Anyone have any ideas about what one might do with a television
receive-only (TVRO) antenna? The thing is 10' diameter and it's
mine for the price of dismantling it and hauling it out of the
present owner's back yard.


First thing that comes to my mind is EME.

Ed K7AAT

"Dave Typinski" wrote in message
...
On Sun, 21 Oct 2007 11:39:12 +0100, Highland Ham
wrote:

Dave Typinski wrote:
Anyone have any ideas about what one might do with a television
receive-only (TVRO) antenna? The thing is 10' diameter and it's mine
for the price of dismantling it and hauling it out of the present
owner's back yard.

I'm thinking radio astronomy. Might be nice to make my own radio map
of the galaxy. I'm guessing that this would work okay somewhere
between 1 and 10 GHz... which means making a feed horn... which is
easy enough to do.

What else could I do with this antenna? Other than covering it in
polyethylene sheet to make a really big bird bath...
==================================
Possible usage:
1) EME amateur comms
2) WiFi low power experiments (provided there is line of sight freedom)
I remember having seen a web site with reports (incl photographs) that
some youngsters bridged a 125 km path using off the shelf equipment and
dishes having a size like yours.

Hopefully you don't have just the dish but also a mounting pedestal and
perhaps even a motorised system .

Frank GM0CSZ / KN6WH

Yep, got the pedestal and the azimuth drive motor.

125 km at 2.4 GHz? How's that work? What were they bouncing the
signal off of? That's definitely further than line of sight.
--
Dave Typinski
AJ4CO

Hi, here is link:
http://hardware.slashdot.org/article...13218&from=rss

"Dave Typinski" wrote in message
...
On Sun, 21 Oct 2007 16:48:28 GMT, "Jerry Martes"
wrote:


"Dave Typinski" wrote in message
. ..
Anyone have any ideas about what one might do with a television
receive-only (TVRO) antenna? The thing is 10' diameter and it's mine
for the price of dismantling it and hauling it out of the present
owner's back yard.

I'm thinking radio astronomy. Might be nice to make my own radio map
of the galaxy. I'm guessing that this would work okay somewhere
between 1 and 10 GHz... which means making a feed horn... which is
easy enough to do.

What else could I do with this antenna? Other than covering it in
polyethylene sheet to make a really big bird bath...
--
Dave Typinski
AJ4CO

Hi Dave

NOAAPORT uses a satellite over the Equator, South of Texas to transmit
satellite images in near Real Time. You can easily build a station for
displaying good images of the Florida as seen from space.

Jerry

Now /that/ would be a cool project! Thanks, Jerry.
--
Dave Typinski
AJ4CO

http://hardware.slashdot.org/article.../09/23/1233219

Dave Typinski ) writes:
On Sun, 21 Oct 2007 01:01:19 -0400, "Jimmie D"
wrote:

"Dave Typinski" wrote in message
. ..
Anyone have any ideas about what one might do with a television
receive-only (TVRO) antenna? The thing is 10' diameter and it's mine
for the price of dismantling it and hauling it out of the present
owner's back yard.

I'm thinking radio astronomy. Might be nice to make my own radio map
of the galaxy. I'm guessing that this would work okay somewhere
between 1 and 10 GHz... which means making a feed horn... which is
easy enough to do.

What else could I do with this antenna? Other than covering it in
polyethylene sheet to make a really big bird bath...
--
Dave Typinski
AJ4CO

I know of a couple of guys that took two of them, one for rx and one for tx,
tx was a microwave oven mgnetron. He and his frined talked to each other via
troposcatter. I do know if a maggie operates within a ham band or not but it
didnt matter too much for these guys because they didnt have a ticket
anyway.

Jimmie

I thought about magnetrons... but not for communication. My idea is
to set it up as a radar station to measure the distance to the Moon. A
microwave oven magnetron operates at 2450 MHz, which is right at the
upper edge of the 13cm ham band. Unfortunately, magnetrons produce a
really dirty, wide output. Worse, being right at the edge of the
band, half the RF energy would be out of band.

How do you think the higher bands were conquered? It was always with
simple equipment that was cheap and easy (relative speaking), with
the more serious work coming later.

So before WWII, it was modulated oscillators and superregen receivers
on 56MHz and 112MHz. After the war, new equipment was available, and
there was a desire for pushing the limits (and laws came in at some
point to require better signals), and there was a move to crystal
controlled transmitters and better receivers. Well, they really
went together, since if you changed one, the other had to follow.

So that equipment got pushed up further, helping to stake out
220MHz and 420MHz. A lot of work was done on the 1215MHz band
after WWII and even through the early sixties with the venerable
APX/6 (I suddenly realize I may have gotten that wrong), which
was a modulated oscillator for the transmitter, and it was often
debated whether it was amplitude of requency modulated. The receiver
was a superhet, but had a nice broad IF bandwidth, so it didn't matter
how much the transmitter drifted. I seem to recall that the APX/6 was
intended as an IFF unit, it gets triggered by radar and identifies
itself as a friend, so nobody shoots at the airplane.

Newer techniques came along, more desire to push the limits, and that
sort of thing was slowly phased out on the band.

But hey, it moved further up. In the late seventies, a lot of hams
played with the 10,000MHz, using garage door openers, modulated
oscillators and broadband receivers.

The further you go up in frequency, the more such cheap and
simple equipment can be tolerated, since the bands get wider (well,
until they get narrowed as bits are allocated away from amateur
radio). So there is long history of both wideband simple equipment
and narrowband DX'ing going on at the same time, albeit at opposite
ends of the band.

But in reality, you dig up that article that was in "73" years ago
that was about adding a phase locked loop to a microwave oven, which
gives a nice narrow signal.

Michael VE2BVW

On Sun, 21 Oct 2007 17:07:10 -0400, "Bob"
wrote:


"Dave Typinski" wrote in message
.. .
On Sun, 21 Oct 2007 11:39:12 +0100, Highland Ham
wrote:

Dave Typinski wrote:
Anyone have any ideas about what one might do with a television
receive-only (TVRO) antenna? The thing is 10' diameter and it's mine
for the price of dismantling it and hauling it out of the present
owner's back yard.

I'm thinking radio astronomy. Might be nice to make my own radio map
of the galaxy. I'm guessing that this would work okay somewhere
between 1 and 10 GHz... which means making a feed horn... which is
easy enough to do.

What else could I do with this antenna? Other than covering it in
polyethylene sheet to make a really big bird bath...
==================================
Possible usage:
1) EME amateur comms
2) WiFi low power experiments (provided there is line of sight freedom)
I remember having seen a web site with reports (incl photographs) that
some youngsters bridged a 125 km path using off the shelf equipment and
dishes having a size like yours.

Hopefully you don't have just the dish but also a mounting pedestal and
perhaps even a motorised system .

Frank GM0CSZ / KN6WH

Yep, got the pedestal and the azimuth drive motor.

125 km at 2.4 GHz? How's that work? What were they bouncing the
signal off of? That's definitely further than line of sight.
--
Dave Typinski
AJ4CO

Hi, here is link:
http://hardware.slashdot.org/article...13218&from=rss

Aha! Living in Florida for the last 15 years has made me forget about
the mountains out west. Yes, you can definitely go line of sight up
to a few hundred miles if you have at your disposal an assortment of
mile-high piles of rocks upon which to mount the antennas.
http://www.wifi-toys.com/wi-fi.php?a=articles&id=91

--
Dave Typinski
AJ4CO

On Sun, 21 Oct 2007 18:15:48 GMT, "Jerry Martes"
wrote:


"Dave Typinski" wrote in message
.. .
On Sun, 21 Oct 2007 16:48:28 GMT, "Jerry Martes"
wrote:


"Dave Typinski" wrote in message
...
Anyone have any ideas about what one might do with a television
receive-only (TVRO) antenna? The thing is 10' diameter and it's mine
for the price of dismantling it and hauling it out of the present
owner's back yard.

I'm thinking radio astronomy. Might be nice to make my own radio map
of the galaxy. I'm guessing that this would work okay somewhere
between 1 and 10 GHz... which means making a feed horn... which is
easy enough to do.

What else could I do with this antenna? Other than covering it in
polyethylene sheet to make a really big bird bath...
--
Dave Typinski
AJ4CO

Hi Dave

NOAAPORT uses a satellite over the Equator, South of Texas to transmit
satellite images in near Real Time. You can easily build a station for
displaying good images of the Florida as seen from space.

Jerry

Now /that/ would be a cool project! Thanks, Jerry.
--
Dave Typinski
AJ4CO

Hi Dave

If you do build a system for receiving the NOAAPORT images, please keep me
informed about your progress.
I too got my dish free. The PCI card TV receiver was low cost. The rest
is computer and software. eBay is a good source of very good antenna parts
at low cost.
I am presently stuck due to my poor Linux skills, and Linux is used by the
guys who write the software (free).

Jerry

I briefly went over the NOAAPORT web site. Looks like they have a
Windows flavor for the software, or maybe that's just a port to a
version that runs under a Windows emulator for Linux. Dunno. The
site wasn't too user-friendly - which just makes me want to build the
thing even more.

If you have any other online references handy for this project, I'd be
much obliged if you'd post them. For instance, in my review of the
site, I didn't notice anything about having to use a video capture /
TV tuner card - although I do have a USB version of one of those.

I shall post my progress, if and when. It's a project that's not at
the top of the list. First up is launching a weather balloon to
100,000 feet with a camera and a few sensors.

Thanks, Jerry.
--
Dave Typinski
AJ4CO

"Dave Typinski" wrote in message
...
On Sun, 21 Oct 2007 18:15:48 GMT, "Jerry Martes"
wrote:


"Dave Typinski" wrote in message
. ..
On Sun, 21 Oct 2007 16:48:28 GMT, "Jerry Martes"
wrote:


"Dave Typinski" wrote in message
m...
Anyone have any ideas about what one might do with a television
receive-only (TVRO) antenna? The thing is 10' diameter and it's mine
for the price of dismantling it and hauling it out of the present
owner's back yard.

I'm thinking radio astronomy. Might be nice to make my own radio map
of the galaxy. I'm guessing that this would work okay somewhere
between 1 and 10 GHz... which means making a feed horn... which is
easy enough to do.

What else could I do with this antenna? Other than covering it in
polyethylene sheet to make a really big bird bath...
--
Dave Typinski
AJ4CO

Hi Dave

NOAAPORT uses a satellite over the Equator, South of Texas to transmit
satellite images in near Real Time. You can easily build a station for
displaying good images of the Florida as seen from space.

Jerry

Now /that/ would be a cool project! Thanks, Jerry.
--
Dave Typinski
AJ4CO

Hi Dave

If you do build a system for receiving the NOAAPORT images, please keep
me
informed about your progress.
I too got my dish free. The PCI card TV receiver was low cost. The rest
is computer and software. eBay is a good source of very good antenna
parts
at low cost.
I am presently stuck due to my poor Linux skills, and Linux is used by
the
guys who write the software (free).

Jerry

I briefly went over the NOAAPORT web site. Looks like they have a
Windows flavor for the software, or maybe that's just a port to a
version that runs under a Windows emulator for Linux. Dunno. The
site wasn't too user-friendly - which just makes me want to build the
thing even more.

If you have any other online references handy for this project, I'd be
much obliged if you'd post them. For instance, in my review of the
site, I didn't notice anything about having to use a video capture /
TV tuner card - although I do have a USB version of one of those.

I shall post my progress, if and when. It's a project that's not at
the top of the list. First up is launching a weather balloon to
100,000 feet with a camera and a few sensors.

Thanks, Jerry.
--
Dave Typinski
AJ4CO

Hi Dave

Hector has most of what is needed to make a low cost PCI TV receiver work
for NOAAPORT. The Twinhan PCI cards are affordable thru eBay and etc.
I thought I'd get more help from the "regulars" on the Yahoo NOAAPORT
site, but am now disappointed. And, I am slow to learn the Linux (Fedora)
that is used to reduce the data.
I want you to learn how to make images so you can teach me. I did go out
and buy parts and assembled a computer for Fedora. Now I have to learn how
to navigate in it. I too have found the"instructions" a bit difficult for
me to understand. But, Hector's instructions
(http://www.hwic.net/projects/weather/noaaport/) are quite direct and
easy to understand.

Jerry

Dave Typinski wrote:
On Sun, 21 Oct 2007 01:01:19 -0400, "Jimmie D"
wrote:

"Dave Typinski" wrote in message
. ..

Anyone have any ideas about what one might do with a television
receive-only (TVRO) antenna? The thing is 10' diameter and it's mine
for the price of dismantling it and hauling it out of the present
owner's back yard.

I'm thinking radio astronomy. Might be nice to make my own radio map
of the galaxy. I'm guessing that this would work okay somewhere
between 1 and 10 GHz... which means making a feed horn... which is
easy enough to do.

What else could I do with this antenna? Other than covering it in
polyethylene sheet to make a really big bird bath...
--
Dave Typinski
AJ4CO

I know of a couple of guys that took two of them, one for rx and one for tx,
tx was a microwave oven mgnetron. He and his frined talked to each other via
troposcatter. I do know if a maggie operates within a ham band or not but it
didnt matter too much for these guys because they didnt have a ticket
anyway.

Jimmie


I thought about magnetrons... but not for communication. My idea is
to set it up as a radar station to measure the distance to the Moon. A
microwave oven magnetron operates at 2450 MHz, which is right at the
upper edge of the 13cm ham band. Unfortunately, magnetrons produce a
really dirty, wide output. Worse, being right at the edge of the
band, half the RF energy would be out of band.

Just how precise a measurement do you want to make? You could do quite
well using a 100W 2m SSB rig and a decent yagi antenna and some signal
processing software.

See, e.g. http://home.earthlink.net/~n5bf/eme2.html





I don't know if one can re-tune a magnetron by the addition of
external components; I'd like to get the thing down to 2.42 GHz to put
the emission in the center of the 13cm band. There are such things as
tunable magnetrons; but, they aren't found in microwave ovens, which
means they won't likely be had for free.

That said, I'd sure like to look at the output from an oven magnetron
with a spectrum analyzer. Maybe the output isn't as dirty and wide as
I think it is.

it is quite dirty, even more so in an oven because:
1) it's fed by a half wave voltage doubler, so it's pulsed at line frequency
2) the voltage waveform is hardly nice and regulated
3) the temperature of the tube changes during operation


Why not build/buy some small no-tune transverters for 3.4 or 5.7 GHz and
use those. At least then, you can do coherent processing over some
reasonable time span, and what you lose in raw pulse power, you pick up
in processing gain.

The beamwidth of your 10ft dish at 2.4 GHz is going to be pretty wide,
so you're illuminating a lot more than the moon (which is wasted power).

In absolute terms, on receive, the fraction of the signal power received
from that power which hits the moon will be the same (same physical
aperture.. gain in dBi is larger, but that's just because an isotrope
has smaller aperture at higher frequencies).

So, your goal should be to illuminate JUST the moon (and a bit more to
cover pointing errors). Beamwidth is approximately = 70*wavelength/d.

So
GHz m deg dBi
2.4 0.125 2.9 35
3.4 0.088 2.0 38
5.7 0.053 1.2 43

Given that you want to light up the moon with the same power, at 2.4 GHz
it will take 8 dB more than 5.7 GHz.

Since the moon is about 1/2 degree wide, even 5.7 GHz is a bit low for a
10 foot reflector.


There's a little more than this to the whole problem, but, in general,
if what you want to do is measure the distance to the moon, a radar
built with an oven magnetron probably isn't the best way to go about
doing it.

Dave Typinski wrote:
On Sun, 21 Oct 2007 11:39:12 +0100, Highland Ham
wrote:


Dave Typinski wrote:

Anyone have any ideas about what one might do with a television
receive-only (TVRO) antenna? The thing is 10' diameter and it's mine
for the price of dismantling it and hauling it out of the present
owner's back yard.

I'm thinking radio astronomy. Might be nice to make my own radio map
of the galaxy. I'm guessing that this would work okay somewhere
between 1 and 10 GHz... which means making a feed horn... which is
easy enough to do.

What else could I do with this antenna? Other than covering it in
polyethylene sheet to make a really big bird bath...

==================================
Possible usage:
1) EME amateur comms
2) WiFi low power experiments (provided there is line of sight freedom)
I remember having seen a web site with reports (incl photographs) that
some youngsters bridged a 125 km path using off the shelf equipment and
dishes having a size like yours.

Hopefully you don't have just the dish but also a mounting pedestal and
perhaps even a motorised system .

Frank GM0CSZ / KN6WH


Yep, got the pedestal and the azimuth drive motor.

125 km at 2.4 GHz? How's that work? What were they bouncing the
signal off of? That's definitely further than line of sight.

Not if the two endpoints are up on mountains....

On Mon, 22 Oct 2007 10:02:57 -0700, Jim Lux
wrote:

Dave Typinski wrote:
On Sun, 21 Oct 2007 01:01:19 -0400, "Jimmie D"
wrote:

"Dave Typinski" wrote in message
...

Anyone have any ideas about what one might do with a television
receive-only (TVRO) antenna? The thing is 10' diameter and it's mine
for the price of dismantling it and hauling it out of the present
owner's back yard.

I'm thinking radio astronomy. Might be nice to make my own radio map
of the galaxy. I'm guessing that this would work okay somewhere
between 1 and 10 GHz... which means making a feed horn... which is
easy enough to do.

What else could I do with this antenna? Other than covering it in
polyethylene sheet to make a really big bird bath...
--
Dave Typinski
AJ4CO

I know of a couple of guys that took two of them, one for rx and one for tx,
tx was a microwave oven mgnetron. He and his frined talked to each other via
troposcatter. I do know if a maggie operates within a ham band or not but it
didnt matter too much for these guys because they didnt have a ticket
anyway.

Jimmie


I thought about magnetrons... but not for communication. My idea is
to set it up as a radar station to measure the distance to the Moon. A
microwave oven magnetron operates at 2450 MHz, which is right at the
upper edge of the 13cm ham band. Unfortunately, magnetrons produce a
really dirty, wide output. Worse, being right at the edge of the
band, half the RF energy would be out of band.

Just how precise a measurement do you want to make? You could do quite
well using a 100W 2m SSB rig and a decent yagi antenna and some signal
processing software.

See, e.g. http://home.earthlink.net/~n5bf/eme2.html

I don't know if one can re-tune a magnetron by the addition of
external components; I'd like to get the thing down to 2.42 GHz to put
the emission in the center of the 13cm band. There are such things as
tunable magnetrons; but, they aren't found in microwave ovens, which
means they won't likely be had for free.

That said, I'd sure like to look at the output from an oven magnetron
with a spectrum analyzer. Maybe the output isn't as dirty and wide as
I think it is.

it is quite dirty, even more so in an oven because:
1) it's fed by a half wave voltage doubler, so it's pulsed at line frequency
2) the voltage waveform is hardly nice and regulated
3) the temperature of the tube changes during operation


Why not build/buy some small no-tune transverters for 3.4 or 5.7 GHz and
use those. At least then, you can do coherent processing over some
reasonable time span, and what you lose in raw pulse power, you pick up
in processing gain.

A nice idea, thank you.

The beamwidth of your 10ft dish at 2.4 GHz is going to be pretty wide,
so you're illuminating a lot more than the moon (which is wasted power).

In absolute terms, on receive, the fraction of the signal power received
from that power which hits the moon will be the same (same physical
aperture.. gain in dBi is larger, but that's just because an isotrope
has smaller aperture at higher frequencies).

So, your goal should be to illuminate JUST the moon (and a bit more to
cover pointing errors). Beamwidth is approximately = 70*wavelength/d.

So
GHz m deg dBi
2.4 0.125 2.9 35
3.4 0.088 2.0 38
5.7 0.053 1.2 43

Given that you want to light up the moon with the same power, at 2.4 GHz
it will take 8 dB more than 5.7 GHz.

Since the moon is about 1/2 degree wide, even 5.7 GHz is a bit low for a
10 foot reflector.

Thanks a bunch for pointing that out. I'd wondered about the
relationship between beam width, reflector diameter, and frequency.

Now that I think about it, doesn't focal length or focal ratio play a
part as well?

I don't suppose you could point me at a decent reference for this
stuff, could you? I've found that Google (i.e., the web) is somewhat
lacking when it comes to explanations - especially accurate ones - of
where those nifty approximation equations come from.

There's a little more than this to the whole problem, but, in general,
if what you want to do is measure the distance to the moon, a radar
built with an oven magnetron probably isn't the best way to go about
doing it.

So noted. The goal here is not so much to do it the best way
possible, but rather to see what kind of results I can obtain using
the scrap (i.e., free) materials I have available.

If I were after accuracy, I'd point a laser at the corner reflectors
left by the Apollo missions. 8^)
--
Dave Typinski
AJ4CO