[Elecraft] KX3 ATU

[Wayne Burdick]

Just to clarify: I'm referring to *end-fed* antennas that are a  
multiple of 1/2-wave. The feedpoint impedance of such antennas is  
extremely high, something like 3-6 Kohms.

A 1/2-wave dipole or inverted V, fed in the middle, will typically be  
50-75 ohms.

Wayne
N6KR

On Apr 24, 2012, at 1:08 PM, Wayne Burdick wrote:

> 67' is very close to a half-wave on 40 m and a full-wave on 20 m. In
> theory the SWR should be insanely high, so I'm surprised the K1 ATU
> handled it on 20 m. Even if it did, the losses would be very high.
> Best to use lengths that aren't close to a multiple of a half-wave on
> any target band.
>
> Wayne
> N6KR
>
> On Apr 24, 2012, at 10:11 AM, Niel Wiegand wrote:
>
>> Robert,
>>
>> I've found that the KX3 ATU loads up a 58' endfed wire just fine on
>> all
>> bands, but it can't load up everything. The 67' endfed wire I have
>> (which, in theory,  is very tough to load up) could be loaded up on  
>> 20
>> with the K1 ATU. The KX3 ATU can not handle it.
>>
>> So, for your loop, depending on the size, you may or may not have
>> trouble depending on the length. For a closed loop I believe you
>> want to
>> avoid odd multiples of half wave lengths. If the possible length you
>> have is pretty inflexible and the KX3 ATU can't handle it you can try
>> inserting an insulator half way around making it an open loop.
>>
>> 73,
>> Niel - W0VLZ
>> KX3 #43
>>
>>> Message: 21
>>> Date: Tue, 24 Apr 2012 12:50:28 +0000
>>> From:va3bxg at gmail.com
>>> Subject: [Elecraft] KX3 ATU
>>> To: "Elecraft"<elecraft at mailman.qth.net>
>>>
>>>
>>> Does anyone know what the capability/efficiency of the internal ATU
>>> is?
>>>
>>> Not talking about the wattage (its up to 20 I believe) but the
>>> tuning the SWR/range
>>>
>>> Looking at deploying a random wire/loop so I am wondering if I need
>>> a separate ATU or can the internal unit handle the range?
>>> Thanks
>>> Robert
>>>
>>> a 'kosher' ham
>>> Sent from my BlackBerry device
>>
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