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CX2SA > SATDIG 20.09.08 07:45l 784 Lines 27551 Bytes #999 (0) @ WW
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To : SATDIG@WW
Today's Topics:
1. Re: Polarity questions (pe0sat)
2. Re: Polarity questions (Clint Bradford)
3. Re: OLPC-HYPERTERM-PICOCOM (Robert Bruninga)
4. Re: Polarity questions (Clint Bradford)
5. Re: Polarity questions (SV1BSX)
6. Re: Polarity questions (Angus)
7. Re: Polarity questions (Bruce Robertson)
8. Tower question (Gilbert Mackall)
9. Re: Polarity questions (Sebastian)
10. Space-X to launch flight 4 (G0MRF(AT)aol.com)
11. Re: Polarity questions (Clint Bradford)
12. Re: Polarity questions (i8cvs)
13. Re: Polarity questions (Michael Tondee)
14. first impression (Jim Danehy)
15. Re: Polarity questions (n3tl(AT)bellsouth.net)
----------------------------------------------------------------------
Message: 1
Date: Fri, 19 Sep 2008 20:02:31 +0200 (CEST)
From: "pe0sat" <pe0sat(AT)vgnet.nl>
Subject: [amsat-bb] Re: Polarity questions
To: amsat-bb(AT)amsat.org
Message-ID:
<fe2af33e3bb9327316eaf93aec2702bb.squirrel(AT)webmail.vgnet.nl>
Content-Type: text/plain;charset=iso-8859-1
On Fri, September 19, 2008 16:58, Ryan Butler wrote:
> Tim Tapio wrote:
Hi Tim,
>> How much signal reduction is there as the result of having the wrong
>> circular polarization?
> The difference between RHCP and LHCP is 20 dB
>
> The difference between Horizontal and Vertical Linear is 20 dB
>
> The difference between (RHCP or LHCP) and (Horizontal or Vertical) is 3 dB
If I understand right, you only get 3db extra when using CW/CCW but I have
also read somewhere that you also lose 3db when running CW/CCW so why use
Circulair polarisation and not just Horizontal or Vertical pol.
> Ryan, NF0T
73's Jan / PE0SAT
------------------------------
Message: 2
Date: Fri, 19 Sep 2008 11:44:41 -0700
From: Clint Bradford <clintbrad4d(AT)earthlink.net>
Subject: [amsat-bb] Re: Polarity questions
To: amsat-bb(AT)amsat.org
Message-ID: <2ED279A6-F99B-4871-B3B4-FBE92093E74D(AT)earthlink.net>
Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes
>>...20-dB, assuming the signal is pure circular polarization.
>>...linear, then -3 dB.
>>...difference between RHCP and LHCP is 20 dB
>>...difference between Horizontal and Vertical Linear is 20 dB
>>...difference between (RHCP or LHCP) and (Horizontal or Vertical)
is 3 dB
>>...the VHF/UHF Manual handbook says 20 -30dB
>>...in the real world, expect around 20~25dB loss from being
completely cross-polarized
>>...Between linear and circular, expect about 3dB loss.
Ahh, thank goodness for the engineers...
Just know that to get started working the FM satellites, you do not
need to spend much to make successful contacts...Working AO-51 from
Southern California (which some claim is not a "real world") at a Watt
or so with an HT and Arrow Antenna is a breeze, and the polarization
of the Yagi makes no difference in quality of TX/RX signal.
And as you refine your satellite comms requirements, you can spend
more money!
Clint Bradford, K6LCS
909-241-7666
------------------------------
Message: 3
Date: Fri, 19 Sep 2008 16:19:49 -0400
From: "Robert Bruninga" <bruninga(AT)usna.edu>
Subject: [amsat-bb] Re: OLPC-HYPERTERM-PICOCOM
To: "'Scott Richardson'" <scott(AT)aves-specta.com>, <amsat-bb(AT)amsat.org>
Message-ID: <7E7482439DC04F758505C21B2167AB33(AT)ewlab.usna.edu>
Content-Type: text/plain; charset="us-ascii"
> OLPC produced a user-repairable (to a degree!),
> 2-watt laptop with built-in wifi, mesh
> networking, and a screen viewable indoors or
> out... so it's easy to see the ham radio
> potential.
I had mine on display at the NASA openouse outside in my Ham
radio idisplay and had it hooked to a 1 watt solar panel. I was
surprised when it went dead a few hours later (initial state of
battery unknown)..
So overnight, I put it on a power supply and observed that the
run current is 480 mA and the sleep current is 360 mA. That
surprised me. At 12 volts, that is more like 6 watts than 2.
No wonder my 100 mA solar panel didn't help much... Yes, the
internal battery is runnning around 6 volts which means about 3
watts, but still you have to give it at least 11.8 volts or so
before the switching regulator kicks in and draws much at all...
So to me it is a surprising 6 watts of etxternal power
consumption to power it...
Still I love it.
Bob, WB4APR
The laptops are designed for
> children (ages
> 6-12) in third-world countries, the Sugar interface is a bit
> awkward, and
> there have been some serious blunders along the way. These
> have dampened
> enthusiasm in the USA.
>
> The official website is at www.laptop.org.
> Solid information is in the wiki:
http://wiki.laptop.org/go/Home
> Unofficial but useful source: http://www.olpcnews.com/
>
> The second 'Give One, Get One' (G1,G1) program starts in
> November and ships
> through Amazon.
>
> 73, Scott N1AIA
>
> _______________________________________________
> Sent via AMSAT-BB(AT)amsat.org. Opinions expressed are those of
> the author.
> Not an AMSAT-NA member? Join now to support the amateur
> satellite program!
> Subscription settings:
http://amsat.org/mailman/listinfo/amsat-bb
>
------------------------------
Message: 4
Date: Fri, 19 Sep 2008 12:18:56 -0700
From: Clint Bradford <clintbrad4d(AT)earthlink.net>
Subject: [amsat-bb] Re: Polarity questions
To: amsat-bb(AT)amsat.org
Message-ID: <F93D04F7-FE22-4586-844A-3436786B2687(AT)earthlink.net>
Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes
>>...20-dB, assuming the signal is pure circular
polarization...linear, then -3 dB...difference between RHCP and LHCP
is 20 dB...difference between Horizontal and Vertical Linear is 20
dB...difference between (RHCP or LHCP) and (Horizontal or Vertical) is
3 dB...the VHF/UHF Manual handbook says 20 -30dB...in the real world,
expect around 20~25dB loss from being completely cross-
polarized...Between linear and circular, expect about 3dB loss...
Ahh, thank goodness for the engineers...
Just know that to get started working the FM satellites, you do not
need to spend much to make successful contacts...Working AO-51 from
Southern California (which some claim is not a "real world") at a Watt
or so with an HT and Arrow Antenna is a breeze, and the polarization
of the Yagi makes no difference in quality of TX/RX signal.
And as you refine your satellite comms requirements, you can spend
more money!
Clint Bradford, K6LCS
909-241-7666
------------------------------
Message: 5
Date: Fri, 19 Sep 2008 22:17:47 +0300
From: "SV1BSX" <sv1bsx(AT)yahoo.gr>
Subject: [amsat-bb] Re: Polarity questions
To: "Angus" <angus(AT)young5769.freeserve.co.uk>, <amsat-bb(AT)amsat.org>
Message-ID: <002701c91a8c$6be2a950$0b09a8c0(AT)zeus>
Content-Type: text/plain; format=flowed; charset="windows-1253";
reply-type=original
....I agree with Gus. And the difference is 20-30 dB depending upon the
construction, reflections,
lobes of antennas and other complex parameters.
In general a Cross-Yagi which appears a very good circularity, then rising
easily to 30 dB
between RHCP-LHCP.
Tim,
also keep in mind, by using CP the fading is much less and never the signal
has
too much "deep" .
Having in mind that the LEOs changing quite often the polarization, I
believe the
switching between RHCP-LHCP is mandatory, if always you looking for good
RX-TX conditions . A mere example was the last pass of AO-7 over my QTH .
During the ascending orbit it was 5 S-units without preamp and almost close
to TCA the signal
dropped down to Zero (Q5). By changing my antenna to the opposite
polarization,
it was again 5 S-units. That is a great difference on receiving.
So, If you want just to play with LEOs and you are not looking for the
optimum,
you can do it by using stable polarization. However it's compromise
and manytimes you will wonder why the satellite is too weak and some other
times "booming".
73, Mak SV1BSX
----- Original Message -----
From: "Angus" <angus(AT)young5769.freeserve.co.uk>
To: <AMSAT-BB(AT)amsat.org>
Sent: Friday, September 19, 2008 5:29 PM
Subject: [amsat-bb] Re: Polarity questions
> if the satellite is running RHCP and you have LHCP the VHF/UHF Manual
> handbook says 20 -30dB which is a lot!
> having spent ages getting a homebrew polarity control box to work just
> right, I can honestly say it was well worth the effort!
> regards
> Gus M0IKB
> ----- Original Message -----
> From: "Tim Tapio" <tim(AT)timtapio.com>
> To: <amsat-bb(AT)amsat.org>
> Sent: Friday, September 19, 2008 1:58 PM
> Subject: [amsat-bb] Polarity questions
>
>
>>
>> Hi,
>>
>> How much signal reduction is there as the result of having the wrong
>> circular polarization?
>> I'm looking at M2 circular antennas for the 70cm downlink, it's another
>> $200
>> for the switching to change polarity (woo hoo).
>>
>> 73 de Tim, K4SHF
>>
>>
>>
>>
>> _______________________________________________
>> Sent via AMSAT-BB(AT)amsat.org. Opinions expressed are those of the author.
>> Not an AMSAT-NA member? Join now to support the amateur satellite
>> program!
>> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
>>
>
>
> _______________________________________________
> Sent via AMSAT-BB(AT)amsat.org. Opinions expressed are those of the author.
> Not an AMSAT-NA member? Join now to support the amateur satellite program!
> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
------------------------------
Message: 6
Date: Fri, 19 Sep 2008 21:19:19 +0100
From: "Angus" <angus(AT)young5769.freeserve.co.uk>
Subject: [amsat-bb] Re: Polarity questions
To: <amsat-bb(AT)amsat.org>
Message-ID: <57AA90D3A3314542A924590664273D30(AT)GusPC>
Content-Type: text/plain; format="flowed"; charset="iso-8859-1";
reply-type="original"
By having circular polarisation that matches the satellite (RHCP or LHCP but
the same polarity) you have very little QSB fading during the pass of the
satellite. Using my own system I normally start a pass on Horizontal as the
satellite is at AOS and then when it rises switch to the correct circular
polarity and as the satellite gets near to LOS I am back on horizontal
polarity with good quality signals through the entire pass.
try listening to a NOAA weather satellite on 137mhz on a fixed polarity
antenna i.e V or H and for some of the pass the signal is very good but as
the signal changes polarity the signal drops down into the noise and through
the satellite pass you will get these peaks and troughs of signals. This is
why if possible it is best to use circular or better still have the ability
to switch polarity during the pass.
regards
Gus
----- Original Message -----
From: "pe0sat" <pe0sat(AT)vgnet.nl>
To: <amsat-bb(AT)amsat.org>
Sent: Friday, September 19, 2008 7:02 PM
Subject: [amsat-bb] Re: Polarity questions
>
>
> On Fri, September 19, 2008 16:58, Ryan Butler wrote:
>> Tim Tapio wrote:
>
> Hi Tim,
>
>>> How much signal reduction is there as the result of having the wrong
>>> circular polarization?
>
>> The difference between RHCP and LHCP is 20 dB
>>
>> The difference between Horizontal and Vertical Linear is 20 dB
>>
>> The difference between (RHCP or LHCP) and (Horizontal or Vertical) is 3
>> dB
>
> If I understand right, you only get 3db extra when using CW/CCW but I have
> also read somewhere that you also lose 3db when running CW/CCW so why use
> Circulair polarisation and not just Horizontal or Vertical pol.
>
>> Ryan, NF0T
>
> 73's Jan / PE0SAT
>
> _______________________________________________
> Sent via AMSAT-BB(AT)amsat.org. Opinions expressed are those of the author.
> Not an AMSAT-NA member? Join now to support the amateur satellite program!
> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
>
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------------------------------
Message: 7
Date: Fri, 19 Sep 2008 17:02:03 -0300
From: "Bruce Robertson" <ve9qrp(AT)gmail.com>
Subject: [amsat-bb] Re: Polarity questions
To: kq6ea(AT)pacbell.net
Cc: amsat-bb(AT)amsat.org
Message-ID:
<49657a760809191302g553c1f7dp7568608bb7450386(AT)mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
A follow-up question --
I'd like to homebrew a circularly polarized antenna. Does anyone have
a favorite relay switch to use for this application? A lot of them
seem not to be weather-proof. It seems BNCs would make good
connectors, but I'd be interested in opinions on this, too.
73, Bruce
VE9QRP
On Fri, Sep 19, 2008 at 1:34 PM, Jim Jerzycke <kq6ea(AT)pacbell.net> wrote:
> Theoretically, it's 'infinite', but out in the real world, expect around
20~25dB loss from being completely cross-polarized. When I was doing
commercial satellite work, if we could get 26~27dB we were happy, but this was
with rigidly controlled satellites and commercial ground stations.
> Between linear and circular, expect about 3dB loss.
> Jim KQ6EA
>
> --- On Fri, 9/19/08, Tim Tapio <tim(AT)timtapio.com> wrote:
>
>> From: Tim Tapio <tim(AT)timtapio.com>
>> Subject: [amsat-bb] Polarity questions
>> To: amsat-bb(AT)amsat.org
>> Date: Friday, September 19, 2008, 5:58 AM
>> Hi,
>>
>> How much signal reduction is there as the result of having
>> the wrong
>> circular polarization?
>> I'm looking at M2 circular antennas for the 70cm
>> downlink, it's another $200
>> for the switching to change polarity (woo hoo).
>>
>> 73 de Tim, K4SHF
>>
>>
>>
>>
>> _______________________________________________
>> Sent via AMSAT-BB(AT)amsat.org. Opinions expressed are those
>> of the author.
>> Not an AMSAT-NA member? Join now to support the amateur
>> satellite program!
>> Subscription settings:
>> http://amsat.org/mailman/listinfo/amsat-bb
> _______________________________________________
> Sent via AMSAT-BB(AT)amsat.org. Opinions expressed are those of the author.
> Not an AMSAT-NA member? Join now to support the amateur satellite program!
> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
>
------------------------------
Message: 8
Date: Fri, 19 Sep 2008 17:10:56 -0400
From: Gilbert Mackall <mackall(AT)goldensquare.net>
Subject: [amsat-bb] Tower question
To: amsat-bb <amsat-bb(AT)amsat.org>
Message-ID: <C606E07E-D910-43F7-A22E-B8615DF69894(AT)goldensquare.net>
Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes
I am looking to get back on the air and would like to put up a tower.
What should I expect in the way of cost for a 40 ft, tilt tower?
Is this a project I can do myself or would I be better off paying to
have it installed?
Are there any permits needed for a tower of this height?
------------------------------
Message: 9
Date: Fri, 19 Sep 2008 17:11:34 -0400
From: Sebastian <w4as(AT)bellsouth.net>
Subject: [amsat-bb] Re: Polarity questions
To: AMSAT BB <AMSAT-BB(AT)amsat.org>
Message-ID: <9D2FB423-71DE-4ABE-B01F-E81ACD32F3FB(AT)bellsouth.net>
Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes
I gotta hand it to the guys who do it with a handheld, and an arrow
antenna. I hear them all the time, they have good signals. They are
standing up, figuring out where to point the antenna, when and where
to turn it, up and down, sideways, and keep up with doppler, and log
the signals and somehow also talk; I don't know how they do it!
This morning I worked a station on one of the birds who was using a
vertical, he was weak, but we made the qso.
I personally enjoy experimenting, and seeing what works best for me.
I don't just throw money at something and hope it somehow gets
better. Not to knock the guys who really know their stuff, the guys
who built the satellites and control them. But as I've said before -
the main issue with the amateur satellites at this time is that they
are UNDERUTILIZED. Just listen during a pass and many times you won't
hear anyone, and most of the time you will end up talking to the same
people over and over again. I hope that statement doesn't waken up
the "we don't have a HEO" complainers!
73 de W4AS
Sebastian
On Sep 19, 2008, at 2:44 PM, Clint Bradford wrote:
>>> ...20-dB, assuming the signal is pure circular polarization.
>>> ...linear, then -3 dB.
>>> ...difference between RHCP and LHCP is 20 dB
>>> ...difference between Horizontal and Vertical Linear is 20 dB
>>> ...difference between (RHCP or LHCP) and (Horizontal or Vertical)
> is 3 dB
>>> ...the VHF/UHF Manual handbook says 20 -30dB
>>> ...in the real world, expect around 20~25dB loss from being
> completely cross-polarized
>>> ...Between linear and circular, expect about 3dB loss.
>
> Ahh, thank goodness for the engineers...
>
> Just know that to get started working the FM satellites, you do not
> need to spend much to make successful contacts...Working AO-51 from
> Southern California (which some claim is not a "real world") at a Watt
> or so with an HT and Arrow Antenna is a breeze, and the polarization
> of the Yagi makes no difference in quality of TX/RX signal.
>
> And as you refine your satellite comms requirements, you can spend
> more money!
>
> Clint Bradford, K6LCS
> 909-241-7666
> _______________________________________________
> Sent via AMSAT-BB(AT)amsat.org. Opinions expressed are those of the
> author.
> Not an AMSAT-NA member? Join now to support the amateur satellite
> program!
> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
------------------------------
Message: 10
Date: Fri, 19 Sep 2008 19:14:41 EDT
From: G0MRF(AT)aol.com
Subject: [amsat-bb] Space-X to launch flight 4
To: amsat-bb(AT)amsat.org
Message-ID: <bff.470c92d2.36058c61(AT)aol.com>
Content-Type: text/plain; charset="US-ASCII"
Hi all.
I see Space X have an initial launch period scheduled for flight 4.
The web site says anytime from Tuesday to Thursday (next week?) from their
Kwajalein Atoll base in the Pacific.
After the unfortunate loss of flight 3 due to a very minor glitch, does
anyone know if the planned RazakSAT is flying of flight 4?
Would be a shame if it isn't and the payload is a mass dummy only.
Thanks
David
( Good luck Space-X )
------------------------------
Message: 11
Date: Fri, 19 Sep 2008 16:29:59 -0700
From: Clint Bradford <clintbrad4d(AT)earthlink.net>
Subject: [amsat-bb] Re: Polarity questions
To: N3TL(AT)bellsouth.net
Cc: amsat-bb(AT)amsat.org
Message-ID: <C275F174-D144-4AAF-A856-9ACFE84482E4(AT)earthlink.net>
Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes
>>...I have to disagree with Clint...
I just must be the luckiest S.O.B.(*) working AO-51, then...During
demonstrations in front of folks, someone in the assemblage almost
always asks about polarization. I twist the Arrow, and we all "hear"
no difference in its strong, clean signal.
Clint, K6LCS
909-241-7666
- S.O.B. - Satellite-operating Bradford
------------------------------
Message: 12
Date: Sat, 20 Sep 2008 01:29:48 +0200
From: "i8cvs" <domenico.i8cvs(AT)tin.it>
Subject: [amsat-bb] Re: Polarity questions
To: "Tim Tapio" <tim(AT)timtapio.com>, "AMSAT-BB" <amsat-bb(AT)amsat.org>
Message-ID: <00a701c91aaf$9c9e7880$0201a8c0(AT)tin.it>
Content-Type: text/plain; charset="iso-8859-1"
----- Original Message -----
From: "Tim Tapio" <tim(AT)timtapio.com>
To: <amsat-bb(AT)amsat.org>
Sent: Friday, September 19, 2008 2:58 PM
Subject: [amsat-bb] Polarity questions
> Hi,
>
> How much signal reduction is there as the result of having the wrong
> circular polarization?
> I'm looking at M2 circular antennas for the 70cm downlink, it's another
> $200 for the switching to change polarity (woo hoo).
>
> 73 de Tim, K4SHF
>
Hi Tim, K4SHF
The above matter has been discussed many time on this BB by the way
the following article is strongly recommended because it answere to your
question with easy.
"The Advantages of Circular Polarization" by K4KJ Sept-12-1975 ARRL
Technical Symposium, Reston Virginia
The above article is available in two zipped files on request off line to
everyone is interested on it.
73" de
i8CVS Domenico
------------------------------
Message: 13
Date: Fri, 19 Sep 2008 21:53:29 -0400
From: "Michael Tondee" <mat_62(AT)netcommander.com>
Subject: [amsat-bb] Re: Polarity questions
Cc: <amsat-bb(AT)amsat.org>
Message-ID: <006e01c91ac3$ae7ad440$6500a8c0(AT)w4hij1>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
I may have misunderstood but the way I got it when I was researching
homebrewing yagi's for my sat station is that if you had to fix the antenna
to either RHCP or LHCP and could not switch between the two because of cost
or complexity or whatever other reason that your best compromise would be to
go with linear polarization.
Feed harnesses for homebrew CP antennas are a stumbling block for me as I
don't have a grid dip meter or SWR anylyzer to properly figure coax velocity
and electrical length. If you don't get the phasing harnesses the right
length then you won't get CP anyway.
I use two of the "cheap yagi" designs by Kent Britain in vertical
polarization and rotate them with a homebrew "SAEBRTrack" Az/El rotor box
and old Gemini OR-360 TV rotators. Works well enough for LEO's anyway.
73,
Michael, W4HIJ
------------------------------
Message: 14
Date: Fri, 19 Sep 2008 22:45:12 -0400
From: "Jim Danehy" <jdanehy(AT)cinci.rr.com>
Subject: [amsat-bb] first impression
To: <amsat-bb(AT)amsat.org>
Message-ID: <5C219EAB96EE4AE1B0FDA5E404EF0414(AT)JamesPC>
Content-Type: text/plain; charset="iso-8859-1"
I operated OSCAR satellites back in 1974-1976. It was simple with 2 meters up
and 10 meters down. Not much doppler effect either. I got back on a month ago
after a lapse of 32 years. I would like to give my impressions to date. I have
had QSOs on 6 or 7 different birds using CW, SSB and of course FM. By far the
most productive mode is FM. It is also the easy way to get on OSCAR. The
transponders on AO7, VO52 and FO29 go aching for use. On 15 minute passes you
can find just one or two other users. Sadly nobody at times. Of course you
need to be able to manage doppler and to track the bird with some degree of
accuracy. I guess I have had over 400 QSOs during the past month. I have
worked 42 states and 7 countries along with about 110 grid squares. Being
newly retired the XYL encourages me to stay in the shack. However of the 400
QSOs I have probably only worked 120 different stations. The biggest
disappointment for me is the lack of information in QST and CQ magazines on
OSCA!
R. I had no idea that there were that many potential birds flying and
providing the opportunity to make contacts. Having been a ham for 56 years and
always active I don't miss a lot. Oh I see the AMSAT booth at Dayton. But
there is little effective public relations going on to attract hams to use
OSCAR satellites. There is some but not to the extent that is needed. I just
rejoined AMSAT. It is obvious that there is plenty of transponder "spectrum"
going unused. It is a very modest challenge to use satellites other than FM
birds, in my opinion. I have some M Square yagis that I put together along
with an elevation and azimuth rotators. I put them up about 15 feet off the
ground. I learned a few things about switching polarity too. We did not have
circular polarity being used in 1974 if my memory is working.
The best part about being back on is the opportunity to meet a new group of
hams. I have learned about SatPC32 and struggle to get it working with the
Vista operating system. I also got the RHCP vs. LHCP wrong on my 2 meter
antenna. I owe thanks to K9QHO and K9CIS for helping me on that issue.
Most use AO51 as the bird of choice. I wonder why there is so little use of
SO50 ? It works great and is under used too. These are my first impressions.
There really is a lack of public relations about how much is out there in the
way of satellite opportunities. Of course that is just my opinion. One thing
for sure you do not need to count the sun spots to see if you can make
contacts. I would like to see folks give a little opening to some of the
Central American stations who come on frequency but get stepped on. A QSO with
a TI4 or a KP4 is still DX even for a guy like me who has been around long
enough to have worked them all. One day HR1LW called me on VO52. What a
thrill. There was no one else on. A few weeks later he called me again and
called me by name. Same for a few European QSOs that I have had.
My XYL wants to thank all of those that have kept me in the shack and out of
her hair as she adjusts to my retirement. I do too.
73 Jim W9VNE
Cincinnati, Ohio EM79tb
------------------------------
Message: 15
Date: Fri, 19 Sep 2008 23:23:09 +0000
From: n3tl(AT)bellsouth.net
Subject: [amsat-bb] Re: Polarity questions
To: Clint Bradford <clintbrad4d(AT)earthlink.net>, amsat-bb(AT)amsat.org
Message-ID:
<091920082323.26677.48D4345D0009E0970000683522243322829B0A02D2089B9A019C
04040A0DBF049BCC02(AT)att.net>
Content-Type: text/plain
" ... and the polarization of the Yagi makes no difference in quality of TX/RX
signal."
I know I haven't been working the satellites nearly as long as Clint and many
others - and with all due respect, my friend - I have to disagree with the
above statement. I routinely work passes during which I swing my Arrow
through, and sometimes beyond, 90 degrees to maintain signal quality. There
also have been times when a quick twist of the wrist has made the difference
between making a contact and getting a new grid square ... and not.
I don't-at-all disagree with the concept that working AO-27, AO-51 and SO-50
isn't terribly difficult with a handheld station. Frankly, that has really
(and pleasantly) surprised me. However, I do believe that adjusting polarity
when hand-holding the Arrow provides improved performance during many passes.
73 to all,
Tim
-------------- Original message from Clint Bradford
<clintbrad4d(AT)earthlink.net>: --------------
> >>...20-dB, assuming the signal is pure circular
> polarization...linear, then -3 dB...difference between RHCP and LHCP
> is 20 dB...difference between Horizontal and Vertical Linear is 20
> dB...difference between (RHCP or LHCP) and (Horizontal or Vertical) is
> 3 dB...the VHF/UHF Manual handbook says 20 -30dB...in the real world,
> expect around 20~25dB loss from being completely cross-
> polarized...Between linear and circular, expect about 3dB loss...
>
> Ahh, thank goodness for the engineers...
>
> Just know that to get started working the FM satellites, you do not
> need to spend much to make successful contacts...Working AO-51 from
> Southern California (which some claim is not a "real world") at a Watt
> or so with an HT and Arrow Antenna is a breeze, and the polarization
> of the Yagi makes no difference in quality of TX/RX signal.
>
> And as you refine your satellite comms requirements, you can spend
> more money!
>
> Clint Bradford, K6LCS
> 909-241-7666
> _______________________________________________
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End of AMSAT-BB Digest, Vol 3, Issue 473
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