wrote in message
oups.com...
Sirs:

I am a programmer and electrician, but not a radio person! I am
sending an experimental balloon to over 100,000 ft. I have purchased
two 900MHz RF Aerocomm ConnexLink Radios. The radios have a power of
1000 m.a., which states it will transmit and receive up to 20 miles
line of sight. I do realize that this is probably under ideal
circumstances and will not likely be the case when I actually deploy.
I would be interested in purchasing some antennas which would somehow
increase the range. What sort of characteristics make up a good
antenna for what I want to do? It is possible that someone could find
me one that would work with my project? Also, anything you might
contribute concerning radio transmission would be very much
appreciated.
Money is no object for this experiment, so any ideas you have are very
much welcome.

Just about any antenna will work . I would look into a 1/4 wave antenna
mounted upside down so it is pointed down for the balloon. I hope you ment
1,000 mw, or one watt of power for the transmitter. I have heard the hams
in the space shuttle and space station with a 5/8 wavelength on my car.
They only run a few watts and are over 100 miles up. Also talked with an
airplane at 40,000 feet that was over 150 miles away. I was using a 10 watt
radio and a small beam. He was using a handy talkey with maybe 5 watts
inside the plane. Unless you are under a bunch of trees , there is not
much beter conditions than to be line of sight. While it will probably be
too small to see without a telescope, as long as the balloon is in sight
almost anything will work.

On Fri, 28 Jul 2006 21:20:43 GMT, "Ralph Mowery"
wrote:


wrote in message
roups.com...
Sirs:

I am a programmer and electrician, but not a radio person! I am
sending an experimental balloon to over 100,000 ft. I have purchased
two 900MHz RF Aerocomm ConnexLink Radios. The radios have a power of
1000 m.a., which states it will transmit and receive up to 20 miles
line of sight. I do realize that this is probably under ideal
circumstances and will not likely be the case when I actually deploy.
I would be interested in purchasing some antennas which would somehow
increase the range. What sort of characteristics make up a good
antenna for what I want to do? It is possible that someone could find
me one that would work with my project? Also, anything you might
contribute concerning radio transmission would be very much
appreciated.
Money is no object for this experiment, so any ideas you have are very
much welcome.

Just about any antenna will work . I would look into a 1/4 wave antenna
mounted upside down so it is pointed down for the balloon. I hope you ment

So that would have its pattern null pointed down at the earth?

Not to imply that the balloon would necessarily be directly above the
observer(s), but if and when it was at the zenith, it would be
relatively hard to hear.

The OP hasn't told us the elevation angles of the locations of the
balloon in flight, how fast it is likely to spin, data rate or
equivalent (eg is this intended to send images back?), etc... they are
all relevant to commenting on suitability of the 1000mA??? radio, and
the type of antennas for the balloon and ground station(s).

Owen

For an amateur balloon project, see
http://members.optusnet.com.au/~phil...oonlaunch1.htm
..
--

On Fri, 28 Jul 2006 22:29:51 GMT, Owen Duffy wrote:


sending an experimental balloon to over 100,000 ft. I have purchased
two 900MHz RF Aerocomm ConnexLink Radios. The radios have a power of
1000 m.a., which states it will transmit and receive up to 20 miles
line of sight. I do realize that this is probably under ideal

I did mean to comment on the temperature spec for the radio. The
temperature in the troposhere can be as low at -50 to -75 deg C, will
the radio get cold enough in transit to fail (eg battery failure,
condensation etc).

Owen
--

Owen Duffy wrote:
On Fri, 28 Jul 2006 22:29:51 GMT, Owen Duffy wrote:



sending an experimental balloon to over 100,000 ft. I have purchased
two 900MHz RF Aerocomm ConnexLink Radios. The radios have a power of
1000 m.a., which states it will transmit and receive up to 20 miles
line of sight. I do realize that this is probably under ideal


I did mean to comment on the temperature spec for the radio. The
temperature in the troposhere can be as low at -50 to -75 deg C, will
the radio get cold enough in transit to fail (eg battery failure,
condensation etc).

Owen
--


YEP!

You have to account for loss of battery power, loss of gain in the
semiconductors, etc. Or, provide a stable thermal environment.

sending an experimental balloon to over 100,000 ft. I have purchased
two 900MHz RF Aerocomm ConnexLink Radios. The radios have a power of
1000 m.a., which states it will transmit and receive up to 20 miles
line of sight. I do realize that this is probably under ideal

I did mean to comment on the temperature spec for the radio. The
temperature in the troposhere can be as low at -50 to -75 deg C, will
the radio get cold enough in transit to fail (eg battery failure,
condensation etc).

You should read Paul Lloyd (Lloyd Paul?) Verhage's long series of
"near space" articles which have been running in Nuts & Volts magazine
for at least a year! He started sending balloons and packages of
scientific experiments (radio telemetry and DF'ing, cameras, once
even included some roaches!) into near space years before that.

FWIW, he is a "ham", and when he started, he was a student here at
Kansas State University. Even better, he launched his balloons
from the "Johnson Near Space Center" about 10 miles south of Manhattan,
Kansas; so-called because Dr. Gary Johnson, K0HGJ, who was working to
duplicate some of Tesla's high-power experiemts, owned a humongous-
big-and-tall metal building with VERY-big sliding doors that was
perfect for inflating balloons inside (out of any wind) and carrying
outside for launching, and the similarity with the name "Johnson Space
Center" was just too good to resist!

I believe Lloyd (the name he used then) is now a high-school teacher
somewhere, and he incorporates his balloon launches into his science
classes.

--
--Myron A. Calhoun.
Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge
NRA Life Member W0PBV "Barbershop" tenor CDL(PTXS) (785) 539-4448
Certified Instructor (KS Concealed Carry, Rifle, Pistol, Home Firearm Safety)

Yes, I did think of temperature concerns. The radio unit itself should
be kept at above freezing if my calculations are correct. However,
does the antenna need to be kept warm?

Owen Duffy wrote:
On Fri, 28 Jul 2006 22:29:51 GMT, Owen Duffy wrote:


sending an experimental balloon to over 100,000 ft. I have purchased
two 900MHz RF Aerocomm ConnexLink Radios. The radios have a power of
1000 m.a., which states it will transmit and receive up to 20 miles
line of sight. I do realize that this is probably under ideal

I did mean to comment on the temperature spec for the radio. The
temperature in the troposhere can be as low at -50 to -75 deg C, will
the radio get cold enough in transit to fail (eg battery failure,
condensation etc).

Owen
--

If the radio is the CL4790-1000 it is rated to -40C. For short term exposure to
cold, have you considered a small thermal blanket? It is drawing 5 watts from
the battery and power output is one watt. So, you have 4 watts of heat. Possibly
enough for a small thermal blanket.

Antenna should not require any heating element.



wrote:

Yes, I did think of temperature concerns. The radio unit itself should
be kept at above freezing if my calculations are correct. However,
does the antenna need to be kept warm?

Owen Duffy wrote:

On Fri, 28 Jul 2006 22:29:51 GMT, Owen Duffy wrote:



sending an experimental balloon to over 100,000 ft. I have purchased
two 900MHz RF Aerocomm ConnexLink Radios. The radios have a power of
1000 m.a., which states it will transmit and receive up to 20 miles
line of sight. I do realize that this is probably under ideal

I did mean to comment on the temperature spec for the radio. The
temperature in the troposhere can be as low at -50 to -75 deg C, will
the radio get cold enough in transit to fail (eg battery failure,
condensation etc).

Owen
--

wrote:
Yes, I did think of temperature concerns. The radio unit itself should
be kept at above freezing if my calculations are correct. However,
does the antenna need to be kept warm?

Hi Brett

In most cases, the transmitter will be in an enclosure. I'm assuming
that there will be an experiment package. Many who do this sort of thing
will make the enclosure out of Styrofoam. Some actually use styro picnic
coolers. For typical flight durations, the inefficiencies of the
electronics equipment on board the payload (read waste heat) will make
up for the nasty temps outside. I've seen some cases where there has
actually been a temperature rise. The criteria is a well sealed
insulating box.

And no, the antenna itself does not need to be warm. Just seal off the
exit port to keep internal heat from leaking out.

Your watt should be sufficient power. At 100 kilofeet, you will reach
more that you likely want to reach! I've seen propagation maps that show
a single balloon repeater at these heights covering 1/3rd of the US.



- 73 de Mike KB3EIA -

Owen Duffy wrote in
:

On Fri, 28 Jul 2006 21:20:43 GMT, "Ralph Mowery"
wrote:


wrote in message
groups.com...
Sirs:

I am a programmer and electrician, but not a radio person! I am
sending an experimental balloon to over 100,000 ft. I have
purchased two 900MHz RF Aerocomm ConnexLink Radios. The radios have
a power of 1000 m.a., which states it will transmit and receive up
to 20 miles line of sight. I do realize that this is probably under
ideal circumstances and will not likely be the case when I actually
deploy. I would be interested in purchasing some antennas which
would somehow increase the range. What sort of characteristics make
up a good antenna for what I want to do? It is possible that
someone could find me one that would work with my project? Also,
anything you might contribute concerning radio transmission would be
very much appreciated.
Money is no object for this experiment, so any ideas you have are
very much welcome.

Just about any antenna will work . I would look into a 1/4 wave
antenna mounted upside down so it is pointed down for the balloon. I
hope you ment

So that would have its pattern null pointed down at the earth?

Not to imply that the balloon would necessarily be directly above the
observer(s), but if and when it was at the zenith, it would be
relatively hard to hear.

I used to do a lot of radiosonde work. Those balloons would go to
110,000 feet at times. The transmitters were small, probably not more
than a watt, but we tracked them with an automatic system. The instrument
used a 1680mhz transmitter with an upside-down ground plane antenna in
the bottom (I think that was the freq. but it was near there). The
tracking antenna, though, was a parabolic dish with a wobbling feed-point
antenna that automatically tracked the balloon's radio, giving us a
continual readout of azimuth and elevation angles. By combining this
data with the received data from the instrument's aneroid barometer,
temperature and humidity sensors, we could locate the balloon with good
accuracy in three dimensions. Thus the run would provide temperature and
humidity profiles as well as data on winds aloft. Balloons almost never
go straight over you and when they do it is almost always early in the
flight when the signal is close and strong.

The OP hasn't told us the elevation angles of the locations of the
balloon in flight, how fast it is likely to spin, data rate or
equivalent (eg is this intended to send images back?), etc... they are
all relevant to commenting on suitability of the 1000mA??? radio, and
the type of antennas for the balloon and ground station(s).

A lot depends on frequency, too. Tracking a 2.4 or 5.8 ghz transmitter
is different from tracking a 35mhz transmitter.



--
Dave Oldridge+
ICQ 1800667