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Re: KX3 & Loop Antennas

Posted by Phil Wheeler-2 on May 31, 2016; 12:42am
URL: http://elecraft.85.s1.nabble.com/KX3-Loop-Antennas-tp7618249p7618259.html

Re "Try it with 1 KW, it will really surprise
you.  And sadly, I don't think a Reynolds Wrap hat
will protect you if you're close.: Not to worry,
because the AlexLoop would fail very quickly if
subjected to a kW!  I'd not want to be under it or
anywhere near it in that case.

73, Phil W7OX

On 5/30/16 5:13 PM, Fred Jensen wrote:

> I replaced my Buddipole with an Alex and use it
> a lot in the field ... understand that as I
> accumulate birthdays, "field" more and more
> means a drive-to a park or friendly hill. It
> works better than the BP ever did, I can set it
> up in 5 min, it is fairly insensitive to ground
> and surrounding objects, including me.  I sit
> under it so I can reach the knob.
>
> It's a resonant transformer.  To be effective,
> it must be EXACTLY resonant.  That's a bit
> touchy on 30 and 40.  You MUST bypass the ATU.
> "Getting close" with the knob and then letting
> the ATU do it's matching job yields a fairly
> pricey dummy load.  On 40, the BW of the Alex
> isn't much more than a SSB signal.
>
> Beware:  Small mag loops can involve some huge
> circulating currents and RF voltages.  The Alex
> is OK to 10W.  Google "magnetic loop calculator"
> for a very cool little calculator.  Try it with
> 1 KW, it will really surprise you.  And sadly, I
> don't think a Reynolds Wrap hat will protect you
> if you're close.
>
> Small mag loops are bi-directional in the plane
> of the loop but it is very broad.  Orthogonal to
> the loop plane, there are two very sharp, deep
> nulls, sometimes useful to eliminate noise from
> a point source or QRM.
>
> 73,
>
> Fred K6DGW
> - Northern California Contest Club
> - CU in the Cal QSO Party 1-2 Oct 2016
> - www.cqp.org
>
> On 5/30/2016 4:38 PM, TFJM via Elecraft wrote:
>> Has anyone had much success using either an
>> Alex Loop or Chameleon P Loop
>> antenna with their KX3? I have few antenna
>> options in an apartment situation
>> and throwing a 25 foot long wire into a nearby
>> tree has not worked for me.
>> Even tried loading up a 33 foot long aluminum
>> balcony railing with no luck.
>>
>> Thanks,
>> Tom W1PDI

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