(K3) Alexloop Antenna

[Elecraft mailing list]

I live in a condo with pretty strict rules re antennas, etc.  I am considering an Alexloop on a tripod on my balcony, Does anybody have any experience with this antenna? Any comments. I have a K3/10 that I operate at 5-10 watts PEP onSSB.Thanks 73 de Dave KJ6CBS
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[k6dgw]

I've had an Alex Loop for about 2 years now, it replaced my Buddipole
[about the same cost].  You can build your own mag loop for a lot less
than the Alex but I wanted the cool carry case and had the $$ from the
BP sale. :-))  I use the loop when activating a SOTA summit and general
field operating, usually with my K2/10.

My Alex easily works as well or discernibly better than the BP ever did.
  It is very narrow BW, and tuning it on 40 requires a steady hand and
care.  It's less touchy on 30 and just fine on 20 and up.

I have mine on a light-weight tripod I found at Home Depot with a Rain
Bird sprinkler on top.  I cut 9 inch piece of 1/2" gray PVC nipple with
threads on one end and screw it into the tripod.  The hollow Alex handle
fits down over the PVC.  I finally filed some shallow slots in the PVC
to keep things stable in wind.

I set up next to the tripod and can reach up and tune the loop with one
hand.  There is one gotcha with loops like this:  It is a resonant
transformer.  At resonance, your SWR will be 1:1 and you'll make Q's.
If you "get it close" with the knob and then let the ATU [if you have
it] match it, you will have created a very well shielded dummy load and
you'll make no Q's.  So, bypass the ATU and get 1:1 with the little knob
on the capacitor.  You can't QSY more than maybe 5 KHz on 40 without
tweaking the capacitor.  BW gets larger on 20 and up.

It is mildly bi-directional in the plane of the loop but the lobes are
quite broad.  There are two very sharp, fairly deep nulls orthogonal to
the loop plane which can sometimes help reduce noise or QRM.  It is
essentially insensitive to ground, and doesn't really care how high it
is, a tremendous advantage in the field over E-field antennas.

Pay attention to the power limits.  Because it is resonant and small in
terms of electrical degrees, RF voltages can get quite high.  It's
definitely a QRP antenna.

Hope this helps,

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 50th Running of the Cal QSO Party 3-4 Oct 2015
- www.cqp.org

On 1/30/2015 12:47 PM, David Guernsey via Elecraft wrote:
> I live in a condo with pretty strict rules re antennas, etc.  I am
> considering an Alexloop on a tripod on my balcony, Does anybody have
> any experience with this antenna? Any comments. I have a K3/10 that I
> operate at 5-10 watts PEP onSSB.Thanks 73 de Dave KJ6CBS

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[Dave-3]

Mine worked well on my apartment balcony in dallas with the KX3. Just be
prepared that you will need to get at it to be able to retune it; it is very
sharp

Dave

G4fre


from: David Guernsey via Elecraft <[hidden email]>
To: Elecraft Reflector <[hidden email]>
Subject: [Elecraft] (K3) Alexloop Antenna
Message-ID:
        <[hidden email]>
Content-Type: text/plain; charset=UTF-8

I live in a condo with pretty strict rules re antennas, etc. ?I am
considering an Alexloop on a tripod on my balcony, Does anybody have any
experience with this antenna? Any comments. I have a K3/10 that I operate at
5-10 watts PEP onSSB.Thanks?73 de Dave KJ6CBS


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[Frank Krozel]

The Alexloop is a very good antenna.
Keep your power under 20 watts.
I have used it with a KX3, a 703 and an 857 turned to 20 watts.
Amazing antenna.
I have tried it on a lawn chair… on a balcony and got amazing results.
Keep in mind that every time you transmit, remember to retune before though.  Even 10 kHz….
Frank KG9H

On Jan 31, 2015, at 10:39 AM, Dave <[hidden email]> wrote:

> Mine worked well on my apartment balcony in dallas with the KX3. Just be
> prepared that you will need to get at it to be able to retune it; it is very
> sharp
>
> Dave
>
> G4fre
>
>
> from: David Guernsey via Elecraft <[hidden email]>
> To: Elecraft Reflector <[hidden email]>
> Subject: [Elecraft] (K3) Alexloop Antenna
> Message-ID:
> <[hidden email]>
> Content-Type: text/plain; charset=UTF-8
>
> I live in a condo with pretty strict rules re antennas, etc. ?I am
> considering an Alexloop on a tripod on my balcony, Does anybody have any
> experience with this antenna? Any comments. I have a K3/10 that I operate at
> 5-10 watts PEP onSSB.Thanks?73 de Dave KJ6CBS
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

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[Michael Babineau-2]

Dave :

I have an AlexLoop on its way from Brazil via Express Mail.  You can also order them from W4RT or GigaParts, both are
US dealers for Alex Loop.  

I finally decided to order one because I wanted an antenna that is ultra-portable, deploys quickly (5 minutes) and travels easily without
taking up too much space in luggage when travelling by air. If you want to see one in action go to YouTube and search
on AlexLoop and you will find a number of videos.

Generally speaking this antenna works extremely well from 20m to 10m and on 30m and 40m it is a bit of a compromise.
Apparently Alex is now working on an add-on that allows for remote tuning of the loop. At the moment it is manual tune only.

BTW I also have a MFJ-1786 (30m to 10m) at home and it works very well and has a control box that allows for remote tuning.
You might want to look at the MFJ if you intend to put up the loop as a permanent installation as it might be more convenient.
The performance of the MFJ is somewhat better than the AlexLoop as it uses a fairly large (> 1 inch) diameter aluminum tube that is
welded to the butterfly capacitor.  

Cheers

Michael VE3WMB - ( K1/KX1/K2 )
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[jciullo]

I have been using the MFJ Magnetic loop in various configuration with great satisfaction with a k3. I believe you should have very good results also with the alexloop