due to its small size, so I
>would not expect it to tune an end-fed 40 meter dipole on 80 meters.
>
>In addition, a half size end fed dipole is no longer an end fed
>dipole, it is just a piece of wire.  The "half wave" part says that
>is true.  A 1/4 wave wire without any other component is only half
>of a half-wave dipole no matter where it is fed.
>
>What I would suggest instead is the so-called W3EDP antenna
>connected to the KX1 with no feedline.  The radiator is 89 feet
>(27.13 meters) and the counterpoise for 3.5 MHz is 17 feet (5.18m).
>
>Take a look at http://www.zerobeat.net/g3ycc/w3edp.htm.  On 80
>meters, you may need the auxiliary (external) tuning circuit, but
>once you have tuned the external circuit inside any one band, you
>can use the KX1 internal tuner as you move around in the band.
>
>73,
>Don W3FPR
>
>On 7/10/2011 5:21 PM, Sante - IK0HBN wrote:
>>Hi all,
>>there is a plenty of schematic about End Fed Half Wave antenna, but
>>all them are within the range 40-10 meter. Is there one of you who
>>was able to run it with a KX1 in the range 80-20 meter? The idea of
>>getting a wire hanged somewhere, without long radials if not a 2-3
>>meters counterpoise is very intriguing.
>>BTW with the internal tuner, should KX1 be able to match it without
>>another external tuner, just to make things simpler with few things
>>to bring along?
>>Ciao
>>Sante

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Re: KX1 and EFHW antenna

Don Wilhelm-4
  Sante,

I would suggest that you do a trial run with the antenna at home - use
an antenna analyzer for this initial tuning.  Once you have found the
right L and C for resonance, remove the variable capacitor, measure it
and substitute a fixed capacitor, there should be no need for further
tuning of that circuit in the field.
Once in the field, some small additional tuning may be required, but the
internal tuner in the KX1 should take care of that.

Take note that a reduced radiator length version of this antenna is
shown on page 9 of the KXAT1 manual - with no external tuning unit.  The
W3EDP radiator wire is close to that 23 feet plus an added half
wavelength on 40 meters, so for 40/30 and 20, this same length wire
should behave about the same as the antenna lengths for which the KX1
tuner was optimized.

73,
Don W3FPR

On 7/11/2011 1:56 PM, Sante - IK0HBN wrote:

> Hi Don,
> thanks for support,
> I'll try to guess how much inductance the coil of W3EDP is, so to use
> a smaller toroid instead of a more invasive and bigger 2 inches coil...
>
> Finally, all I need is (if possible) a single wire antenna for 80-20
> meter range, so to not have to change wire every time I will change a
> band. Even with somewhat like a tuner could do fine, but also with
> something to check the SWR with KX1.
> I know the little jewelty shows the SWR, but only after having tuned
> a wire, so using an external tuner without SWR reading should be
> quite difficult to prune a tuner not having an istantaneus reading of
> what I am going to do.
> Thanks for now
> Ciao
> Sante
>
>
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Re: KX1 and EFHW antenna

Albers
In reply to this post by Sante - IK0HBN
I’ve posted this before, but maybe it bears repeating:

On my camping trips with the KX-1 (with autotuner)  I have had very good results on all 4 bands with my simple wire antenna.

I bought a 50 ft roll of stranded speaker wire at Radio Shack (I believe it was 16 or 18 ga, but I doubt that the thickness matters much).  I un-zipped it to make two wires. Actual length turned out to be 51 ft 8 inches (thanks for being generous, RS!) but here, too, I doubt actual length is critical.

One 50 ft wire lies on the ground. The other goes up as I high as I can get it using available supports. I’ve had it go up as a sloper to a tall tree or the light pole in a motel parking lot, or as an inverted L, and once as an inverted U over a large rock formation in AZ (admittedly, that one didn’t work terribly well). The tuner loads it up nicely and I’ve made lots of nice contacts with it.

You may wish to try it.

73

Ray K2HYD
KX-1 #608
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Re: KX1 and EFHW antenna

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