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CX2SA > SATDIG 21.07.14 06:23l 700 Lines 27157 Bytes #999 (0) @ WW
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Today's Topics:
1. Re: ANS-199 AMSAT News Service Special Bulletin - AMSAT
Fox-1C Launch Opportunity Announced (Robert Bruninga)
2. Re: going digital (Phil Karn)
3. CQ Hawaii (Paul Stoetzer)
4. Re: ANS-199 AMSAT News Service Special Bulletin - AMSAT
Fox-1C Launch Opportunity Announced (Phil Karn)
5. Re: going digital (Gus)
6. Re: The root of all the problems (Phil Karn)
7. 1969-07-20 (B J)
8. Re: going digital (Phil Karn)
9. Re: ANS-199 AMSAT News Service Special Bulletin - AMSAT
Fox-1C Launch Opportunity Announced (Phil Karn)
10. Re: 1969-07-20 (Dale Hershberger)
11. Re: The root of all the problems (Bryce Salmi)
12. Re: ANS-199 AMSAT News Service Special Bulletin - AMSAT
Fox-1C Launch Opportunity Announced (Phil Karn)
13. 432 10-13 -Element Antenna? (Les Rayburn)
----------------------------------------------------------------------
Message: 1
Date: Sun, 20 Jul 2014 19:58:26 -0400
From: Robert Bruninga <bruninga@xxxx.xxx>
To: amsat bb <amsat-bb@xxxxx.xxx>
Subject: Re: [amsat-bb] ANS-199 AMSAT News Service Special Bulletin -
AMSAT Fox-1C Launch Opportunity Announced
Message-ID:
<CALdCfNKf2nnrxP2wdFwxEkLG4i2sAUv2UYhFsD_o1c2+j8wxVA@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=UTF-8
Hummh,
We get an equilibrium of a cube to be about 55F (13C) when exposed to the
sun on one side and all the other sides radiating to cold space. (assuming
they are thermally connected).
I wonder why the big difference between our calculations?
Bob, WB4aPR
On Sun, Jul 20, 2014 at 6:59 AM, Phil Karn <karn@xxxx.xxx> wrote:
> On 07/19/2014 09:23 PM, Robert Bruninga wrote:
>
> > I cannot believe that. The equilibrium of a nominally black (solar
> panels
> > on all sides) spacecraft is something like about 0 to 30 C (32F to 90F) a
> > very benign operational range. The only time you DO have thermal issues
> is
> > when you DO have attitude control and have things that are not equally
> over
> > time seeing the sun and dark sky.
>
> See Dick's paper for the details; I'm just quoting his results. I know
> the basic physics of heat transfer in space but I would never call
> myself an expert. He is.
>
> But I can do a back-of-the-envelope calculation that tells me he's right.
>
> The solar cells they're using have an absorptivity and emissivity that
> is both 0.98, as I recall, so a cubesat covered with them is essentially
> a perfect blackbody.
>
> A blackbody cube with one face normal to the sun at 1 AU will reach an
> equilibrium temperature of -21.35 C. The problem is that the ratio of
> radiating area to absorbing area for a cube is 6:1 (with the sun normal
> to one surface). A sphere would be warmer because its ratio of radiating
> to absorbing area is only 4:1. A thin flat plate normal to the sun (like
> a solar wing) would be even warmer -- 2:1.
>
> And that -21.35 C figure is for continuous sunlight. Throw in eclipses
> and things get much worse. Yes, it would be a little better when the sun
> shines on a corner rather than normal to a face, and Earth albedo and IR
> radiation will warm things a little, but not enough to matter.
>
> --Phil
>
> PS: Temperature of 10 cm blackbody cube at 1 AU:
>
> Area facing sun: .01 m^2
> Solar constant: 1367.5 W/m^2
> Absorbed power = 13.675 W
>
> Total radiating area: .06 m^2
> Emissivity = 1.0 (perfect blackbody)
> Stefan-Boltzmann constant = 5.6703e-8 W/(m^2K^4)
>
>
> T = (13.675 W / (5.6703e-8 * 1.0 * .06)) ** (1/4)
> = 251.8K == -21.35 C
> _______________________________________________
> Sent via AMSAT-BB@xxxxx.xxx. 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: 2
Date: Sun, 20 Jul 2014 17:50:02 -0700
From: Phil Karn <karn@xxxx.xxx>
To: amsat-bb@xxxxx.xxx
Subject: Re: [amsat-bb] going digital
Message-ID: <53CC63BA.9060602@xxxx.xxx>
Content-Type: text/plain; charset=windows-1252
On 07/20/2014 03:45 AM, John / NS1Z wrote:
> Is there some reason why a digital signal cannot be passed thru an
> analog/linear transponder? What goes in is what comes out.
I forgot to mention that a FM repeater is not a linear transponder.
Although FM is constant envelope and a FM RF power amplifier can
therefore be made pretty efficient, it will not support a
power-efficient modulation mode like coherent BPSK.
Single channel FM is about the worst possible choice for a multiple
access satellite uplink. Not only is it analog and noncoherent, but
because it's noncoherent it has a capture effect. For a signal to come
through at all, it must capture the channel over all noise and
interference. This also severely limits the power improvement that can
be attained with forward error correction; if the demodulator is below
threshold, coding can't help you.
Depending on the demodulator design the capture ratio is somewhere
around 10 dB or slightly less, which means that the capturing signal
must be at least 10 times as strong as *all* of the interferers
combined. This makes it more or less useless unless there's only one
user (in which case it's no longer multiple access) or the users are
highly disciplined (which is hardly the case in the amateur service).
--Phil
------------------------------
Message: 3
Date: Sun, 20 Jul 2014 21:01:02 -0400
From: Paul Stoetzer <n8hm@xxxx.xxx>
To: "amsat-bb@xxxxx.xxxx <amsat-bb@xxxxx.xxx>
Subject: [amsat-bb] CQ Hawaii
Message-ID:
<CABzOSOoEtKTKm-Bgy+eYf-S_=NfMcWgOWnE6F0pKgXDzfybPkg@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=UTF-8
Good evening,
Thanks to Shane, NV7SW, in Nevada, I have now worked 49 states on the
satellites. All that remains is Hawaii, a significant challenge. AO-7
is the only satellite with a footprint that reaches both the DC area
and Hawaii; suitable passes generally occur every other day, with
maximum elevations of 1-1.5 degrees on both ends.
I can arrange to set up a station that can work AO-7 down to the
horizon within the allowable distance from my home QTH under WAS
rules, but I need to find someone in Hawaii who can also work AO-7
down to the horizon.
Any assistance would be greatly appreciated.
Thanks and 73,
Paul Stoetzer, N8HM
Washington, DC (FM18lv)
------------------------------
Message: 4
Date: Sun, 20 Jul 2014 18:36:06 -0700
From: Phil Karn <karn@xxxx.xxx>
To: amsat-bb@xxxxx.xxx
Subject: Re: [amsat-bb] ANS-199 AMSAT News Service Special Bulletin -
AMSAT Fox-1C Launch Opportunity Announced
Message-ID: <53CC6E86.8080506@xxxx.xxx>
Content-Type: text/plain; charset=windows-1252
On 07/19/2014 09:23 PM, Robert Bruninga wrote:
> Yes, but with who? 95% of everyone in view is more than 45 degrees OUT of
> the main beam. Directional antennas have zero value on LEO birds that need
> to serve everyone in view at the same time. And if you only serve those in
> the main beam, then the duration is under 1 minute.
Run the link budgets. With reasonable numbers (transmit power 100 mW,
range 1,000 km, Rx T = 50K) you only need a few dB of transmit gain to
get megabits/sec into a 60 cm DBS dish at 10 GHz. A few dB can easily
cover an entire hemisphere, though you might want to squash the pattern
to cover it more uniformly (as the GPS satellites do).
The big reason to use attitude control isn't high on-axis antenna gain,
it's AVOIDING ANTENNA NULLS. Fading was the major factor in every one of
the modulation/coding schemes I've designed for AMSAT. It forces me to
use noncoherent (DBPSK) modulation, which even with FEC can cost as much
as 4-5dB over coherent BPSK. And that's WITHOUT fading.
Fading is a major headache in coding design because you need to know how
long a fade will last to know how long to make your interleaver, and you
simply don't know when the spacecraft is unstabilized.
At least I had a good idea with AO-40 because the fading was caused by
the spacecraft spin so it was quite predictable. But ARISSat-1 was
completely unstabilized and I didn't even have an antenna pattern, so I
basically had to pull a maximum fade duration out of my butt.
Same with FOX-1, although it's somewhat less severe in the
data-under-voice mode since it's the fade duration relative to the data
rate that matters, and the data rate in that mode is so extremely low.
But it's a serious problem in the high speed (data only) mode.
And for truly interesting data rates (hundreds of kilobits/sec and up),
slow fading is simply intolerable. Attitude stabilized antennas are the
only way.
--Phil
------------------------------
Message: 5
Date: Sun, 20 Jul 2014 23:00:09 -0400
From: Gus <gus@xxxxx.xxx>
To: amsat-bb@xxxxx.xxx
Subject: Re: [amsat-bb] going digital
Message-ID: <53CC8239.4050703@xxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
I'm all in favour of new modes and new technology. Pushing the
boundaries should be a primary goal. But before any new bird is put in
the sky, surely the target audience must be considered?
I'd hazard to guess that the 'average' shack has multi-mode HF
capability, along with VHF/UHF FM. Some lesser number of 'average'
shacks will have multi-mode VHF/UHF, or could readily acquire that
capability without too much expenditure in resources (time, effort, money).
Accept that we want to launch boundary-expanding, technologically
advanced satellites if possible. What sort of equipment should we
expect to find in the shacks of those hams who are the target audience
for these new satellites? How big is this suitably equipped target
audience? Big enough to justify having their own satellite? How much
time, effort and money will it take to upgrade an 'average' shack (like
mine) to meet the requirements of being a part of the target audience?
I'm really pro- and not anti- here. But it may be that any new, digital
satellite will have to be developed in parallel with readily available
ground station modules (Funcube Dongle Deluxe?) that provide the
'average' ham a path to participation.
Again: Interested to hear roughly what capabilities would be needed to
join the gang working the new digital birds, when they fly.
--
Gus 8P6SM
The Easternmost Isle
------------------------------
Message: 6
Date: Sun, 20 Jul 2014 20:00:48 -0700
From: Phil Karn <karn@xxxx.xxx>
To: amsat-bb@xxxxx.xxx
Subject: Re: [amsat-bb] The root of all the problems
Message-ID: <53CC8260.5050904@xxxx.xxx>
Content-Type: text/plain; charset=windows-1252
On 07/20/2014 06:10 AM, Thomas Doyle wrote:
> - What the majority wants is more important than any individual want.
>
> How do you determine what the majority wants.
>
> - Voting
The results of an election are strongly determined by who gets to vote.
If you poll the tiny fraction of the amateur community currently active
on satellites, you'll get one answer.
If you poll the much larger pool of people (including people who aren't
even hams yet) who might be interested in something else, you may well
get another answer.
But not right away; it's been shown time and again that people often
don't know they want something until you show it to them, and then they
simply have to have it. Think mobile phones and Internet, the two things
I spent my career on. It wasn't long ago that people (including most
hams) rolled their eyes whenever I talked up the idea of global computer
networking and mobile personal communications. Who couldn't wait until
they got home to make a phone call? Who needed to send a letter
instantly when they had the phone or the US mail? Who cared about
talking to other countries unless they had relatives there?
Don't also forget that the AMSAT membership hardly pays for its
satellites. The volunteer engineering that goes into each one of them is
easily worth millions of dollars at market rates. And it must be
understood that there is no such thing as a volunteer willing to work
for nothing, even though they don't get paid in money. You have to give
them something else, and in the case of engineering an amateur satellite
that "something else" is an interesting technical challenge that makes
them feel like they've really accomplished something.
Doing the same thing over and over certainly doesn't make me feel like
I've accomplished something.
--Phil
------------------------------
Message: 7
Date: Mon, 21 Jul 2014 03:05:05 +0000
From: B J <va6bmj@xxxxx.xxx>
To: amsat-bb <amsat-bb@xxxxx.xxx>
Subject: [amsat-bb] 1969-07-20
Message-ID:
<CAP7QzkNoC4vgSJbGKWC_WiykLnzbwcY-EdcYaNoqnkCqJQzAOA@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=UTF-8
It was the space program that persuaded me to study engineering and
also to become involved with satellites.
Many thanks to all who made the events of that day possible.
73s
Bernhard VA6BMJ @ DO33FL
------------------------------
Message: 8
Date: Sun, 20 Jul 2014 20:18:43 -0700
From: Phil Karn <karn@xxxx.xxx>
To: amsat-bb@xxxxx.xxx
Subject: Re: [amsat-bb] going digital
Message-ID: <53CC8693.2090407@xxxx.xxx>
Content-Type: text/plain; charset=windows-1252
On 07/20/2014 06:13 AM, Simon Brown wrote:
> John,
>
> If both side have good Doppler correction then it can be done, but you have
> to choose the correct mode as there are other issues even if the Doppler
> correction is perfect, especially when the range is changing at its maximum,
> for example as the satellite passes overhead.
Correct, but Doppler actually gets much easier to deal with as the data
rate increases. What matters is the *ratio* of the Doppler to the data
rate (actually the channel symbol rate, which is usually higher).
At the very high rates possible from LEO on the microwave bands, Doppler
on a BPSK signal can be easily tracked by a Costas loop even without
orbit prediction steering (though it's still a good idea).
E.g., a relative velocity of 3 km/s at 10 GHz is a Doppler of 100 kHz,
considerably less than the symbol rates possible from LEO with even
small transmitter powers and antenna gains. Compare this with the
numbers for current amateur satellites on VHF and UHF.
--Phil
------------------------------
Message: 9
Date: Sun, 20 Jul 2014 20:22:49 -0700
From: Phil Karn <karn@xxxx.xxx>
To: amsat-bb@xxxxx.xxx
Subject: Re: [amsat-bb] ANS-199 AMSAT News Service Special Bulletin -
AMSAT Fox-1C Launch Opportunity Announced
Message-ID: <53CC8789.2030109@xxxx.xxx>
Content-Type: text/plain; charset=windows-1252
On 07/20/2014 06:27 AM, Rick Walter wrote:
> I was not going to post but since no one else has, I thought there needs
to be a correction to a statement made in case some younger people are
reading the thread.
>
> Phil said:
> "Good analogy, actually. They returned to the moon six times (succeeding
> on five) because they had excess hardware originally built in the
> expectation that the first attempts would fail."
>
> There were actually seven manned missions to the moon. Six succeeded.
Apollo 13 never landed on the moon and returned to earth safely. Apollo
11,12,14,15,16, and 17 landed. 12 American astronauts walked on the moon.
That's exactly what I said. They *returned* to the moon (i.e., after
landing the first time on Apollo 11) six times, succeeding on five.
Three missions went to the moon without landing: Apollos 8, 10 and 13,
for a total of nine Apollo lunar missions. Two more (7 & 9) remained in
earth orbit.
--Phil
------------------------------
Message: 10
Date: Sun, 20 Jul 2014 19:39:01 -0800
From: Dale Hershberger <daleh@xxxxxx.xxx>
To: amsat-bb@xxxxx.xxx
Subject: Re: [amsat-bb] 1969-07-20
Message-ID: <53CC8B55.5040400@xxxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
I concur , Bernhard. It was rewarding for me to be able to work with school
students and do ISS Contacts with astronauts that really got me
interested in
working different satellites. Possibilities are unlimited... I support
AMSAT.
73,
Dale-KL7XJ
On 7/20/2014 7:05 PM, B J wrote:
> It was the space program that persuaded me to study engineering and
> also to become involved with satellites.
>
> Many thanks to all who made the events of that day possible.
>
> 73s
>
> Bernhard VA6BMJ @ DO33FL
> _______________________________________________
> Sent via AMSAT-BB@xxxxx.xxx. 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: 11
Date: Sun, 20 Jul 2014 20:42:30 -0700
From: Bryce Salmi <bstguitarist@xxxxx.xxx>
To: Phil Karn <karn@xxxx.xxx>
Cc: Amsat BB <amsat-bb@xxxxx.xxx>
Subject: Re: [amsat-bb] The root of all the problems
Message-ID:
<CAN5j0sp05umw3YgKNmxF1MXu5jMxho3cU5Xa_4_iJ=nfMtsGCQ@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=UTF-8
I'll finally charm in on this.
Don't also forget that the AMSAT membership hardly pays for its
> satellites. The volunteer engineering that goes into each one of them is
> easily worth millions of dollars at market rates. And it must be
> understood that there is no such thing as a volunteer willing to work
> for nothing, even though they don't get paid in money. You have to give
> them something else, and in the case of engineering an amateur satellite
> that "something else" is an interesting technical challenge that makes
> them feel like they've really accomplished something.
> Doing the same thing over and over certainly doesn't make me feel like
> I've accomplished something.
Most of this is true. However, you're looking at a narrow slice of the
Fox-1 satellites, that being the operating mode of FM/Analog.
I'm currently building the Fox-1 series satellite Maximum Power Point
Tracker. It's a hell of a project. Could AMSAT have bought one off the
shelf, yes. However, it's also true that what the majority wants is what
the majority gets. In the cubesat world Universities are the majority. They
have money, lots of it. Their missions are 6 months to a year. Most
commercial cubesat MPPTs are not designed for much longer of missions.
In contrast AMSAT is gaining a huge amount of Intellectual property by
designing an analog MPPT where the algorithm is completely stateless and
part selection is aimed at helping guarantee that a 5+ year mission is
possible. Most of the market doesn't care about this, it's hard to do and
using a microcontroller is ridiculously more straightforward. Just do a
Google search for MPPT, nearly everything you find will be using perturb
and observe with a microcontroller or super pricey/almost non-existant
analog multipliers or the maximum current method (which relies on the
battery being present). The Fox-1 MPPT is specifically designed to not need
a battery at all for nominal operation.
Cubesats are standardizing AMSATs satellites and there's much much more to
the satellite than simply the amateur radio mode used to communicate. If I
do my job right, and others working on their Fox-1 subsystems do their jobs
right too, you will never know it... it will be invisible to the average
user.
Once AMSAT can rapidly and reliable get basic cubesats into orbit, then it
can start going wild on experimental modes and such.
For the record, I'm all for digital satellites. I also understand how too
much complexity too quickly isn't a good thing either.
Bryce
KB1LQC
On Sun, Jul 20, 2014 at 8:00 PM, Phil Karn <karn@xxxx.xxx> wrote:
> On 07/20/2014 06:10 AM, Thomas Doyle wrote:
>
> > - What the majority wants is more important than any individual want.
> >
> > How do you determine what the majority wants.
> >
> > - Voting
>
> The results of an election are strongly determined by who gets to vote.
>
> If you poll the tiny fraction of the amateur community currently active
> on satellites, you'll get one answer.
>
> If you poll the much larger pool of people (including people who aren't
> even hams yet) who might be interested in something else, you may well
> get another answer.
>
> But not right away; it's been shown time and again that people often
> don't know they want something until you show it to them, and then they
> simply have to have it. Think mobile phones and Internet, the two things
> I spent my career on. It wasn't long ago that people (including most
> hams) rolled their eyes whenever I talked up the idea of global computer
> networking and mobile personal communications. Who couldn't wait until
> they got home to make a phone call? Who needed to send a letter
> instantly when they had the phone or the US mail? Who cared about
> talking to other countries unless they had relatives there?
>
> Don't also forget that the AMSAT membership hardly pays for its
> satellites. The volunteer engineering that goes into each one of them is
> easily worth millions of dollars at market rates. And it must be
> understood that there is no such thing as a volunteer willing to work
> for nothing, even though they don't get paid in money. You have to give
> them something else, and in the case of engineering an amateur satellite
> that "something else" is an interesting technical challenge that makes
> them feel like they've really accomplished something.
>
> Doing the same thing over and over certainly doesn't make me feel like
> I've accomplished something.
>
> --Phil
> _______________________________________________
> Sent via AMSAT-BB@xxxxx.xxx. 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: 12
Date: Sun, 20 Jul 2014 20:59:14 -0700
From: Phil Karn <karn@xxxx.xxx>
To: amsat-bb@xxxxx.xxx
Subject: Re: [amsat-bb] ANS-199 AMSAT News Service Special Bulletin -
AMSAT Fox-1C Launch Opportunity Announced
Message-ID: <53CC9012.6060908@xxxx.xxx>
Content-Type: text/plain; charset=windows-1252
On 07/20/2014 08:09 AM, Graham Shirville wrote:
> Hi Phil,
>
> The reality is, even with no battery heater on FUNcube-1 we seem to have
> an acceptable battery temperature of between 0 and +5C. The temp sensor
> is, of course, actually external to the battery itself.
You must be using different solar cells, or perhaps you don't fully
cover the exterior with them. I did wonder why Dick didn't consider the
same thing for Fox-1; if you're going to dissipate some of the
electricity they generate in resistance heaters, you might consider
covering less than 100% of the surface with them and cover the remainder
with thermal blankets. I haven't worked out this alternative, and as I
said I'm not a thermal design expert.
At the time I believe Dick said he was considering gold plating the
inside surfaces of the cells to isolate them from the interior, since
there was little or no room for any other kind of insulation. In that
case you would no longer have thermal equilibrium and my back of the
envelope calculation would not apply.
There's one additional factor to make things worse, though I haven't
quantified it. Space-rated solar cells are getting good enough that the
spacecraft as a whole actually converts a non-insignificant amount of
the sunlight hitting it into transmitted RF, and that power is no longer
available to keep the spacecraft warm. So it gets even colder.
That's right, turn on the transmitter and the spacecraft cools down --
at least if the solar cells are not thermally isolated from the interior.
> Our orbit is sun synchronous so we "suffer" eclipses for approx 33% of
> the orbit ..but then we are relatively close to the earth!
Yes, and you do pick up longwave IR from the earth even on the night
side. According to my copy of "Spacecraft Thermal Control Handbook Vol
1", this is only about 150 W/m^2 in LEO, so it doesn't seem to help that
much. Albedo is greater (about 250 W/m^2) but only over the subsolar
point so again it doesn't help much on average.
It *would* help a lot if you could insulate those sides facing dark sky,
and that's where attitude control comes in.
During his after-dinner talk at the AMSAT Symposium a couple of years
ago, astronaut Sam Durrance described just how cold that dark sky is. He
flew with Ron Parise on the Astro-1 and -2 shuttle missions. Because
these were astronomy missions, the shuttle payload bay spent long
periods pointed at dark sky, as opposed to its usual practice (when not
docked to the ISS) of keeping the payload bay toward earth. He said it
got so cold near the orbiter's overhead windows that they had to don
sweaters.
But the real issue that Dick drove home to me in his talk was just how
variable the thermal situation was when you can't control your attitude
and when eclipse durations and beta angles vary so drastically over a
year. Even if you could design for acceptable equilibrium temperatures
under one set of conditions you can't maintain them as they vary so much.
> I would also comment that any active attitude control system will
> consume power...which we don't have much of..
Yes, but active attitude control lets you keep those panels pointed at
the sun to produce much more power on average. Only two of the six
surfaces of a 1U cubesat even need solar cells with my stabilized
design. You can do much better with deployable, steerable panels --
which pretty much demands active attitude control.
The fact that virtually every military, commercial and scientific
spacecraft launched today is three-axis stabilized should settle the
question: active attitude control is the way to go, if you can do it.
--Phil
------------------------------
Message: 13
Date: Sun, 20 Jul 2014 23:18:48 -0500
From: Les Rayburn <les@xxxxxxxxxxxx.xxx>
To: AMSAT Mailing List <amsat-bb@xxxxx.xxx>, Star-Com BB
<starcom-bb@xxxxxxxx.xxx>
Subject: [amsat-bb] 432 10-13 -Element Antenna?
Message-ID: <53CC94A8.9090306@xxxxxxxxxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
I'm limited to indoor antennas for all my amateur operations, including
satellite operation. Right now, I'm running a 6 element 2 Meter yagi,
along with the 7 element 432 beam (part of an arrow antenna). I have
room to rotate a larger, and longer 432 antenna, and I'd love to have
more gain.
Most of the commercial antennas seem to be either small and portable,
like the Arrow or much longer intended for weak signal operations. Is
anyone aware of something in between, such as a 10 to 13 element antenna
available commercially. No time or interest in homebrewing one right now.
Even better, does anyone have one that is surplus to their needs that
they'd like to sell?
--
--
73,
Les Rayburn, N1LF
121 Mayfair Park
Maylene, AL 35114
EM63nf
6M VUCC #1712
AMSAT #38965
Grid Bandits #222
Southeastern VHF Society
Central States VHF Society Life Member
Six Club #2484
Active on 6 Meters thru 1296, 10GHz & Light
------------------------------
_______________________________________________
Sent via amsat-bb@xxxxx.xxx. Opinions expressed are those of the author.
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 243
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