On Thu, 23 Apr 2015 11:56:18 -0700, Oregonian Haruspex
wrote:

How about a tethered helium balloon instead? This way you don't have
to worry about powering the thing. Bell wire will handle 100 watts all
day without turning into smoke.

I've been on a few field days that had helium balloon antennas. Like
all ham projects, we successfully duplicated every mistake possible:

- The wind blew the balloon and antenna horizontally. The downdraft
on the lee side of the hilltop finished the job by pushing the balloon
down further, and into the trees. I suspect a kite and a balloon
might have prevented this problem, but we never tried it.

- We didn't install a static bleeder on the antenna terminal. After
throwing a few lightning bolts, a bleeder to ground was hastily
fabricated to prevent vaporizing the receiver front end.

- A large part of the antenna tuning is the capacitance between the
antenna and ground. That can be tuned out easily with an antenna
tuner, but not so easily if the antenna is flopping around in the wind
with the capacitance changing rapidly. An automagic antenna tuner
helps, but is not capable of tuning continuously or at operating power
levels.

- The wind resistance of a 3 ft dia balloon is fairly substantial.
The air flow is turbulent. The result is considerable pull on the
antenna wire. I would have expected the wire to break. Instead, it
dragged the radio off the operating table and later caused the knot
holding the balloon to the wire to come apart.

- Helium is expensive. 1 liter of helium can lift about 1 gram.
If the 1/4 wave 160 meter antenna uses #16 AWG wire, which weighs;
40 meters * 11.6 grams/meter = 464 grams antenna weight
Add to that a 200 gram 3ft dia weather balloon for a total of 664
grams load which requires:
664 grams * 1 liter/gram = 664 liters
of helium required for neutral buoyancy. To get it off the ground, I
would add about 10%:
1.1 * 664 = 730 liters of helium.
Helium previously costs about $8/liter but is now running about
$20/liter thanks to the helium shortage. That's $14,600 for 730
liters. Are you sure you want to do this?





--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Thu, 23 Apr 2015 11:56:18 -0700, Oregonian Haruspex wrote:

How about a tethered helium balloon instead? This way you don't have
to worry about powering the thing. Bell wire will handle 100 watts all
day without turning into smoke.

Then (for a full sized Top Band vertical) you'd better be
prepared for some VERY SERIOUS static electricity issues.
(And, it won't be vertical. It'll be a "slooper", I believe.)

One Field Day we threw up a cross-valley long wire (running horizontal,
of course) and, after the violent static display made itself known
inside the Field Day trailer, several fellas got knocked on their asses
trying to get it disconnected and away from all the other gear and
antennas around the site. That sucker was approx. 2200 feet long.
(Could've gotten 100 pts for "Natural Power", I s'pose...)

The Colorado Rockies: Low humidity - steady breeze -- sure was exciting
for awhile!

Jonesy
--
Marvin L Jones | W3DHJ | W3DHJ | http://W3DHJ.net/
Pueblo, Colorado | @ | Jonesy | __
38.238N 104.547W | jonz.net | DM78rf | 73 SK

On Thu, 23 Apr 2015 18:32:56 -0700, Jeff Liebermann
wrote:

Helium previously costs about $8/liter but is now running about
$20/liter thanks to the helium shortage. That's $14,600 for 730
liters. Are you sure you want to do this?

Hmmm... that can't be right. The problem is that I'm getting prices
for helium that are all over the map. For example:
http://www.reuters.com/article/2013/09/19/us-helium-shortage-analysis-idUSBRE98I0AN20130919
"... spot price of liquid helium has jumped to $25-$30 per
liter from $8 last year."

http://www.crainsnewyork.com/article/20140126/FINANCE/301269974/helium-shortage-deflates-party-city
"prices have doubled since 2006, to $6.13 per-cubic meter,
according to the latest figures from the U.S. Geological Survey."
1 cubic-meter = 1000 liters, so that is $0.00613/liter which seems
rather low.

http://minerals.usgs.gov/minerals/pubs/commodity/helium/mcs-2014-heliu.pdf
"The estimated price range for private industry’s Grade-A gaseous
helium was about $7.21 per cubic meter ($200 per thousand cubic
feet), with some producers posting surcharges to this price.
1 cubic-meter = 1000 liters, so that is $0.00721/liter, which agrees
with the previous article, mostly because the price came from the same
source.

Ok, let's try party helium:
http://www.sfparty.com/products.php?product=Helium%3A-Balloon-Time-Disposable-Helium-Tank-Purchase
$55 for 14.9 cubic-ft.
14.9 ft^3 = 422 liters
$55 / 422 liters = $0.13/liter

Does anyone have the real price of helium?

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Thu, 23 Apr 2015 19:25:21 -0700, Jeff Liebermann
wrote:

On Thu, 23 Apr 2015 18:32:56 -0700, Jeff Liebermann
wrote:

Helium previously costs about $8/liter but is now running about
$20/liter thanks to the helium shortage. That's $14,600 for 730
liters. Are you sure you want to do this?

Hmmm... that can't be right. The problem is that I'm getting prices
for helium that are all over the map. For example:
http://www.reuters.com/article/2013/09/19/us-helium-shortage-analysis-idUSBRE98I0AN20130919
"... spot price of liquid helium has jumped to $25-$30 per
liter from $8 last year."

http://www.crainsnewyork.com/article/20140126/FINANCE/301269974/helium-shortage-deflates-party-city
"prices have doubled since 2006, to $6.13 per-cubic meter,
according to the latest figures from the U.S. Geological Survey."
1 cubic-meter = 1000 liters, so that is $0.00613/liter which seems
rather low.

http://minerals.usgs.gov/minerals/pubs/commodity/helium/mcs-2014-heliu.pdf
"The estimated price range for private industry’s Grade-A gaseous
helium was about $7.21 per cubic meter ($200 per thousand cubic
feet), with some producers posting surcharges to this price.
1 cubic-meter = 1000 liters, so that is $0.00721/liter, which agrees
with the previous article, mostly because the price came from the same
source.

Ok, let's try party helium:
http://www.sfparty.com/products.php?product=Helium%3A-Balloon-Time-Disposable-Helium-Tank-Purchase
$55 for 14.9 cubic-ft.
14.9 ft^3 = 422 liters
$55 / 422 liters = $0.13/liter

Does anyone have the real price of helium?

Never mind. I see the problem. There's a big difference between
medical grade helium used to cool MRI machines, and the helium sold at
party stores for filling balloons.
http://www.bbc.com/news/uk-19676639
The party store helium is recycled from the MRI gas and is mixed (i.e.
diluted) with air.
"The helium we use is not pure," he said. "It's recycled from the
gas which is used in the medical industry, and mixed with air.
We call it balloon gas rather than helium for that reason."
Mythbusters found this out the hard way when they tried to lift a 3
year old with a large number of helium balloons.
http://www.discovery.com/tv-shows/mythbusters/videos/balloon-girl-minimyth/
They needed over double the number of balloons needed to lift the kid
mostly because they used party balloon gas instead of the pure stuff.
That also explains the price difference.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On 4/19/2015 2:17 PM, Jeff Liebermann wrote:
On 19 Apr 2015 10:45:10 GMT, Rob wrote:

But do you want a radio controlled gadget with 4 electric motors at
the top end of your vertical?

A drone would work, but does not have enough battery capacity to be
able to keep the antenna in place for more than about 10-20 mins.
Longer would require seperate power wires, which would interfere with
the radiation pattern.

Weight might be a problem. I'll guess(tm) #16 AWG wire, which weighs
7.82 lbs/1000ft or 11.6 gm/meter. 1/4 wave at 160 meters is 40 meters
so that antenna would weigh:
11.6 gm/meter * 40 = 464 gm
Hmmm... Probably too heavy. By comparison, a GoPro camera body weighs
100 gm. Ok, smaller guage wire or bigger quadcopter.

Did you read the OP? He discusses all of the above and suggests a way
to work around.

--

Rick

On 4/23/2015 10:38 PM, Jeff Liebermann wrote:
On Thu, 23 Apr 2015 19:25:21 -0700, Jeff Liebermann
wrote:

On Thu, 23 Apr 2015 18:32:56 -0700, Jeff Liebermann
wrote:

Helium previously costs about $8/liter but is now running about
$20/liter thanks to the helium shortage. That's $14,600 for 730
liters. Are you sure you want to do this?

Hmmm... that can't be right. The problem is that I'm getting prices
for helium that are all over the map. For example:
http://www.reuters.com/article/2013/09/19/us-helium-shortage-analysis-idUSBRE98I0AN20130919
"... spot price of liquid helium has jumped to $25-$30 per
liter from $8 last year."

http://www.crainsnewyork.com/article/20140126/FINANCE/301269974/helium-shortage-deflates-party-city
"prices have doubled since 2006, to $6.13 per-cubic meter,
according to the latest figures from the U.S. Geological Survey."
1 cubic-meter = 1000 liters, so that is $0.00613/liter which seems
rather low.

http://minerals.usgs.gov/minerals/pubs/commodity/helium/mcs-2014-heliu.pdf
"The estimated price range for private industry’s Grade-A gaseous
helium was about $7.21 per cubic meter ($200 per thousand cubic
feet), with some producers posting surcharges to this price.
1 cubic-meter = 1000 liters, so that is $0.00721/liter, which agrees
with the previous article, mostly because the price came from the same
source.

Ok, let's try party helium:
http://www.sfparty.com/products.php?product=Helium%3A-Balloon-Time-Disposable-Helium-Tank-Purchase
$55 for 14.9 cubic-ft.
14.9 ft^3 = 422 liters
$55 / 422 liters = $0.13/liter

Does anyone have the real price of helium?

Never mind. I see the problem. There's a big difference between
medical grade helium used to cool MRI machines, and the helium sold at
party stores for filling balloons.
http://www.bbc.com/news/uk-19676639
The party store helium is recycled from the MRI gas and is mixed (i.e.
diluted) with air.
"The helium we use is not pure," he said. "It's recycled from the
gas which is used in the medical industry, and mixed with air.
We call it balloon gas rather than helium for that reason."
Mythbusters found this out the hard way when they tried to lift a 3
year old with a large number of helium balloons.
http://www.discovery.com/tv-shows/mythbusters/videos/balloon-girl-minimyth/
They needed over double the number of balloons needed to lift the kid
mostly because they used party balloon gas instead of the pure stuff.
That also explains the price difference.

You are also confusing gaseous helium and liquid helium. Not much in
common.

--

Rick

On 2015-04-23, Oregonian Haruspex wrote:
On 2015-04-18 08:38:31 +0000, gareth said:

How about a tethered helium balloon instead? This way you don't have
to worry about powering the thing. Bell wire will handle 100 watts all
day without turning into smoke.

This sounds like a neat experiment, which one of our members tried on field
day. There are several problems in the electrical side of things, but more
importantly on the physical side. As you rise in altitude the wind speed
will increase, generally speaking, and perhaps change directions. If the day
is completely calm especialy above the tree line, say 100-200ft, then the
balloon will remain straight up. But launching a balloon in a 10mph wind,
which becomes 15-20mph above the tree line, leads to interesting
developments with the tether wire/cord definitely sloping and perhaps being
pushed into surrounding objects such as trees, power lines (eh gads!) which
can cause it to break or other things. So you need plenty of space with few
impediments for the balloon to catch on as it ascends. You certainly can't
predict a perfectly calm day, so this can be an unpredictable venture. ha

73 ...Edwin, KD5ZLB
__________________________________________________ __________
"Once you have flown, you will walk the earth with your eyes
turned skyward, for there you have been, there you long to
return."-da Vinci http://www.kd5zlb.org

In message , Edwin Johnson
writes
On 2015-04-23, Oregonian Haruspex wrote:
On 2015-04-18 08:38:31 +0000, gareth said:

How about a tethered helium balloon instead? This way you don't have
to worry about powering the thing. Bell wire will handle 100 watts all
day without turning into smoke.

This sounds like a neat experiment, which one of our members tried on field
day. There are several problems in the electrical side of things, but more
importantly on the physical side. As you rise in altitude the wind speed
will increase, generally speaking, and perhaps change directions. If the day
is completely calm especialy above the tree line, say 100-200ft, then the
balloon will remain straight up. But launching a balloon in a 10mph wind,
which becomes 15-20mph above the tree line, leads to interesting
developments with the tether wire/cord definitely sloping and perhaps being
pushed into surrounding objects such as trees, power lines (eh gads!) which
can cause it to break or other things. So you need plenty of space with few
impediments for the balloon to catch on as it ascends. You certainly can't
predict a perfectly calm day, so this can be an unpredictable venture. ha

See
http://www.allsopp.co.uk/
etc.
--
Ian

On Fri, 24 Apr 2015 08:11:20 -0400, rickman wrote:

Did you read the OP? He discusses all of the above and suggests a way
to work around.

Yep. He talked about using 1kV at 10KHz to somehow control the drone.
That's rather impractical, so I supplied what I thought might be more
practical methods and some numbers as a sanity check.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Sun, 19 Apr 2015, wrote:

Jeff wrote:
On 18/04/2015 17:58, wrote:
gareth wrote:
This current interest (and privacy furore) about drones set me thinking,
what an interesting way to elevate a TopBand vertical, but being a temporary
structure, not breaching any planning permission (Brit) or zonal (Yank)
restrictions.

However the height of a 1/4 vertical would be such that it may fall
under the regulations of the CAA (UK) and the FAA (US) depending on
the location.



Under 60m (~200') does not require any permission in the UK.

Jeff

I didn't say anything about "permission", I said regulations, and you
may want to check the fine print, e.g. the FAA has language about 200
feet AGL within 3 nautical miles of an airport, which is why I said
"depending on the location".

And if one is thinking about a balloon or kite antenna, the FAA also
has language about within 5 miles of an airport and visibily of less
than 3 miles.

I vaguely recall reading about rules for antenna height near airports.

Michael

I am sure the CAA has similar fine print.



--
Jim Pennino