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CX2SA > SATDIG 18.09.14 14:06l 235 Lines 9107 Bytes #999 (0) @ WW
BID : AMSATBB9327
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Subj: AMSAT-BB-digest V9 327
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Sent: 140918/1201Z @:CX2SA.SAL.URY.SOAM #:10578 [Salto] FBB7.00e $:AMSATBB9327
From: CX2SA@CX2SA.SAL.URY.SOAM
To : SATDIG@WW
Today's Topics:
1. Re: Lindenblads (Jerry Buxton)
2. Re: Lindenblads (Robin Midgett)
3. New AMSAT-NA BOD (Clint Bradford)
4. Re: Lindenblads (Gus)
----------------------------------------------------------------------
Message: 1
Date: Wed, 17 Sep 2014 09:49:15 -0500
From: Jerry Buxton <amsat@xxxx.xxx>
To: amsat-bb@xxxxx.xxx
Subject: Re: [amsat-bb] Lindenblads
Message-ID: <54199F6B.1020607@xxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Hi Robin,
I built two Lindenblad antennas some 18 years ago using information from
the ARRL Antenna Book, if I recall. One for 2m, one for 70cm.
I built them with yardsticks, household wiring, PVC, and twin lead.
The worked quite well for MIR and as recently as about 3 years ago I
took one out to use at a public service event we did, and also used it
to copy the HO-68 beacon during event downtime.
I used the set at Field Day that same year, although with no preamp the
linear birds were a bit rough unless they were pretty high up. But we
were in a noisy location, too.
They worked very well for FM AO-51 and ISS packet, pretty good on SO-50.
On these I can switch polarity by simply changing the angle of the
yardstick-elements, with them being mounted to the PVC with a bolt you
just rotate them around the bolt to the opposite polarity and put it
back up on the pole.
To your question then, when using these if I'm working a linear
polarization bird I usually just leave it alone. If it's a CP bird then
I match that and leave it alone. Of course, I don't get too excited if
it fades because it's not like a terrestrial band opening where you
don't know if it will happen again and to where. With satellites it
will either fade back the other way or worst case, I work the same bird
on the next pass in 1 1/2 or 12 hours.
And they are very picky about their configuration for circularity. At
one Field Day, I forgot what the angle was supposed to be. It was
marked on the PVC but in transit when I fold the "arms" all horizontal,
the PVC marking/end caps got turned as well. I set it (guessed) wrong,
it didn't work worth a hoot. Go home, look it up (this was B.S., Before
Smart-phone) go back and set it right made a big difference for the rest
of the event!
You can just see the 2 meter in this picture from Field Day. If you
look closely, you'll see the folded dipole of house wiring on the
element to the right.
http://n0jy.org/Symposium/lindy.jpg
Good luck, 73!
Jerry Buxton, N?JY
On 9/14/2014 8:38 PM, Robin Midgett wrote:
> Hello to the group,
> I'd like to hear from any users of the Lindenblad antennas regarding
> switching polarity & circularity.
> Based on the article on the AMSAT web page by W6SHP at
> http://www.amsat.org/amsat/articles/w6shp/lindy.html, I'm led to believe
> that the maximum effect comes from having one Lindy for each of RHCP & LHCP
> per band in addition to being able to invert the polarity of each.
> I'd like to hear from users concerning how often switching between RH & LH
> circularity yields benefits as compared to switching polarity on a single
> Lindy.
>
> I've long had an interest in satellite operation. Due to being involved
> with a recent ARISS event, the interest level has been elevated..it's time
> for me to get on the birds. I welcome your input regarding the Lindenblad
> antennas.
> _______________________________________________
> Sent via AMSAT-BB@xxxxx.xxx. AMSAT-NA makes this open forum available
> to all interested persons worldwide without requiring membership. Opinions
expressed
> are solely those of the author, and do not reflect the official views of
AMSAT-NA.
> Not an AMSAT-NA member? Join now to support the amateur satellite program!
> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
>
>
------------------------------
Message: 2
Date: Wed, 17 Sep 2014 10:51:18 -0500
From: Robin Midgett <K4IDC@xxxxxxx.xxx>
To: AMSAT-BB <amsat-bb@xxxxx.xxx>
Cc: kq6ea@xxxxxxx.xxx
Subject: Re: [amsat-bb] Lindenblads
Message-ID:
<CAJHj7F4KrLPy5dxCTfvsQojyDZrkam2d+H1euLufMFYdpvwrxA@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=UTF-8
Gentlemen,
Perhaps I didn't phrase my question plainly enough. Doug is correct; my
question centers around the perceived benefit of having both LHCP & RHCP
Lindenblads with a switch to select between the two...is there a real
benefit?
Having recently been part of an ARRISS event, I witnessed the benefit of
being able to reverse the sense of the cross-polarized Yagi we were using
for the QSO, so it seems to carry forward that having that agility would be
beneficial for Lindenblad antennas, which is why I asked for input from
experienced Lindenblad users.
And yes, the sense of a single Lindy can be changed if the elements are
mechanically rotated in phase with one another about the Z axis. Saying
that it can't be done is akin to saying a Yagi can only be used in one
direction, and none of us accept that as truth.
Again, I appreciate the input from experienced users of this antenna array.
On Wed, Sep 17, 2014 at 4:39 AM, Francesco Messineo <
francesco.messineo@xxxxx.xxx> wrote:
> >
> > -----Original Message-----
> > From: Robin Midgett <K4IDC@xxxxxxx.xxx>
> > To: AMSAT-BB <amsat-bb@xxxxx.xxx>
> > Sent: Mon, 15 Sep 2014 6:23
> > Subject: [amsat-bb] Lindenblads
> >
> >
> > Hello to the group,
> > I'd like to hear from any users of the Lindenblad antennas regarding
> > switching polarity & circularity.
> > Based on the article on the AMSAT web page by W6SHP at
> > http://www.amsat.org/amsat/articles/w6shp/lindy.html, I'm led to believe
> > that the maximum effect comes from having one Lindy for each of RHCP &
> LHCP
> > per band in addition to being able to invert the polarity of each.
> > I'd like to hear from users concerning how often switching between RH &
> LH
> > circularity yields benefits as compared to switching polarity on a single
> > Lindy.
>
> I have used for some time a small satellite station composed of two
> lindenblads, one for 145 MHz and the other for 435 MHz. The UHF one
> was a parasitic lindenblad from a well known project of some years ago
> that I think is still available on the web (I don't remember the
> details now). I have commented on my experience with lindenblads on
> this mailing list a few times in the past, so there might be my
> messages in the archives (if they exist at all).
> What I can say is: signals are nowhere near the ones you can have with
> even small yagis with azimuth and elevation controls, also adding two
> preamplfiers under the antennas greatly improved the chances to make
> QSOs.
> I was able to work many contacts with that setup (FT-847 as rtx),
> mostly CW on the linear sats, but also some FM contacts on all
> satellites available some years ago (2008-2010), and of course some
> SSB contacts on the linear sats.
> I assume that having switchable polarity can only make things better.
>
>
> HTH
> Frank IZ8DWF
> _______________________________________________
> Sent via AMSAT-BB@xxxxx.xxx. AMSAT-NA makes this open forum available
> to all interested persons worldwide without requiring membership. Opinions
> expressed
> are solely those of the author, and do not reflect the official views of
> AMSAT-NA.
> Not an AMSAT-NA member? Join now to support the amateur satellite program!
> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
>
------------------------------
Message: 3
Date: Wed, 17 Sep 2014 08:52:49 -0700
From: Clint Bradford <clintbradford@xxx.xxx>
To: AMSAT BB <amsat-bb@xxxxx.xxx>
Subject: [amsat-bb] New AMSAT-NA BOD
Message-ID: <92FB9158-A789-4D79-A905-47CEC162985C@xxx.xxx>
Content-Type: text/plain; charset=us-ascii
Congratulations to the newly elected AMSAT-NA board members.
Clint K6LCS
------------------------------
Message: 4
Date: Wed, 17 Sep 2014 15:49:48 -0400
From: Gus <gus@xxxxx.xxx>
To: Robin Midgett <K4IDC@xxxxxxx.xxx>, AMSAT-BB <amsat-bb@xxxxx.xxx>
Subject: Re: [amsat-bb] Lindenblads
Message-ID: <5419E5DC.7020004@xxxxx.xxx>
Content-Type: text/plain; charset=UTF-8; format=flowed
On 09/17/2014 11:51 AM, Robin Midgett wrote:
> And yes, the sense of a single Lindy can be changed if the elements
> are mechanically rotated in phase with one another about the Z axis.
Similarly, the sense of an axial-mode helix can be changed by simply
unwinding the helix and winding it back in the other direction. Some
would call this "rebuilding the antenna", rather than "switching the
polarity", but I am not one of those.
--
Gus 8P6SM
The Easternmost Isle
------------------------------
_______________________________________________
Sent via amsat-bb@xxxxx.xxx.
AMSAT-NA makes this open forum available to all interested persons worldwide
without requiring membership. Opinions expressed
are solely those of the author, and do not reflect the official views of
AMSAT-NA.
Not an AMSAT member? Join now to support the amateur satellite program!
http://amsat.org/mailman/listinfo/amsat-bb
End of AMSAT-BB Digest, Vol 9, Issue 327
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